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Description of surgical procedure
Setting
Inpatient surgery is performed in a hospital, and the person undergoing surgery stays at least one night in the hospital after the surgery. Outpatient surgery occurs in a hospital outpatient department or freestanding ambulatory surgery center, and the person who had surgery is discharged the same working day. Office-based surgery occurs in a physician's office, and the person is discharged the same day.
At a hospital, modern surgery is often performed in an operating theater using surgical instruments, an operating table, and other equipment. Among United States hospitalizations for non-maternal and non-neonatal conditions in 2012, more than one-fourth of stays and half of hospital costs involved stays that included operating room (OR) procedures. The environment and procedures used in surgery are governed by the principles of aseptic technique: the strict separation of "sterile" (free of microorganisms) things from "unsterile" or "contaminated" things. All surgical instruments must be sterilized, and an instrument must be replaced or re-sterilized if it becomes contaminated (i.e. handled in an unsterile manner, or allowed to touch an unsterile surface). Operating room staff must wear sterile attire (scrubs, a scrub cap, a sterile surgical gown, sterile latex or non-latex polymer gloves and a surgical mask), and they must scrub hands and arms with an approved disinfectant agent before each procedure.
Preoperative care
Prior to surgery, the person is given a medical examination, receives certain pre-operative tests, and their physical status is rated according to the ASA physical status classification system. If these results are satisfactory, the person requiring surgery signs a consent form and is given a surgical clearance. If the procedure is expected to result in significant blood loss, an autologous blood donation may be made some weeks prior to surgery. If the surgery involves the digestive system, the person requiring surgery may be instructed to perform a bowel prep by drinking a solution of polyethylene glycol the night before the procedure. People preparing for surgery are also instructed to abstain from food or drink (an NPO order after midnight on the night before the procedure), to minimize the effect of stomach contents on pre-operative medications and reduce the risk of aspiration if the person vomits during or after the procedure. | Surgery | Wikipedia | 485 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Some medical systems have a practice of routinely performing chest x-rays before surgery. The premise behind this practice is that the physician might discover some unknown medical condition which would complicate the surgery, and that upon discovering this with the chest x-ray, the physician would adapt the surgery practice accordingly. However, medical specialty professional organizations recommend against routine pre-operative chest x-rays for people who have an unremarkable medical history and presented with a physical exam which did not indicate a chest x-ray. Routine x-ray examination is more likely to result in problems like misdiagnosis, overtreatment, or other negative outcomes than it is to result in a benefit to the person. Likewise, other tests including complete blood count, prothrombin time, partial thromboplastin time, basic metabolic panel, and urinalysis should not be done unless the results of these tests can help evaluate surgical risk.
Preparing for surgery
A surgical team may include a surgeon, anesthetist, a circulating nurse, and a "scrub tech", or surgical technician, as well as other assistants who provide equipment and supplies as required. While informed consent discussions may be performed in a clinic or acute care setting, the pre-operative holding area is where documentation is reviewed and where family members can also meet the surgical team. Nurses in the preoperative holding area confirm orders and answer additional questions of the family members of the patient prior to surgery. In the pre-operative holding area, the person preparing for surgery changes out of their street clothes and are asked to confirm the details of his or her surgery as previously discussed during the process of informed consent. A set of vital signs are recorded, a peripheral IV line is placed, and pre-operative medications (antibiotics, sedatives, etc.) are given. | Surgery | Wikipedia | 371 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
When the patient enters the operating room and is appropriately anesthetized, the team will then position the patient in an appropriate surgical position. If hair is present at the surgical site, it is clipped (instead of shaving). The skin surface within the operating field is cleansed and prepared by applying an antiseptic (typically chlorhexidine gluconate in alcohol, as this is twice as effective as povidone-iodine at reducing the risk of infection). Sterile drapes are then used to cover the borders of the operating field. Depending on the type of procedure, the cephalad drapes are secured to a pair of poles near the head of the bed to form an "ether screen", which separate the anesthetist/anesthesiologist's working area (unsterile) from the surgical site (sterile).
Anesthesia is administered to prevent pain from the trauma of cutting, tissue manipulation, application of thermal energy, and suturing. Depending on the type of operation, anesthesia may be provided locally, regionally, or as general anesthesia. Spinal anesthesia may be used when the surgical site is too large or deep for a local block, but general anesthesia may not be desirable. With local and spinal anesthesia, the surgical site is anesthetized, but the person can remain conscious or minimally sedated. In contrast, general anesthesia may render the person unconscious and paralyzed during surgery. The person is typically intubated to protect their airway and placed on a mechanical ventilator, and anesthesia is produced by a combination of injected and inhaled agents. The choice of surgical method and anesthetic technique aims to solve the indicated problem, minimize the risk of complications, optimize the time needed for recovery, and limit the surgical stress response.
Intraoperative phase
The intraoperative phase begins when the surgery subject is received in the surgical area (such as the operating theater or surgical department), and lasts until the subject is transferred to a recovery area (such as a post-anesthesia care unit). | Surgery | Wikipedia | 429 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
An incision is made to access the surgical site. Blood vessels may be clamped or cauterized to prevent bleeding, and retractors may be used to expose the site or keep the incision open. The approach to the surgical site may involve several layers of incision and dissection, as in abdominal surgery, where the incision must traverse skin, subcutaneous tissue, three layers of muscle and then the peritoneum. In certain cases, bone may be cut to further access the interior of the body; for example, cutting the skull for brain surgery or cutting the sternum for thoracic (chest) surgery to open up the rib cage. Whilst in surgery aseptic technique is used to prevent infection or further spreading of the disease. The surgeons' and assistants' hands, wrists and forearms are washed thoroughly for at least 4 minutes to prevent germs getting into the operative field, then sterile gloves are placed onto their hands. An antiseptic solution is applied to the area of the person's body that will be operated on. Sterile drapes are placed around the operative site. Surgical masks are worn by the surgical team to avoid germs on droplets of liquid from their mouths and noses from contaminating the operative site.
Work to correct the problem in body then proceeds. This work may involve: | Surgery | Wikipedia | 271 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
excision – cutting out an organ, tumor, or other tissue.
resection – partial removal of an organ or other bodily structure.
reconnection of organs, tissues, etc., particularly if severed. Resection of organs such as intestines involves reconnection. Internal suturing or stapling may be used. Surgical connection between blood vessels or other tubular or hollow structures such as loops of intestine is called anastomosis.
reduction – the movement or realignment of a body part to its normal position. e.g. Reduction of a broken nose involves the physical manipulation of the bone or cartilage from their displaced state back to their original position to restore normal airflow and aesthetics.
ligation – tying off blood vessels, ducts, or "tubes".
grafts – may be severed pieces of tissue cut from the same (or different) body or flaps of tissue still partly connected to the body but resewn for rearranging or restructuring of the area of the body in question. Although grafting is often used in cosmetic surgery, it is also used in other surgery. Grafts may be taken from one area of the person's body and inserted to another area of the body. An example is bypass surgery, where clogged blood vessels are bypassed with a graft from another part of the body. Alternatively, grafts may be from other persons, cadavers, or animals.
insertion of prosthetic parts when needed. Pins or screws to set and hold bones may be used. Sections of bone may be replaced with prosthetic rods or other parts. Sometimes a plate is inserted to replace a damaged area of skull. Artificial hip replacement has become more common. Heart pacemakers or valves may be inserted. Many other types of prostheses are used.
creation of a stoma, a permanent or semi-permanent opening in the body
in transplant surgery, the donor organ (taken out of the donor's body) is inserted into the recipient's body and reconnected to the recipient in all necessary ways (blood vessels, ducts, etc.).
arthrodesis – surgical connection of adjacent bones so the bones can grow together into one. Spinal fusion is an example of adjacent vertebrae connected allowing them to grow together into one piece.
modifying the digestive tract in bariatric surgery for weight loss.
repair of a fistula, hernia, or prolapse. | Surgery | Wikipedia | 497 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
repair according to the ICD-10-PCS, in the Medical and Surgical Section 0, root operation Q, means restoring, to the extent possible, a body part to its normal anatomic structure and function. This definition, repair, is used only when the method used to accomplish the repair is not one of the other root operations. Examples would be colostomy takedown, herniorrhaphy of a hernia, and the surgical suture of a laceration.
other procedures, including:
clearing clogged ducts, blood or other vessels
removal of calculi (stones)
draining of accumulated fluids
debridement – removal of dead, damaged, or diseased tissue
Blood or blood expanders may be administered to compensate for blood lost during surgery. Once the procedure is complete, sutures or staples are used to close the incision. Once the incision is closed, the anesthetic agents are stopped or reversed, and the person is taken off ventilation and extubated (if general anesthesia was administered). | Surgery | Wikipedia | 212 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Postoperative care
After completion of surgery, the person is transferred to the post anesthesia care unit and closely monitored. When the person is judged to have recovered from the anesthesia, he/she is either transferred to a surgical ward elsewhere in the hospital or discharged home. During the post-operative period, the person's general function is assessed, the outcome of the procedure is assessed, and the surgical site is checked for signs of infection. There are several risk factors associated with postoperative complications, such as immune deficiency and obesity. Obesity has long been considered a risk factor for adverse post-surgical outcomes. It has been linked to many disorders such as obesity hypoventilation syndrome, atelectasis and pulmonary embolism, adverse cardiovascular effects, and wound healing complications. If removable skin closures are used, they are removed after 7 to 10 days post-operatively, or after healing of the incision is well under way.
It is not uncommon for surgical drains to be required to remove blood or fluid from the surgical wound during recovery. Mostly these drains stay in until the volume tapers off, then they are removed. These drains can become clogged, leading to abscess.
Postoperative therapy may include adjuvant treatment such as chemotherapy, radiation therapy, or administration of medication such as anti-rejection medication for transplants. For postoperative nausea and vomiting (PONV), solutions like saline, water, controlled breathing placebo and aromatherapy can be used in addition to medication. Other follow-up studies or rehabilitation may be prescribed during and after the recovery period. A recent post-operative care philosophy has been early ambulation. Ambulation is getting the patient moving around. This can be as simple as sitting up or even walking around. The goal is to get the patient moving as early as possible. It has been found to shorten the patient's length of stay. Length of stay is the amount of time a patient spends in the hospital after surgery before they are discharged. In a recent study done with lumbar decompressions, the patient's length of stay was decreased by 1–3 days. | Surgery | Wikipedia | 444 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
The use of topical antibiotics on surgical wounds to reduce infection rates has been questioned. Antibiotic ointments are likely to irritate the skin, slow healing, and could increase risk of developing contact dermatitis and antibiotic resistance. It has also been suggested that topical antibiotics should only be used when a person shows signs of infection and not as a preventative. A systematic review published by Cochrane (organisation) in 2016, though, concluded that topical antibiotics applied over certain types of surgical wounds reduce the risk of surgical site infections, when compared to no treatment or use of antiseptics. The review also did not find conclusive evidence to suggest that topical antibiotics increased the risk of local skin reactions or antibiotic resistance.
Through a retrospective analysis of national administrative data, the association between mortality and day of elective surgical procedure suggests a higher risk in procedures carried out later in the working week and on weekends. The odds of death were 44% and 82% higher respectively when comparing procedures on a Friday to a weekend procedure. This "weekday effect" has been postulated to be from several factors including poorer availability of services on a weekend, and also, decrease number and level of experience over a weekend.
Postoperative pain affects an estimated 80% of people who underwent surgery. While pain is expected after surgery, there is growing evidence that pain may be inadequately treated in many people in the acute period immediately after surgery. It has been reported that incidence of inadequately controlled pain after surgery ranged from 25.1% to 78.4% across all surgical disciplines. There is insufficient evidence to determine if giving opioid pain medication pre-emptively (before surgery) reduces postoperative pain the amount of medication needed after surgery.
Postoperative recovery has been defined as an energy‐requiring process to decrease physical symptoms, reach a level of emotional well‐being, regain functions, and re‐establish activities. Moreover, it has been identified that patients who have undergone surgery are often not fully recovered on discharge.
Epidemiology
United States
In 2011, of the 38.6 million hospital stays in U.S. hospitals, 29% included at least one operating room procedure. These stays accounted for 48% of the total $387 billion in hospital costs.
The overall number of procedures remained stable from 2001 to 2011. In 2011, over 15 million operating room procedures were performed in U.S. hospitals. | Surgery | Wikipedia | 487 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Data from 2003 to 2011 showed that U.S. hospital costs were highest for the surgical service line; the surgical service line costs were $17,600 in 2003 and projected to be $22,500 in 2013. For hospital stays in 2012 in the United States, private insurance had the highest percentage of surgical expenditure. in 2012, mean hospital costs in the United States were highest for surgical stays.
Special populations
Elderly people
Older adults have widely varying physical health. Frail elderly people are at significant risk of post-surgical complications and the need for extended care. Assessment of older people before elective surgery can accurately predict the person's recovery trajectories. One frailty scale uses five items: unintentional weight loss, muscle weakness, exhaustion, low physical activity, and slowed walking speed. A healthy person scores 0; a very frail person scores 5. Compared to non-frail elderly people, people with intermediate frailty scores (2 or 3) are twice as likely to have post-surgical complications, spend 50% more time in the hospital, and are three times as likely to be discharged to a skilled nursing facility instead of to their own homes. People who are frail and elderly (score of 4 or 5) have even worse outcomes, with the risk of being discharged to a nursing home rising to twenty times the rate for non-frail elderly people.
Children
Surgery on children requires considerations that are not common in adult surgery. Children and adolescents are still developing physically and mentally making it difficult for them to make informed decisions and give consent for surgical treatments. Bariatric surgery in youth is among the controversial topics related to surgery in children.
Vulnerable populations
Doctors perform surgery with the consent of the person undergoing surgery. Some people are able to give better informed consent than others. Populations such as incarcerated persons, people living with dementia, the mentally incompetent, persons subject to coercion, and other people who are not able to make decisions with the same authority as others, have special needs when making decisions about their personal healthcare, including surgery. | Surgery | Wikipedia | 413 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Global surgery
Global surgery has been defined as 'the multidisciplinary enterprise of providing improved and equitable surgical care to the world's population, with its core belief as the issues of need, access and quality". Halfdan T. Mahler, the 3rd Director-General of the World Health Organization (WHO), first brought attention to the disparities in surgery and surgical care in 1980 when he stated in his address to the World Congress of the International College of Surgeons, "'the vast majority of the world's population has no access whatsoever to skilled surgical care and little is being done to find a solution.As such, surgical care globally has been described as the 'neglected stepchild of global health,' a term coined by Paul Farmer to highlight the urgent need for further work in this area. Furthermore, Jim Young Kim, the former President of the World Bank, proclaimed in 2014 that "surgery is an indivisible, indispensable part of health care and of progress towards universal health coverage."
In 2015, the Lancet Commission on Global Surgery (LCoGS) published the landmark report titled "Global Surgery 2030: evidence and solutions for achieving health, welfare, and economic development", describing the large, pre-existing burden of surgical diseases in low- and middle-income countries (LMICs) and future directions for increasing universal access to safe surgery by the year 2030. The Commission highlighted that about 5 billion people lack access to safe and affordable surgical and anesthesia care and 143 million additional procedures were needed every year to prevent further morbidity and mortality from treatable surgical conditions as well as a $12.3 trillion loss in economic productivity by the year 2030. This was especially true in the poorest countries, which account for over one-third of the population but only 3.5% of all surgeries that occur worldwide. It emphasized the need to significantly improve the capacity for Bellwether procedures – laparotomy, caesarean section, open fracture care – which are considered a minimum level of care that first-level hospitals should be able to provide in order to capture the most basic emergency surgical care. In terms of the financial impact on the patients, the lack of adequate surgical and anesthesia care has resulted in 33 million individuals every year facing catastrophic health expenditure – the out-of-pocket healthcare cost exceeding 40% of a given household's income. | Surgery | Wikipedia | 491 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
In alignment with the LCoGS call for action, the World Health Assembly adopted the resolution WHA68.15 in 2015 that stated, "Strengthening emergency and essential surgical care and anesthesia as a component of universal health coverage." This not only mandated the WHO to prioritize strengthening the surgical and anesthesia care globally, but also led to governments of the member states recognizing the urgent need for increasing capacity in surgery and anesthesia. Additionally, the third edition of Disease Control Priorities (DCP3), published in 2015 by the World Bank, declared surgery as essential and featured an entire volume dedicated to building surgical capacity.
Data from WHO and the World Bank indicate that scaling up infrastructure to enable access to surgical care in regions where it is currently limited or is non-existent is a low-cost measure relative to the significant morbidity and mortality caused by lack of surgical treatment. In fact, a systematic review found that the cost-effectiveness ratio – dollars spent per DALYs averted – for surgical interventions is on par or exceeds those of major public health interventions such as oral rehydration therapy, breastfeeding promotion, and even HIV/AIDS antiretroviral therapy. This finding challenged the common misconception that surgical care is financially prohibitive endeavor not worth pursuing in LMICs.
A key policy framework that arose from this renewed global commitment towards surgical care worldwide is the National Surgical Obstetric and Anesthesia Plan (NSOAP). NSOAP focuses on policy-to-action capacity building for surgical care with tangible steps as follows: (1) analysis of baseline indicators, (2) partnership with local champions, (3) broad stakeholder engagement, (4) consensus building and synthesis of ideas, (5) language refinement, (6) costing, (7) dissemination, and (8) implementation. This approach has been widely adopted and has served as guiding principles between international collaborators and local institutions and governments. Successful implementations have allowed for sustainability in terms of longterm monitoring, quality improvement, and continued political and financial support.
Human rights | Surgery | Wikipedia | 422 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Access to surgical care is increasingly recognized as an integral aspect of healthcare and therefore is evolving into a normative derivation of human right to health. The ICESCR Article 12.1 and 12.2 define the human right to health as "the right of everyone to the enjoyment of the highest attainable standard of physical and mental health" In the August 2000, the UN Committee on Economic, Social and Cultural Rights (CESCR) interpreted this to mean "right to the enjoyment of a variety of facilities, goods, services, and conditions necessary for the realization of the highest attainable health". Surgical care can be thereby viewed as a positive right – an entitlement to protective healthcare.
Woven through the International Human and Health Rights literature is the right to be free from surgical disease. The 1966 ICESCR Article 12.2a described the need for "provision for the reduction of the stillbirth-rate and of infant mortality and for the healthy development of the child" which was subsequently interpreted to mean "requiring measures to improve… emergency obstetric services". Article 12.2d of the ICESCR stipulates the need for "the creation of conditions which would assure to all medical service and medical attention in the event of sickness", and is interpreted in the 2000 comment to include timely access to "basic preventative, curative services… for appropriate treatment of injury and disability.". Obstetric care shares close ties with reproductive rights, which includes access to reproductive health.
Surgeons and public health advocates, such as Kelly McQueen, have described surgery as "Integral to the right to health". This is reflected in the establishment of the WHO Global Initiative for Emergency and Essential Surgical Care in 2005, the 2013 formation of the Lancet Commission for Global Surgery, the 2015 World Bank Publication of Volume 1 of its Disease Control Priorities Project "Essential Surgery", and the 2015 World Health Assembly 68.15 passing of the Resolution for Strengthening Emergency and Essential Surgical Care and Anesthesia as a Component of Universal Health Coverage. The Lancet Commission for Global Surgery outlined the need for access to "available, affordable, timely and safe" surgical and anesthesia care; dimensions paralleled in ICESCR General Comment No. 14, which similarly outlines need for available, accessible, affordable and timely healthcare.
History | Surgery | Wikipedia | 463 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Trepanation
Surgical treatments date back to the prehistoric era. The oldest for which there is evidence is trepanation, in which a hole is drilled or scraped into the skull, thus exposing the dura mater in order to treat health problems related to intracranial pressure.
