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Human anatomy, physiology and biochemistry are complementary basic medical sciences, which are generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically; that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray's Anatomy, has been reorganized from a systems format to a regional format, in line with modern teaching methods. A thorough working knowledge of anatomy is required by physicians, especially surgeons and doctors working in some diagnostic specialties, such as histopathology and radiology.
Academic anatomists are usually employed by universities, medical schools or teaching hospitals. They are often involved in teaching anatomy, and research into certain systems, organs, tissues or cells.
Invertebrate anatomy.
Invertebrates constitute a vast array of living organisms ranging from the simplest unicellular eukaryotes such as "Paramecium" to such complex multicellular animals as the octopus, lobster and dragonfly. They constitute about 95% of the animal species. By definition, none of these creatures has a backbone. The cells of single-cell protozoans have the same basic structure as those of multicellular animals but some parts are specialized into the equivalent of tissues and organs. Locomotion is often provided by cilia or flagella or may proceed via the advance of pseudopodia, food may be gathered by phagocytosis, energy needs may be supplied by photosynthesis and the cell may be supported by an endoskeleton or an exoskeleton. Some protozoans can form multicellular colonies.
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Metazoans are a multicellular organism, with different groups of cells serving different functions. The most basic types of metazoan tissues are epithelium and connective tissue, both of which are present in nearly all invertebrates. The outer surface of the epidermis is normally formed of epithelial cells and secretes an extracellular matrix which provides support to the organism. An endoskeleton derived from the mesoderm is present in echinoderms, sponges and some cephalopods. Exoskeletons are derived from the epidermis and is composed of chitin in arthropods (insects, spiders, ticks, shrimps, crabs, lobsters). Calcium carbonate constitutes the shells of molluscs, brachiopods and some tube-building polychaete worms and silica forms the exoskeleton of the microscopic diatoms and radiolaria. Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians (polyps, sea anemones, jellyfish) and the collagenous cuticle of annelids. The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli, cilia, bristles, spines and tubercles.
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Marcello Malpighi, the father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring.
Arthropod anatomy.
Arthropods comprise the largest phylum of invertebrates in the animal kingdom with over a million known species.
Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton, made mostly of chitin. The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen. The head typically bears a pair of sensory antennae, a pair of compound eyes, one to three simple eyes (ocelli) and three sets of modified appendages that form the mouthparts. The thorax has three pairs of segmented legs, one pair each for the three segments that compose the thorax and one or two pairs of wings. The abdomen is composed of eleven segments, some of which may be fused and houses the digestive, respiratory, excretory and reproductive systems. There is considerable variation between species and many adaptations to the body parts, especially wings, legs, antennae and mouthparts.
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Spiders a class of arachnids have four pairs of legs; a body of two segments—a cephalothorax and an abdomen. Spiders have no wings and no antennae. They have mouthparts called chelicerae which are often connected to venom glands as most spiders are venomous. They have a second pair of appendages called pedipalps attached to the cephalothorax. These have similar segmentation to the legs and function as taste and smell organs. At the end of each male pedipalp is a spoon-shaped cymbium that acts to support the copulatory organ.
History.
Ancient.
In 1600 BCE, the Edwin Smith Papyrus, an Ancient Egyptian medical text, described the heart and its vessels, as well as the brain and its meninges and cerebrospinal fluid, and the liver, spleen, kidneys, uterus and bladder. It showed the blood vessels diverging from the heart. The Ebers Papyrus () features a "treatise on the heart", with vessels carrying all the body's fluids to or from every member of the body.
Ancient Greek anatomy and physiology underwent great changes and advances throughout the early medieval world. Over time, this medical practice expanded due to a continually developing understanding of the functions of organs and structures in the body. Phenomenal anatomical observations of the human body were made, which contributed to the understanding of the brain, eye, liver, reproductive organs, and nervous system.
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The Hellenistic Egyptian city of Alexandria was the stepping-stone for Greek anatomy and physiology. Alexandria not only housed the biggest library for medical records and books of the liberal arts in the world during the time of the Greeks but was also home to many medical practitioners and philosophers. Great patronage of the arts and sciences from the Ptolemaic dynasty of Egypt helped raise Alexandria up, further rivalling other Greek states' cultural and scientific achievements.
Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century were Herophilus and Erasistratus. These two physicians helped pioneer human dissection for medical research, using the cadavers of condemned criminals, which was considered taboo until the Renaissance—Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine.
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Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that the atria were parts of the heart. Herophilus's knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum During his study in Alexandria, Erasistratus was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body's sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery.
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His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery. Erasistratus was also responsible for naming and describing the function of the epiglottis and the heart's valves, including the tricuspid. During the third century, Greek physicians were able to differentiate nerves from blood vessels and tendons and to realize that the nerves convey neural impulses. It was Herophilus who made the point that damage to motor nerves induced paralysis. Herophilus named the meninges and ventricles in the brain, appreciated the division between cerebellum and cerebrum and recognized that the brain was the "seat of intellect" and not a "cooling chamber" as propounded by Aristotle Herophilus is also credited with describing the optic, oculomotor, motor division of the trigeminal, facial, vestibulocochlear and hypoglossal nerves.
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Incredible feats were made during the third century BCE in both the digestive and reproductive systems. Herophilus discovered and described not only the salivary glands but also the small intestine and liver. He showed that the uterus is a hollow organ and described the ovaries and uterine tubes. He recognized that spermatozoa were produced by the testes and was the first to identify the prostate gland.
The anatomy of the muscles and skeleton is described in the "Hippocratic Corpus", an Ancient Greek medical work written by unknown authors. Aristotle described vertebrate anatomy based on animal dissection. Praxagoras identified the difference between arteries and veins. Also in the 4th century BCE, Herophilos and Erasistratus produced more accurate anatomical descriptions based on vivisection of criminals in Alexandria during the Ptolemaic period.
In the 2nd century, Galen of Pergamum, an anatomist, clinician, writer, and philosopher, wrote the final and highly influential anatomy treatise of ancient times. He compiled existing knowledge and studied anatomy through the dissection of animals. He was one of the first experimental physiologists through his vivisection experiments on animals. Galen's drawings, based mostly on dog anatomy, became effectively the only anatomical textbook for the next thousand years. His work was known to Renaissance doctors only through Islamic Golden Age medicine until it was translated from Greek sometime in the 15th century.
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Medieval to early modern.
Anatomy developed little from classical times until the sixteenth century; as the historian Marie Boas writes, "Progress in anatomy before the sixteenth century is as mysteriously slow as its development after 1500 is startlingly rapid". Between 1275 and 1326, the anatomists Mondino de Luzzi, Alessandro Achillini and Antonio Benivieni at Bologna carried out the first systematic human dissections since ancient times. Mondino's "Anatomy" of 1316 was the first textbook in the medieval rediscovery of human anatomy. It describes the body in the order followed in Mondino's dissections, starting with the abdomen, thorax, head, and limbs. It was the standard anatomy textbook for the next century.
Leonardo da Vinci (1452–1519) was trained in anatomy by Andrea del Verrocchio. He made use of his anatomical knowledge in his artwork, making many sketches of skeletal structures, muscles and organs of humans and other vertebrates that he dissected.
Andreas Vesalius (1514–1564), professor of anatomy at the University of Padua, is considered the founder of modern human anatomy. Originally from Brabant, Vesalius published the influential book "De humani corporis fabrica" ("the structure of the human body"), a large format book in seven volumes, in 1543. The accurate and intricately detailed illustrations, often in allegorical poses against Italianate landscapes, are thought to have been made by the artist Jan van Calcar, a pupil of Titian.
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In England, anatomy was the subject of the first public lectures given in any science; these were provided by the Company of Barbers and Surgeons in the 16th century, joined in 1583 by the Lumleian lectures in surgery at the Royal College of Physicians.
Late modern.
Medical schools began to be set up in the United States towards the end of the 18th century. Classes in anatomy needed a continual stream of cadavers for dissection, and these were difficult to obtain. Philadelphia, Baltimore, and New York were all renowned for body snatching activity as criminals raided graveyards at night, removing newly buried corpses from their coffins. A similar problem existed in Britain where demand for bodies became so great that grave-raiding and even anatomy murder were practised to obtain cadavers. Some graveyards were, in consequence, protected with watchtowers. The practice was halted in Britain by the Anatomy Act of 1832, while in the United States, similar legislation was enacted after the physician William S. Forbes of Jefferson Medical College was found guilty in 1882 of "complicity with resurrectionists in the despoliation of graves in Lebanon Cemetery".
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The teaching of anatomy in Britain was transformed by Sir John Struthers, Regius Professor of Anatomy at the University of Aberdeen from 1863 to 1889. He was responsible for setting up the system of three years of "pre-clinical" academic teaching in the sciences underlying medicine, including especially anatomy. This system lasted until the reform of medical training in 1993 and 2003. As well as teaching, he collected many vertebrate skeletons for his museum of comparative anatomy, published over 70 research papers, and became famous for his public dissection of the Tay Whale. From 1822 the Royal College of Surgeons regulated the teaching of anatomy in medical schools. Medical museums provided examples in comparative anatomy, and were often used in teaching. Ignaz Semmelweis investigated puerperal fever and he discovered how it was caused. He noticed that the frequently fatal fever occurred more often in mothers examined by medical students than by midwives. The students went from the dissecting room to the hospital ward and examined women in childbirth. Semmelweis showed that when the trainees washed their hands in chlorinated lime before each clinical examination, the incidence of puerperal fever among the mothers could be reduced dramatically.
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Before the modern medical era, the primary means for studying the internal structures of the body were dissection of the dead and inspection, palpation, and auscultation of the living. The advent of microscopy opened up an understanding of the building blocks that constituted living tissues. Technical advances in the development of achromatic lenses increased the resolving power of the microscope, and around 1839, Matthias Jakob Schleiden and Theodor Schwann identified that cells were the fundamental unit of organization of all living things. The study of small structures involved passing light through them, and the microtome was invented to provide sufficiently thin slices of tissue to examine. Staining techniques using artificial dyes were established to help distinguish between different tissue types. Advances in the fields of histology and cytology began in the late 19th century along with advances in surgical techniques allowing for the painless and safe removal of biopsy specimens. The invention of the electron microscope brought a significant advance in resolution power and allowed research into the ultrastructure of cells and the organelles and other structures within them. About the same time, in the 1950s, the use of X-ray diffraction for studying the crystal structures of proteins, nucleic acids, and other biological molecules gave rise to a new field of molecular anatomy.
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Equally important advances have occurred in "non-invasive" techniques for examining the body's interior structures. X-rays can be passed through the body and used in medical radiography and fluoroscopy to differentiate interior structures that have varying degrees of opaqueness. Magnetic resonance imaging, computed tomography, and ultrasound imaging have all enabled the examination of internal structures in unprecedented detail to a degree far beyond the imagination of earlier generations.