Ancient Egypt
Prehistoric surgical techniques are seen in Ancient Egypt, where a mandible dated to approximately 2650 BC shows two perforations just below the root of the first molar, indicating the draining of an abscessed tooth. Surgical texts from ancient Egypt date back about 3500 years ago. Surgical operations were performed by priests, specialized in medical treatments similar to today, and used sutures to close wounds. Infections were treated with honey.
India
9,000-year-old skeletal remains of a prehistoric individual from the Indus River valley show evidence of teeth having been drilled. Sushruta Samhita is one of the oldest known surgical texts and its period is usually placed in the first millennium BCE. It describes in detail the examination, diagnosis, treatment, and prognosis of numerous ailments, as well as procedures for various forms of cosmetic surgery, plastic surgery and rhinoplasty.
Sri Lanka
In 1982 archaeologists were able to find significant evidence when the ancient land, called 'Alahana Pirivena' situated in Polonnaruwa, with ruins, was excavated. In that place ruins of an ancient hospital emerged. The hospital building was 147.5 feet in width and 109.2 feet in length. The instruments which were used for complex surgeries were there among the things discovered from the place, including forceps, scissors, probes, lancets, and scalpels. The instruments discovered may be dated to 11th century AD.
Ancient and Medieval Greece | Surgery | Wikipedia | 353 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
In ancient Greece, temples dedicated to the healer-god Asclepius, known as Asclepieia (, sing. Asclepieion Ασκληπιείον), functioned as centers of medical advice, prognosis, and healing. In the Asclepieion of Epidaurus, some of the surgical cures listed, such as the opening of an abdominal abscess or the removal of traumatic foreign material, are realistic enough to have taken place. The Greek Galen was one of the greatest surgeons of the ancient world and performed many audacious operations – including brain and eye surgery – that were not tried again for almost two millennia. Hippocrates stated in the oath () "I will not use the knife, even upon those suffering from stones, but I will leave this to those who are trained in this craft."
Researchers from the Adelphi University discovered in the Paliokastro on Thasos ten skeletal remains, four women and six men, who were buried between the fourth and seventh centuries A.D. Their bones illuminated their physical activities, traumas, and even a complex form of brain surgery. According to the researchers: "The very serious trauma cases sustained by both males and females had been treated surgically or orthopedically by a very experienced physician/surgeon with great training in trauma care. We believe it to have been a military physician". The researchers were impressed by the complexity of the brain surgical operation.
In 1991 at the Polystylon fort in Greece, researchers discovered the head of a Byzantine warrior of the 14th century. Analysis of the lower jaw revealed that a surgery has been performed, when the warrior was alive, to the jaw which had been badly fractured and it tied back together until it healed. | Surgery | Wikipedia | 363 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Islamic world
During the Islamic Golden Age, largely based upon Paul of Aegina's Pragmateia, the writings of Albucasis (Abu al-Qasim Khalaf ibn al-Abbas Al-Zahrawi), an Andalusian-Arab physician and scientist who practiced in the Zahra suburb of Córdoba, were influential. Al-Zahrawi specialized in curing disease by cauterization. He invented several surgical instruments for purposes such as inspection of the interior of the urethra and for removing foreign bodies from the throat, the ear, and other body organs. He was also the first to illustrate the various cannulae and to treat warts with an iron tube and caustic metal as a boring instrument. He describes what is thought to be the first attempt at reduction mammaplasty for the management of gynaecomastia and the first mastectomy to treat breast cancer. He is credited with the performance of the first thyroidectomy. Al-Zahrawi pioneered techniques of neurosurgery and neurological diagnosis, treating head injuries, skull fractures, spinal injuries, hydrocephalus, subdural effusions and headache. The first clinical description of an operative procedure for hydrocephalus was given by Al-Zahrawi, who clearly describes the evacuation of superficial intracranial fluid in hydrocephalic children.
Early modern Europe
In Europe, the demand grew for surgeons to formally study for many years before practicing; universities such as Montpellier, Padua and Bologna were particularly renowned. In the 12th century, Rogerius Salernitanus composed his Chirurgia, laying the foundation for modern Western surgical manuals. Barber-surgeons generally had a bad reputation that was not to improve until the development of academic surgery as a specialty of medicine, rather than an accessory field. Basic surgical principles for asepsis etc., are known as Halsteads principles.
There were some important advances to the art of surgery during this period. The professor of anatomy at the University of Padua, Andreas Vesalius, was a pivotal figure in the Renaissance transition from classical medicine and anatomy based on the works of Galen, to an empirical approach of 'hands-on' dissection. In his anatomic treaties De humani corporis fabrica, he exposed the many anatomical errors in Galen and advocated that all surgeons should train by engaging in practical dissections themselves. | Surgery | Wikipedia | 497 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
The second figure of importance in this era was Ambroise Paré (sometimes spelled "Ambrose"), a French army surgeon from the 1530s until his death in 1590. The practice for cauterizing gunshot wounds on the battlefield had been to use boiling oil; an extremely dangerous and painful procedure. Paré began to employ a less irritating emollient, made of egg yolk, rose oil and turpentine. He also described more efficient techniques for the effective ligation of the blood vessels during an amputation.
Modern surgery
The discipline of surgery was put on a sound, scientific footing during the Age of Enlightenment in Europe. An important figure in this regard was the Scottish surgical scientist, John Hunter, generally regarded as the father of modern scientific surgery. He brought an empirical and experimental approach to the science and was renowned around Europe for the quality of his research and his written works. Hunter reconstructed surgical knowledge from scratch; refusing to rely on the testimonies of others, he conducted his own surgical experiments to determine the truth of the matter. To aid comparative analysis, he built up a collection of over 13,000 specimens of separate organ systems, from the simplest plants and animals to humans.
He greatly advanced knowledge of venereal disease and introduced many new techniques of surgery, including new methods for repairing damage to the Achilles tendon and a more effective method for applying ligature of the arteries in case of an aneurysm. He was also one of the first to understand the importance of pathology, the danger of the spread of infection and how the problem of inflammation of the wound, bone lesions and even tuberculosis often undid any benefit that was gained from the intervention. He consequently adopted the position that all surgical procedures should be used only as a last resort.
Other important 18th- and early 19th-century surgeons included Percival Pott (1713–1788) who described tuberculosis on the spine and first demonstrated that a cancer may be caused by an environmental carcinogen (he noticed a connection between chimney sweep's exposure to soot and their high incidence of scrotal cancer). Astley Paston Cooper (1768–1841) first performed a successful ligation of the abdominal aorta, and James Syme (1799–1870) pioneered the Symes Amputation for the ankle joint and successfully carried out the first hip disarticulation. | Surgery | Wikipedia | 476 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Modern pain control through anesthesia was discovered in the mid-19th century. Before the advent of anesthesia, surgery was a traumatically painful procedure and surgeons were encouraged to be as swift as possible to minimize patient suffering. This also meant that operations were largely restricted to amputations and external growth removals. Beginning in the 1840s, surgery began to change dramatically in character with the discovery of effective and practical anaesthetic chemicals such as ether, first used by the American surgeon Crawford Long, and chloroform, discovered by Scottish obstetrician James Young Simpson and later pioneered by John Snow, physician to Queen Victoria. In addition to relieving patient suffering, anaesthesia allowed more intricate operations in the internal regions of the human body. In addition, the discovery of muscle relaxants such as curare allowed for safer applications.
Infection and antisepsis
The introduction of anesthetics encouraged more surgery, which inadvertently caused more dangerous patient post-operative infections. The concept of infection was unknown until relatively modern times. The first progress in combating infection was made in 1847 by the Hungarian doctor Ignaz Semmelweis who noticed that medical students fresh from the dissecting room were causing excess maternal death compared to midwives. Semmelweis, despite ridicule and opposition, introduced compulsory handwashing for everyone entering the maternal wards and was rewarded with a plunge in maternal and fetal deaths; however, the Royal Society dismissed his advice. | Surgery | Wikipedia | 295 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Until the pioneering work of British surgeon Joseph Lister in the 1860s, most medical men believed that chemical damage from exposures to bad air (see "miasma") was responsible for infections in wounds, and facilities for washing hands or a patient's wounds were not available. Lister became aware of the work of French chemist Louis Pasteur, who showed that rotting and fermentation could occur under anaerobic conditions if micro-organisms were present. Pasteur suggested three methods to eliminate the micro-organisms responsible for gangrene: filtration, exposure to heat, or exposure to chemical solutions. Lister confirmed Pasteur's conclusions with his own experiments and decided to use his findings to develop antiseptic techniques for wounds. As the first two methods suggested by Pasteur were inappropriate for the treatment of human tissue, Lister experimented with the third, spraying carbolic acid on his instruments. He found that this remarkably reduced the incidence of gangrene and he published his results in The Lancet. Later, on 9 August 1867, he read a paper before the British Medical Association in Dublin, on the Antiseptic Principle of the Practice of Surgery, which was reprinted in the British Medical Journal. His work was groundbreaking and laid the foundations for a rapid advance in infection control that saw modern antiseptic operating theatres widely used within 50 years.
Lister continued to develop improved methods of antisepsis and asepsis when he realised that infection could be better avoided by preventing bacteria from getting into wounds in the first place. This led to the rise of sterile surgery. Lister introduced the Steam Steriliser to sterilize equipment, instituted rigorous hand washing and later implemented the wearing of rubber gloves. These three crucial advances – the adoption of a scientific methodology toward surgical operations, the use of anaesthetic and the introduction of sterilised equipment – laid the groundwork for the modern invasive surgical techniques of today.
The use of X-rays as an important medical diagnostic tool began with their discovery in 1895 by German physicist Wilhelm Röntgen. He noticed that these rays could penetrate the skin, allowing the skeletal structure to be captured on a specially treated photographic plate.
Surgical specialties
General surgery | Surgery | Wikipedia | 438 | 45599 | https://en.wikipedia.org/wiki/Surgery | Biology and health sciences | Health, fitness, and medicine | null |
Breast
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In information theory and coding theory, Reed–Solomon codes are a group of error-correcting codes that were introduced by Irving S. Reed and Gustave Solomon in 1960.
They have many applications, including consumer technologies such as MiniDiscs, CDs, DVDs, Blu-ray discs, QR codes, Data Matrix, data transmission technologies such as DSL and WiMAX, broadcast systems such as satellite communications, DVB and ATSC, and storage systems such as RAID 6.
Reed–Solomon codes operate on a block of data treated as a set of finite-field elements called symbols. Reed–Solomon codes are able to detect and correct multiple symbol errors. By adding = − check symbols to the data, a Reed–Solomon code can detect (but not correct) any combination of up to erroneous symbols, or locate and correct up to erroneous symbols at unknown locations. As an erasure code, it can correct up to erasures at locations that are known and provided to the algorithm, or it can detect and correct combinations of errors and erasures. Reed–Solomon codes are also suitable as multiple-burst bit-error correcting codes, since a sequence of consecutive bit errors can affect at most two symbols of size . The choice of is up to the designer of the code and may be selected within wide limits.
There are two basic types of Reed–Solomon codes original view and BCH view with BCH view being the most common, as BCH view decoders are faster and require less working storage than original view decoders. | Reed–Solomon error correction | Wikipedia | 312 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
History
Reed–Solomon codes were developed in 1960 by Irving S. Reed and Gustave Solomon, who were then staff members of MIT Lincoln Laboratory. Their seminal article was titled "Polynomial Codes over Certain Finite Fields" . The original encoding scheme described in the Reed and Solomon article used a variable polynomial based on the message to be encoded where only a fixed set of values (evaluation points) to be encoded are known to encoder and decoder. The original theoretical decoder generated potential polynomials based on subsets of k (unencoded message length) out of n (encoded message length) values of a received message, choosing the most popular polynomial as the correct one, which was impractical for all but the simplest of cases. This was initially resolved by changing the original scheme to a BCH-code-like scheme based on a fixed polynomial known to both encoder and decoder, but later, practical decoders based on the original scheme were developed, although slower than the BCH schemes. The result of this is that there are two main types of Reed–Solomon codes: ones that use the original encoding scheme and ones that use the BCH encoding scheme.
Also in 1960, a practical fixed polynomial decoder for BCH codes developed by Daniel Gorenstein and Neal Zierler was described in an MIT Lincoln Laboratory report by Zierler in January 1960 and later in an article in June 1961. The Gorenstein–Zierler decoder and the related work on BCH codes are described in a book "Error-Correcting Codes" by W. Wesley Peterson (1961). By 1963 (or possibly earlier), J. J. Stone (and others) recognized that Reed–Solomon codes could use the BCH scheme of using a fixed generator polynomial, making such codes a special class of BCH codes, but Reed–Solomon codes based on the original encoding scheme are not a class of BCH codes, and depending on the set of evaluation points, they are not even cyclic codes.
In 1969, an improved BCH scheme decoder was developed by Elwyn Berlekamp and James Massey and has since been known as the Berlekamp–Massey decoding algorithm.
In 1975, another improved BCH scheme decoder was developed by Yasuo Sugiyama, based on the extended Euclidean algorithm. | Reed–Solomon error correction | Wikipedia | 470 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
In 1977, Reed–Solomon codes were implemented in the Voyager program in the form of concatenated error correction codes. The first commercial application in mass-produced consumer products appeared in 1982 with the compact disc, where two interleaved Reed–Solomon codes are used. Today, Reed–Solomon codes are widely implemented in digital storage devices and digital communication standards, though they are being slowly replaced by Bose–Chaudhuri–Hocquenghem (BCH) codes. For example, Reed–Solomon codes are used in the Digital Video Broadcasting (DVB) standard DVB-S, in conjunction with a convolutional inner code, but BCH codes are used with LDPC in its successor, DVB-S2.
In 1986, an original scheme decoder known as the Berlekamp–Welch algorithm was developed.
In 1996, variations of original scheme decoders called list decoders or soft decoders were developed by Madhu Sudan and others, and work continues on these types of decoders (see Guruswami–Sudan list decoding algorithm).
In 2002, another original scheme decoder was developed by Shuhong Gao, based on the extended Euclidean algorithm.
Applications
Data storage
Reed–Solomon coding is very widely used in mass storage systems to correct
the burst errors associated with media defects. | Reed–Solomon error correction | Wikipedia | 267 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Reed–Solomon coding is a key component of the compact disc. It was the first use of strong error correction coding in a mass-produced consumer product, and DAT and DVD use similar schemes. In the CD, two layers of Reed–Solomon coding separated by a 28-way convolutional interleaver yields a scheme called Cross-Interleaved Reed–Solomon Coding (CIRC). The first element of a CIRC decoder is a relatively weak inner (32,28) Reed–Solomon code, shortened from a (255,251) code with 8-bit symbols. This code can correct up to 2 byte errors per 32-byte block. More importantly, it flags as erasures any uncorrectable blocks, i.e., blocks with more than 2 byte errors. The decoded 28-byte blocks, with erasure indications, are then spread by the deinterleaver to different blocks of the (28,24) outer code. Thanks to the deinterleaving, an erased 28-byte block from the inner code becomes a single erased byte in each of 28 outer code blocks. The outer code easily corrects this, since it can handle up to 4 such erasures per block.
The result is a CIRC that can completely correct error bursts up to 4000 bits, or about 2.5 mm on the disc surface. This code is so strong that most CD playback errors are almost certainly caused by tracking errors that cause the laser to jump track, not by uncorrectable error bursts.
DVDs use a similar scheme, but with much larger blocks, a (208,192) inner code, and a (182,172) outer code.
Reed–Solomon error correction is also used in parchive files which are commonly posted accompanying multimedia files on USENET. The distributed online storage service Wuala (discontinued in 2015) also used Reed–Solomon when breaking up files.
Bar code
Almost all two-dimensional bar codes such as PDF-417, MaxiCode, Datamatrix, QR Code, Aztec Code and Han Xin code use Reed–Solomon error correction to allow correct reading even if a portion of the bar code is damaged. When the bar code scanner cannot recognize a bar code symbol, it will treat it as an erasure.
Reed–Solomon coding is less common in one-dimensional bar codes, but is used by the PostBar symbology. | Reed–Solomon error correction | Wikipedia | 490 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Data transmission
Specialized forms of Reed–Solomon codes, specifically Cauchy-RS and Vandermonde-RS, can be used to overcome the unreliable nature of data transmission over erasure channels. The encoding process assumes a code of RS(N, K) which results in N codewords of length N symbols each storing K symbols of data, being generated, that are then sent over an erasure channel.
Any combination of K codewords received at the other end is enough to reconstruct all of the N codewords. The code rate is generally set to 1/2 unless the channel's erasure likelihood can be adequately modelled and is seen to be less. In conclusion, N is usually 2K, meaning that at least half of all the codewords sent must be received in order to reconstruct all of the codewords sent.
Reed–Solomon codes are also used in xDSL systems and CCSDS's Space Communications Protocol Specifications as a form of forward error correction.
Space transmission
One significant application of Reed–Solomon coding was to encode the digital pictures sent back by the Voyager program.
Voyager introduced Reed–Solomon coding concatenated with convolutional codes, a practice that has since become very widespread in deep space and satellite (e.g., direct digital broadcasting) communications.
Viterbi decoders tend to produce errors in short bursts. Correcting these burst errors is a job best done by short or simplified Reed–Solomon codes.
Modern versions of concatenated Reed–Solomon/Viterbi-decoded convolutional coding were and are used on the Mars Pathfinder, Galileo, Mars Exploration Rover and Cassini missions, where they perform within about 1–1.5 dB of the ultimate limit, the Shannon capacity.
These concatenated codes are now being replaced by more powerful turbo codes:
Constructions (encoding)
The Reed–Solomon code is actually a family of codes, where every code is characterised by three parameters: an alphabet size , a block length , and a message length , with . The set of alphabet symbols is interpreted as the finite field of order , and thus, must be a prime power. In the most useful parameterizations of the Reed–Solomon code, the block length is usually some constant multiple of the message length, that is, the rate is some constant, and furthermore, the block length is either equal to the alphabet size or one less than it, i.e., or . | Reed–Solomon error correction | Wikipedia | 501 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Reed & Solomon's original view: The codeword as a sequence of values
There are different encoding procedures for the Reed–Solomon code, and thus, there are different ways to describe the set of all codewords.
In the original view of , every codeword of the Reed–Solomon code is a sequence of function values of a polynomial of degree less than . In order to obtain a codeword of the Reed–Solomon code, the message symbols (each within the q-sized alphabet) are treated as the coefficients of a polynomial of degree less than k, over the finite field with elements.
In turn, the polynomial p is evaluated at n ≤ q distinct points of the field F, and the sequence of values is the corresponding codeword. Common choices for a set of evaluation points include {0, 1, 2, ..., n − 1}, {0, 1, α, α2, ..., αn−2}, or for n < q, {1, α, α2, ..., αn−1}, ... , where α is a primitive element of F.
Formally, the set of codewords of the Reed–Solomon code is defined as follows:
Since any two distinct polynomials of degree less than agree in at most points, this means that any two codewords of the Reed–Solomon code disagree in at least positions. Furthermore, there are two polynomials that do agree in points but are not equal, and thus, the distance of the Reed–Solomon code is exactly . Then the relative distance is , where is the rate. This trade-off between the relative distance and the rate is asymptotically optimal since, by the Singleton bound, every code satisfies .
Being a code that achieves this optimal trade-off, the Reed–Solomon code belongs to the class of maximum distance separable codes. | Reed–Solomon error correction | Wikipedia | 383 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
While the number of different polynomials of degree less than k and the number of different messages are both equal to , and thus every message can be uniquely mapped to such a polynomial, there are different ways of doing this encoding. The original construction of interprets the message x as the coefficients of the polynomial p, whereas subsequent constructions interpret the message as the values of the polynomial at the first k points and obtain the polynomial p by interpolating these values with a polynomial of degree less than k. The latter encoding procedure, while being slightly less efficient, has the advantage that it gives rise to a systematic code, that is, the original message is always contained as a subsequence of the codeword.
Simple encoding procedure: The message as a sequence of coefficients
In the original construction of , the message is mapped to the polynomial with
The codeword of is obtained by evaluating at different points of the field . Thus the classical encoding function for the Reed–Solomon code is defined as follows:
This function is a linear mapping, that is, it satisfies for the following -matrix with elements from :
This matrix is a Vandermonde matrix over . In other words, the Reed–Solomon code is a linear code, and in the classical encoding procedure, its generator matrix is .
Systematic encoding procedure: The message as an initial sequence of values
There are alternative encoding procedures that produce a systematic Reed–Solomon code. One method uses Lagrange interpolation to compute polynomial such that Then is evaluated at the other points .
This function is a linear mapping. To generate the corresponding systematic encoding matrix G, multiply the Vandermonde matrix A by the inverse of A's left square submatrix.
for the following -matrix with elements from :
Discrete Fourier transform and its inverse
A discrete Fourier transform is essentially the same as the encoding procedure; it uses the generator polynomial to map a set of evaluation points into the message values as shown above:
The inverse Fourier transform could be used to convert an error free set of n < q message values back into the encoding polynomial of k coefficients, with the constraint that in order for this to work, the set of evaluation points used to encode the message must be a set of increasing powers of α:
However, Lagrange interpolation performs the same conversion without the constraint on the set of evaluation points or the requirement of an error free set of message values and is used for systematic encoding, and in one of the steps of the Gao decoder. | Reed–Solomon error correction | Wikipedia | 502 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The BCH view: The codeword as a sequence of coefficients
In this view, the message is interpreted as the coefficients of a polynomial . The sender computes a related polynomial of degree where and sends the polynomial . The polynomial is constructed by multiplying the message polynomial , which has degree , with a generator polynomial of degree that is known to both the sender and the receiver. The generator polynomial is defined as the polynomial whose roots are sequential powers of the Galois field primitive
For a "narrow sense code", .
Systematic encoding procedure
The encoding procedure for the BCH view of Reed–Solomon codes can be modified to yield a systematic encoding procedure, in which each codeword contains the message as a prefix, and simply appends error correcting symbols as a suffix. Here, instead of sending , the encoder constructs the transmitted polynomial such that the coefficients of the largest monomials are equal to the corresponding coefficients of , and the lower-order coefficients of are chosen exactly in such a way that becomes divisible by . Then the coefficients of are a subsequence of the coefficients of . To get a code that is overall systematic, we construct the message polynomial by interpreting the message as the sequence of its coefficients.
Formally, the construction is done by multiplying by to make room for the check symbols, dividing that product by to find the remainder, and then compensating for that remainder by subtracting it. The check symbols are created by computing the remainder :
The remainder has degree at most , whereas the coefficients of in the polynomial are zero. Therefore, the following definition of the codeword has the property that the first coefficients are identical to the coefficients of :
As a result, the codewords are indeed elements of , that is, they are divisible by the generator polynomial :
This function is a linear mapping. To generate the corresponding systematic encoding matrix G, set G's left square submatrix to the identity matrix and then encode each row:
Ignoring leading zeroes, the last row = .
for the following -matrix with elements from :
Properties | Reed–Solomon error correction | Wikipedia | 425 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The Reed–Solomon code is a [n, k, n − k + 1] code; in other words, it is a linear block code of length n (over F) with dimension k and minimum Hamming distance The Reed–Solomon code is optimal in the sense that the minimum distance has the maximum value possible for a linear code of size (n, k); this is known as the Singleton bound. Such a code is also called a maximum distance separable (MDS) code.
The error-correcting ability of a Reed–Solomon code is determined by its minimum distance, or equivalently, by , the measure of redundancy in the block. If the locations of the error symbols are not known in advance, then a Reed–Solomon code can correct up to erroneous symbols, i.e., it can correct half as many errors as there are redundant symbols added to the block. Sometimes error locations are known in advance (e.g., "side information" in demodulator signal-to-noise ratios)—these are called erasures. A Reed–Solomon code (like any MDS code) is able to correct twice as many erasures as errors, and any combination of errors and erasures can be corrected as long as the relation is satisfied, where is the number of errors and is the number of erasures in the block.
The theoretical error bound can be described via the following formula for the AWGN channel for FSK:
and for other modulation schemes:
where , , , is the symbol error rate in uncoded AWGN case and is the modulation order.
For practical uses of Reed–Solomon codes, it is common to use a finite field with elements. In this case, each symbol can be represented as an -bit value.
The sender sends the data points as encoded blocks, and the number of symbols in the encoded block is . Thus a Reed–Solomon code operating on 8-bit symbols has symbols per block. (This is a very popular value because of the prevalence of byte-oriented computer systems.) The number , with , of data symbols in the block is a design parameter. A commonly used code encodes eight-bit data symbols plus 32 eight-bit parity symbols in an -symbol block; this is denoted as a code, and is capable of correcting up to 16 symbol errors per block. | Reed–Solomon error correction | Wikipedia | 485 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The Reed–Solomon code properties discussed above make them especially well-suited to applications where errors occur in bursts. This is because it does not matter to the code how many bits in a symbol are in error — if multiple bits in a symbol are corrupted it only counts as a single error. Conversely, if a data stream is not characterized by error bursts or drop-outs but by random single bit errors, a Reed–Solomon code is usually a poor choice compared to a binary code.
The Reed–Solomon code, like the convolutional code, is a transparent code. This means that if the channel symbols have been inverted somewhere along the line, the decoders will still operate. The result will be the inversion of the original data. However, the Reed–Solomon code loses its transparency when the code is shortened (see 'Remarks' at the end of this section). The "missing" bits in a shortened code need to be filled by either zeros or ones, depending on whether the data is complemented or not. (To put it another way, if the symbols are inverted, then the zero-fill needs to be inverted to a one-fill.) For this reason it is mandatory that the sense of the data (i.e., true or complemented) be resolved before Reed–Solomon decoding.
Whether the Reed–Solomon code is cyclic or not depends on subtle details of the construction. In the original view of Reed and Solomon, where the codewords are the values of a polynomial, one can choose the sequence of evaluation points in such a way as to make the code cyclic. In particular, if is a primitive root of the field , then by definition all non-zero elements of take the form for , where . Each polynomial over gives rise to a codeword . Since the function is also a polynomial of the same degree, this function gives rise to a codeword ; since holds, this codeword is the cyclic left-shift of the original codeword derived from . So choosing a sequence of primitive root powers as the evaluation points makes the original view Reed–Solomon code cyclic. Reed–Solomon codes in the BCH view are always cyclic because BCH codes are cyclic.
Remarks | Reed–Solomon error correction | Wikipedia | 448 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Designers are not required to use the "natural" sizes of Reed–Solomon code blocks. A technique known as "shortening" can produce a smaller code of any desired size from a larger code. For example, the widely used (255,223) code can be converted to a (160,128) code by padding the unused portion of the source block with 95 binary zeroes and not transmitting them. At the decoder, the same portion of the block is loaded locally with binary zeroes.
The QR code, Ver 3 (29×29) uses interleaved blocks. The message has 26 data bytes and is encoded using two Reed-Solomon code blocks. Each block is a (255,233) Reed Solomon code shortened to a (35,13) code.
The Delsarte–Goethals–Seidel theorem illustrates an example of an application of shortened Reed–Solomon codes. In parallel to shortening, a technique known as puncturing allows omitting some of the encoded parity symbols.
BCH view decoders
The decoders described in this section use the BCH view of a codeword as a sequence of coefficients. They use a fixed generator polynomial known to both encoder and decoder.
Peterson–Gorenstein–Zierler decoder
Daniel Gorenstein and Neal Zierler developed a decoder that was described in a MIT Lincoln Laboratory report by Zierler in January 1960 and later in a paper in June 1961. The Gorenstein–Zierler decoder and the related work on BCH codes are described in a book Error Correcting Codes by W. Wesley Peterson (1961).
Formulation
The transmitted message, , is viewed as the coefficients of a polynomial
As a result of the Reed–Solomon encoding procedure, s(x) is divisible by the generator polynomial
where α is a primitive element.
Since s(x) is a multiple of the generator g(x), it follows that it "inherits" all its roots:
Therefore,
The transmitted polynomial is corrupted in transit by an error polynomial
to produce the received polynomial
Coefficient ei will be zero if there is no error at that power of x, and nonzero if there is an error. If there are ν errors at distinct powers ik of x, then | Reed–Solomon error correction | Wikipedia | 465 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The goal of the decoder is to find the number of errors (ν), the positions of the errors (ik), and the error values at those positions (eik). From those, e(x) can be calculated and subtracted from r(x) to get the originally sent message s(x).
Syndrome decoding
The decoder starts by evaluating the polynomial as received at points . We call the results of that evaluation the "syndromes" Sj. They are defined as
Note that because has roots at , as shown in the previous section.
The advantage of looking at the syndromes is that the message polynomial drops out. In other words, the syndromes only relate to the error and are unaffected by the actual contents of the message being transmitted. If the syndromes are all zero, the algorithm stops here and reports that the message was not corrupted in transit.
Error locators and error values
For convenience, define the error locators Xk and error values Yk as
Then the syndromes can be written in terms of these error locators and error values as
This definition of the syndrome values is equivalent to the previous since .
The syndromes give a system of equations in 2ν unknowns, but that system of equations is nonlinear in the Xk and does not have an obvious solution. However, if the Xk were known (see below), then the syndrome equations provide a linear system of equations
which can easily be solved for the Yk error values.
Consequently, the problem is finding the Xk, because then the leftmost matrix would be known, and both sides of the equation could be multiplied by its inverse, yielding Yk
In the variant of this algorithm where the locations of the errors are already known (when it is being used as an erasure code), this is the end. The error locations (Xk) are already known by some other method (for example, in an FM transmission, the sections where the bitstream was unclear or overcome with interference are probabilistically determinable from frequency analysis). In this scenario, up to errors can be corrected.
The rest of the algorithm serves to locate the errors and will require syndrome values up to , instead of just the used thus far. This is why twice as many error-correcting symbols need to be added as can be corrected without knowing their locations.
Error locator polynomial | Reed–Solomon error correction | Wikipedia | 487 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
There is a linear recurrence relation that gives rise to a system of linear equations. Solving those equations identifies those error locations Xk.
Define the error locator polynomial as
The zeros of are the reciprocals . This follows from the above product notation construction, since if , then one of the multiplied terms will be zero, , making the whole polynomial evaluate to zero:
Let be any integer such that . Multiply both sides by , and it will still be zero:
Sum for k = 1 to ν, and it will still be zero:
Collect each term into its own sum:
Extract the constant values of that are unaffected by the summation:
These summations are now equivalent to the syndrome values, which we know and can substitute in. This therefore reduces to
Subtracting from both sides yields
Recall that j was chosen to be any integer between 1 and v inclusive, and this equivalence is true for all such values. Therefore, we have v linear equations, not just one. This system of linear equations can therefore be solved for the coefficients Λi of the error-location polynomial:
The above assumes that the decoder knows the number of errors ν, but that number has not been determined yet. The PGZ decoder does not determine ν directly but rather searches for it by trying successive values. The decoder first assumes the largest value for a trial ν and sets up the linear system for that value. If the equations can be solved (i.e., the matrix determinant is nonzero), then that trial value is the number of errors. If the linear system cannot be solved, then the trial ν is reduced by one and the next smaller system is examined .
Find the roots of the error locator polynomial
Use the coefficients Λi found in the last step to build the error location polynomial. The roots of the error location polynomial can be found by exhaustive search. The error locators Xk are the reciprocals of those roots. The order of coefficients of the error location polynomial can be reversed, in which case the roots of that reversed polynomial are the error locators (not their reciprocals ). Chien search is an efficient implementation of this step.
Calculate the error values
Once the error locators Xk are known, the error values can be determined. This can be done by direct solution for Yk in the error equations matrix given above, or using the Forney algorithm.
Calculate the error locations | Reed–Solomon error correction | Wikipedia | 497 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Calculate ik by taking the log base of Xk. This is generally done using a precomputed lookup table.
Fix the errors
Finally, e(x) is generated from ik and eik and then is subtracted from r(x) to get the originally sent message s(x), with errors corrected.
Example
Consider the Reed–Solomon code defined in with and (this is used in PDF417 barcodes) for a RS(7,3) code. The generator polynomial is
If the message polynomial is , then a systematic codeword is encoded as follows:
Errors in transmission might cause this to be received instead:
The syndromes are calculated by evaluating r at powers of α:
yielding the system
Using Gaussian elimination,
so
with roots x1 = 757 = 3−3 and x2 = 562 = 3−4.
The coefficients can be reversed:
to produce roots 27 = 33 and 81 = 34 with positive exponents, but typically this isn't used. The logarithm of the inverted roots corresponds to the error locations (right to left, location 0 is the last term in the codeword).
To calculate the error values, apply the Forney algorithm:
Subtracting from the received polynomial r(x) reproduces the original codeword s.
Berlekamp–Massey decoder
The Berlekamp–Massey algorithm is an alternate iterative procedure for finding the error locator polynomial. During each iteration, it calculates a discrepancy based on a current instance of Λ(x) with an assumed number of errors e:
and then adjusts Λ(x) and e so that a recalculated Δ would be zero. The article Berlekamp–Massey algorithm has a detailed description of the procedure. In the following example, C(x) is used to represent Λ(x).
Example
Using the same data as the Peterson Gorenstein Zierler example above:
The final value of C is the error locator polynomial, Λ(x).
Euclidean decoder
Another iterative method for calculating both the error locator polynomial and the error value polynomial is based on Sugiyama's adaptation of the extended Euclidean algorithm .
Define S(x), Λ(x), and Ω(x) for t syndromes and e errors:
The key equation is:
For t = 6 and e = 3:
The middle terms are zero due to the relationship between Λ and syndromes. | Reed–Solomon error correction | Wikipedia | 506 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The extended Euclidean algorithm can find a series of polynomials of the form
where the degree of R decreases as i increases. Once the degree of Ri(x) < t/2, then
B(x) and Q(x) don't need to be saved, so the algorithm becomes:
R−1 := xt
R0 := S(x)
A−1 := 0
A0 := 1
i := 0
while degree of Ri ≥ t/2
i := i + 1
Q := Ri-2 / Ri-1
Ri := Ri-2 - Q Ri-1
Ai := Ai-2 - Q Ai-1
to set low order term of Λ(x) to 1, divide Λ(x) and Ω(x) by Ai(0):
Ai(0) is the constant (low order) term of Ai.
Example
Using the same data as the Peterson–Gorenstein–Zierler example above:
Decoder using discrete Fourier transform
A discrete Fourier transform can be used for decoding. To avoid conflict with syndrome names, let c(x) = s(x) the encoded codeword. r(x) and e(x) are the same as above. Define C(x), E(x), and R(x) as the discrete Fourier transforms of c(x), e(x), and r(x). Since r(x) = c(x) + e(x), and since a discrete Fourier transform is a linear operator, R(x) = C(x) + E(x).
Transform r(x) to R(x) using discrete Fourier transform. Since the calculation for a discrete Fourier transform is the same as the calculation for syndromes, t coefficients of R(x) and E(x) are the same as the syndromes:
Use through as syndromes (they're the same) and generate the error locator polynomial using the methods from any of the above decoders.
Let v = number of errors. Generate E(x) using the known coefficients to , the error locator polynomial, and these formulas
Then calculate C(x) = R(x) − E(x) and take the inverse transform (polynomial interpolation) of C(x) to produce c(x).
Decoding beyond the error-correction bound | Reed–Solomon error correction | Wikipedia | 488 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The Singleton bound states that the minimum distance d of a linear block code of size (n,k) is upper-bounded by . The distance d was usually understood to limit the error-correction capability to . The Reed–Solomon code achieves this bound with equality, and can thus correct up to errors. However, this error-correction bound is not exact.
In 1999, Madhu Sudan and Venkatesan Guruswami at MIT published "Improved Decoding of Reed–Solomon and Algebraic-Geometry Codes" introducing an algorithm that allowed for the correction of errors beyond half the minimum distance of the code. It applies to Reed–Solomon codes and more generally to algebraic geometric codes. This algorithm produces a list of codewords (it is a list-decoding algorithm) and is based on interpolation and factorization of polynomials over and its extensions.
In 2023, building on three exciting works, coding theorists showed that Reed-Solomon codes defined over random evaluation points can actually achieve list decoding capacity (up to errors) over linear size alphabets with high probability. However, this result is combinatorial rather than algorithmic.
Soft-decoding
The algebraic decoding methods described above are hard-decision methods, which means that for every symbol a hard decision is made about its value. For example, a decoder could associate with each symbol an additional value corresponding to the channel demodulator's confidence in the correctness of the symbol. The advent of LDPC and turbo codes, which employ iterated soft-decision belief propagation decoding methods to achieve error-correction performance close to the theoretical limit, has spurred interest in applying soft-decision decoding to conventional algebraic codes. In 2003, Ralf Koetter and Alexander Vardy presented a polynomial-time soft-decision algebraic list-decoding algorithm for Reed–Solomon codes, which was based upon the work by Sudan and Guruswami.
In 2016, Steven J. Franke and Joseph H. Taylor published a novel soft-decision decoder.
MATLAB example | Reed–Solomon error correction | Wikipedia | 413 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Encoder
Here we present a simple MATLAB implementation for an encoder.
function encoded = rsEncoder(msg, m, prim_poly, n, k)
% RSENCODER Encode message with the Reed-Solomon algorithm
% m is the number of bits per symbol
% prim_poly: Primitive polynomial p(x). Ie for DM is 301
% k is the size of the message
% n is the total size (k+redundant)
% Example: msg = uint8('Test')
% enc_msg = rsEncoder(msg, 8, 301, 12, numel(msg));
% Get the alpha
alpha = gf(2, m, prim_poly);
% Get the Reed-Solomon generating polynomial g(x)
g_x = genpoly(k, n, alpha);
% Multiply the information by X^(n-k), or just pad with zeros at the end to
% get space to add the redundant information
msg_padded = gf([msg zeros(1, n - k)], m, prim_poly);
% Get the remainder of the division of the extended message by the
% Reed-Solomon generating polynomial g(x)
[~, remainder] = deconv(msg_padded, g_x);
% Now return the message with the redundant information
encoded = msg_padded - remainder;
end
% Find the Reed-Solomon generating polynomial g(x), by the way this is the
% same as the rsgenpoly function on matlab
function g = genpoly(k, n, alpha)
g = 1;
% A multiplication on the galois field is just a convolution
for k = mod(1 : n - k, n)
g = conv(g, [1 alpha .^ (k)]);
end
end | Reed–Solomon error correction | Wikipedia | 409 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
Decoder
Now the decoding part:
function [decoded, error_pos, error_mag, g, S] = rsDecoder(encoded, m, prim_poly, n, k)
% RSDECODER Decode a Reed-Solomon encoded message
% Example:
% [dec, ~, ~, ~, ~] = rsDecoder(enc_msg, 8, 301, 12, numel(msg))
max_errors = floor((n - k) / 2);
orig_vals = encoded.x;
% Initialize the error vector
errors = zeros(1, n);
g = [];
S = [];
% Get the alpha
alpha = gf(2, m, prim_poly);
% Find the syndromes (Check if dividing the message by the generator
% polynomial the result is zero)
Synd = polyval(encoded, alpha .^ (1:n - k));
Syndromes = trim(Synd);
% If all syndromes are zeros (perfectly divisible) there are no errors
if isempty(Syndromes.x)
decoded = orig_vals(1:k);
error_pos = [];
error_mag = [];
g = [];
S = Synd;
return;
end
% Prepare for the euclidean algorithm (Used to find the error locating
% polynomials)
r0 = [1, zeros(1, 2 * max_errors)]; r0 = gf(r0, m, prim_poly); r0 = trim(r0);
size_r0 = length(r0);
r1 = Syndromes;
f0 = gf([zeros(1, size_r0 - 1) 1], m, prim_poly);
f1 = gf(zeros(1, size_r0), m, prim_poly);
g0 = f1; g1 = f0;
% Do the euclidean algorithm on the polynomials r0(x) and Syndromes(x) in
% order to find the error locating polynomial
while true
% Do a long division
[quotient, remainder] = deconv(r0, r1);
% Add some zeros
quotient = pad(quotient, length(g1)); | Reed–Solomon error correction | Wikipedia | 508 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
% Find quotient*g1 and pad
c = conv(quotient, g1);
c = trim(c);
c = pad(c, length(g0));
% Update g as g0-quotient*g1
g = g0 - c;
% Check if the degree of remainder(x) is less than max_errors
if all(remainder(1:end - max_errors) == 0)
break;
end
% Update r0, r1, g0, g1 and remove leading zeros
r0 = trim(r1); r1 = trim(remainder);
g0 = g1; g1 = g;
end
% Remove leading zeros
g = trim(g);
% Find the zeros of the error polynomial on this galois field
evalPoly = polyval(g, alpha .^ (n - 1 : - 1 : 0));
error_pos = gf(find(evalPoly == 0), m);
% If no error position is found we return the received work, because
% basically is nothing that we could do and we return the received message
if isempty(error_pos)
decoded = orig_vals(1:k);
error_mag = [];
return;
end
% Prepare a linear system to solve the error polynomial and find the error
% magnitudes
size_error = length(error_pos);
Syndrome_Vals = Syndromes.x;
b(:, 1) = Syndrome_Vals(1:size_error);
for idx = 1 : size_error
e = alpha .^ (idx * (n - error_pos.x));
err = e.x;
er(idx, :) = err;
end
% Solve the linear system
error_mag = (gf(er, m, prim_poly) \ gf(b, m, prim_poly))';
% Put the error magnitude on the error vector
errors(error_pos.x) = error_mag.x;
% Bring this vector to the galois field
errors_gf = gf(errors, m, prim_poly); | Reed–Solomon error correction | Wikipedia | 479 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
% Now to fix the errors just add with the encoded code
decoded_gf = encoded(1:k) + errors_gf(1:k);
decoded = decoded_gf.x;
end
% Remove leading zeros from Galois array
function gt = trim(g)
gx = g.x;
gt = gf(gx(find(gx, 1) : end), g.m, g.prim_poly);
end
% Add leading zeros
function xpad = pad(x, k)
len = length(x);
if len < k
xpad = [zeros(1, k - len) x];
end
end
Reed Solomon original view decoders
The decoders described in this section use the Reed Solomon original view of a codeword as a sequence of polynomial values where the polynomial is based on the message to be encoded. The same set of fixed values are used by the encoder and decoder, and the decoder recovers the encoding polynomial (and optionally an error locating polynomial) from the received message.