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Affirming the consequent
In propositional logic, affirming the consequent (also known as converse error, fallacy of the converse, or confusion of necessity and sufficiency) is a formal fallacy (or an invalid form of argument) that is committed when, in the context of an indicative conditional statement, it is stated that because the consequent is true, therefore the antecedent is true. It takes on the following form:
which may also be phrased as
For example, it may be true that a broken lamp would cause a room to become dark. It is not true, however, that a dark room implies the presence of a broken lamp. There may be no lamp (or any light source). The lamp may also be off. In other words, the consequent (a dark room) can have other antecedents (no lamp, off-lamp), and so can still be true even if the stated antecedent is not.
Converse errors are common in everyday thinking and communication and can result from, among other causes, communication issues, misconceptions about logic, and failure to consider other causes.
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A related fallacy is denying the antecedent. Two related "valid" forms of logical argument include "modus tollens" (denying the consequent) and "modus ponens" (affirming the antecedent).
Formal description.
Affirming the consequent is the action of taking a true statement formula_3 and invalidly concluding its converse formula_4. The name "affirming the consequent" derives from using the consequent, "Q", of formula_3, to conclude the antecedent "P". This fallacy can be summarized formally as formula_6 or, alternatively, formula_7.
The root cause of such a logical error is sometimes failure to realize that just because "P" is a "possible" condition for "Q", "P" may not be the "only" condition for "Q", i.e. "Q" may follow from another condition as well.
Affirming the consequent can also result from overgeneralizing the experience of many statements "having" true converses. If "P" and "Q" are "equivalent" statements, i.e. formula_8, it "is" possible to infer "P" under the condition "Q". For example, the statements "It is August 13, so it is my birthday" formula_3 and "It is my birthday, so it is August 13" formula_4 are equivalent and both true consequences of the statement "August 13 is my birthday" (an abbreviated form of formula_8).
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Of the possible forms of "mixed hypothetical syllogisms," two are valid and two are invalid. Affirming the antecedent (modus ponens) and denying the consequent (modus tollens) are valid. Affirming the consequent and denying the antecedent are invalid.
Additional examples.
Example 1
One way to demonstrate the invalidity of this argument form is with a counterexample with true premises but an obviously false conclusion. For example:
There are many places to live in California other than San Diego. On the other hand, one can affirm with certainty that "if someone does not live in California" ("non-Q"), then "this person does not live in San Diego" ("non-P"). This is the contrapositive of the first statement, and it must be true if and only if the original statement is true.
Example 2
Here, it is immediately intuitive that any number of other antecedents ("If an animal is a deer...", "If an animal is an elephant...", "If an animal is a moose...", "etc.") can give rise to the consequent ("then it has four legs"), and that it is preposterous to suppose that having four legs "must" imply that the animal is a dog and nothing else. This is useful as a teaching example since most people can immediately recognize that the conclusion reached must be wrong (intuitively, a cat cannot be a dog), and that the method by which it was reached must therefore be fallacious. This argument was featured in Euguene Ionesco's Rhinoceros in a conversation between a Logician and an Old Gentleman.
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Example 3
In "Catch-22", the chaplain is interrogated for supposedly being "Washington Irving"/"Irving Washington", who has been blocking out large portions of soldiers' letters home. The colonel has found such a letter, but with the chaplain's name signed.
"P" in this case is 'The chaplain signs his own name', and "Q" 'The chaplain's name is written'. The chaplain's name may be written, but he did not necessarily write it, as the colonel falsely concludes."
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Andrei Tarkovsky
Andrei Arsenyevich Tarkovsky (, ; 4 April 1932 – 29 December 1986) was a Soviet film director and screenwriter of Russian origin. He is widely considered one of the greatest directors in cinema history. His films explore spiritual and metaphysical themes and are known for their slow pacing and long takes, dreamlike visual imagery and preoccupation with nature and memory.
Tarkovsky studied film at the All-Union State Institute of Cinematography under filmmaker Mikhail Romm and subsequently directed his first five features in the Soviet Union: "Ivan's Childhood" (1962), "Andrei Rublev" (1966), "Solaris" (1972), "Mirror" (1975), and "Stalker" (1979). After years of creative conflict with state film authorities, he left the country in 1979 and made his final two films—"Nostalghia" (1983) and "The Sacrifice" (1986)—abroad. In 1986, he published "Sculpting in Time", a book about cinema and art. He died later that year of cancer, a condition possibly caused by the toxic locations used in the filming of "Stalker".
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Tarkovsky was the recipient of numerous accolades throughout his career, including the FIPRESCI prize, the Prize of the Ecumenical Jury and the Grand Prix Spécial du Jury at the Cannes Film Festival in addition to the Golden Lion at the Venice Film Festival for his debut film, "Ivan's Childhood" as well as the BAFTA Film Award for "The Sacrifice". In 1990, he was posthumously awarded the Soviet Union's prestigious Lenin Prize. Three of his films—"Andrei Rublev", "Mirror", and "Stalker"—featured in "Sight & Sound" 2012 poll of the 100 greatest films of all time.
Life and career.
Childhood and early life.
Andrei Tarkovsky was born in the village of Zavrazhye in the Yuryevetsky District of the Ivanovo Industrial Oblast (modern-day Kadyysky District of the Kostroma Oblast, Russia) to the poet and translator Arseny Aleksandrovich Tarkovsky, a native of Yelysavethrad (now Kropyvnytskyi, Ukraine), and Maria Ivanova Vishnyakova, a graduate of the Maxim Gorky Literature Institute who later worked as a proofreader; she was born in Moscow in the Dubasov family estate.
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Andrei's paternal grandfather Aleksandr Karlovich Tarkovsky (in ) was a Polish nobleman who worked as a bank clerk. His wife Maria Danilovna Rachkovskaya was a Romanian language teacher who arrived from Iași. Andrei's maternal grandmother Vera Nikolayevna Vishnyakova (née Dubasova) belonged to an old Dubasov family of Russian nobility that traces its history back to the 17th century; among her relatives was Admiral Fyodor Dubasov, a fact she had to conceal during the Soviet days. She was married to Ivan Ivanovich Vishnyakov, a native of the Kaluga Governorate who studied law at the Moscow State University and served as a judge in Kozelsk.
According to the family legend, Tarkovsky's ancestors on his father's side were princes from the Shamkhalate of Tarki, Dagestan, although his sister, Marina Tarkovskaya, who conducted detailed research on their genealogy, called it "a myth, even a prank of sorts," stressing that no document confirms this narrative.
Tarkovsky spent his childhood in Yuryevets. His father left the family in 1937, subsequently volunteering for the army in 1941. He returned home in 1943, having been awarded a Red Star after being shot in one of his legs (which he would eventually need to have amputated due to gangrene). Tarkovsky stayed with his mother, moving with her and his sister Marina to Moscow, where she worked as a proofreader at a printing press.
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In 1939, Tarkovsky enrolled at the Moscow School No. 554. During the war, the three evacuated to Yuryevets, living with his maternal grandmother. In 1943, the family returned to Moscow. Tarkovsky continued his studies at his old school, where the poet Andrei Voznesensky was one of his classmates. He studied piano at a music school and attended classes at an art school. The family lived on Shchipok Street in the Zamoskvorechye District in Moscow. From November 1947 to spring 1948 he was in the hospital with tuberculosis. Many themes of his childhood—the evacuation, his mother and her two children, the withdrawn father, the time in the hospital—feature prominently in his film "Mirror".
In his school years, Tarkovsky was a troublemaker and a poor student. He still managed to graduate, and from 1951 to 1952 studied Arabic at the Oriental Institute in Moscow, a branch of the Academy of Sciences of the Soviet Union. He did not finish his studies and dropped out to work as a prospector for the Academy of Science Institute for Non-Ferrous Metals and Gold. He participated in a year-long research expedition to the river Kureyka near Turukhansk in the Krasnoyarsk Province. During this time in the taiga, Tarkovsky decided to study film.
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Film school student.
Upon returning from the research expedition in 1954, Tarkovsky applied at the State Institute of Cinematography (VGIK) and was admitted to the film-directing program. He was in the same class as Irma Raush (Irina) whom he married in April 1957.
The early Khrushchev era offered good opportunities for young film directors. Before 1953, annual film production was low and most films were directed by veteran directors. After 1953, more films were produced, many of them by young directors. The Khrushchev Thaw relaxed Soviet social restrictions a bit and permitted a limited influx of European and North American literature, films and music. This allowed Tarkovsky to see films of the Italian neorealists, French New Wave, and of directors such as Kurosawa, Buñuel, Bergman, Bresson, Wajda (whose film "Ashes and Diamonds" influenced Tarkovsky) and Mizoguchi.
Tarkovsky's teacher and mentor was Mikhail Romm, who taught many film students who would later become influential film directors. In 1956, Tarkovsky directed his first student short film, "The Killers", from a short story of Ernest Hemingway. The longer television film "There Will Be No Leave Today" followed in 1959. Both films were a collaboration between the VGIK students. Classmate Aleksandr Gordon, who married Tarkovsky's sister, in particular directed, wrote, edited, and acted in the two films with Tarkovsky.
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During his third year at the VGIK, Tarkovsky met Andrei Konchalovsky. They found much in common as they liked the same film directors and shared ideas on cinema and films. In 1959, they wrote the script "Antarctica – Distant Country", which was later published in the "Moskovsky Komsomolets". Tarkovsky submitted the script to Lenfilm, but it was rejected. They were more successful with the script "The Steamroller and the Violin", which they sold to Mosfilm. This became Tarkovsky's graduation project, earning him his diploma in 1960 and winning First Prize at the New York Student Film Festival in 1961.
Film career in the Soviet Union.
Tarkovsky's first feature film was "Ivan's Childhood" in 1962. He had inherited the film from director Eduard Abalov, who had to abort the project. The film earned Tarkovsky international acclaim and won the Golden Lion award at the Venice Film Festival in the year 1962. In the same year, on 30 September, his first son Arseny (called Senka in Tarkovsky's diaries) Tarkovsky was born.
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In 1965, he directed the film "Andrei Rublev" about the life of Andrei Rublev, the fifteenth-century Russian icon painter. "Andrei Rublev" was not, except for a single screening in Moscow in 1966, immediately released after completion due to problems with Soviet authorities. Tarkovsky had to cut the film several times, resulting in several different versions of varying lengths. The film was widely released in the Soviet Union in a cut version in 1971. Nevertheless, the film had a budget of more than 1 million rubles – a significant sum for that period. A version of the film was presented at the Cannes Film Festival in 1969 and won the FIPRESCI prize.
He divorced his wife, Irina, in June 1970. In the same year, he married Larisa Kizilova (née Egorkina), who had been a production assistant for the film "Andrei Rublev" (they had been living together since 1965). Their son, Andrei Andreyevich Tarkovsky, (nicknamed Andriosha, meaning "little Andre" or "Andre Junior") was born in the same year on 7 August.
In 1972, he completed "Solaris", an adaptation of the novel "Solaris" by Stanisław Lem. He had worked on this together with screenwriter Friedrich Gorenstein as early as 1968. The film was presented at the Cannes Film Festival, won the Grand Prix Spécial du Jury, and was nominated for the Palme d'Or.
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From 1973 to 1974, he shot the film "Mirror", a highly autobiographical and unconventionally structured film drawing on his childhood and incorporating some of his father's poems. In this film Tarkovsky portrayed the plight of childhood affected by war. Tarkovsky had worked on the screenplay for this film since 1967, under the consecutive titles "Confession", "White day" and "A white, white day". From the beginning the film was not well received by Soviet authorities due to its content and its perceived elitist nature. Soviet authorities placed the film in the "third category", a severely limited distribution, and only allowed it to be shown in third-class cinemas and workers' clubs. Few prints were made and the film-makers received no returns. Third category films also placed the film-makers in danger of being accused of wasting public funds, which could have serious effects on their future productivity. These difficulties are presumed to have made Tarkovsky play with the idea of going abroad and producing a film outside the Soviet film industry.
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During 1975, Tarkovsky also worked on the screenplay "Hoffmanniana", about the German writer and poet E. T. A. Hoffmann. In December 1976, he directed "Hamlet", his only stage play, at the Lenkom Theatre in Moscow. The main role was played by Anatoly Solonitsyn, who also acted in several of Tarkovsky's films. At the end of 1978, he also wrote the screenplay "Sardor" together with the writer Aleksandr Misharin.
The last film Tarkovsky completed in the Soviet Union was "Stalker", inspired by the novel "Roadside Picnic" by the brothers Arkady and Boris Strugatsky. Tarkovsky had met the brothers first in 1971 and was in contact with them until his death in 1986. Initially he wanted to shoot a film based on their novel "Dead Mountaineer's Hotel" and he developed a raw script. Influenced by a discussion with Arkady Strugatsky he changed his plan and began to work on the script based on "Roadside Picnic". Work on this film began in 1976. The production was mired in troubles; improper development of the negatives had ruined all the exterior shots. Tarkovsky's relationship with cinematographer Georgy Rerberg deteriorated to the point where he hired Alexander Knyazhinsky as a new first cinematographer. Furthermore, Tarkovsky had a heart attack in April 1978, resulting in further delay. The film was completed in 1979 and won the Prize of the Ecumenical Jury at the Cannes Film Festival. In a question and answer session at the Edinburgh Filmhouse on 11 February 1981, Tarkovsky trenchantly rejected suggestions that the film was either impenetrably mysterious or a political allegory.
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Film career outside the Soviet Union.
During the summer of 1979, Tarkovsky traveled to Italy, where he shot the documentary "Voyage in Time" together with his long-time friend Tonino Guerra. Tarkovsky returned to Italy in 1980 for an extended trip, during which he and Guerra completed the script for the film "Nostalghia". During this period, he took Polaroid photographs depicting his personal life.
Tarkovsky returned to Italy in 1982 to start shooting "Nostalghia", but Mosfilm then withdrew from the project, so he sought and received financial backing from the Italian RAI. Tarkovsky completed the film in 1983, and it was presented at the Cannes Film Festival where it won the FIPRESCI prize and the Prize of the Ecumenical Jury. Tarkovsky also shared a special prize called "Grand Prix du cinéma de création" with Robert Bresson. Soviet authorities lobbied to prevent the film from winning the Palme d'Or, a fact that hardened Tarkovsky's resolve to never work in the Soviet Union again. After Cannes he went to London to stage and choreograph the opera "Boris Godunov" at the Royal Opera House under the musical direction of Claudio Abbado.
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At a press conference in Milan on 10 July 1984, he announced that he would never return to the Soviet Union and would remain in Western Europe. He stated, "I am not a Soviet dissident, I have no conflict with the Soviet Government," but if he returned home, he added, "I would be unemployed." At that time, his son Andriosha was still in the Soviet Union and not allowed to leave the country. On 28 August 1985, Tarkovsky was processed as a Soviet Defector at a refugee camp in Latina, Italy, registered with the serial number 13225/379, and officially welcomed to the West.
Tarkovsky spent most of 1984 preparing the film "The Sacrifice". It was finally shot in 1985 in Sweden, with many of the crew being alumni from Ingmar Bergman's films, including cinematographer Sven Nykvist. Tarkovsky's vision of his film was greatly influenced by Bergman's style.
While "The Sacrifice" is about an apocalypse and impending death, faith, and possible redemption, in the making-of documentary "Directed by Andrei Tarkovsky", in a particularly poignant scene, writer/director Michal Leszczylowski follows Tarkovsky on a walk as he expresses his sentiments on death—he claims himself to be immortal and has no fear of dying. Ironically, at the end of the year Tarkovsky was diagnosed with terminal lung cancer. In January 1986, he began treatment in Paris and was joined there by his son, Andre Jr, who was finally allowed to leave the Soviet Union. What would be Tarkovsky's final film was dedicated to him.
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"The Sacrifice" was presented at the Cannes Film Festival and received the Grand Prix Spécial du Jury, the FIPRESCI prize and the Prize of the Ecumenical Jury. As Tarkovsky was unable to attend due to his illness, the prizes were collected by his son.
Death.
In Tarkovsky's last entry (15 December 1986), he wrote: "But now I have no strength left—that is the problem". The diaries are sometimes also known as "" and were published posthumously in 1989 and in English in 1991.
Tarkovsky died in Paris on 29 December 1986. His funeral ceremony was held at the Alexander Nevsky Cathedral. He was buried on 3 January 1987 in the Russian Cemetery in Sainte-Geneviève-des-Bois in France. The inscription on his gravestone, which was erected in 1994, was conceived by Tarkovsky's wife, Larisa, reads: "To the man who saw the Angel". Larisa died in 1998 and is buried beside her husband.
Tarkovsky, his wife Larisa, and actor Anatoly Solonitsyn all died from the same type of cancer. Vladimir Sharun, a sound designer for "Stalker", was convinced that all three died due to exposure to chemicals released from a chemical plant upstream from where the film was shot.
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Influences and thoughts on film.
Tarkovsky became a film director during the mid and late 1950s, a period referred to as the Khrushchev Thaw, during which Soviet society opened to foreign films, literature and music, among other things. This allowed Tarkovsky to see films of European, American and Japanese directors, an experience that influenced his own film making. His teacher and mentor at the film school, Mikhail Romm, allowed his students considerable freedom and emphasized the independence of the film director.
Tarkovsky was, according to fellow student Shavkat Abdusalmov, fascinated by Japanese films. He was amazed by how every character on the screen is exceptional and how everyday events such as a Samurai cutting bread with his sword are elevated to something special and put into the limelight. Tarkovsky has also expressed interest in the art of Haiku and its ability to create "images in such a way that they mean nothing beyond themselves".
Tarkovsky was also a deeply religious Orthodox Christian, who believed great art should have a higher spiritual purpose. He was a perfectionist not given to humor or humility: his signature style was ponderous and literary, having many characters that pondered over religious themes and issues regarding faith.
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Tarkovsky perceived that the art of cinema has only been truly mastered by very few filmmakers, stating in a 1970 interview with Naum Abramov that "they can be counted on the fingers of one hand". In 1972, Tarkovsky told film historian Leonid Kozlov his ten favorite films. The list is as follows: "Diary of a Country Priest" and "Mouchette" by Robert Bresson; "Winter Light", "Wild Strawberries", and "Persona" by Ingmar Bergman; "Nazarín" by Luis Buñuel; "City Lights" by Charlie Chaplin; "Ugetsu" by Kenji Mizoguchi; "Seven Samurai" by Akira Kurosawa, and "Woman in the Dunes" by Hiroshi Teshigahara. He also liked Pier Paolo Pasolini's film "The Gospel According to St. Matthew". Among his favorite directors were Buñuel, Mizoguchi, Bergman, Bresson, Kurosawa, Michelangelo Antonioni, Jean Vigo, and Carl Theodor Dreyer.
With the exception of "City Lights", the list does not contain any films of the early silent era. The reason is that Tarkovsky saw film as an art as only a relatively recent phenomenon, with the early film-making forming only a prelude. The list has also no films or directors from Tarkovsky's native Soviet Union, although he rated Soviet directors such as Boris Barnet, Sergei Parajanov and Alexander Dovzhenko highly. He said of Dovzhenko's "Earth": "I have lived a lot among very simple farmers and met extraordinary people. They spread calmness, had such tact, they conveyed a feeling of dignity and displayed wisdom that I have seldom come across on such a scale. Dovzhenko had obviously understood wherein the sense of life resides. [...] This trespassing of the border between nature and mankind is an ideal place for the existence of man. Dovzhenko understood this."
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He was also not a fan of blockbusters or science fiction, largely dismissing the latter for its "comic book" trappings and vulgar commercialism. He equally liked George Lucas's "Star Wars" according to his son, Andrei A. Tarkovsky.
Cinematic style.
In a 1962 interview, Tarkovsky argued: "All art, of course, is intellectual, but for me, all the arts, and cinema even more so, must above all be emotional and act upon the heart." His films are characterized by metaphysical themes, extremely long takes, and images often considered by critics to be of exceptional beauty. Recurring motifs are dreams, memory, childhood, running water accompanied by fire, rain indoors, reflections, levitation, and characters re-appearing in the foreground of long panning movements of the camera. He once said: "Juxtaposing a person with an environment that is boundless, collating him with a countless number of people passing by close to him and far away, relating a person to the whole world, that is the meaning of cinema."
Tarkovsky incorporated levitation scenes into several of his films, most notably "Solaris". To him these scenes possess great power and are used for their photogenic value and magical inexplicability. Water, clouds, and reflections were used by him for their surreal beauty and photogenic value, as well as their symbolism, such as waves or the forms of brooks or running water. Bells and candles are also frequent symbols. These are symbols of film, sight and sound, and Tarkovsky's film frequently has themes of self-reflection.
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Tarkovsky developed a theory of cinema that he called "sculpting in time". By this he meant that the unique characteristic of cinema as a medium was to take our experience of time and alter it. Unedited movie footage transcribes time in real time. By using long takes and few cuts in his films, he aimed to give the viewers a sense of time passing, time lost, and the relationship of one moment in time to another.
Up to, and including, his film "Mirror", Tarkovsky focused his cinematic works on exploring this theory. After "Mirror", he announced that he would focus his work on exploring the dramatic unities proposed by Aristotle: a concentrated action, happening in one place, within the span of a single day.
Several of Tarkovsky's films have color or black-and-white sequences. This first occurs in the otherwise monochrome "Andrei Rublev", which features a color epilogue of Rublev's authentic religious icon paintings. All of his films afterwards contain monochrome, and in "Stalker's" case sepia sequences, while otherwise being in color. In 1966, in an interview conducted shortly after finishing "Andrei Rublev", Tarkovsky dismissed color film as a "commercial gimmick" and cast doubt on the idea that contemporary films meaningfully use color. He claimed that in everyday life one does not consciously notice colors most of the time, and that color should therefore be used in film mainly to emphasize certain moments, but not all the time, as this distracts the viewer. To him, films in color were like moving paintings or photographs, which are too beautiful to be a realistic depiction of life.