Theoretical decoder
described a theoretical decoder that corrected errors by finding the most popular message polynomial. The decoder only knows the set of values to and which encoding method was used to generate the codeword's sequence of values. The original message, the polynomial, and any errors are unknown. A decoding procedure could use a method like Lagrange interpolation on various subsets of n codeword values taken k at a time to repeatedly produce potential polynomials, until a sufficient number of matching polynomials are produced to reasonably eliminate any errors in the received codeword. Once a polynomial is determined, then any errors in the codeword can be corrected, by recalculating the corresponding codeword values. Unfortunately, in all but the simplest of cases, there are too many subsets, so the algorithm is impractical. The number of subsets is the binomial coefficient, , and the number of subsets is infeasible for even modest codes. For a code that can correct 3 errors, the naïve theoretical decoder would examine 359 billion subsets.
Berlekamp Welch decoder | Reed–Solomon error correction | Wikipedia | 452 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
In 1986, a decoder known as the Berlekamp–Welch algorithm was developed as a decoder that is able to recover the original message polynomial as well as an error "locator" polynomial that produces zeroes for the input values that correspond to errors, with time complexity , where is the number of values in a message. The recovered polynomial is then used to recover (recalculate as needed) the original message.
Example
Using RS(7,3), GF(929), and the set of evaluation points ai = i − 1
If the message polynomial is
The codeword is
Errors in transmission might cause this to be received instead.
The key equations are:
Assume maximum number of errors: e = 2. The key equations become:
Using Gaussian elimination:
Recalculate where to correct resulting in the corrected codeword:
Gao decoder
In 2002, an improved decoder was developed by Shuhong Gao, based on the extended Euclid algorithm.
Example
Using the same data as the Berlekamp Welch example above:
Lagrange interpolation of for i = 1 to n
divide Q(x) and E(x) by most significant coefficient of E(x) = 708. (Optional)
Recalculate where to correct resulting in the corrected codeword: | Reed–Solomon error correction | Wikipedia | 270 | 45600 | https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon%20error%20correction | Mathematics | Information theory | null |
The cheetah (Acinonyx jubatus) is a large cat and the fastest land animal. It has a tawny to creamy white or pale buff fur that is marked with evenly spaced, solid black spots. The head is small and rounded, with a short snout and black tear-like facial streaks. It reaches at the shoulder, and the head-and-body length is between . Adults weigh between . The cheetah is capable of running at ; it has evolved specialized adaptations for speed, including a light build, long thin legs and a long tail.
The cheetah was first described in the late 18th century. Four subspecies are recognised today that are native to Africa and central Iran. An African subspecies was introduced to India in 2022. It is now distributed mainly in small, fragmented populations in northwestern, eastern and southern Africa and central Iran. It lives in a variety of habitats such as savannahs in the Serengeti, arid mountain ranges in the Sahara, and hilly desert terrain.
The cheetah lives in three main social groups: females and their cubs, male "coalitions", and solitary males. While females lead a nomadic life searching for prey in large home ranges, males are more sedentary and instead establish much smaller territories in areas with plentiful prey and access to females. The cheetah is active during the day, with peaks during dawn and dusk. It feeds on small- to medium-sized prey, mostly weighing under , and prefers medium-sized ungulates such as impala, springbok and Thomson's gazelles. The cheetah typically stalks its prey within before charging towards it, trips it during the chase and bites its throat to suffocate it to death. It breeds throughout the year. After a gestation of nearly three months, females give birth to a litter of three or four cubs. Cheetah cubs are highly vulnerable to predation by other large carnivores. They are weaned at around four months and are independent by around 20 months of age. | Cheetah | Wikipedia | 420 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The cheetah is threatened by habitat loss, conflict with humans, poaching and high susceptibility to diseases. The global cheetah population was estimated in 2021 at 6,517; it is listed as Vulnerable on the IUCN Red List. It has been widely depicted in art, literature, advertising, and animation. It was tamed in ancient Egypt and trained for hunting ungulates in the Arabian Peninsula and India. It has been kept in zoos since the early 19th century.
Etymology
The vernacular name "cheetah" is derived from Hindustani and (). This in turn comes from () meaning 'variegated', 'adorned' or 'painted'. In the past, the cheetah was often called "hunting leopard" because they could be tamed and used for coursing. The generic name Acinonyx probably derives from the combination of two Greek words: () meaning 'unmoved' or 'motionless', and () meaning 'nail' or 'hoof'. A rough translation is "immobile nails", a reference to the cheetah's limited ability to retract its claws. A similar meaning can be obtained by the combination of the Greek prefix a– (implying a lack of) and () meaning 'to move' or 'to set in motion'. The specific name is Latin for 'crested, having a mane'.
A few old generic names such as Cynailurus and Cynofelis allude to the similarities between the cheetah and canids.
Taxonomy
In 1777, Johann Christian Daniel von Schreber described the cheetah based on a skin from the Cape of Good Hope and gave it the scientific name Felis jubatus. Joshua Brookes proposed the generic name Acinonyx in 1828. In 1917, Reginald Innes Pocock placed the cheetah in a subfamily of its own, Acinonychinae, given its striking morphological resemblance to the greyhound and significant deviation from typical felid features; the cheetah was classified in Felinae in later taxonomic revisions. | Cheetah | Wikipedia | 431 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In the 19th and 20th centuries, several cheetah zoological specimens were described; some were proposed as subspecies.
A South African specimen with notably dense fur was proposed as (Felis lanea) by Philip Sclater in 1877 and became known as the "woolly cheetah". Its classification as a species was mostly disputed. There has been considerable confusion in the nomenclature of the cheetah and leopard (Panthera pardus) as authors often confused the two; some considered "hunting leopards" an independent species, or equal to the leopard.
Subspecies
In 1975, five cheetah subspecies were considered valid taxa: A. j. hecki, A. j. jubatus, A. j. raineyi, A. j. soemmeringii and A. j. venaticus. In 2011, a phylogeographic study found minimal genetic variation between A. j. jubatus and A. j. raineyi; only four subspecies were identified. In 2017, the Cat Classification Task Force of the IUCN Cat Specialist Group revised felid taxonomy and recognised these four subspecies as valid. Their details are tabulated below:
Phylogeny and evolution
The cheetah's closest relatives are the cougar (Puma concolor) and the jaguarundi (Herpailurus yagouaroundi). Together, these three species form the Puma lineage, one of the eight lineages of the extant felids; the Puma lineage diverged from the rest 6.7 mya. The sister group of the Puma lineage is a clade of smaller Old World cats that includes the genera Felis, Otocolobus and Prionailurus. | Cheetah | Wikipedia | 350 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The oldest cheetah fossils, excavated in eastern and southern Africa, date to 3.5–3 mya; the earliest known specimen from South Africa is from the lowermost deposits of the Silberberg Grotto (Sterkfontein). Though incomplete, these fossils indicate forms larger but less cursorial than the modern cheetah. The first occurrence of the modern species A. jubatus in Africa may come from Cooper's D, a site in South Africa dating back to 1.5 to 1.4 Ma, during the Calabrian stage. Fossil remains from Europe are limited to a few Middle Pleistocene specimens from Hundsheim (Austria) and Mosbach Sands (Germany). Cheetah-like cats are known from as late as 10,000 years ago from the Old World. The giant cheetah (A. pardinensis), significantly larger and slower compared to the modern cheetah, occurred in Eurasia and eastern and southern Africa in the Villafranchian period roughly 3.8–1.9 mya. In the Middle Pleistocene a smaller cheetah, A. intermedius, ranged from Europe to China. The modern cheetah appeared in Africa around 1.9 mya; its fossil record is restricted to Africa.
Extinct North American cheetah-like cats had historically been classified in Felis, Puma or Acinonyx; two such species, F. studeri and F. trumani, were considered to be closer to the puma than the cheetah, despite their close similarities to the latter. Noting this, palaeontologist Daniel Adams proposed Miracinonyx, a new subgenus under Acinonyx, in 1979 for the North American cheetah-like cats; this was later elevated to genus rank. Adams pointed out that North American and Old World cheetah-like cats may have had a common ancestor, and Acinonyx might have originated in North America instead of Eurasia. However, subsequent research has shown that Miracinonyx is phylogenetically closer to the cougar than the cheetah; the similarities to cheetahs have been attributed to parallel evolution. | Cheetah | Wikipedia | 449 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The three species of the Puma lineage may have had a common ancestor during the Miocene (roughly 8.25 mya). Some suggest that North American cheetahs possibly migrated to Asia via the Bering Strait, then dispersed southward to Africa through Eurasia at least 100,000 years ago; some authors have expressed doubt over the occurrence of cheetah-like cats in North America, and instead suppose the modern cheetah to have evolved from Asian populations that eventually spread to Africa. The cheetah is thought to have experienced two population bottlenecks that greatly decreased the genetic variability in populations; one occurred about 100,000 years ago that has been correlated to migration from North America to Asia, and the second 10,000–12,000 years ago in Africa, possibly as part of the Late Pleistocene extinction event.
Genetics
The diploid number of chromosomes in the cheetah is 38, the same as in most other felids. The cheetah was the first felid observed to have unusually low genetic variability among individuals, which has led to poor breeding in captivity, increased spermatozoal defects, high juvenile mortality and increased susceptibility to diseases and infections. A prominent instance was the deadly feline coronavirus outbreak in a cheetah breeding facility of Oregon in 1983 which had a mortality rate of 60%, higher than that recorded for previous epizootics of feline infectious peritonitis in any felid. The remarkable homogeneity in cheetah genes has been demonstrated by experiments involving the major histocompatibility complex (MHC); unless the MHC genes are highly homogeneous in a population, skin grafts exchanged between a pair of unrelated individuals would be rejected. Skin grafts exchanged between unrelated cheetahs are accepted well and heal, as if their genetic makeup were the same.
The low genetic diversity is thought to have been created by two population bottlenecks from about 100,000 years and about 12,000 years ago, respectively. The resultant level of genetic variation is around 0.1–4% of average living species, lower than that of Tasmanian devils, Virunga gorillas, Amur tigers, and even highly inbred domestic cats and dogs.
Selective retention of gene variants (Duplication) has been found in 10 genes candidates to explain energetics and anabolism related to muscle specialization in cheetahs. | Cheetah | Wikipedia | 487 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
•Regulation of muscle contraction (Five genes: ADORA1, ADRA1B, CACNA1C, RGS2, SCN5A).
•Physiological stress response (Two genes: ADORA1, TAOK2).
•Negative regulation of catabolic process (Four genes: APOC3, SUFU, DDIT4, PPARA).
Potentially harmful mutations has been found in a gene related to spermatogenesis (AKAP4). This could explain the high proportion of abnormal sperma in male cheetahs and poor reproductive success in the species.
King cheetah
The king cheetah is a variety of cheetah with a rare mutation for cream-coloured fur marked with large, blotchy spots and three dark, wide stripes extending from the neck to the tail. In Manicaland, Zimbabwe, it was known as nsuifisi and thought to be a cross between a leopard and a hyena. In 1926, Major A. Cooper wrote about a cheetah-like animal he had shot near modern-day Harare, with fur as thick as that of a snow leopard and spots that merged to form stripes. He suggested it could be a cross between a leopard and a cheetah. As more such individuals were observed it was seen that they had non-retractable claws like the cheetah.
In 1927, Pocock described these individuals as a new species by the name of Acinonyx rex ("king cheetah"). However, in the absence of proof to support his claim, he withdrew his proposal in 1939. Abel Chapman considered it a colour morph of the normally spotted cheetah. Since 1927, the king cheetah has been reported five more times in the wild in Zimbabwe, Botswana and northern Transvaal; one was photographed in 1975. | Cheetah | Wikipedia | 378 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In 1981, two female cheetahs that had mated with a wild male from Transvaal at the De Wildt Cheetah and Wildlife Centre (South Africa) gave birth to one king cheetah each; subsequently, more king cheetahs were born at the centre. In 2012, the cause of this coat pattern was found to be a mutation in the gene for transmembrane aminopeptidase (Taqpep), the same gene responsible for the striped "mackerel" versus blotchy "classic" pattern seen in tabby cats. The appearance is caused by reinforcement of a recessive allele; hence if two mating cheetahs are heterozygous carriers of the mutated allele, a quarter of their offspring can be expected to be king cheetahs.
Characteristics
The cheetah is a lightly built, spotted cat characterised by a small rounded head, a short snout, black tear-like facial streaks, a deep chest, long thin legs and a long tail. Its slender, canine-like form is highly adapted for speed, and contrasts sharply with the robust build of the genus Panthera. Cheetahs typically reach at the shoulder and the head-and-body length is between . The weight can vary with age, health, location, sex and subspecies; adults typically range between . Cubs born in the wild weigh at birth, while those born in captivity tend to be larger and weigh around . The cheetah is sexually dimorphic, with males larger and heavier than females, but not to the extent seen in other large cats; females have a much lower body mass index than males. Studies differ significantly on morphological variations among the subspecies. | Cheetah | Wikipedia | 344 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The coat is typically tawny to creamy white or pale buff (darker in the mid-back portion). The chin, throat and underparts of the legs and the belly are white and devoid of markings. The rest of the body is covered with around 2,000 evenly spaced, oval or round solid black spots, each measuring roughly . Each cheetah has a distinct pattern of spots which can be used to identify unique individuals. Besides the clearly visible spots, there are other faint, irregular black marks on the coat. Newly born cubs are covered in fur with an unclear pattern of spots that gives them a dark appearance—pale white above and nearly black on the underside. The hair is mostly short and often coarse, but the chest and the belly are covered in soft fur; the fur of king cheetahs has been reported to be silky. There is a short, rough mane, covering at least along the neck and the shoulders; this feature is more prominent in males. The mane starts out as a cape of long, loose blue to grey hair in juveniles. Melanistic cheetahs are rare and have been seen in Zambia and Zimbabwe. In 1877–1878, Sclater described two partially albino specimens from South Africa.
The head is small and more rounded compared to other big cats. Saharan cheetahs have canine-like slim faces. The ears are small, short and rounded; they are tawny at the base and on the edges and marked with black patches on the back. The eyes are set high and have round pupils. The whiskers, shorter and fewer than those of other felids, are fine and inconspicuous. The pronounced tear streaks (or malar stripes), unique to the cheetah, originate from the corners of the eyes and run down the nose to the mouth. The role of these streaks is not well understood—they may protect the eyes from the sun's glare (a helpful feature as the cheetah hunts mainly during the day), or they could be used to define facial expressions. The exceptionally long and muscular tail, with a bushy white tuft at the end, measures . While the first two-thirds of the tail are covered in spots, the final third is marked with four to six dark rings or stripes. | Cheetah | Wikipedia | 465 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The cheetah is superficially similar to the leopard, which has a larger head, fully retractable claws, rosettes instead of spots, lacks tear streaks and is more muscular. Moreover, the cheetah is taller than the leopard. The serval also resembles the cheetah in physical build, but is significantly smaller, has a shorter tail and its spots fuse to form stripes on the back. The cheetah appears to have evolved convergently with canids in morphology and behaviour; it has canine-like features such as a relatively long snout, long legs, a deep chest, tough paw pads and blunt, semi-retractable claws. The cheetah has often been likened to the greyhound, as both have similar morphology and the ability to reach tremendous speeds in a shorter time than other mammals, but the cheetah can attain much higher maximum speeds.
Internal anatomy | Cheetah | Wikipedia | 180 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Sharply contrasting with the other big cats in its morphology, the cheetah shows several specialized adaptations for prolonged chases to catch prey at some of the fastest speeds reached by land animals. Its light, streamlined body makes it well-suited to short, explosive bursts of speed, rapid acceleration, and an ability to execute extreme changes in direction while moving at high speed. The large nasal passages, accommodated well due to the smaller size of the canine teeth, ensure fast flow of sufficient air, and the enlarged heart and lungs allow the enrichment of blood with oxygen in a short time. This allows cheetahs to rapidly regain their stamina after a chase. During a typical chase, their respiratory rate increases from 60 to 150 breaths per minute. The cheetah has a fast heart rate, averaging 126–173 beats per minute at resting without arrhythmia. Moreover, the reduced viscosity of the blood at higher temperatures (common in frequently moving muscles) could ease blood flow and increase oxygen transport. While running, in addition to having good traction due to their semi-retractable claws, cheetahs use their tail as a rudder-like means of steering that enables them to make sharp turns, necessary to outflank antelopes which often change direction to escape during a chase. The protracted claws increase grip over the ground, while rough paw pads make the sprint more convenient over tough ground. The limbs of the cheetah are longer than what is typical for other cats its size; the thigh muscles are large, and the tibia and fibula are held close together making the lower legs less likely to rotate. This reduces the risk of losing balance during runs, but compromises the cat's ability to climb trees. The highly reduced clavicle is connected through ligaments to the scapula, whose pendulum-like motion increases the stride length and assists in shock absorption. The extension of the vertebral column can add as much as to the stride length.
Muscle tissue has been analyzed in the cheetah and it has been found that there are little differences in type IIx muscle fibers concentration, anaerobic LDH enzyme activity, as well glycogen concentration between sexes, in contrast to humans where women had LDH activity much lower that men, although type IIx muscle fibers concentration were similar. Cheetah males had larger cross-sectional area fibers. | Cheetah | Wikipedia | 485 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The cheetah resembles the smaller cats in cranial features, and in having a long and flexible spine, as opposed to the stiff and short one in other large felids. The roughly triangular skull has light, narrow bones and the sagittal crest is poorly developed, possibly to reduce weight and enhance speed. The mouth can not be opened as widely as in other cats given the shorter length of muscles between the jaw and the skull. A study suggested that the limited retraction of the cheetah's claws may result from the earlier truncation of the development of the middle phalanx bone in cheetahs.
The cheetah has a total of 30 teeth; the dental formula is . The small, flat canines are used to bite the throat and suffocate the prey. A study gave the bite force quotient (BFQ) of the cheetah as 119, close to that for the lion (112), suggesting that adaptations for a lighter skull may not have reduced the power of the cheetah's bite. Unlike other cats, the cheetah's canines have no gap or diastema behind them when the jaws close, as the top and bottom cheek teeth show extensive overlap. Cheetahs have relatively elongated, blade-like shape carnassial teeth, with reduced lingual cusps; this may have been an adaptation to consume quickly the flesh of a prey before more heavy-built predators from other species arrive to take it from them. The slightly curved claws, shorter and straighter than those of other cats, lack a protective sheath and are partly retractable. The claws are blunt due to lack of protection, but the large and strongly curved dewclaw is remarkably sharp. Cheetahs have a high concentration of nerve cells arranged in a band in the centre of the eyes, a visual streak, the most efficient among felids. This significantly sharpens the vision and enables the cheetah to swiftly locate prey against the horizon. The cheetah is unable to roar due to the presence of a sharp-edged vocal fold within the larynx. | Cheetah | Wikipedia | 437 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In stressful situations, the cheetah has a lower cortisol level than the leopard, indicating better stress response; it also has lower immunoglobulin G and Serum amyloid A levels but a higher lysozyme level and a higher bacterial killing capacity than the leopard, indicating a poorer adaptive and induced innate immune systems but a better constitutive innate immune system; its constitutive innate immune system compensates for its low variation of major histocompatibility complex and poorer immune adaptability.
Speed and acceleration
The cheetah is the world's fastest land animal. Estimates of the maximum speed attained range from . A commonly quoted value is , recorded in 1957, but this measurement is disputed. In 2012, an 11-year-old cheetah from the Cincinnati Zoo set a world record by running in 5.95 seconds over a set run, recording a maximum speed of .
Cheetahs equipped with GPS collars hunted at speeds during most of the chase much lower than the highest recorded speed; their run was interspersed with a few short bursts of a few seconds when they attained peak speeds. The average speed recorded during the high speed phase was , or within the range including error. The highest recorded value was . A hunt consists of two phases, an initial fast acceleration phase when the cheetah tries to catch up with the prey, followed by slowing down as it closes in on it, the deceleration varying by the prey in question. The initial linear acceleration observed was 13 m/s², more than twice than 6 m/s² of horses and greater than 10 m/s² of greyhounds. Cheetahs can increase up 3 m/s (10.8 km/h) and decrease up 4 m/s (14.4 km/h) in a single stride. Speed and acceleration values for a hunting cheetah may be different from those for a non-hunter because while engaged in the chase, the cheetah is more likely to be twisting and turning and may be running through vegetation. The speeds attained by the cheetah may be only slightly greater than those achieved by the pronghorn at and the springbok at , but the cheetah additionally has an exceptional acceleration. | Cheetah | Wikipedia | 460 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
One stride of a galloping cheetah measures ; the stride length and the number of jumps increases with speed. During more than half the duration of the sprint, the cheetah has all four limbs in the air, increasing the stride length. Running cheetahs can retain up to 90% of the heat generated during the chase. A 1973 study suggested the length of the sprint is limited by excessive build-up of body heat when the body temperature reaches . However, a 2013 study recorded the average temperature of cheetahs after hunts to be , suggesting high temperatures need not cause hunts to be abandoned.
The running speed of of the cheetah was obtained as an result of a single run of one individual by dividing the distance traveled for time spent. The run lasted 2.25 seconds and was supposed to have been long, but was later found to have been long. It was therefore discredited for a faulty method of measurement.
Cheetahs have subsequently been measured at running at a speed of as the fastest speed from three runs including in opposite direction, for a single individual, over a marked course, even starting the run behind the start line, starting the run already running on the course. Again dividing the distance by time, but this time to determine the maximum sustained speed, completing the runs in an time of 7.0, 6.9 and 7.2 seconds. Being a more accurate method of measurement, this test was made in 1965 but published in 1997.
Subsequently, with GPS-IMU collars, running speed was measured for wild cheetahs during hunts with turns and maneuvers, and the maximum speed recorded was sustained for 1–2 seconds. The speed was obtained by dividing the length by the time between footfalls of a stride. Cheetahs can go from in less than 3 seconds.
There are indirect ways to measure how fast a cheetah can run. One case is known of a cheetah that overtook a young male pronghorn. Cheetahs can overtake a running antelope with a head start. Both animals were clocked at by speedometer reading while running alongside a vehicle at full speed. Cheetahs can easily capture gazelles galloping at full speed (). | Cheetah | Wikipedia | 451 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The physiological reasons for speed in cheetahs are:
Small head and long lumbar region of the spine, 36.8% of the presacral vertebral column.
A tibia and radius longer than the femur and humerus, with a femorotibial index of 101.9–105 and a humeroradial index of 100.1–103.3.
Elongated and slender long bones of the limbs, especially femur, tibia, humerus, radius and pelvis, specially the ischium.
A cool nose and enlarged respiratory passages that allow it to inhale and exhale more air with each breath, which helps dissipate body heat.
A higher concentration of glycolytic fast twitch muscle fibers (Type IIx) than other cats and animals in general. A very high LDH activity is indicative of this principally anaerobic muscle metabolism.
Most of the locomotor muscle mass is concentrated proximally close to the body in shoulders, thighs and spine, and is reduced in shins and forearms. Long tendons finish off the distal locomotor muscles.
Muscular hindlimbs form 19.8% of the body mass, whereas the forelimbs form 15.1%. The hamstrings, quadriceps, adductor muscles of the hip and psoas major muscles are especially large.
Enlarged Betz cells in the motor cortex M1 and innervating muscle fibers, with longer dendrites and more numerous dendritic segments to fit predominant type IIx muscle fibers. | Cheetah | Wikipedia | 319 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Ecology and behaviour
Cheetahs are active mainly during the day, whereas other carnivores such as leopards and lions are active mainly at night; These larger carnivores can kill cheetahs and steal their kills; hence, the diurnal tendency of cheetahs helps them avoid larger predators in areas where they are sympatric, such as the Okavango Delta. In areas where the cheetah is the major predator (such as farmlands in Botswana and Namibia), activity tends to increase at night. This may also happen in highly arid regions such as the Sahara, where daytime temperatures can reach . The lunar cycle can also influence the cheetah's routine—activity might increase on moonlit nights as prey can be sighted easily, though this comes with the danger of encountering larger predators. Hunting is the major activity throughout the day, with peaks during dawn and dusk. Groups rest in grassy clearings after dusk. Cheetahs often inspect their vicinity at observation points such as elevations to check for prey or larger carnivores; even while resting, they take turns at keeping a lookout.
Social organisation
Cheetahs have a flexible and complex social structure and tend to be more gregarious than several other cats (except the lion). Individuals typically avoid one another but are generally amicable; males may fight over territories or access to females in oestrus, and on rare occasions such fights can result in severe injury and death. Females are not social and have minimal interaction with other individuals, barring the interaction with males when they enter their territories or during the mating season. Some females, generally mother and offspring or siblings, may rest beside one another during the day. Females tend to lead a solitary life or live with offspring in undefended home ranges; young females often stay close to their mothers for life but young males leave their mother's range to live elsewhere. | Cheetah | Wikipedia | 388 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Some males are territorial, and group together for life, forming coalitions that collectively defend a territory which ensures maximum access to females—this is unlike the behaviour of the male lion who mates with a particular group (pride) of females. In most cases, a coalition will consist of brothers born in the same litter who stayed together after weaning, but biologically unrelated males are often allowed into the group; in the Serengeti, 30% of members in coalitions are unrelated males. If a cub is the only male in a litter, he will typically join an existing group, or form a small group of solitary males with two or three other lone males who may or may not be territorial. In the Kalahari Desert around 40% of the males live in solitude.
Males in a coalition are affectionate toward each other, grooming mutually and calling out if any member is lost; unrelated males may face some aversion in their initial days in the group. All males in the coalition typically have equal access to kills when the group hunts together, and possibly also to females who may enter their territory. A coalition generally has a greater chance of encountering and acquiring females for mating; however, its large membership demands greater resources than do solitary males. A 1987 study showed that solitary and grouped males have a nearly equal chance of coming across females, but the males in coalitions are notably healthier and have better chances of survival than their solitary counterparts.
Home ranges and territories
Unlike many other felids, among cheetahs, females tend to occupy larger areas compared to males. Females typically disperse over large areas in pursuit of prey, but they are less nomadic and roam in a smaller area if prey availability in the area is high. As such, the size of their home range depends on the distribution of prey in a region. In central Namibia, where most prey species are sparsely distributed, home ranges average , whereas in the woodlands of the Phinda Game Reserve (South Africa), which have plentiful prey, home ranges are in size. Cheetahs can travel long stretches overland in search of food; a study in the Kalahari Desert recorded an average displacement of nearly every day and walking speeds ranged between . | Cheetah | Wikipedia | 446 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Males are generally less nomadic than females; often males in coalitions (and sometimes solitary males staying far from coalitions) establish territories. Whether males settle in territories or disperse over large areas forming home ranges depends primarily on the movements of females. Territoriality is preferred only if females tend to be more sedentary, which is more feasible in areas with plenty of prey. Some males, called floaters, switch between territoriality and nomadism depending on the availability of females. A 1987 study showed territoriality depended on the size and age of males and the membership of the coalition. The ranges of floaters averaged in the Serengeti to in central Namibia. In the Kruger National Park (South Africa) territories were much smaller. A coalition of three males occupied a territory measuring , and the territory of a solitary male measured . When a female enters a territory, the males will surround her; if she tries to escape, the males will bite or snap at her. Generally, the female can not escape on her own; the males themselves leave after they lose interest in her. They may smell the spot she was sitting or lying on to determine if she was in oestrus.
Communication
The cheetah is a vocal felid with a broad repertoire of calls and sounds; the acoustic features and the use of many of these have been studied in detail. The vocal characteristics, such as the way they are produced, are often different from those of other cats. For instance, a study showed that exhalation is louder than inhalation in cheetahs, while no such distinction was observed in the domestic cat. Listed below are some commonly recorded vocalisations observed in cheetahs: | Cheetah | Wikipedia | 340 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Chirping: A chirp (or a "stutter-bark") is an intense bird-like call and lasts less than a second. Cheetahs chirp when they are excited, for instance, when gathered around a kill. Other uses include summoning concealed or lost cubs by the mother, or as a greeting or courtship between adults. The cheetah's chirp is similar to the soft roar of the lion, and its churr as the latter's loud roar. A similar but louder call ('yelp') can be heard from up to away; this call is typically used by mothers to locate lost cubs, or by cubs to find their mothers and siblings.
Churring (or churtling): A churr is a shrill, staccato call that can last up to two seconds. Churring and chirping have been noted for their similarity to the soft and loud roars of the lion. It is produced in similar context as chirping, but a study of feeding cheetahs found chirping to be much more common.
Purring: Similar to purring in domestic cats but much louder, it is produced when the cheetah is content, and as a form of greeting or when licking one another. It involves continuous sound production alternating between egressive and ingressive airstreams.
Agonistic sounds: These include bleating, coughing, growling, hissing, meowing and moaning (or yowling). A bleat indicates distress, for instance when a cheetah confronts a predator that has stolen its kill. Growls, hisses and moans are accompanied by multiple, strong hits on the ground with the front paw, during which the cheetah may retreat by a few metres. A meow, though a versatile call, is typically associated with discomfort or irritation.
Other vocalisations: Individuals can make a gurgling noise as part of a close, amicable interaction. A "nyam nyam" sound may be produced while eating. Apart from chirping, mothers can use a repeated "ihn ihn" is to gather cubs, and a "prr prr" is to guide them on a journey. A low-pitched alarm call is used to warn the cubs to stand still. Bickering cubs can let out a "whirr"—the pitch rises with the intensity of the quarrel and ends on a harsh note. | Cheetah | Wikipedia | 503 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Another major means of communication is by scent—the male will often raise his tail and spray urine on elevated landmarks such as a tree trunks, stumps or rocks; other cheetahs will sniff these landmarks and repeat the ritual. Females may also show marking behaviour but less prominently than males do. Females in oestrus will show maximum urine-marking, and their excrement can attract males from far off. In Botswana, cheetahs are frequently captured by ranchers to protect livestock by setting up traps in traditional marking spots; the calls of the trapped cheetah can attract more cheetahs to the place.
Touch and visual cues are other ways of signalling in cheetahs. Social meetings involve mutual sniffing of the mouth, anus and genitals. Individuals will groom one another, lick each other's faces and rub cheeks. However, they seldom lean on or rub their flanks against each other. The tear streaks on the face can sharply define expressions at close range. Mothers probably use the alternate light and dark rings on the tail to signal their cubs to follow them.
Diet and hunting
The cheetah is a carnivore that hunts small to medium-sized prey weighing , but mostly less than . Its primary prey are medium-sized ungulates. They are the major component of the diet in certain areas, such as Dama and Dorcas gazelles in the Sahara, impala in the eastern and southern African woodlands, springbok in the arid savannas to the south and Thomson's gazelle in the Serengeti. Smaller antelopes like the common duiker are frequent prey in the southern Kalahari. Larger ungulates are typically avoided, though nyala, whose males weigh around , were found to be the major prey in a study in the Phinda Game Reserve. In Namibia cheetahs are the major predators of livestock. The diet of the Asiatic cheetah consists of chinkara, desert hare, goitered gazelle, urial, wild goats, and livestock; in India cheetahs used to prey mostly on blackbuck. | Cheetah | Wikipedia | 426 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Prey preferences and hunting success vary with the age, sex and number of cheetahs involved in the hunt and on the vigilance of the prey. Generally, only groups of cheetahs (coalitions or mother and cubs) will try to kill larger prey; mothers with cubs especially look out for larger prey and tend to be more successful than females without cubs. Individuals on the periphery of the prey herd are common targets; vigilant prey which would react quickly on seeing the cheetah are not preferred.
Cheetahs are one of the most iconic pursuit predators, hunting primarily throughout the day, sometimes with peaks at dawn and dusk; they tend to avoid larger predators like the primarily nocturnal lion. Cheetahs in the Sahara and Maasai Mara in Kenya hunt after sunset to escape the high temperatures of the day. Cheetahs use their vision to hunt instead of their sense of smell; they keep a lookout for prey from resting sites or low branches. The cheetah will stalk its prey, trying to conceal itself in cover, and approach as close as possible, often within of the prey (or even closer for less alert prey). Alternatively the cheetah can lie hidden in cover and wait for the prey to come nearer. A stalking cheetah assumes a partially crouched posture, with the head lower than the shoulders; it will move slowly and be still at times. In areas of minimal cover, the cheetah will approach within of the prey and start the chase. The chase typically lasts a minute; in a 2013 study, the length of chases averaged , and the longest run measured . The cheetah can give up the chase if it is detected by the prey early or if it cannot make a kill quickly. Being lightly built, cheetahs lack the raw strength to tackle down the prey, and instead catch the prey by performing a kind of foot sweep by hitting the prey's leg or rump with the forepaw or using the strong dewclaw to knock the prey off its balance. Such a fall during a high-speed chase may cause the prey to collapse hard enough to break some of its limbs, and allow the cheetah to then pounce on the fallen and vulnerable prey. | Cheetah | Wikipedia | 452 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Cheetahs can decelerate dramatically towards the end of the hunt, slowing down from to in just three strides, and can easily follow any twists and turns the prey makes as it tries to flee. To kill medium- to large-sized prey, the cheetah bites the prey's throat to strangle it, maintaining the bite for around five minutes, within which the prey succumbs to asphyxiation and stops struggling. A bite on the nape of the neck or the snout (and sometimes on the skull) suffices to kill smaller prey. Cheetahs have an average hunting success rate of 25–40%, higher for smaller and more vulnerable prey.
Once the hunt is over, the prey is taken near a bush or under a tree; the cheetah, highly exhausted after the chase, rests beside the kill and pants heavily for five to 55 minutes. Meanwhile, cheetahs nearby, who did not take part in the hunt, might feed on the kill immediately. Groups of cheetah consume the kill peacefully, though minor noises and snapping may be observed. Cheetahs can consume large quantities of food; a cheetah at the Etosha National Park (Namibia) was found to consume as much as within two hours. However, on a daily basis, a cheetah feeds on around of meat. Cheetahs, especially mothers with cubs, remain cautious even as they eat, pausing to look around for vultures and predators who may steal the kill. | Cheetah | Wikipedia | 307 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Cheetahs move their heads from side to side so the sharp carnassial teeth tear the flesh, which can then be swallowed without chewing. They typically begin with the hindquarters where the tissue is the softest, and then progress toward the abdomen and the spine. Ribs are chewed on at the ends, and the limbs are not generally torn apart while eating. Unless the prey is very small, the skeleton is left almost intact after feeding on the meat. Cheetahs might lose up 13–14% of their kills to larger and stronger carnivores. To defend itself or its prey, a cheetah will hold its body low to the ground and snarl with its mouth wide open, the eyes staring threateningly ahead and the ears folded backward. This may be accompanied by moans, hisses and growls, and hitting the ground with the forepaws. Cheetahs have rarely been observed scavenging kills; this may be due to vultures and spotted hyena adroitly capturing and consuming heavy carcasses within a short time.
Cheetahs appear to have a comparatively higher hunting success rate than other predators. Their success rate for hunting Thomson gazelles is 70%, whereas the success rate of African wild dogs is 57%, of spotted hyenas 33%, and of lions 26%. Their success rate for hunting impalas is 26%, but of African wild dogs only 15.5%.
Reproduction and life cycle
The cheetah breeds throughout the year; females are polyestrous and induced ovulators with an estrous cycle of 12 days on average that can vary from three days to a month. They have their first litter at two to three years of age and can conceive again after 17 to 20 months from giving birth, or even sooner if a whole litter is lost. Males can breed at less than two years of age in captivity, but this may be delayed in the wild until the male acquires a territory. A 2007 study showed that females who gave birth to more litters early in their life often died younger, indicating a trade-off between longevity and yearly reproductive success. | Cheetah | Wikipedia | 437 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Urine-marking in males can become more pronounced when a female in their vicinity comes into estrus. Males, sometimes even those in coalitions, fight among one another to secure access to the female. Often one male will eventually win dominance over the others and mate with the female, though a female can mate with different males. Mating begins with the male approaching the female, who lies down on the ground; individuals often chirp, purr or yelp at this time. No courtship behaviour is observed; the male immediately secures hold of the female's nape, and copulation takes place. The pair then ignore each other, but meet and copulate a few more times three to five times a day for the next two to three days before finally parting ways.
After a gestation of nearly three months, a litter of one to eight cubs is born (though those of three to four cubs are more common). Births take place at 20–25 minute intervals in a sheltered place such as thick vegetation. The eyes are shut at birth, and open in four to 11 days. Newborn cubs might spit a lot and make soft churring noises; they start walking by two weeks. Their nape, shoulders and back are thickly covered with long bluish-grey hair, called a mantle, which gives them a mohawk-type appearance; this fur is shed as the cheetah grows older. A study suggested that this mane gives a cheetah cub the appearance of a honey badger, and could act as camouflage from attacks by these badgers or predators that tend to avoid them. | Cheetah | Wikipedia | 319 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Compared to other felids, cheetah cubs are highly vulnerable to several predators during the first few weeks of their life. Mothers keep their cubs hidden in dense vegetation for the first two months and nurse in the early morning. The mother is extremely vigilant at this stage; she stays within of the lair, frequently visits her cubs, moves them every five to six days, and remains with them after dark. Despite trying to make minimal noise, she cannot generally defend her litter from predators. Predation is the leading cause of mortality in cheetah cubs; a study showed that in areas with a low density of predators (such as Namibian farmlands) around 70% of the cubs make it beyond the age of 14 months, whereas in areas like the Serengeti National Park, where several large carnivores exist, the survival rate was just 17%. Deaths also occur from starvation if their mothers abandon them, fires, or pneumonia because of exposure to bad weather. Generation length of the cheetah is six years.