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Director Ingmar Bergman commented on Tarkovsky:
Contrarily, however, Bergman conceded the truth in the claim made by a critic who wrote that "with "Autumn Sonata" Bergman does Bergman", adding: "Tarkovsky began to make Tarkovsky films, and that Fellini began to make Fellini films [...] Buñuel nearly always made Buñuel films." This pastiche of one's own work has been derogatorily termed as "self-karaoke".
Vadim Yusov.
Tarkovsky worked in close collaboration with cinematographer Vadim Yusov from 1958 to 1972, and much of the visual style of Tarkovsky's films can be attributed to this collaboration. Tarkovsky would spend two days preparing for Yusov to film a single long take, and due to the preparation, usually only a single take was needed.
Sven Nykvist.
In his last film, "The Sacrifice", Tarkovsky worked with cinematographer Sven Nykvist, who had worked on many films with director Ingmar Bergman. (Nykvist was not alone: several people involved in the production had previously collaborated with Bergman, notably lead actor Erland Josephson, who had also acted for Tarkovsky in "Nostalghia".) Nykvist complained that Tarkovsky would frequently look through the camera and even direct actors through it, but ultimately stated that choosing to work with Tarkovsky was one of the best choices he had ever made.
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Filmography.
Tarkovsky is mainly known as a film director. During his career he directed seven feature films, as well as three shorts from his time at VGIK. His features are:
He also wrote several screenplays. Furthermore, he directed the play "Hamlet" for the stage in Moscow, directed the opera "Boris Godunov" in London, and he directed a radio production of the short story "Turnabout" by William Faulkner. He also wrote "Sculpting in Time", a book on film theory.
Tarkovsky's first feature film was "Ivan's Childhood" in 1962. He then directed "Andrei Rublev" in 1966, "Solaris" in 1972, "Mirror" in 1975 and "Stalker" in 1979. The documentary "Voyage in Time" was produced in Italy in 1982, as was "Nostalghia" in 1983. His last film "The Sacrifice" was produced in Sweden in 1986. Tarkovsky was personally involved in writing the screenplays for all his films, sometimes with a cowriter. Tarkovsky once said that a director who realizes somebody else's screenplay without being involved in it becomes a mere illustrator, resulting in dead and monotonous films.
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Unproduced screenplays.
"Concentrate".
Concentrate (, "Kontsentrat") is a never-filmed 1958 screenplay by Tarkovsky. The screenplay is based on Tarkovsky's year in the taiga as a member of a research expedition, prior to his enrollment in film school. It's about the leader of a geological expedition, who waits for the boat that brings back the concentrates collected by the expedition. The expedition is surrounded by mystery, and its purpose is a state secret.
Although some authors claim that the screenplay was filmed, according to Marina Tarkovskaya, Tarkovsky's sister (and wife of Aleksandr Gordon, a fellow student of Tarkovsky during his film school years) the screenplay was never filmed. Tarkovsky wrote the screenplay during his entrance examination at the State Institute of Cinematography (VGIK) in a single sitting. He earned the highest possible grade, "excellent" () for this work. In 1994, fragments of "Concentrate" were filmed and used in the documentary "Andrei Tarkovsky's Taiga Summer" by Marina Tarkovskaya and Aleksandr Gordon.
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"Hoffmanniana".
Hoffmanniana () is a never-filmed 1974 screenplay by Tarkovsky. The screenplay is based on the life and work of German author E. T. A. Hoffmann. In 1974, an acquaintance from Tallinnfilm approached Tarkovsky to write a screenplay on a German theme. Tarkovsky considered Thomas Mann and E. T. A. Hoffmann, and also thought about Ibsen's "Peer Gynt". In the end Tarkovsky signed a contract for a script based on the life and work of Hoffmann. He planned to write the script during the summer of 1974 at his dacha. Writing was not without difficulty, less than a month before the deadline he had not written a single page. He finally finished the project in late 1974 and submitted the final script to Tallinnfilm in October.
Although the script was well received by the officials at Tallinnfilm, it was the consensus that no one but Tarkovsky would be able to direct it. The script was sent to Goskino in February 1976, and although approval was granted for proceeding with making the film, the screenplay was never realized. In 1984, during the time of his exile in the West, Tarkovsky revisited the screenplay and made a few changes. He also considered to finally direct a film based on the screenplay but ultimately dropped this idea.
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Awards and commemoration.
Numerous awards were bestowed on Tarkovsky throughout his lifetime.
Under the influence of Glasnost and Perestroika, Tarkovsky was finally recognized in the Soviet Union in the Autumn of 1986, shortly before his death, by a retrospective of his films in Moscow. After his death, an entire issue of the film magazine "Iskusstvo Kino" was devoted to Tarkovsky. In their obituaries, the film committee of the Council of Ministers of the Soviet Union and the Union of Soviet Film Makers expressed their sorrow that Tarkovsky had to spend the last years of his life in exile.
Posthumously, he was awarded the Lenin Prize in 1990, one of the highest state honors in the Soviet Union. In 1989, the "Andrei Tarkovsky Memorial Prize" was established, with its first recipient being the Russian animator Yuri Norstein. In three consecutive events, the Moscow International Film Festival awarded the "Andrei Tarkovsky Award" in 1993, 1995, and 1997.
In 1996, the Andrei Tarkovsky Museum opened in Yuryevets, his childhood town. A minor planet, 3345 Tarkovskij, discovered by Soviet astronomer Lyudmila Karachkina in 1982, has been named after him.
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Tarkovsky has been the subject of several documentaries. Most notable is the 1988 documentary "Moscow Elegy", by Russian film director Alexander Sokurov. Sokurov's own work has been heavily influenced by Tarkovsky. The film consists mostly of narration over stock footage from Tarkovsky's films. "Directed by Andrei Tarkovsky" is a 1988 documentary film by Michal Leszczylowski, an editor of the film "The Sacrifice". Film director Chris Marker produced the television documentary "One Day in the Life of Andrei Arsenevich" as an homage to Andrei Tarkovsky in 2000.
At the entrance to the Gerasimov Institute of Cinematography in Moscow, there is a monument that includes statues of Tarkovsky, Gennady Shpalikov and Vasily Shukshin.
Reception and legacy.
Andrei Tarkovsky and his works have received praise from many filmmakers, critics and thinkers.
The Swedish filmmaker Ingmar Bergman was quoted as saying: "Tarkovsky for me is the greatest [of us all], the one who invented a new language, true to the nature of film, as it captures life as a reflection, life as a dream".
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The Japanese filmmaker Akira Kurosawa remarked on Tarkovsky's films as saying: "His unusual sensitivity is both overwhelming and astounding. It almost reaches a pathological intensity. Probably there is no equal among film directors alive now." Kurosawa also commented: "I love all of Tarkovsky's films. I love his personality and all his works. Every cut from his films is a marvelous image in itself. But the finished image is nothing more than the imperfect accomplishment of his idea. His ideas are only realized in part. And he had to make do with it."
The Iranian filmmaker Abbas Kiarostami remarked that: "Tarkovsky's works separate me completely from physical life, and are the most spiritual films I have seen".
The Polish filmmaker Krzysztof Kieślowski commented that: "Andrei Tarkovsky was one of the greatest directors of recent years," and regarded Tarkovsky's film "Ivan's Childhood" as an influence on his own work.
The Turkish filmmaker Nuri Bilge Ceylan said that when he first discovered the films of Andrei Tarkovsky as a college student, unsure of what he wanted to do with his life, he was utterly baffled by the lauded Soviet master. He walked out of a screening of "Solaris" at the halfway point, and stopped a VHS tape of "Mirror" at a similar juncture. Today, he considers the latter to be the greatest film ever made. "I've seen it maybe 20 times," he says.
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The Armenian filmmaker Sergei Parajanov remarked that watching Tarkovsky's film, "Ivan's Childhood" was his main inspiration to become a filmmaker by saying: "I did not know how to do anything and I would not have done anything if there had not been "Ivan's Childhood"".
The Austrian filmmaker Michael Haneke voted for "Mirror" on his top 10 films in the 2002 "Sight & Sound" directors' poll and later said that he has seen the picture at least 25 times.
The American filmmaker Stan Brakhage said that: "I personally think that the three greatest tasks for film in the 20th century are (1) To make the epic, that is to tell the tales of the tribes of the world. (2) To keep it personal, because only in the eccentricities of our personal lives do we have any chances at the truth. (3) To do the dream work, that is, to illuminate the borders of the unconscious. The only filmmaker I know that does all these three things equally in every film he makes is Andrei Tarkovsky, and that's why I think he's the greatest living narrative filmmaker."
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The German filmmaker Wim Wenders dedicated his film "Wings of Desire" to Tarkovsky (along with François Truffaut and Yasujirō Ozu).
The French filmmaker Chris Marker directed a documentary film as a homage to Tarkovsky called "One Day in the Life of Andrei Arsenevich" and used Tarkovsky's concept of "The Zone" (from the film, "Stalker") for his 1983 film essay, "Sans Soleil".
The Greek filmmaker Theo Angelopoulos regarded Tarkovsky's film "Stalker" as one of the films that influenced him.
The Polish filmmaker Andrzej Żuławski remarked that: "If anybody influenced anybody, it's me being influenced by Tarkovsky, not the reverse", and called Tarkovsky's film Andrei Rublev a "masterpiece".
The Greek-Australian filmmaker Alex Proyas was "extremely influenced" by Tarkovsky's work and cited "Stalker" as one of his favorite films.
The French philosopher Jean-Paul Sartre highly praised Tarkovsky's film "Ivan's Childhood", saying that it was one of the most beautiful films he had ever seen.
The Japanese anime filmmaker Mamoru Oshii, known for his works such as "Ghost in the Shell", was influenced by Tarkovsky.
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The Indian-born British American novelist Salman Rushdie praised Tarkovsky and his work "Solaris" by calling it "a sci-fi masterpiece".
Film historian Steven Dillon says that much of subsequent film was deeply influenced by the films of Tarkovsky.
Mexican filmmaker Alejandro González Iñarritu is a huge fan of Tarkovsky. He once said in an interview: ""Andrei Rublev" is maybe my favorite film ever", and in another interview, he added: "I remember, the first time I saw a Tarkovsky film, I was shocked by it. I did not know what to do. I was shocked by it. I was fascinated, because suddenly I realized that film could have so many more layers to it than what I had imagined before". There are many direct references and hidden tributes to Tarkovsky's movies in Iñarritu's 2015 Oscar-winning drama "The Revenant".
Danish film director Lars von Trier is a fervent admirer of Tarkovsky. He dedicated his 2009 film "Antichrist" to him, and, while discussing it with critic David Jenkins, asked: "Have you seen "Mirror"? I was hypnotised! I've seen it 20 times. It's the closest thing I've got to a religion – to me he is a god".
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The Japanese composer Ryuichi Sakamoto was an admirer of Tarkovsky's work, describing his penultimate solo album, "async" as "a soundtrack for an imaginary Tarkovsky film." On Tarkovsky's overall influence on his own work, Sakamoto stated, "As I've been making music and trying to go deeper and deeper, I was finally able to understand what the Tarkovsky movies are about — how symphonic they are — it's almost music. Not just the sounds — it's a symphony of moving images and sounds. They are more complex than music."