Cubs start coming out of the lair at two months of age, trailing after their mother wherever she goes. At this point the mother nurses less and brings solid food to the cubs; they retreat away from the carcass in fear initially, but gradually start eating it. The cubs might purr as the mother licks them clean after the meal. Weaning occurs at four to six months. To train her cubs in hunting, the mother will catch and let go of live prey in front of her cubs. Cubs' play behaviour includes chasing, crouching, pouncing and wrestling; there is plenty of agility, and attacks are seldom lethal. Playing can improve catching skills in cubs, though the ability to crouch and hide may not develop remarkably.
Cubs as young as six months try to capture small prey like hares and young gazelles. However, they may have to wait until as long as 15 months of age to make a successful kill on their own. At around 20 months, offspring become independent; mothers might have conceived again by then. Siblings may remain together for a few more months before parting ways. While females stay close to their mothers, males move farther off. The lifespan of wild cheetahs is 14 to 15 years for females, and their reproductive cycle typically ends by 12 years of age; males generally live as long as ten years.
Distribution and habitat | Cheetah | Wikipedia | 487 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In eastern and southern Africa, the cheetah occurs mostly in savannas like the Kalahari and Serengeti. In central, northern and western Africa, it inhabits arid mountain ranges and valleys; in the harsh climate of the Sahara, it prefers high mountains, which receive more rainfall than the surrounding desert. The vegetation and water resources in these mountains support antelopes. In Iran, it occurs in hilly terrain of deserts at elevations up to , where annual precipitation is generally below ; the primary vegetation in these areas is thinly distributed shrubs, less than tall.
The cheetah inhabits a variety of ecosystems and appears to be less selective in habitat choice than other felids; it prefers areas with greater availability of prey, good visibility and minimal chances of encountering larger predators. It seldom occurs in tropical forests. It has been reported at the elevation of . An open area with some cover, such as diffused bushes, is probably ideal for the cheetah because it needs to stalk and pursue its prey over a distance. This also minimises the risk of encountering larger carnivores. The cheetah tends to occur in low densities typically between 0.3 and 3.0 adults per ; these values are 10–30% of those reported for leopards and lions.
Historical range
In prehistoric times, the cheetah was distributed throughout Africa, Asia and Europe. It gradually fell to extinction in Europe, possibly because of competition with the lion. Today the cheetah has been extirpated in most of its historical range; the numbers of the Asiatic cheetah had begun plummeting since the late 1800s, long before the other subspecies started their decline. As of 2017, cheetahs occur in just nine per cent of their erstwhile range in Africa, mostly in unprotected areas. | Cheetah | Wikipedia | 374 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In the past until the mid-20th century, the cheetah ranged across vast stretches in Asia, from the Arabian Peninsula in the west to the Indian subcontinent in the east, and as far north as the Aral and Caspian Seas. A few centuries ago the cheetah was abundant in India, and its range coincided with the distribution of major prey like the blackbuck. However, its numbers in India plummeted from the 19th century onward; Divyabhanusinh of the Bombay Natural History Society notes that the last three individuals in the wild were killed by Maharaja Ramanuj Pratap Singh of Surguja in 1947. The last confirmed sighting in India was of a cheetah that drowned in a well near Hyderabad in 1957. In Iran there were around 400 cheetahs before World War II, distributed across deserts and steppes to the east and the borderlands with Iraq to the west; the numbers were falling because of a decline in prey. In Iraq, cheetahs were reported from Basra in the 1920s. Conservation efforts in the 1950s stabilised the population, but prey species declined again in the wake of the Iranian Revolution (1979) and the Iran–Iraq War (1980–1988), leading to a significant contraction of the cheetah's historical range in the region.
In 1975, the cheetah population was estimated at 15,000 individuals throughout Sub-Saharan Africa, following the first survey in this region by Norman Myers. The range covered most of eastern and southern Africa, except for the desert region on the western coast of modern-day Angola and Namibia. In the following years, cheetah populations across the region have become smaller and more fragmented as their natural habitat has been modified dramatically. | Cheetah | Wikipedia | 353 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Present distribution
The cheetah occurs mostly in eastern and southern Africa; its presence in Asia is limited to the central deserts of Iran, though there have been unconfirmed reports of sightings in Afghanistan, Iraq and Pakistan in the last few decades. The global population of cheetahs was estimated at nearly 7,100 mature individuals in 2016. The Iranian population appears to have decreased from 60–100 individuals in 2007 to 43 in 2016, distributed in three subpopulations over less than in Iran's central plateau. The largest population of nearly 4,000 individuals is sparsely distributed over Angola, Botswana, Mozambique, Namibia, South Africa and Zambia. Another population in Kenya and Tanzania comprises about 1,000 individuals. All other cheetahs occur in small, fragmented groups of less than 100 individuals each. Populations are thought to be declining.
Threats
The cheetah is threatened by several factors, like habitat loss and fragmentation of populations. Habitat loss is caused mainly by the introduction of commercial land use, such as agriculture and industry. It is further aggravated by ecological degradation, like woody plant encroachment, which is common in southern Africa. Moreover, the species apparently requires a sizeable area to live in as indicated by its low population densities. Shortage of prey and conflict with other species such as humans and large carnivores are other major threats. The cheetah appears to be less capable of coexisting with humans than the leopard. With 76% of its range consisting of unprotected land, the cheetah is often targeted by farmers and pastoralists who attempt to protect their livestock, especially in Namibia. Illegal wildlife trade and trafficking is another problem in some places (like Ethiopia). Some tribes, like the Maasai people in Tanzania, have been reported to use cheetah skins in ceremonies. Roadkill is another threat, especially in areas where roads have been constructed near natural habitat or protected areas. Cases of roadkill involving cheetahs have been reported from Kalmand, Touran National Park, and Bafq in Iran. The reduced genetic variability makes cheetahs more vulnerable to diseases; however, the threat posed by infectious diseases may be minor, given the low population densities and hence a reduced chance of infection.
Conservation
The cheetah has been classified as Vulnerable by the IUCN; it is listed under AppendixI of the CMS and AppendixI of CITES. The Endangered Species Act enlists the cheetah as Endangered.
In Africa | Cheetah | Wikipedia | 504 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Until the 1970s, cheetahs and other carnivores were frequently killed to protect livestock in Africa. Gradually the understanding of cheetah ecology increased and their falling numbers became a matter of concern. The De Wildt Cheetah and Wildlife Centre was set up in 1971 in South Africa to provide care for wild cheetahs regularly trapped or injured by Namibian farmers. By 1987, the first major research project to outline cheetah conservation strategies was underway. The Cheetah Conservation Fund, founded in 1990 in Namibia, put efforts into field research and education about cheetahs on the global platform. The CCF runs a cheetah genetics laboratory, the only one of its kind, in Otjiwarongo (Namibia); "Bushblok" is an initiative to restore habitat systematically through targeted bush thinning and biomass utilisation. Several more cheetah-specific conservation programmes have since been established, like Cheetah Outreach in South Africa.
The Global Cheetah Action Plan Workshop in 2002 laid emphasis on the need for a range-wide survey of wild cheetahs to demarcate areas for conservation efforts and on creating awareness through training programs. The Range Wide Conservation Program for Cheetah and African Wild Dogs (RWCP) began in 2007 as a joint initiative of the IUCN Cat and Canid Specialist Groups, the Wildlife Conservation Society and the Zoological Society of London. National conservation plans have been developed successfully for several African countries. In 2014, the CITES Standing Committee recognised the cheetah as a "species of priority" in their strategies in northeastern Africa to counter wildlife trafficking. In December 2016 the results of an extensive survey detailing the distribution and demography of cheetahs throughout the range were published; the researchers recommended listing the cheetah as Endangered on the IUCN Red List.
The cheetah was reintroduced in Malawi in 2017.
In Asia | Cheetah | Wikipedia | 381 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
In 2001, the Iranian government collaborated with the CCF, the IUCN, Panthera Corporation, UNDP and the Wildlife Conservation Society on the Conservation of Asiatic Cheetah Project (CACP) to protect the natural habitat of the Asiatic cheetah and its prey. In 2004, the Iranian Centre for Sustainable Development (CENESTA) conducted an international workshop to discuss conservation plans with local stakeholders. Iran declared 31August as National Cheetah Day in 2006. The Iranian Cheetah Strategic Planning meet in 2010 formulated a five-year conservation plan for Asiatic cheetahs. The CACP Phase II was implemented in 2009, and the third phase was drafted in 2018.
During the early 2000s scientists from the Centre for Cellular and Molecular Biology (Hyderabad) proposed a plan to clone Asiatic cheetahs from Iran for reintroduction in India, but Iran denied the proposal. In September 2009, the Minister of Environment and Forests assigned the Wildlife Trust of India and the Wildlife Institute of India with examining the potential of importing African cheetahs to India. Kuno Wildlife Sanctuary and Nauradehi Wildlife Sanctuary were suggested as reintroduction sites for the cheetah because of their high prey density. However, plans for reintroduction were stalled in May 2012 by the Supreme Court of India because of a political dispute and concerns over introducing a non-native species to the country. Opponents stated the plan was "not a case of intentional movement of an organism into a part of its native range". On 28 January 2020, the Supreme Court allowed the central government to introduce cheetahs to a suitable habitat in India on an experimental basis to see if they can adapt to it. In 2020, India signed a memorandum of understanding with Namibia as part of Project Cheetah. In July 2022, it was announced that eight cheetahs would be transferred from Namibia to India in August. The eight cheetahs were released into Kuno on 17 September 2022, by Prime Minister Narendra Modi. Since their introduction, 17 cubs have been born in India. However, as of September 2024, eight adult cheetahs and four cubs have already died.
Interaction with humans
Taming | Cheetah | Wikipedia | 443 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The cheetah shows little aggression toward humans, and can be tamed easily, as it has been since antiquity. The earliest known depictions of the cheetah are from the Chauvet Cave in France, dating back to 32,000–26,000 BC. According to historians such as Heinz Friederichs and Burchard Brentjes, the cheetah was first tamed in Sumer and this gradually spread out to central and northern Africa, from where it reached India. The evidence for this is mainly pictorial; for instance, a Sumerian seal dating back to , featuring a long-legged leashed animal has fueled speculation that the cheetah was first tamed in Sumer. However, Thomas Allsen argues that the depicted animal might be a large dog. Other historians, such as Frederick Zeuner, have opined that ancient Egyptians were the first to tame the cheetah, from where it gradually spread into central Asia, Iran and India.
In comparison, theories of the cheetah's taming in Egypt are stronger and include timelines proposed on this basis. Mafdet, one of the ancient Egyptian deities worshiped during the First Dynasty (3100–2900BC), was sometimes depicted as a cheetah. Ancient Egyptians believed the spirits of deceased pharaohs were taken away by cheetahs. Reliefs in the Deir el-Bahari temple complex tell of an expedition by Egyptians to the Land of Punt during the reign of Hatshepsut (1507–1458BC) that fetched, among other things, animals called "panthers". During the New Kingdom (16th to 11th centuries BC), cheetahs were common pets for royalty, who adorned them with ornate collars and leashes. Rock carvings depicting cheetahs dating back to 2000–6000 years ago have been found in Twyfelfontein; little else has been discovered in connection to the taming of cheetahs (or other cats) in southern Africa. | Cheetah | Wikipedia | 408 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Hunting cheetahs are known in pre-Islamic Arabic art from Yemen. Hunting with cheetahs became more prevalent toward the seventh centuryAD. In the Middle East, the cheetah would accompany the nobility to hunts in a special seat on the back of the saddle. Taming was an elaborate process and could take a year to complete. The Romans may have referred to the cheetah as the () or (), believing it to be a hybrid between a leopard and a lion because of the mantle seen in cheetah cubs and the difficulty of breeding them in captivity. A Roman hunting cheetah is depicted in a 4th-century mosaic from Lod, Israel. Cheetahs continued to be used into the Byzantine period of the Roman empire, with "hunting leopards" being mentioned in the Cynegetica (283/284 AD).
In eastern Asia, records are confusing as regional names for the leopard and the cheetah may be used interchangeably. The earliest depiction of cheetahs from eastern Asia dates back to the Tang dynasty (7th to 10th centuriesAD); paintings depict tethered cheetahs and cheetahs mounted on horses. Chinese emperors would use cheetahs and caracals as gifts. In the 13th and 14th centuries, the Yuan rulers bought numerous cheetahs from the western parts of the empire and from Muslim merchants. According to the , the subsequent Ming dynasty (14th to 17th centuries) continued this practice. Tomb figurines from the Mongol empire, dating back to the reign of Kublai Khan (1260–1294AD), represent cheetahs on horseback. The Mughal ruler Akbar the Great (1556–1605AD) is said to have kept as many as 1000 khasa (imperial) cheetahs. His son Jahangir wrote in his memoirs, Tuzk-e-Jahangiri, that only one of them gave birth. Mughal rulers trained cheetahs and caracals in a similar way as the western Asians, and used them to hunt game, especially blackbuck. The rampant hunting severely affected the populations of wild animals in India; by 1927, cheetahs had to be imported from Africa.
In captivity | Cheetah | Wikipedia | 452 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The first cheetah to be brought into captivity in a zoo was at the Zoological Society of London in 1829. Early captive cheetahs showed a high mortality rate, with an average lifespan of 3–4 years. After trade of wild cheetahs was delimited by the enforcement of CITES in 1975, more efforts were put into breeding in captivity; in 2014 the number of captive cheetahs worldwide was estimated at 1730 individuals, with 87% born in captivity.
Mortality under captivity is generally high; in 2014, 23% of the captive cheetahs worldwide died under one year of age, mostly within a month of birth. Deaths result from several reasons—stillbirths, birth defects, cannibalism, hypothermia, maternal neglect, and infectious diseases. Compared to other felids, cheetahs need specialised care because of their higher vulnerability to stress-induced diseases; this has been attributed to their low genetic variability and factors of captive life. Common diseases of cheetahs include feline herpesvirus, feline infectious peritonitis, gastroenteritis, glomerulosclerosis, leukoencephalopathy, myelopathy, nephrosclerosis and veno-occlusive disease. High density of cheetahs in a place, closeness to other large carnivores in enclosures, improper handling, exposure to public and frequent movement between zoos can be sources of stress for cheetahs. Recommended management practices for cheetahs include spacious and ample access to outdoors, stress minimisation by exercise and limited handling, and following proper hand-rearing protocols (especially for pregnant females).
Wild cheetahs are far more successful breeders than captive cheetahs; this has also been linked to increased stress levels in captive individuals. In a study in the Serengeti, females were found to have a 95% success rate in breeding, compared to 20% recorded for North American captive cheetahs in another study. On 26 November 2017, a female cheetah gave birth to eight cubs in the Saint Louis Zoo, setting a record for the most births recorded by the Association of Zoos and Aquariums. Chances of successful mating in captive males can be improved by replicating social groups such as coalitions observed in the wild. | Cheetah | Wikipedia | 472 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Attacks on humans
There are no documented records of lethal attacks on humans by wild cheetahs. However, there have been instances of people being fatally mauled by captive cheetahs. In 2007, a 37-year-old woman from Antwerp was killed by a cheetah in a Belgian zoo after sneaking into its cage outside of visiting hours. In 2017, a three-year-old child was attacked by a captive cheetah on a farm in Philippolis, South Africa. Despite being airlifted to a hospital in Bloemfontein, the boy died from his injuries.
In culture
The cheetah has been widely portrayed in a variety of artistic works. In Bacchus and Ariadne, an oil painting by the 16th-century Italian painter Titian, the chariot of the Greek god Dionysus (Bacchus) is depicted as being drawn by two cheetahs. The cheetahs in the painting were previously considered to be leopards. In 1764, English painter George Stubbs commemorated the gifting of a cheetah to George III by the English Governor of Madras, Sir George Pigot in his painting Cheetah with Two Indian Attendants and a Stag. The painting depicts a cheetah, hooded and collared by two Indian servants, along with a stag it was supposed to prey upon. The 1896 painting The Caress by the 19th-century Belgian symbolist painter Fernand Khnopff is a representation of the myth of Oedipus and the Sphinx and portrays a creature with a woman's head and a cheetah's body.
Two cheetahs are depicted standing upright and supporting a crown in the coat of arms of the Free State (South Africa).
In 1969, Joy Adamson, of Born Free fame, wrote The Spotted Sphinx, a biography of her pet cheetah Pippa. Hussein, An Entertainment, a novel by Patrick O'Brian set in the British Raj period in India, illustrates the practice of royalty keeping and training cheetahs to hunt antelopes. The book How It Was with Dooms tells the true story of a family raising an orphaned cheetah cub named Dooms in Kenya. The 2005 film Duma was based loosely on this book. The animated series ThunderCats had a character named "Cheetara", an anthropomorphic cheetah, voiced by Lynne Lipton. Comic book heroine Wonder Woman's chief adversary is Barbara Ann Minerva alias The Cheetah. | Cheetah | Wikipedia | 508 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
The Bill Thomas Cheetah American racing car, a Chevrolet-based coupe first designed and driven in 1963, was an attempt to challenge Carroll Shelby's Shelby Cobra in American sports car competition of the 1960s. Because only two dozen or fewer chassis were built, with only a dozen complete cars, the Cheetah was never homologated for competition beyond prototype status; its production ended in 1966. In 1986, Frito-Lay introduced Chester Cheetah, an anthropomorphic cheetah, as the mascot for their snack food Cheetos. The Mac OS X 10.0 was code-named "Cheetah". | Cheetah | Wikipedia | 130 | 45609 | https://en.wikipedia.org/wiki/Cheetah | Biology and health sciences | Carnivora | null |
Nightjars are medium-sized nocturnal or crepuscular birds in the family Caprimulgidae and order Caprimulgiformes, characterised by long wings, short legs, and very short bills. They are sometimes called bugeaters, their primary source of food being insects. Some New World species are called nighthawks. The English word nightjar originally referred to the European nightjar.
Nightjars are found all around the world, with the exception of Antarctica, and certain island groups such as the Seychelles. They can be found in a variety of habitats, most commonly the open country with some vegetation. They usually nest on the ground, with a habit of resting and roosting on roads.
The subfamilies of nightjars have similar characteristics, including small feet, of little use for walking, and long, pointed wings. Typical nightjars have rictal bristles, longer bills, and softer plumage. The colour of their plumage and their unusual perching habits help conceal them during the day.
Systematics
Caprimulgiformes
Previously, all members of the orders Apodiformes, Aegotheliformes, Nyctibiiformes, Podargiformes, and Steatornithiformes were lumped alongside nightjars in the Caprimulgiformes. In 2021, the International Ornithological Congress redefined the Caprimulgiformes as only applying to nightjars, with potoos, frogmouths, oilbirds, and owlet-nightjars all being reclassified into their own orders. See Strisores for more info about the disputes over the taxonomy of Caprimulgiformes. A phylogenetic analysis found that the extinct family Archaeotrogonidae, known from the Eocene and Oligocene of Europe, are the closest known relatives of nightjars. | Nightjar | Wikipedia | 384 | 45648 | https://en.wikipedia.org/wiki/Nightjar | Biology and health sciences | Caprimulgiformes | null |
Caprimulgidae
Traditionally, nightjars have been divided into two subfamilies—the Caprimulginae, or typical nightjars with 79 known species, and the Chordeilinae, or nighthawks of the New World, with 10 known species. The groups are similar in most respects, but the typical nightjars have rictal bristles, longer bills, and softer plumage. The underside of the claw of the middle toe is comb-like with serrations. Their soft plumage is cryptically coloured to resemble bark or leaves, and some species, unusual for birds, perch along a branch rather than across it, helping to conceal them during the day. The subfamilies of nightjars have similar characteristics, including small feet, of little use for walking, and long, pointed wings.
The common poorwill, Phalaenoptilus nuttallii, is unique as a bird that undergoes a form of hibernation, becoming torpid and with a much reduced body temperature for weeks or months, although other nightjars can enter a state of torpor for shorter periods.
In their pioneering DNA–DNA hybridisation work, Charles Sibley and Jon E. Ahlquist found that the genetic difference between the eared nightjars and the typical nightjars was, in fact, greater than that between the typical nightjars and the nighthawks of the New World. Accordingly, they placed the eared nightjars in a separate family, the Eurostopodidae (9 known species), but the family has not yet been widely adopted.
Subsequent work, both morphological and genetic, has provided support for the separation of the typical and the eared nightjars, and some authorities have adopted this Sibley–Ahlquist recommendation, and also the more far-reaching one to group all the owls (traditionally Strigiformes) together in the Caprimulgiformes. The listing below retains a more orthodox arrangement, but recognises the eared nightjars as a separate group. For more detail and an alternative classification scheme, see Caprimulgiformes and Sibley–Ahlquist taxonomy. | Nightjar | Wikipedia | 441 | 45648 | https://en.wikipedia.org/wiki/Nightjar | Biology and health sciences | Caprimulgiformes | null |
†Ventivorus Mourer-Chauviré 1988
Subfamily Eurostopodinae
Genus Eurostopodus (7 species)
Genus Lyncornis (2 species)
Subfamily Caprimulginae (typical nightjars)
Genus Gactornis – collared nightjar
Genus Nyctipolus (2 species)
Genus Nyctidromus (2 species)
Genus Hydropsalis (4 species)
Genus Siphonorhis (2 species)
Genus Nyctiphrynus (4 species)
Genus Phalaenoptilus – common poorwill
Genus Antrostomus (12 species)
Genus Caprimulgus (40 species, including the European nightjar)
Genus Setopagis (4 species)
Genus Uropsalis (2 species)
Genus Macropsalis – long-trained nightjar
Genus Eleothreptus (2 species)
Genus Systellura (2 species)
Subfamily Chordeilinae (nighthawks)
Genus Chordeiles (6 species; includes Podager)
Genus Nyctiprogne (2 species)
Genus Lurocalis (2 species)
Also see a list of nightjars, sortable by common and binomial names.
Distribution and habitat
Nightjars inhabit all continents other than Antarctica, as well as some island groups such as Madagascar, the Seychelles, New Caledonia and the islands of Caribbean. They are not known to live in extremely arid desert regions. Nightjars can occupy all elevations from sea level to , and a number of species are montane specialists. Nightjars occupy a wide range of habitats, from deserts to rainforests but are most common in open country with some vegetation.
The nighthawks are confined to the New World, and the eared nightjars to Asia and Australia.
A number of species undertake migrations, although the secretive nature of the family may account for the incomplete understanding of their migratory habits. Species that live in the far north, such as the European nightjar or the common nighthawk, migrate southward with the onset of winter. Geolocators placed on European nightjars in southern England found they wintered in the south of the Democratic Republic of the Congo. Other species make shorter migrations.
Conservation and status
Some species of nightjars are threatened with extinction. Road-kills of this species by cars are thought to be a major cause of mortality for many members of the family because of their habit of resting and roosting on roads. | Nightjar | Wikipedia | 494 | 45648 | https://en.wikipedia.org/wiki/Nightjar | Biology and health sciences | Caprimulgiformes | null |
They also usually nest on the ground, laying one or two patterned eggs directly onto bare ground. Nightjars possibly move their eggs and chicks from the nesting site in the event of danger by carrying them in their mouths. This suggestion has been repeated many times in ornithology books, but surveys of nightjar research have found very little evidence to support this idea.
Developing conservation strategies for some species presents a particular challenge in that scientists do not have enough data to determine whether or not a species is endangered due to the difficulty in locating, identifying, and/or categorizing their limited number (e.g. 10,000) known to exist, a good example being the Vaurie's nightjar in China's south-western Xinjiang Province (as seen only once in-hand). Surveys in the 1970s and 1990s failed to find the species., implying that the species has become extinct, endangered, or found only in a few small areas. | Nightjar | Wikipedia | 196 | 45648 | https://en.wikipedia.org/wiki/Nightjar | Biology and health sciences | Caprimulgiformes | null |
In history and popular culture
Nighthawk as a name has been applied to numerous places, characters, and objects throughout history.
Nebraska's state nickname was once the "Bugeater State" and its people were sometimes called "bugeaters" (presumably named after the common nighthawk). The Nebraska Cornhuskers college athletic teams were also briefly known the Bugeaters, before adopting their current name, also adopted by the state as a whole. A semi-professional soccer team in Nebraska now uses the Bugeaters moniker.
Nightjars feature prominently in the lyrics of the Elton John/Bernie Taupin song "Come Down in Time": "While a cluster of nightjars sang some songs out of tune". Sting, in an interview about this song and about Elton John, said, "It's a very beautiful song. ... I love Bernie's lyrics ... It is one of those songs you wish you had written...."
They are also featured prominently in the lyrics of Joanna Newsom's bird-heavy fourth album Divers; the opening track "Anecdotes" name-checks four different varieties (Rufous, Whip-poor-will, Star-Spotted and Sickle-Winged) and the final track ends with a repeated radio transmission to the fictional soldier Rufous Nightjar.
The Welsh name for the nightjar is "Troellwr Mawr", meaning "big spinner", referring to its whirling sound (the grass warbler is named "Troellwr Bach"). | Nightjar | Wikipedia | 322 | 45648 | https://en.wikipedia.org/wiki/Nightjar | Biology and health sciences | Caprimulgiformes | null |
Eggplant (US, CA, AU, NZ, PH), aubergine (UK, IE), brinjal (IN, SG, MY, ZA), or baigan (IN, GY) is a plant species in the nightshade family Solanaceae. Solanum melongena is grown worldwide for its edible fruit.
Most commonly purple, the spongy, absorbent fruit is used in several cuisines. Typically used as a vegetable in cooking, it is a berry by botanical definition. As a member of the genus Solanum, it is related to the tomato, chili pepper, and potato, although those are of the New World while the eggplant is of the Old World. Like the tomato, its skin and seeds can be eaten, but it is usually eaten cooked. Eggplant is nutritionally low in macronutrient and micronutrient content, but the capability of the fruit to absorb oils and flavors into its flesh through cooking expands its use in the culinary arts.
It was originally domesticated from the wild nightshade species thorn or bitter apple, S. incanum, probably with two independent domestications: one in South Asia, and one in East Asia. In 2021, world production of eggplants was 59 million tonnes, with China and India combined accounting for 86% of the total.
Description
The eggplant is a delicate, tropical perennial plant often cultivated as a tender or half-hardy annual in temperate climates. The stem is often spiny. The flowers are white to purple in color, with a five-lobed corolla and yellow stamens. Some common cultivars have fruit that is egg-shaped, glossy, and purple with white flesh and a spongy, "meaty" texture. Some other cultivars are white and longer in shape. The cut surface of the flesh rapidly turns brown when the fruit is cut open (oxidation).
Eggplant grows tall, with large, coarsely lobed leaves that are long and broad. Semiwild types can grow much larger, to , with large leaves over long and broad. On wild plants, the fruit is less than in diameter
Botanically classified as a berry, the fruit contains numerous small, soft, edible seeds that taste bitter because they contain or are covered in nicotinoid alkaloids, like the related tobacco.
The eggplant genome has 12 chromosomes.
History | Eggplant | Wikipedia | 496 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
There is no consensus about the place of origin of eggplant; the plant species has been described as native to South Asia, where it continues to grow wild, or Africa. It has been cultivated in southern and eastern Asia since prehistory. The first known written record of the plant is found in Qimin Yaoshu, an ancient Chinese agricultural treatise completed in 544 CE.
Eggplant was introduced to Europe through the Iberian Peninsula, where it became a staple among Muslim and Jewish communities. The presence of numerous Arabic and North African names for the vegetable, coupled with the absence of ancient Greek and Roman names, suggests that it was cultivated in the Mediterranean area by Arabs during the early Middle Ages, arriving in Spain in the 8th century. A book on agriculture by Ibn Al-Awwam in 12th-century Muslim Spain described how to grow aubergines. Records exist from later medieval Catalan and Spanish, as well as from 14th-century Italy. Unlike its popularity in Spain and limited presence in southern Italy, the eggplant remained relatively obscure in other regions of Europe until the 17th century.
The aubergine is unrecorded in England until the 16th century. An English botany book in 1597 described the madde or raging Apple:
The Europeans brought it to the Americas.
Because of the plant's relationship with various other nightshades, the fruit was at one time believed to be extremely poisonous. The flowers and leaves can be poisonous if consumed in large quantities due to the presence of solanine.
The eggplant has a special place in folklore. In 13th-century Italian traditional folklore, the eggplant can cause insanity. In 19th-century Egypt, insanity was said to be "more common and more violent" when the eggplant is in season in the summer.
Etymology and regional names
The plant and fruit have a profusion of English names.
Eggplant-type names
The name eggplant is usual in North American English and Australian English. First recorded in 1763, the word "eggplant" was originally applied to white cultivars, which look very much like hen's eggs (see image). Similar names are widespread in other languages, such as the Icelandic term eggaldin or the Welsh planhigyn ŵy.
The white, egg-shaped varieties of the eggplant's fruits are also known as garden eggs, a term first attested in 1811. The Oxford English Dictionary records that between 1797 and 1888, the name vegetable egg was also used. | Eggplant | Wikipedia | 510 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Aubergine-type names
Whereas eggplant was coined in English, most of the diverse other European names for the plant derive from the bāḏinjān . Bāḏinjān is itself a loan-word in Arabic, whose earliest traceable origins lie in the Dravidian languages. The Hobson-Jobson dictionary comments that "probably there is no word of the kind which has undergone such extraordinary variety of modifications, whilst retaining the same meaning, as this".
In English usage, modern names deriving from Arabic bāḏinjān include:
Aubergine, usual in British English (as well as German, French and Dutch).
Brinjal or brinjaul, usual in South Asia and South African English.
Solanum melongena, the Linnaean name.
From Dravidian to Arabic
All the aubergine-type names have the same origin, in the Dravidian languages. Modern descendants of this ancient Dravidian word include Malayalam vaṟutina and Tamil vaṟutuṇai.
The Dravidian word was borrowed into the Indo-Aryan languages, giving ancient forms such as Sanskrit and Pali vātiṅ-gaṇa (alongside Sanskrit vātigama) and Prakrit vāiṃaṇa. According to the entry brinjal in the Oxford English Dictionary, the Sanskrit word vātin-gāna denoted 'the class (that removes) the wind-disorder (windy humour)': that is, vātin-gāna came to be the name for eggplants because they were thought to cure flatulence. The modern Hindustani words descending directly from the Sanskrit name are baingan and began.
The Indic word vātiṅ-gaṇa was then borrowed into Persian as bādingān. Persian bādingān was borrowed in turn into Arabic as bāḏinjān (or, with the definite article, al-bāḏinjān). From Arabic, the word was borrowed into European languages.
From Arabic into Iberia and beyond
In al-Andalus, the Arabic word (al-)bāḏinjān was borrowed into the Romance languages in forms beginning with b- or, with the definite article included, alb-:
Portuguese , , .
Spanish , .
The Spanish word was then borrowed into French, giving (along with French dialectal forms like , , , and ). The French name was then borrowed into British English, appearing there first in the late eighteenth century. | Eggplant | Wikipedia | 488 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Through the colonial expansion of Portugal, the Portuguese form was borrowed into a variety of other languages:
Indian, Malaysian, Singaporean and South African English brinjal, brinjaul (first attested in the seventeenth century).
West Indian English brinjalle and (through folk-etymology) brown-jolly.
French bringelle in La Réunion.
Thus although Indian English brinjal ultimately originates in languages of the Indian Subcontinent, it actually came into Indian English via Portuguese.
From Arabic into Greek and beyond
The Arabic word bāḏinjān was borrowed into Greek by the eleventh century CE. The Greek loans took a variety of forms, but crucially they began with m-, partly because Greek lacked the initial b- sound and partly through folk-etymological association with the Greek word μέλας (melas), 'black'. Attested Greek forms include ματιζάνιον (matizanion, eleventh-century), μελιντζάνα (melintzana, fourteenth-century), and μελιντζάνιον (melintzanion, seventeenth-century).
From Greek, the word was borrowed into Italian and medieval Latin, and onwards into French. Early forms include:
Melanzāna, recorded in Sicilian in the twelfth century.
Melongena, recorded in Latin in the thirteenth century.
Melongiana, recorded in Veronese in the fourteenth century.
Melanjan, recorded in Old French.
From these forms came the botanical Latin melongēna. This was used by Tournefort as a genus name in 1700, then by Linnaeus as a species name in 1753. It remains in scientific use.
These forms also gave rise to the Caribbean English melongene.
The Italian melanzana, through folk-etymology, was adapted to mela insana ('mad apple'): already by the thirteenth century, this name had given rise to a tradition that eggplants could cause insanity. Translated into English as 'mad-apple', 'rage-apple', or 'raging apple', this name for eggplants is attested from 1578 and the form 'mad-apple' may still be found in Southern American English.
Other English names
The plant is also known as guinea squash in Southern American English. The term guinea in the name originally denoted the fact that the fruits were associated with West Africa, specifically the region that is now the modern day country Guinea. | Eggplant | Wikipedia | 508 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
It has been known as 'Jew's apple', apparently in relation to a belief that the fruit was first imported to the West Indies by Jewish people.
Cultivars
Different cultivars of the plant produce fruit of different size, shape, and color, though typically purple. The less common white varieties of eggplant are also known as Easter white eggplants, garden eggs, Casper or white eggplant. The most widely cultivated varieties—cultivars—in Europe and North America today are elongated ovoid, long and broad with a dark purple skin.
A much wider range of shapes, sizes, and colors is grown in India and elsewhere in Asia. Larger cultivars weighing up to a kilogram (2.2 pounds) grow in the region between the Ganges and Yamuna Rivers, while smaller ones are found elsewhere. Colors vary from white to yellow or green, as well as reddish-purple and dark purple. Some cultivars have a color gradient—white at the stem, to bright pink, deep purple or even black. Green or purple cultivars with white striping also exist. Chinese cultivars are commonly shaped like a narrower, slightly pendulous cucumber. Also, Asian cultivars of Japanese breeding are grown.
Oval or elongated oval-shaped and black-skinned cultivars include 'Harris Special Hibush', 'Burpee Hybrid', 'Bringal Bloom', 'Black Magic', 'Classic', 'Dusky', and 'Black Beauty'.
Slim cultivars in purple-black skin include 'Little Fingers', 'Ichiban', 'Pingtung Long', and 'Tycoon'
In green skin, 'Louisiana Long Green' and 'Thai (Long) Green'
In white skin, 'Dourga'.
Traditional, white-skinned, egg-shaped cultivars include 'Casper' and 'Easter Egg'.
Bicolored cultivars with color gradient include 'Rosa Bianca', 'Violetta di Firenze', 'Bianca Sfumata di Rosa' (heirloom), and 'Prosperosa' (heirloom).
Bicolored cultivars with striping include 'Listada de Gandia' and 'Udumalapet'.
In some parts of India, miniature cultivars, most commonly called baigan, are popular. | Eggplant | Wikipedia | 492 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Varieties
S. m. var. esculentum – common aubergine, including white varieties, with many cultivars
S. m. var. depressum – dwarf aubergine
S. m. var. serpentium – snake aubergine
Genetically engineered eggplant
Bt brinjal is a transgenic eggplant that contains a gene from the soil bacterium Bacillus thuringiensis. This variety was designed to give the plant resistance to lepidopteran insects such as the brinjal fruit and shoot borer (Leucinodes orbonalis) and fruit borer (Helicoverpa armigera).
On 9 February 2010, the Environment Ministry of India imposed a moratorium on the cultivation of Bt brinjal after protests against regulatory approval of cultivated Bt brinjal in 2009, stating the moratorium would last "for as long as it is needed to establish public trust and confidence". This decision was deemed controversial, as it deviated from previous practices with other genetically modified crops in India. Bt brinjal was approved for commercial cultivation in Bangladesh in 2013.
Uses
Culinary
Raw eggplant can have a bitter taste, with an astringent quality, but it becomes tender when cooked and develops a rich, complex flavor. Rinsing, draining, and salting the sliced fruit before cooking may remove the bitterness. The fruit is capable of absorbing cooking fats and sauces, which may enhance the flavor of eggplant dishes.
Eggplant is used in the cuisines of many countries. Due to its texture and bulk, it is sometimes used as a meat substitute in vegan and vegetarian cuisines. Eggplant flesh is smooth. Its numerous seeds are small, soft and edible, along with the rest of the fruit, and do not have to be removed. Its thin skin is also edible, and so it does not have to be peeled. However, the green part at the top, the calyx, does have to be removed when preparing an eggplant for cooking.
Eggplant can be steamed, stir-fried, pan fried, deep fried, barbecued, roasted, stewed, curried, or pickled. Many eggplant dishes are sauces made by mashing the cooked fruit. It can be stuffed. It is frequently, but not always, cooked with oil or fat.
East Asia
Korean and Japanese eggplant varieties are typically thin-skinned. | Eggplant | Wikipedia | 498 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
In Chinese cuisine, eggplants are known as qiézi (). They are often deep fried and made into dishes such as yúxiāng-qiézi ("fish fragrance eggplant") or di sān xiān ("three earthen treasures"). Elsewhere in China, such as in Yunnan cuisine (in particular the cuisine of the Dai people) they are barbecued or roasted, then split and either eaten directly with garlic, chilli, oil and coriander, or the flesh is removed and pounded to a mash (typically with a wooden pestle and mortar) before being eaten with rice or other dishes.
In Japanese cuisine, eggplants are known as nasu or nasubi and use the same characters as Chinese (). An example of it use is in the dish hasamiyaki () in which slices of eggplant are grilled and filled with a meat stuffing. Eggplants also feature in several Japanese expression and proverbs, such as (because their lack of seeds will reduce her fertility) and .
In Korean cuisine, eggplants are known as gaji (). They are steamed, stir-fried, or pan-fried and eaten as banchan (side dishes), such as namul, bokkeum, and jeon.