Film festival.
Two film festivals have been named in his honor:
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Ambiguity
Ambiguity is the type of meaning in which a phrase, statement, or resolution is not explicitly defined, making for several interpretations; others describe it as a concept or statement that has no real reference. A common aspect of ambiguity is uncertainty. It is thus an attribute of any idea or statement whose intended meaning cannot be definitively resolved, according to a rule or process with a finite number of steps. (The prefix "ambi-" reflects the idea of "two", as in "two meanings").
The concept of ambiguity is generally contrasted with vagueness. In ambiguity, specific and distinct interpretations are permitted (although some may not be immediately obvious), whereas with vague information it is difficult to form any interpretation at the desired level of specificity.
Linguistic forms.
Lexical ambiguity is contrasted with semantic ambiguity. The former represents a choice between a finite number of known and meaningful context-dependent interpretations. The latter represents a choice between any number of possible interpretations, none of which may have a standard agreed-upon meaning. This form of ambiguity is closely related to vagueness.
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Ambiguity in human language is argued to reflect principles of efficient communication. Languages that communicate efficiently will avoid sending information that is redundant with information provided in the context. This can be shown mathematically to result in a system that is ambiguous when context is neglected. In this way, ambiguity is viewed as a generally useful feature of a linguistic system.
Linguistic ambiguity can be a problem in law, because the interpretation of written documents and oral agreements is often of paramount importance.
Lexical ambiguity.
The lexical ambiguity of a word or phrase applies to it having more than one meaning in the language to which the word belongs. "Meaning" here refers to whatever should be represented by a good dictionary. For instance, the word "bank" has several distinct lexical definitions, including "financial institution" and "edge of a river". Or consider "apothecary". One could say "I bought herbs from the apothecary". This could mean one actually spoke to the apothecary (pharmacist) or went to the apothecary (pharmacy).
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The context in which an ambiguous word is used often makes it clearer which of the meanings is intended. If, for instance, someone says "I put $100 in the bank", most people would not think someone used a shovel to dig in the mud. However, some linguistic contexts do not provide sufficient information to make a used word clearer.
Lexical ambiguity can be addressed by algorithmic methods that automatically associate the appropriate meaning with a word in context, a task referred to as word-sense disambiguation.
The use of multi-defined words requires the author or speaker to clarify their context, and sometimes elaborate on their specific intended meaning (in which case, a less ambiguous term should have been used). The goal of clear concise communication is that the receiver(s) have no misunderstanding about what was meant to be conveyed. An exception to this could include a politician whose "weasel words" and obfuscation are necessary to gain support from multiple constituents with mutually exclusive conflicting desires from his or her candidate of choice. Ambiguity is a powerful tool of political science.
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More problematic are words whose multiple meanings express closely related concepts. "Good", for example, can mean "useful" or "functional" ("That's a good hammer"), "exemplary" ("She's a good student"), "pleasing" ("This is good soup"), "moral" ("a good person" versus "the lesson to be learned from a story"), "righteous", etc. "I have a good daughter" is not clear about which sense is intended. The various ways to apply prefixes and suffixes can also create ambiguity ("unlockable" can mean "capable of being opened" or "impossible to lock").
Semantic and syntactic ambiguity.
Semantic ambiguity occurs when a word, phrase or sentence, taken out of context, has more than one interpretation. In "We saw her duck" (example due to Richard Nordquist), the words "her duck" can refer either
Syntactic ambiguity arises when a sentence can have two (or more) different meanings because of the structure of the sentence—its syntax. This is often due to a modifying expression, such as a prepositional phrase, the application of which is unclear. "He ate the cookies on the couch", for example, could mean that he ate those cookies that were on the couch (as opposed to those that were on the table), or it could mean that he was sitting on the couch when he ate the cookies. "To get in, you will need an entrance fee of $10 or your voucher and your drivers' license." This could mean that you need EITHER ten dollars OR BOTH your voucher and your license. Or it could mean that you need your license AND you need EITHER ten dollars OR a voucher. Only rewriting the sentence, or placing appropriate punctuation can resolve a syntactic ambiguity.
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For the notion of, and theoretic results about, syntactic ambiguity in artificial, formal languages (such as computer programming languages), see Ambiguous grammar.
Usually, semantic and syntactic ambiguity go hand in hand. The sentence "We saw her duck" is also syntactically ambiguous. Conversely, a sentence like "He ate the cookies on the couch" is also semantically ambiguous. Rarely, but occasionally, the different parsings of a syntactically ambiguous phrase result in the same meaning. For example, the command "Cook, cook!" can be parsed as "Cook (noun used as vocative), cook (imperative verb form)!", but also as "Cook (imperative verb form), cook (noun used as vocative)!". It is more common that a syntactically unambiguous phrase has a semantic ambiguity; for example, the lexical ambiguity in "Your boss is a funny man" is purely semantic, leading to the response "Funny ha-ha or funny peculiar?"
Spoken language can contain many more types of ambiguities that are called phonological ambiguities, where there is more than one way to compose a set of sounds into words. For example, "ice cream" and "I scream". Such ambiguity is generally resolved according to the context. A mishearing of such, based on incorrectly resolved ambiguity, is called a mondegreen.
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Philosophy.
Philosophers (and other users of logic) spend a lot of time and effort searching for and removing (or intentionally adding) ambiguity in arguments because it can lead to incorrect conclusions and can be used to deliberately conceal bad arguments. For example, a politician might say, "I oppose taxes which hinder economic growth", an example of a glittering generality. Some will think they oppose taxes in general because they hinder economic growth. Others may think they oppose only those taxes that they believe will hinder economic growth. In writing, the sentence can be rewritten to reduce possible misinterpretation, either by adding a comma after "taxes" (to convey the first sense) or by changing "which" to "that" (to convey the second sense) or by rewriting it in other ways. The devious politician hopes that each constituent will interpret the statement in the most desirable way, and think the politician supports everyone's opinion. However, the opposite can also be true—an opponent can turn a positive statement into a bad one if the speaker uses ambiguity (intentionally or not). The logical fallacies of amphiboly and equivocation rely heavily on the use of ambiguous words and phrases.
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In continental philosophy (particularly phenomenology and existentialism), there is much greater tolerance of ambiguity, as it is generally seen as an integral part of the human condition. Martin Heidegger argued that the relation between the subject and object is ambiguous, as is the relation of mind and body, and part and whole. In Heidegger's phenomenology, Dasein is always in a meaningful world, but there is always an underlying background for every instance of signification. Thus, although some things may be certain, they have little to do with Dasein's sense of care and existential anxiety, e.g., in the face of death. In calling his work Being and Nothingness an "essay in phenomenological ontology" Jean-Paul Sartre follows Heidegger in defining the human essence as ambiguous, or relating fundamentally to such ambiguity. Simone de Beauvoir tries to base an ethics on Heidegger's and Sartre's writings (The Ethics of Ambiguity), where she highlights the need to grapple with ambiguity: "as long as there have been philosophers and they have thought, most of them have tried to mask it ... And the ethics which they have proposed to their disciples has always pursued the same goal.
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Simone de Beauvoir tries to base an ethics on Heidegger's and Sartre's writings (The Ethics of Ambiguity), where she highlights the need to grapple with ambiguity: "as long as there have been philosophers and they have thought, most of them have tried to mask it ... And the ethics which they have proposed to their disciples has always pursued the same goal. It has been a matter of eliminating the ambiguity by making oneself pure inwardness or pure externality, by escaping from the sensible world or being engulfed by it, by yielding to eternity or enclosing oneself in the pure moment." Ethics cannot be based on the authoritative certainty given by mathematics and logic, or prescribed directly from the empirical findings of science. She states: "Since we do not succeed in fleeing it, let us, therefore, try to look the truth in the face. Let us try to assume our fundamental ambiguity. It is in the knowledge of the genuine conditions of our life that we must draw our strength to live and our reason for acting". Other continental philosophers suggest that concepts such as life, nature, and sex are ambiguous.
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It is in the knowledge of the genuine conditions of our life that we must draw our strength to live and our reason for acting". Other continental philosophers suggest that concepts such as life, nature, and sex are ambiguous. Corey Anton has argued that we cannot be certain what is separate from or unified with something else: language, he asserts, divides what is not, in fact, separate. Following Ernest Becker, he argues that the desire to 'authoritatively disambiguate' the world and existence has led to numerous ideologies and historical events such as genocide. On this basis, he argues that ethics must focus on 'dialectically integrating opposites' and balancing tension, rather than seeking a priori validation or certainty. Like the existentialists and phenomenologists, he sees the ambiguity of life as the basis of creativity.
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Literature and rhetoric.
In literature and rhetoric, ambiguity can be a useful tool. Groucho Marx's classic joke depends on a grammatical ambiguity for its humor, for example: "Last night I shot an elephant in my pajamas. How he got in my pajamas, I'll never know". Songs and poetry often rely on ambiguous words for artistic effect, as in the song title "Don't It Make My Brown Eyes Blue" (where "blue" can refer to the color, or to sadness).
In the narrative, ambiguity can be introduced in several ways: motive, plot, character. F. Scott Fitzgerald uses the latter type of ambiguity with notable effect in his novel "The Great Gatsby".
Mathematical notation.
Mathematical notation is a helpful tool that eliminates a lot of misunderstandings associated with natural language in physics and other sciences. Nonetheless, there are still some inherent ambiguities due to lexical, syntactic, and semantic reasons that persist in mathematical notation.
Names of functions.
The ambiguity in the style of writing a function should not be confused with a multivalued function, which can (and should) be defined in a deterministic and unambiguous way. Several special functions still do not have established notations. Usually, the conversion to another notation requires to scale the argument or the resulting value; sometimes, the same name of the function is used, causing confusions. Examples of such underestablished functions:
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Expressions.
Ambiguous expressions often appear in physical and mathematical texts.
It is common practice to omit multiplication signs in mathematical expressions. Also, it is common to give the same name to a variable and a function, for example, Then, if one sees there is no way to distinguish whether it means formula_1 multiplied by or function formula_2 evaluated at argument equal to In each case of use of such notations, the reader is supposed to be able to perform the deduction and reveal the true meaning.
Creators of algorithmic languages try to avoid ambiguities. Many algorithmic languages (C++ and Fortran) require the character * as symbol of multiplication. The Wolfram Language used in Mathematica allows the user to omit the multiplication symbol, but requires square brackets to indicate the argument of a function; square brackets are not allowed for grouping of expressions. Fortran, in addition, does not allow use of the same name (identifier) for different objects, for example, function and variable; in particular, the expression formula_3 is qualified as an error.
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The order of operations may depend on the context. In most programming languages, the operations of division and multiplication have equal priority and are executed from left to right. Until the last century, many editorials assumed that multiplication is performed first, for example, formula_4 is interpreted as in this case, the insertion of parentheses is required when translating the formulas to an algorithmic language. In addition, it is common to write an argument of a function without parenthesis, which also may lead to ambiguity.
In the scientific journal style, one uses roman letters to denote elementary functions, whereas variables are written using italics.
For example, in mathematical journals the expression formula_5 does not denote the sine function, but the product of the three variables although in the informal notation of a slide presentation it may stand for
Commas in multi-component subscripts and superscripts are sometimes omitted; this is also potentially ambiguous notation.
For example, in the notation the reader can only infer from the context whether it means a single-index object, taken with the subscript equal to product of variables formula_6 and or it is an indication to a trivalent tensor.
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Examples of potentially confusing ambiguous mathematical expressions.
An expression such as formula_7 can be understood to mean either formula_8 or Often the author's intention can be understood from the context, in cases where only one of the two makes sense, but an ambiguity like this should be avoided, for example by writing
The expression formula_9 means formula_10 in several texts, though it might be thought to mean since formula_11 commonly means Conversely, formula_12 might seem to mean as this exponentiation notation usually denotes function iteration: in general, formula_13 means However, for trigonometric and hyperbolic functions, this notation conventionally means exponentiation of the result of function application.
The expression formula_14 can be interpreted as meaning however, it is more commonly understood to mean
Notations in quantum optics and quantum mechanics.
It is common to define the coherent states in quantum optics with formula_15 and states with fixed number of photons with Then, there is an "unwritten rule": the state is coherent if there are more Greek characters than Latin characters in the argument, and formula_6-photon state if the Latin characters dominate. The ambiguity becomes even worse, if formula_17 is used for the states with certain value of the coordinate, and formula_18 means the state with certain value of the momentum, which may be used in books on quantum mechanics. Such ambiguities easily lead to confusions, especially if some normalized adimensional, dimensionless variables are used. Expression formula_19 may mean a state with single photon, or the coherent state with mean amplitude equal to 1, or state with momentum equal to unity, and so on. The reader is supposed to guess from the context.
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Ambiguous terms in physics and mathematics.
Some physical quantities do not yet have established notations; their value (and sometimes even dimension, as in the case of the Einstein coefficients), depends on the system of notations. Many terms are ambiguous. Each use of an ambiguous term should be preceded by the definition, suitable for a specific case. Just like Ludwig Wittgenstein states in Tractatus Logico-Philosophicus: "... Only in the context of a proposition has a name meaning."
A highly confusing term is "gain". For example, the sentence "the gain of a system should be doubled", without context, means close to nothing.
The term "intensity" is ambiguous when applied to light. The term can refer to any of irradiance, luminous intensity, radiant intensity, or radiance, depending on the background of the person using the term.
Also, confusions may be related with the use of atomic percent as measure of concentration of a dopant, or resolution of an imaging system, as measure of the size of the smallest detail that still can be resolved at the background of statistical noise. See also "Accuracy and precision".
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The Berry paradox arises as a result of systematic ambiguity in the meaning of terms such as "definable" or "nameable". Terms of this kind give rise to vicious circle fallacies. Other terms with this type of ambiguity are: satisfiable, true, false, function, property, class, relation, cardinal, and ordinal.
Mathematical interpretation of ambiguity.
In mathematics and logic, ambiguity can be considered to be an instance of the logical concept of underdetermination—for example, formula_20 leaves open what the value of formula_21 is—while overdetermination, except when like formula_22, is a self-contradiction, also called inconsistency, paradoxicalness, or oxymoron, or in mathematics an inconsistent system—such as which has no solution.
Logical ambiguity and self-contradiction is analogous to visual ambiguity and impossible objects, such as the Necker cube and impossible cube, or many of the drawings of M. C. Escher.
Constructed language.
Some languages have been created with the intention of avoiding ambiguity, especially lexical ambiguity. Lojban and Loglan are two related languages that have been created for this, focusing chiefly on syntactic ambiguity as well. The languages can be both spoken and written. These languages are intended to provide a greater technical precision over big natural languages, although historically, such attempts at language improvement have been criticized. Languages composed from many diverse sources contain much ambiguity and inconsistency. The many exceptions to syntax and semantic rules are time-consuming and difficult to learn.
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Biology.
In structural biology, ambiguity has been recognized as a problem for studying protein conformations. The analysis of a protein three-dimensional structure consists in dividing the macromolecule into subunits called domains. The difficulty of this task arises from the fact that different definitions of what a domain is can be used (e.g. folding autonomy, function, thermodynamic stability, or domain motions), which sometimes results in a single protein having different—yet equally valid—domain assignments.
Christianity and Judaism.
Christianity and Judaism employ the concept of paradox synonymously with "ambiguity". Many Christians and Jews endorse Rudolf Otto's description of the sacred as 'mysterium tremendum et fascinans', the awe-inspiring mystery that fascinates humans. The apocryphal Book of Judith is noted for the "ingenious ambiguity" expressed by its heroine; for example, she says to the villain of the story, Holofernes, "my lord will not fail to achieve his purposes", without specifying whether "my lord" refers to the villain or to God.
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The orthodox Catholic writer G. K. Chesterton regularly employed paradox to tease out the meanings in common concepts that he found ambiguous or to reveal meaning often overlooked or forgotten in common phrases: the title of one of his most famous books, "Orthodoxy" (1908), itself employed such a paradox.
Music.
In music, pieces or sections that confound expectations and may be or are interpreted simultaneously in different ways are ambiguous, such as some polytonality, polymeter, other ambiguous meters or rhythms, and ambiguous phrasing, or (Stein 2005, p. 79) any aspect of music. The music of Africa is often purposely ambiguous. To quote Sir Donald Francis Tovey (1935, p. 195), "Theorists are apt to vex themselves with vain efforts to remove uncertainty just where it has a high aesthetic value."
Visual art.
In visual art, certain images are visually ambiguous, such as the Necker cube, which can be interpreted in two ways. Perceptions of such objects remain stable for a time, then may flip, a phenomenon called multistable perception.
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The opposite of such ambiguous images are impossible objects.
Pictures or photographs may also be ambiguous at the semantic level: the visual image is unambiguous, but the meaning and narrative may be ambiguous: is a certain facial expression one of excitement or fear, for instance?
Social psychology and the bystander effect.
In social psychology, ambiguity is a factor used in determining peoples' responses to various situations. High levels of ambiguity in an emergency (e.g. an unconscious man lying on a park bench) make witnesses less likely to offer any sort of assistance, due to the fear that they may have misinterpreted the situation and acted unnecessarily. Alternately, non-ambiguous emergencies (e.g. an injured person verbally asking for help) elicit more consistent intervention and assistance. With regard to the bystander effect, studies have shown that emergencies deemed ambiguous trigger the appearance of the classic bystander effect (wherein more witnesses decrease the likelihood of any of them helping) far more than non-ambiguous emergencies.
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Computer science.
In computer science, the SI prefixes kilo-, mega- and giga- were historically used in certain contexts to mean either the first three powers of 1024 (1024, 10242 and 10243) contrary to the metric system in which these units unambiguously mean one thousand, one million, and one billion. This usage is particularly prevalent with electronic memory devices (e.g. DRAM) addressed directly by a binary machine register where a decimal interpretation makes no practical sense.
Subsequently, the Ki, Mi, and Gi prefixes were introduced so that binary prefixes could be written explicitly, also rendering k, M, and G "unambiguous" in texts conforming to the new standard—this led to a "new" ambiguity in engineering documents lacking outward trace of the binary prefixes (necessarily indicating the new style) as to whether the usage of k, M, and G remains ambiguous (old style) or not (new style). 1 M (where M is ambiguously or ) is "less" uncertain than the engineering value (defined to designate the interval ). As non-volatile storage devices begin to exceed 1 GB in capacity (where the ambiguity begins to routinely impact the second significant digit), GB and TB almost always mean 109 and 1012 bytes.
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Abel
Abel ( "Hébel", in pausa "Hā́ḇel"; "Hábel"; , "Hābēl") is a biblical figure in the Book of Genesis within the Abrahamic religions. Born as the second son of Adam and Eve, the first two humans created by God, he was a shepherd who offered his firstborn flock to God as a religious offering. God accepted Abel's offering but not the offering of his older brother Cain, leading Cain to stone Abel to death out of jealousy. This act marked the first death in biblical history, making Abel the first murder victim.
Interpretations.
Jewish and Christian interpretations.
According to the narrative in Genesis, Abel is Eve's second son. His name in Hebrew is composed of the same three consonants as a root meaning "the air that remains after you exhale" also synonymous in Hebrew to "nothing", as stated in Ecclesiastes. Julius Wellhausen has proposed that the name is independent of the root. Eberhard Schrader had previously put forward the Akkadian (Old Assyrian dialect) "ablu" ("son") as a more likely etymology.
In Christianity, comparisons are sometimes made between the death of Abel and that of Jesus, the former thus seen as being the first martyr. In Matthew 23:35 Jesus speaks of Abel as "righteous", and the Epistle to the Hebrews states that "The blood of sprinkling ... [speaks] better things than that of Abel" (Hebrews 12:24). The blood of Jesus is interpreted as bringing mercy; but that of Abel as demanding vengeance (hence the curse and mark).
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Abel is invoked in the litany for the dying in the Roman Catholic Church, and his sacrifice is mentioned in the Canon of the Mass along with those of Abraham and Melchizedek. The Alexandrian Rite commemorates him with a feast day on December 28.
According to the Coptic Book of Adam and Eve (at 2:1–15), and the Syriac Cave of Treasures, Abel's body, after many days of mourning, was placed in the "Cave of Treasures", before which Adam and Eve, and descendants, offered their prayers. In addition, the Sethite line of the Generations of Adam swear by Abel's blood to segregate themselves from the "unrighteous".
In the Book of Enoch (22:7), regarded by most Christian and Jewish traditions as extra-biblical, the soul of Abel is described as having been appointed as the chief of martyrs, crying for vengeance, for the destruction of the seed of Cain. A similar view is later shown in the Testament of Abraham (A:13 / B:11), where Abel has been raised to the position as the judge of the souls.
In Bereshit Rabbah (22:2), a discussion of Gen. 4:1 ff. has Rabbi Yehoshua ben Korcha mentioning that Cain was born with a twin sister, and Abel with two twin sisters. This is based on the principle that the otherwise superfluous accusative article "et" always conveys some additional teaching (Pesachim 22b). The "et"'s are parsed slightly differently in Yebamot 62a where the two "et"'s in Gen. 4:2 indicate Cain and his sister, and Abel and his (one) sister.
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Sethian Gnostic interpretation.
In the Apocryphon of John, a work belonging to Sethian Gnosticism, Abel is the offspring of Yaldaboath and Eve, who is placed over the elements of water and earth as Elohim, but was only given his name as a form of deception.
Mandaean interpretation.
According to Mandaean beliefs and scriptures including the Qulasta, the Book of John and Genzā Rabbā, Abel is cognate with the angelic soteriological figure Hibil Ziwa, (, sometimes translated "Splendid Hibel"), who is spoken of as a son of Hayyi or of Manda d-Hayyi, and as a brother to Anush (Enosh) and to Sheetil (Seth), who is the son of Adam. Elsewhere, Anush is spoken of as the son of Sheetil, and Sheetil as the son of Hibil, where Hibil came to Adam and Eve as a young boy when they were still virgins, but was called their son. Hibil is an important lightworld being (uthra) who conquered the World of Darkness. As Yawar Hibil, he is one of multiple figures known as Yawar (), being so named by and after his father.