Southeast Asia
In the Philippines, eggplants are of the long and slender purple variety. They are known as talong and is widely used in many stew and soup dishes, like pinakbet. However the most popular eggplant dish is tortang talong, an omelette made from grilling an eggplant, dipping it into beaten eggs, and pan-frying the mixture. The dish is characteristically served with the stalk attached. The dish has several variants, including rellenong talong which is stuffed with meat and vegetables. Eggplant can also be grilled, skinned and eaten as a salad called ensaladang talong. Another popular dish is adobong talong, which is diced eggplant prepared with vinegar, soy sauce, and garlic as an adobo. | Eggplant | Wikipedia | 435 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
South Asia
Eggplant is widely used in its native India, for example in sambar (a tamarind lentil stew), dalma (a dal preparation with vegetables, native to Odisha), chutney, curry (vankai), and achaar (a pickled dish). Owing to its versatile nature and wide use in both everyday and festive Indian food, it is often described as the "king of vegetables". Roasted, skinned, mashed, mixed with onions, tomatoes, and spices, and then slow cooked gives the South Asian dish baingan bharta or gojju, similar to salată de vinete in Romania. Another version of the dish, begun-pora (eggplant charred or burnt), is very popular in Bangladesh and the east Indian states of Odisha and West Bengal where the pulp of the vegetable is mixed with raw chopped shallot, green chilies, salt, fresh coriander, and mustard oil. Sometimes fried tomatoes and deep-fried potatoes are also added, creating a dish called begun bhorta. In a dish from Maharashtra called , small brinjals are stuffed with ground coconut, peanuts, onions, tamarind, jaggery and masala spices, and then cooked in oil. Maharashtra and the adjacent state of Karnataka also have an eggplant-based vegetarian pilaf called 'vangi bhat'. | Eggplant | Wikipedia | 287 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Middle East and the Mediterranean
Eggplant is often stewed, as in the French ratatouille, or deep-fried as in the Italian parmigiana di melanzane, the Turkish karnıyarık, or Turkish, Greek, and Levantine musakka/moussaka, and Middle Eastern and South Asian dishes. Eggplants can also be battered before deep-frying and served with a sauce made of tahini and tamarind. In Iranian cuisine, it is blended with whey as kashk e bademjan, tomatoes as mirza ghassemi, or made into stew as khoresht-e-bademjan. It can be sliced and deep-fried, then served with plain yogurt (optionally topped with a tomato and garlic sauce), such as in the Turkish dish patlıcan kızartması (meaning fried aubergines), or without yogurt, as in patlıcan şakşuka. Perhaps the best-known Turkish eggplant dishes are imam bayıldı (vegetarian) and karnıyarık (with minced meat). It may also be roasted in its skin until charred, so the pulp can be removed and blended with other ingredients, such as lemon, tahini, and garlic, as in the Levantine baba ghanoush, Greek melitzanosalata, Moroccan zaalouk and Romanian salată de vinete. A mix of roasted eggplant, roasted red peppers, chopped onions, tomatoes, mushrooms, carrots, celery, and spices is called zacuscă in Romania, and ajvar or pinjur in the Balkans. | Eggplant | Wikipedia | 351 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
A Spanish dish called escalivada in Catalonia calls for strips of roasted aubergine, sweet pepper, onion, and tomato. In Andalusia, eggplant is mostly cooked thinly sliced, deep-fried in olive oil and served hot with honey (berenjenas a la Cordobesa). In the La Mancha region of central Spain, a small eggplant is pickled in vinegar, paprika, olive oil, and red peppers. The result is berenjena of Almagro, Ciudad Real. A Levantine specialty is makdous, another pickling of eggplants, stuffed with red peppers and walnuts in olive oil. Eggplant can be hollowed out and stuffed with meat, rice, or other fillings, and then baked. In Georgia, for example, it is fried and stuffed with walnut paste to make nigvziani badrijani.
In medieval Spain, eggplant, along with ingredients such as Swiss chard and chickpeas, was closely associated with Jewish cuisine. The Kitāb al-Ṭabikh, a 13th-century Andalusian cookbook, features eggplant as the main ingredient in fifteen out of its nineteen vegetable dishes, indicating its significance in the local cuisine at the time. Jewish communities in Spain prepared eggplant in various ways, including in dishes like almodrote, a casserole of eggplant and cheese. This dish and others became identifiers for Jews during their expulsion from Spain and the Inquisition, and they were carried by the expelled Jews to their new homes in the Ottoman Empire. The classic Judaeo-Spanish song "Siete modos de gizar la berendgena" lists various methods of preparing eggplant that persisted among Jews in the Ottoman Empire. Today, eggplant remains a defining ingredient of Sephardic Jewish cuisine. | Eggplant | Wikipedia | 389 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Iran
In Iranian cuisine, eggplant (called bādenjān or bādemjān in Persian) can be used in both appetizers and main courses. It can also be pickled in vinegar. The ideal eggplant in Iranian cuisine is long, straight, firm, and black. Based on how al-Razi uses the color of eggplant as a shorthand for purpleness in his Kitab al-hawi, it can be assumed that the dark purple kind of eggplant was the widely grown variety in Iran at his time (9th century). Its importance in Iran is alluded to in the Ain-i-Akbari of Abu'l-Fazl ibn Mubarak, which says "this vegetable is on sale in the markets in Iran all the year round and in such abundance that it is sold for 1.5 dams per seer" (which was a cheap price at that time).
In Iran, unlike places like Greece, Turkey, and North Africa, eggplant is cooked peeled and usually seasoned with cinnamon or especially turmeric. Most eggplant dishes are classified as nankhoreshi (eaten with bread), and they are commonly served as snacks alongside alcoholic beverages. | Eggplant | Wikipedia | 250 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
The 14th-century poet Boshaq At'ema refers to an early eggplant dish called burani-e badenjan: chopped eggplant sautéed with onions and turmeric, then slowly cooked, and finally mixed with yogurt. The combination of eggplant and kashk (condensed whey) is popular in Iranian cuisine; it is found in dishes like kashk o badenjan as well as ash-e kashk o badenjan (involving layers of sautéed eggplant, grilled onions, and red beans topped by kashk seasoned with turmeric). Another eggplant dish is mast o badenjan, also known as nazkhatun in Tehran, which involves eggplant, yogurt, and dried mint. Eggplant can also be cooked in stews (khoreshes), either with lamb (khoresh-e badenjan) or with chicken and either unripe grapes or pomegranate juice (mosamma-ye badenjan). Variants of ab-gusht, eshkana, fesenjan, and kuku also make use of eggplant. Some regional dishes involving eggplant include badenjan-polow, a dish mainly from Fars and Kerman that combines white rice with a paste of chopped sautéed eggplant, chopped meat, and spices; as well as the northern Iranian badenjan-e qasemi, a casserole using grilled eggplant, garlic, tomatoes, and eggs.
Eggplants are traditionally among the foods that get preserved and stored for winter in Iran. They are selected in the last month of summer, when they are most readily available, then peeled, and finally preserved in one of two ways. In the first way, the peeled eggplants are cut, salted, and left to "sweat" (to make them less bilious); then they are sun-dried by hanging them on a line. The dried eggplants are then rehydrated 24 hours before being cooked. In the second way, the peeled eggplants are cooked in oil, put in a copper pot, and finally covered with plenty of hot oil, "which congeals to seal them". | Eggplant | Wikipedia | 471 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Medieval Iranian writers such as al-Razi and al-Biruni cautioned that eggplant contains harmful qualities, and it must be ripe and cooked before eating to neutralize them. They wrote that it could cause heat and dryness and an excess of black bile, contributing to a wide range of health problems. If the "salt" in it was removed, or it was cooked in oil or vinegar, then they wrote that eggplant gained healthy attributes. Present-day Iranian attitudes to the eggplant reflect this medical tradition's influence: the eggplant is "considered rather dangerous... a cook in Tehran will say that the poison must be taken out". People also use eggplant seeds as an expectorant to relieve asthma and catarrh.
Nutrition
Raw eggplant is 92% water, 6% carbohydrates, 1% protein, and has negligible fat (table). It provides low amounts of essential nutrients, with only manganese having a moderate percentage (10%) of the Daily Value. Minor changes in nutrient composition occur with season, environment of cultivation (open field or greenhouse), and genotype.
Cultivation and pests
In tropical and subtropical climates, eggplant can be sown in the garden. Eggplant grown in temperate climates fares better when transplanted into the garden after all danger of frost has passed. Eggplant prefers hot weather, and when grown in cold climates or in areas with low humidity, the plants languish or fail to set and produce mature fruit. Seeds are typically started eight to 10 weeks prior to the anticipated frost-free date. S. melongena is included on a list of low flammability plants, indicating that it is suitable for growing within a building protection zone.
Spacing should be between plants, depending on cultivar, and between rows, depending on the type of cultivation equipment being used. Mulching helps conserve moisture and prevent weeds and fungal diseases and the plants benefit from some shade during the hottest part of the day. Hand pollination by shaking the flowers improves the set of the first blossoms. Growers typically cut fruits from the vine just above the calyx owing to the somewhat woody stems. Flowers are complete, containing both female and male structures, and may be self- or cross-pollinated. | Eggplant | Wikipedia | 476 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Many of the pests and diseases that afflict other solanaceous plants, such as tomato, capsicum, and potato, are also troublesome to eggplants. For this reason, it should generally not be planted in areas previously occupied by its close relatives. However, since eggplants can be particularly susceptible to pests such as whiteflies, they are sometimes grown with slightly less susceptible plants, such as chili pepper, as a sacrificial trap crop. Four years should separate successive crops of eggplants to reduce pest pressure.
Common North American pests include the potato beetles, flea beetles, aphids, whiteflies, and spider mites. Good sanitation and crop rotation practices are extremely important for controlling fungal disease, the most serious of which is Verticillium.
The potato tuber moth (Phthorimaea operculella) is an oligophagous insect that prefers to feed on plants of the family Solanaceae such as eggplants. Female P. operculella use the leaves to lay their eggs and the hatched larvae will eat away at the mesophyll of the leaf.
Several different Phytoplasmas cause little leaf of brinjal, which is agriculturally significant in South Asia. This is spread by the leafhopper Hishimonus phycitis.
Production
In 2022, world production was 59 million tonnes, led by China with 65% and India with 22% (table).
Chemistry
The color of purple skin cultivars is due to the anthocyanin nasunin.
The browning of eggplant flesh results from the oxidation of polyphenols, such as the most abundant phenolic compound in the fruit, chlorogenic acid.
Allergies
Case reports of itchy skin or mouth, mild headache, and stomach upset after handling or eating eggplant have been reported anecdotally and published in medical journals (see also oral allergy syndrome). A 2021 review indicated that possibly four interacting mechanisms may elicit an allergic response from consuming eggplant: lipid transfer protein, profilin, polyphenol oxidase, and pollen reactions. | Eggplant | Wikipedia | 447 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
A 2008 study of a sample of 741 people in India, where eggplant is commonly consumed, found nearly 10% reported some allergic symptoms after consuming eggplant, with 1.4% showing symptoms within two hours. Contact dermatitis from eggplant leaves and allergy to eggplant flower pollen have also been reported.
Individuals who are atopic (genetically predisposed to developing certain allergic hypersensitivity reactions) are more likely to have a reaction to eggplant, which may be because eggplant is high in histamines. Cooking eggplant thoroughly seems to preclude reactions in some individuals, but some of the allergenic proteins may survive the cooking process.
Taxonomy
The eggplant is quite often featured in the older scientific literature under the junior synonyms S. ovigerum and S. trongum. Several other names that are now invalid have been uniquely applied to it:
Melongena ovata
Solanum album
Solanum insanum
Solanum longum
Solanum melanocarpum
Solanum melongenum
Solanum oviferum
Prachi
A number of subspecies and varieties have been named, mainly by Dikii, Dunal, and (invalidly) by Sweet. Names for various eggplant types, such as , are not considered to refer to anything more than cultivar groups at best. However, Solanum incanum and cockroach berry (S. capsicoides), other eggplant-like nightshades described by Linnaeus and Allioni, respectively, were occasionally considered eggplant varieties, but this is not correct.
The eggplant has a long history of taxonomic confusion with the scarlet and Ethiopian eggplants (Solanum aethiopicum), known as gilo and nakati, respectively, and described by Linnaeus as S. aethiopicum. The eggplant was sometimes considered a variety violaceum of that species. S. violaceum of de Candolle applies to Linnaeus' S. aethiopicum. An actual S. violaceum, an unrelated plant described by Ortega, included Dunal's S. amblymerum and was often confused with the same author's S. brownii. | Eggplant | Wikipedia | 461 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Like the potato and S. lichtensteinii, but unlike the tomato, which then was generally put in a different genus, the eggplant was also described as S. esculentum, in this case once more in the course of Dunal's work. He also recognized the varieties aculeatum, inerme, and subinerme at that time. Similarly, H.C.F. Schuhmacher and Peter Thonning named the eggplant as S. edule, which is also a junior synonym of sticky nightshade (S. sisymbriifolium). Scopoli's S. zeylanicum refers to the eggplant, and that of Blanco to S. lasiocarpum. | Eggplant | Wikipedia | 159 | 45712 | https://en.wikipedia.org/wiki/Eggplant | Biology and health sciences | Solanales | null |
Horseradish (Armoracia rusticana, syn. Cochlearia armoracia) is a perennial plant of the family Brassicaceae (which also includes mustard, wasabi, broccoli, cabbage, and radish). It is a root vegetable, cultivated and used worldwide as a spice and as a condiment. The species is probably native to Southeastern Europe and Western Asia.
Description
Horseradish grows up to tall, with hairless bright green unlobed leaves up to long that may be mistaken for docks (Rumex). It is cultivated primarily for its large, white, tapered root. The white four-petalled flowers are scented and are borne in dense panicles. Established plants may form extensive patches and may become invasive unless carefully managed.
Intact horseradish root has little aroma. When cut or grated, enzymes from within the plant cells digest sinigrin (a glucosinolate) to produce allyl isothiocyanate (mustard oil), which irritates the mucous membranes of the sinuses and eyes. Once exposed to air or heat, horseradish loses its pungency, darkens in color, and develops a bitter flavor.
History
Horseradish has been cultivated since antiquity. Dioscorides listed horseradish equally as Persicon sinapi (Diosc. 2.186) or Sinapi persicum (Diosc. 2.168), which Pliny's Natural History reported as Persicon napy; Cato discusses the plant in his treatises on agriculture. A mural in Ostia Antica shows the plant. Horseradish is probably the plant mentioned by Pliny the Elder in his Natural History under the name of Amoracia, and recommended by him for its medicinal qualities, and possibly the wild radish, or raphanos agrios of the Greeks. The early Renaissance herbalists Pietro Andrea Mattioli and John Gerard showed it under Raphanus. Its modern Linnaean genus Armoracia was first applied to it by Heinrich Bernhard Ruppius, in his Flora Jenensis, 1745, but Linnaeus himself called it Cochlearia armoracia. | Horseradish | Wikipedia | 454 | 45714 | https://en.wikipedia.org/wiki/Horseradish | Biology and health sciences | Brassicales | null |
Both roots and leaves were used as a traditional medicine during the Middle Ages. The root was used as a condiment on meats in Germany, Scandinavia, and Britain. It was introduced to North America during European colonization; both George Washington and Thomas Jefferson mention horseradish in garden accounts. Native Americans used it to stimulate the glands, stave off scurvy, and as a diaphoretic treatment for the common cold.
William Turner mentions horseradish as Red Cole in his "Herbal" (1551–1568), but not as a condiment. In The Herball, or Generall Historie of Plantes (1597), John Gerard describes it under the name of raphanus rusticanus, stating that it occurs wild in several parts of England. After referring to its medicinal uses, he says:
Etymology and common names
The word horseradish is attested in English from the 1590s. It combines the word horse (formerly used in a figurative sense to mean strong or coarse) and the word radish. Some sources say that the term originates from a mispronunciation of the German word "meerrettich" as "mareradish". However, this hypothesis has been disputed, as there is no historical evidence of this term being used. | Horseradish | Wikipedia | 264 | 45714 | https://en.wikipedia.org/wiki/Horseradish | Biology and health sciences | Brassicales | null |
In Slavic languages, the word for mustard derives from a root meaning fire or burning, often used metaphorically to refer to spicy or bitter foods. The Czech word for mustard for example is hořčice. Hořký is the adjectival form in Czech, meaning hot (spicy) or bitter. Horseradish is a plant in the mustard family. The first syllable horse in English appears to be a cognate or borrowing from the Slavic root. This likely derivation In Central and Eastern Europe may frequently be neglected since the Slavic words for horseradish chren, hren and ren (in various spellings like kren) in many Slavic languages is distinct from that for mustard referenced above. In Austria, in parts of Germany (where the other German name Meerrettich is not used), in North-East Italy, and in Yiddish (כריין transliterated as khreyn). It is common in Ukraine (under the name of , khrin), in Belarus (under the name of , chren), in Poland (under the name of ), in Czechia (), in Slovakia (), in Russia (, khren), in Hungary (), in Romania (), in Lithuania (), and in Bulgaria (under the name of ).
Cultivation
Horseradish is perennial in hardiness zones 2–9 and can be grown as an annual in other zones, although not as successfully as in zones with both a long growing season and winter temperatures cold enough to ensure plant dormancy. After the first frost in autumn kills the leaves, the root is dug and divided. The main root is harvested and one or more large offshoots of the main root are replanted to produce next year's crop. Horseradish left undisturbed in the garden spreads via underground shoots and can become invasive. Older roots left in the ground become woody, after which they are no longer culinarily useful, although older plants can be dug and re-divided to start new plants. The early season leaves can be distinctively different, asymmetric spiky, before the mature typical flat broad leaves start to be developed. | Horseradish | Wikipedia | 445 | 45714 | https://en.wikipedia.org/wiki/Horseradish | Biology and health sciences | Brassicales | null |
Pests and diseases
Introduced by accident, "cabbageworms", the larvae of Pieris rapae, are a common caterpillar pest in horseradish. Mature caterpillars chew large, ragged holes in the leaves leaving the large veins intact. Handpicking is an effective control strategy in home gardens. Another common pest of horseradish is the mustard leaf beetle (Phaedon cochleariae). These beetles are undeterred by the defense mechanisms produced by Brassicaceae plants like horseradish.
Production
In the United States, horseradish is grown in several areas such as Eau Claire, Wisconsin, and Tule Lake, California. The most concentrated growth occurs in the Collinsville, Illinois region.
30,000 metric tonnes of horseradish are produced in Europe annually, of which Hungary produces 12,000, making it the biggest single producer.
Culinary uses
The distinctive pungent taste of horseradish is from the compound allyl isothiocyanate. Upon crushing the flesh of horseradish, the enzyme myrosinase is released and acts on the glucosinolates sinigrin and gluconasturtiin, which are precursors to the allyl isothiocyanate. The allyl isothiocyanate serves the plant as a natural defense against herbivores. Since allyl isothiocyanate is harmful to the plant itself, it is stored in the harmless form of the glucosinolate, separate from the enzyme myrosinase. When an animal chews the plant, the allyl isothiocyanate is released, repelling the animal. Allyl isothiocyanate is an unstable compound, degrading over the course of days at . Because of this instability, horseradish sauces lack the pungency of the freshly crushed roots.
Cooks may use the terms "horseradish" or "prepared horseradish" to refer to the mashed (or grated) root of the horseradish plant mixed with vinegar. Prepared horseradish is white to creamy-beige in color. It can be stored for up to 3 months under refrigeration, but eventually will darken, indicating less flavour. The leaves of the plant are edible, either cooked or raw when young, with a flavor similar but weaker than the roots. | Horseradish | Wikipedia | 484 | 45714 | https://en.wikipedia.org/wiki/Horseradish | Biology and health sciences | Brassicales | null |
On Passover, many Ashkenazi Jews use grated horseradish as a choice for Maror (bitter herbs) at the Passover Seder.
Horseradish sauce
Horseradish sauce made from grated horseradish root and vinegar is a common condiment in the United Kingdom, in Denmark (with sugar added) and in Poland. In the UK, it is usually served with roast beef, often as part of a traditional Sunday roast, but can be used in a number of other dishes, including sandwiches or salads. A variation of horseradish sauce, which in some cases may replace the vinegar with other products like lemon juice or citric acid, is known in Germany as Tafelmeerrettich. Also available in the UK is Tewkesbury mustard, a blend of mustard and grated horseradish originating in medieval times and mentioned by Shakespeare (Falstaff says: "his wit's as thick as Tewkesbury Mustard" in Henry IV Part II). A similar mustard, called Krensenf or Meerrettichsenf, is common in Austria and parts of Germany. In France, sauce au raifort is used in Alsatian cuisine. In Russia, horseradish root is usually mixed with grated garlic and a small amount of tomatoes for color (Khrenovina sauce).
In the United States, the term "horseradish sauce" refers to grated horseradish combined with mayonnaise or salad dressing. In Denmark, it is mixed with whipping cream and as such used on top of traditional Danish open sandwiches with beef (boiled or steaked) slices. Prepared horseradish is a common ingredient in Bloody Mary cocktails and in cocktail sauce and is used as a sauce or sandwich spread. Horseradish cream is a mixture of horseradish and sour cream and is served au jus for a prime rib dinner.
Vegetable | Horseradish | Wikipedia | 390 | 45714 | https://en.wikipedia.org/wiki/Horseradish | Biology and health sciences | Brassicales | null |
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