Islamic interpretation.
According to Shi'a Muslim belief, Abel ("Habeel") is buried in the Nabi Habeel Mosque, located on the west mountains of Damascus, near the Zabadani Valley, overlooking the villages of the Barada river (Wadi Barada), in Syria. Shi'a are frequent visitors of this mosque for ziyarat. The mosque was built by Ottoman Wali Ahmad Pasha in 1599.
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Animal (disambiguation)
An animal is a multicellular, eukaryotic organism of the kingdom Animalia or Metazoa.
Animal, Animals, or The Animal may also refer to:
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Aardvark
Aardvarks ( ; Orycteropus afer) are medium-sized, burrowing, nocturnal mammals native to Africa. Aardvarks are the only living species of the family Orycteropodidae and the order Tubulidentata. They have a long proboscis, similar to a pig's snout, which is used to sniff out food.
They are afrotheres, a clade that also includes elephants, manatees, and hyraxes.
They are found over much of the southern two-thirds of the African continent, avoiding areas that are mainly rocky. Nocturnal feeders, aardvarks subsist on ants and termites by using their sharp claws and powerful legs to dig the insects out of their hills. Aardvarks also dig to create burrows in which to live and rear their young.
Name and taxonomy.
Name.
The aardvark is sometimes colloquially called the "African ant bear", "anteater" (not to be confused with the South American anteaters), or the "Cape anteater" after the Cape of Good Hope.
The name "aardvark" is Afrikaans () and comes from earlier Afrikaans . It means "earth pig" or "ground pig" (: , : ), because of its burrowing habits.
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The name "Orycteropus" means "burrowing foot", and the name "afer" refers to Africa. The name of the aardvark's order, "Tubulidentata", comes from the tubule-style teeth.
Taxonomy.
The aardvark is not closely related to the pig; rather, it is the sole extant representative of the obscure mammalian order Tubulidentata, in which it is usually considered to form one variable species of the genus "Orycteropus", the sole surviving genus in the family Orycteropodidae. The aardvark is not closely related to the South American anteater, despite sharing some characteristics and a superficial resemblance. The similarities are the outcome of convergent evolution. The closest living relatives of the aardvark are the elephant shrews, Tenrecidae, and golden moles. Along with sirenians, hyraxes, elephants, and their extinct relatives, these animals form the superorder Afrotheria. Studies of the brain have shown the similarities with Condylarthra.
Evolutionary history.
Based on his study of fossils, Bryan Patterson has concluded that early relatives of the aardvark appeared in Africa around the end of the Paleocene. The ptolemaiidans, a mysterious clade of mammals with uncertain affinities, may actually be stem-aardvarks, either as a sister clade to Tubulidentata or as a grade leading to true tubulidentates.
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The first unambiguous tubulidentate was probably "Myorycteropus africanus" from Kenyan Miocene deposits. The earliest example from the genus "Orycteropus" was "Orycteropus mauritanicus", found in Algeria in deposits from the middle Miocene, with an equally old version found in Kenya. Fossils from the aardvark have been dated to 5 million years, and have been located throughout Europe and the Near East.
The mysterious Pleistocene "Plesiorycteropus" from Madagascar was originally thought to be a tubulidentate that was descended from ancestors that entered the island during the Eocene. However, a number of subtle anatomical differences coupled with recent molecular evidence now lead researchers to believe that "Plesiorycteropus" is a relative of golden moles and tenrecs that achieved an aardvark-like appearance and ecological niche through convergent evolution.
Subspecies.
The aardvark has seventeen poorly defined subspecies listed:
The 1911 Encyclopædia Britannica also mentions "O. a. capensis" or Cape ant-bear from South Africa.
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Description.
The aardvark is vaguely pig-like in appearance. Its body is stout with a prominently arched back and is sparsely covered with coarse hairs. The limbs are of moderate length, with the rear legs being longer than the forelegs. The front feet have lost the pollex (or 'thumb'), resulting in four toes, while the rear feet have all five toes. Each toe bears a large, robust nail which is somewhat flattened and shovel-like, and appears to be intermediate between a claw and a hoof. Whereas the aardvark is considered digitigrade, it appears at times to be plantigrade. This confusion happens because when it squats it stands on its soles. A contributing characteristic to the burrow digging capabilities of aardvarks is an endosteal tissue called compacted coarse cancellous bone (CCCB). The stress and strain resistance provided by CCCB allows aardvarks to create their burrows, ultimately leading to a favourable environment for plants and a variety of animals. Digging is also facilitated by its forearm's unusually stout ulna and radius.An aardvark's weight is typically between . An aardvark's length is usually between , and can reach lengths of when its tail (which can be up to ) is taken into account. It is tall at the shoulder, and has a girth of about . It does not exhibit sexual dimorphism.
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It is the largest member of the proposed clade Afroinsectiphilia. The aardvark is pale yellowish-grey in colour and often stained reddish-brown by soil. The aardvark's coat is thin, and the animal's primary protection is its tough skin. Its hair is short on its head and tail; however its legs tend to have longer hair. The hair on the majority of its body is grouped in clusters of three to four hairs. The hair surrounding its nostrils is dense to help filter particulate matter out as it digs. Its tail is very thick at the base and gradually tapers.
Head.
The greatly elongated head is set on a short, thick neck, and the end of the snout bears a disc, which houses the nostrils. It contains a thin but complete zygomatic arch. The head of the aardvark contains many unique and different features. One of the most distinctive characteristics of the Tubulidentata is their teeth. Instead of having a pulp cavity, each tooth has a cluster of thin, hexagonal, upright, parallel tubes of vasodentin (a modified form of dentine), with individual pulp canals, held together by cementum. The number of columns is dependent on the size of the tooth, with the largest having about 1,500. The teeth have no enamel coating and are worn away and regrow continuously. The aardvark is born with conventional incisors and canines at the front of the jaw, which fall out and are not replaced. Adult aardvarks have only cheek teeth at the back of the jaw, and have a dental formula of: These remaining teeth are peg-like and rootless and are of unique composition. The teeth consist of 14 upper and 12 lower jaw molars. The nasal area of the aardvark is another unique area, as it contains ten nasal conchae, more than any other placental mammal.
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The sides of the nostrils are thick with hair. The tip of the snout is highly mobile and is moved by modified mimetic muscles. The fleshy dividing tissue between its nostrils probably has sensory functions, but it is uncertain whether they are olfactory or vibratory in nature. Its nose is made up of more turbinate bones than any other mammal, with between nine and 11, compared to dogs with four to five. With a large quantity of turbinate bones, the aardvark has more space for the moist epithelium, which is the location of the olfactory bulb. The nose contains nine olfactory bulbs, more than any other mammal. Its keen sense of smell is not just from the quantity of bulbs in the nose but also in the development of the brain, as its olfactory lobe is very developed. The snout resembles an elongated pig snout. The mouth is small and tubular, typical of species that feed on ants and termites. The aardvark has a long, thin, snakelike, protruding tongue (as much as long) and elaborate structures supporting a keen sense of smell. The ears, which are very effective, are disproportionately long, about long. The eyes are small for its head, and consist only of rods.
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Digestive system.
The aardvark's stomach has a muscular pyloric area that acts as a gizzard to grind swallowed food up, thereby rendering chewing unnecessary. Its cecum is large. Both sexes emit a strong smelling secretion from an anal gland. Its salivary glands are highly developed and almost completely ring the neck; their output is what causes the tongue to maintain its tackiness. The female has two pairs of teats in the inguinal region.
Genetically speaking, the aardvark is a living fossil, as its chromosomes are highly conserved, reflecting much of the early eutherian arrangement before the divergence of the major modern taxa.
Habitat and range.
Aardvarks are found in sub-Saharan Africa, where suitable habitat (savannas, grasslands, woodlands and bushland) and food (i.e., ants and termites) is available. They spend the daylight hours in dark burrows to avoid the heat of the day. The only major habitat that they are not present in is swamp forest, as the high water table precludes digging to a sufficient depth. They also avoid terrain rocky enough to cause problems with digging. They have been documented as high as in Ethiopia. They can be found throughout sub-Saharan Africa from Ethiopia all the way to Cape of Good Hope in South Africa with few exceptions including the coastal areas of Namibia, Ivory Coast, and Ghana. They are not found in Madagascar.
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Ecology and behaviour.
Aardvarks live for up to 23 years in captivity. Its keen hearing warns it of predators: lions, leopards, cheetahs, African wild dogs, hyenas, and pythons. Some humans also hunt aardvarks for meat. Aardvarks can dig fast or run in zigzag fashion to elude enemies, but if all else fails, they will strike with their claws, tail and shoulders, sometimes flipping onto their backs lying motionless except to lash out with all four feet. They are capable of causing substantial damage to unprotected areas of an attacker. They will also dig to escape as they can. Sometimes, when pressed, aardvarks can dig extremely quickly.
Feeding.
The aardvark is nocturnal and is a solitary creature that feeds almost exclusively on ants and termites (myrmecophagy); studies in the Nama Karoo revealed that ants, especially "Anoplolepis custodiens", were the predominant prey year-round, followed by termites like "Trinervitermes trinervoides". In winter, when ant numbers declined, aardvarks relied more on termites, often feeding on epigeal mounds coinciding with the presence of alates, possibly to meet their nutritional needs. They avoid eating the African driver ant and red ants. Due to their stringent diet requirements, they require a large range to survive.
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The only fruit eaten by aardvarks is the aardvark cucumber. In fact, the cucumber and the aardvark have a symbiotic relationship as they eat the subterranean fruit, then defecate the seeds near their burrows, which then grow rapidly due to the loose soil and fertile nature of the area. The time spent in the intestine of the aardvark helps the fertility of the seed, and the fruit provides needed moisture for the aardvark.
An aardvark emerges from its burrow in the late afternoon or shortly after sunset, and forages over a considerable home range encompassing . While foraging for food, the aardvark will keep its nose to the ground and its ears pointed forward, which indicates that both smell and hearing are involved in the search for food. They zig-zag as they forage and will usually not repeat a route for five to eight days as they appear to allow time for the termite nests to recover before feeding on it again.
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On a nightly basis they tend to be more active during the first portion of night (roughly the four hours between 8:00p.m. and 12:00a.m.); however, they do not seem to prefer bright or dark nights over the other. During adverse weather or if disturbed they will retreat to their burrow systems. They cover between per night; however, some studies have shown that they may traverse as far as in a night.
Aardvarks shift their circadian rhythms to more diurnal activity patterns in response to a reduced food supply. This survival tactic may signify an increased risk of imminent mortality.
Vocalisation.
The aardvark is a rather quiet animal. However, it does make soft grunting sounds as it forages and loud grunts as it makes for its tunnel entrance. It makes a bleating sound if frightened. When it is threatened it will make for one of its burrows. If one is not close it will dig a new one rapidly. This new one will be short and require the aardvark to back out when the coast is clear.
Movement.
The aardvark is known to be a good swimmer and has been witnessed successfully swimming in strong currents. It can dig a yard of tunnel in about five minutes, but otherwise moves fairly slowly.
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When leaving the burrow at night, they pause at the entrance for about ten minutes, sniffing and listening. After this period of watchfulness, it will bound out and within seconds it will be away. It will then pause, prick its ears, twisting its head to listen, then jump and move off to start foraging.
Aside from digging out ants and termites, the aardvark also excavates burrows in which to live, which generally fall into one of three categories: burrows made while foraging, refuge and resting location, and permanent homes. Temporary sites are scattered around the home range and are used as refuges, while the main burrow is also used for breeding. Main burrows can be deep and extensive, have several entrances and can be as long as . These burrows can be large enough for a person to enter. The aardvark changes the layout of its home burrow regularly, and periodically moves on and makes a new one. The old burrows are an important part of the African wildlife scene. As they are vacated, then they are inhabited by smaller animals like the African wild dog, ant-eating chat, "Nycteris thebaica" and warthogs. Other animals that use them are hares, mongooses, hyenas, owls, pythons, and lizards. Without these refuges many animals would die during wildfire season. Only mothers and young share burrows; however, the aardvark is known to live in small family groups or as a solitary creature. If attacked in the tunnel, it will escape by digging out of the tunnel thereby placing the fresh fill between it and its predator, or if it decides to fight it will roll onto its back, and attack with its claws. The aardvark has been known to sleep in a recently excavated ant nest, which also serves as protection from its predators.
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Reproduction.
It is believed to exhibit polygamous breeding behavior. During mating, the male secures himself to the female's back using his claws, which can occasionally result in noticeable scratches. Males play no role on parental care.
Aardvarks pair only during the breeding season; after a gestation period of seven months, one cub weighing around is born during May–July. When born, the young has flaccid ears and many wrinkles. When nursing, it will nurse off each teat in succession. After two weeks, the folds of skin disappear and after three, the ears can be held upright. After 5–6 weeks, body hair starts growing. It is able to leave the burrow to accompany its mother after only two weeks and eats termites at nine weeks, and is weaned between three months and 16 weeks. At six months of age, it is able to dig its own burrows, but it will often remain with the mother until the next mating season, and is sexually mature from approximately two years of age.
Conservation.
Aardvarks were thought to have declining numbers, however, this is possibly because they are not readily seen. There are no definitive counts because of their nocturnal and secretive habits; however, their numbers seem to be stable overall. They are not considered common anywhere in Africa, but due to their large range, they maintain sufficient numbers. There may be a slight decrease in numbers in eastern, northern, and western Africa. Southern African numbers are not decreasing. It has received an official designation from the IUCN as least concern. However, they are a species in a precarious situation, as they are so dependent on such specific food; therefore if a problem arises with the abundance of termites, the species as a whole would be affected drastically.
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Recent research suggests that aardvarks may be particularly vulnerable to alterations in temperature caused by climate change. Droughts negatively impact the availability of termites and ants, which comprise the bulk of an aardvark's diet. Nocturnal species faced with resource scarcity may increase their diurnal activity to spare the energy costs of staying warm at night, but this comes at the cost of withstanding high temperatures during the day. A study on aardvarks in the Kalahari Desert saw that five out of six aardvarks being studied perished following a drought. Aardvarks that survive droughts can take long periods of time to regain health and optimal thermoregulatory physiology, reducing the reproductive potential of the species.
Aardvarks adapt well to captivity. The first recorded instance was at London Zoo in 1869, which housed an individual from South Africa.
Mythology and popular culture.
In African folklore, the aardvark is much admired because of its diligent quest for food and its fearless response to soldier ants. Hausa magicians make a charm from the heart, skin, forehead, and nails of the aardvark, which they then proceed to pound together with the root of a certain tree. Wrapped in a piece of skin and worn on the chest, the charm is said to give the owner the ability to pass through walls or roofs at night. The charm is said to be used by burglars and those seeking to visit young girls without their parents' permission. Also, some tribes, such as the Margbetu, Ayanda, and Logo, will use aardvark teeth to make bracelets, which are regarded as good luck charms. The meat, which has a resemblance to pork, is eaten in certain cultures. In the mythology of the Dagbon people of Ghana, the aardvark is believed to possess superpowers. The Dagombas believe this animal can transfigure into and interact with humans.
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The ancient Egyptian god Set is usually depicted with the head of an unidentified animal, whose similarity to an aardvark has been noted in scholarship.
The titular character and his families from "Arthur", an animated television series for children based on a book series and produced by WGBH, shown in more than 180 countries, is an aardvark. In the first book of the series, "Arthur's Nose" (1976), he has a long, aardvark-like nose, but in later books, his face becomes more rounded.
Otis the Aardvark was a puppet character used on Children's BBC programming.
An aardvark features as the antagonist in the cartoon "The Ant and the Aardvark" as well as in the Canadian animated series "The Raccoons".
The supersonic fighter-bomber F-111/FB-111 was nicknamed the Aardvark because of its long nose resembling the animal. It also had similarities with its nocturnal missions flown at a very low level employing ordnance that could penetrate deep into the ground. In the US Navy, the squadron VF-114 was nicknamed the Aardvarks, flying F-4s and then F-14s. The squadron mascot was adapted from the animal in the comic strip "B.C.", which the F-4 was said to resemble.
"Cerebus the Aardvark" is a 300-issue comic book series by Dave Sim.
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Aardwolf
The aardwolf (Proteles cristatus) is an insectivorous hyaenid species, native to East and Southern Africa. Its name means "earth-wolf" in Afrikaans and Dutch. It is also called the maanhaar-jackal (Afrikaans for "mane-jackal"), termite-eating hyena and civet hyena, based on its habit of secreting substances from its anal gland, a characteristic shared with the African civet.
Unlike many of its relatives in the order Carnivora, the aardwolf does not hunt large animals. It eats insects and their larvae, mainly termites; one aardwolf can lap up as many as 300,000 termites during a single night using its long, sticky tongue. The aardwolf's tongue has adapted to be tough enough to withstand the strong bite of termites.
The aardwolf lives in the shrublands of eastern and southern Africa – open lands covered with stunted trees and shrubs. It is nocturnal, resting in burrows during the day and emerging at night to seek food.
Taxonomy.
The aardwolf is generally classified as part of the hyena family Hyaenidae. However, it was formerly placed in its own family Protelidae. Early on, scientists felt that it was merely mimicking the striped hyena, which subsequently led to the creation of Protelidae. Recent studies have suggested that the aardwolf probably diverged from other hyaenids early on; how early is still unclear, as the fossil record and genetic studies disagree by 10 million years.
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The aardwolf is the only surviving species in the subfamily Protelinae. There is disagreement as to whether the species is monotypic, or can be divided into subspecies. A 2021 study found the genetic differences in eastern and southern aardwolves may be pronounced enough to categorize them as species.
A 2006 molecular analysis indicates it is phylogenetically the most basal of the four extant hyaenidae species.
Etymology.
The generic name "Proteles" is derived from two words of Greek origin: , "prōtos" and "téleios", which combined mean "complete in front" referring to the aardwolf's five toes on the front paws and four on the hindpaws.
The specific name "cristatus" is derived from Latin and means "provided with a comb or tuft", relating to its mane.
Description.
The aardwolf resembles a much smaller and thinner striped hyena, with a more slender muzzle, black vertical stripes on a coat of yellowish fur, and a long, distinct mane down the midline of the neck and back. It also has one or two diagonal stripes down the fore and hindquarters and several stripes on its legs. The mane is raised during confrontations to make the aardwolf appear larger. It is missing the throat spot that others in the family have. Its lower leg (from the knee down) is all black, and its tail is bushy with a black tip.
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The aardwolf is about long, excluding its bushy tail, which is about long, and stands about tall at the shoulders. An adult aardwolf weighs approximately , sometimes reaching . The aardwolves in the south of the continent tend to be slightly smaller (about ) than the eastern version (around ). This makes the aardwolf the smallest extant member of the Hyaenidae family. The front feet have five toes each, unlike the four-toed hyena. The skull is similar in shape to those of other hyenas, though much smaller, and its cheek teeth are specialised for eating insects. It still has canines, but unlike other hyenas, these teeth are used primarily for fighting and defense. Its ears, which are large, are very similar to those of the striped hyena.
As an aardwolf ages, it will typically lose some of its teeth, though this has little impact on its feeding habits due to the softness of the insects that it eats.
Distribution and habitat.
Aardwolves live in open, dry plains and bushland, avoiding mountainous areas. Due to their specific food requirements, they are found only in regions where termites of the family Hodotermitidae occur. Termites of this family depend on dead and withered grass and are most populous in heavily grazed grasslands and savannahs, including farmland. For most of the year, aardwolves spend time in shared territories consisting of up to a dozen dens, which are occupied for six weeks at a time.
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There are two distinct populations: one in Southern Africa, and another in East and Northeast Africa. The species does not occur in the intermediary miombo forests.
An adult pair, along with their most-recent offspring, occupies a territory of .
Behavior and ecology.
Aardwolves are shy and nocturnal, sleeping in burrows by day. They will, on occasion during the winter, become diurnal feeders. This happens during the coldest periods as they then stay in at night to conserve heat.
They are primarily solitary animals, though during mating season they form monogamous pairs which occupy a territory with their young. If their territory is infringed upon by another aardwolf, they will chase the intruder away for up to or to the border. If the intruder is caught, which rarely happens, a fight will occur, which is accompanied by soft clucking, hoarse barking, and a type of roar. The majority of incursions occur during mating season, when they can occur once or twice per week. When food is scarce, the stringent territorial system may be abandoned and as many as three pairs may occupy a single territory.
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The territory is marked by both sexes, as they both have developed anal glands from which they extrude a black substance that is smeared on rocks or grass stalks in -long streaks. Aardwolves also have scent glands on the forefoot and penile pad. They often mark near termite mounds within their territory every 20 minutes or so. If they are patrolling their territorial boundaries, the marking frequency increases drastically, to once every . At this rate, an individual may mark 60 marks per hour, and upwards of 200 per night.
An aardwolf pair's territory may have up to 10 dens, and numerous middens where they dig small holes and bury their feces with sand. Their dens are usually abandoned aardvark, springhare, or porcupine dens, or on occasion they are crevices in rocks. They will also dig their own dens, or enlarge dens started by springhares. They typically will only use one or two dens at a time, rotating through all of their dens every six months. During the summer, they may rest outside their den during the night and sleep underground during the heat of the day.
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Aardwolves are not fast runners nor are they particularly adept at fighting off predators. Therefore, when threatened, the aardwolf may attempt to mislead its foe by doubling back on its tracks. If confronted, it may raise its mane in an attempt to appear more menacing. It also emits a foul-smelling liquid from its anal glands.
Feeding.
The aardwolf feeds primarily on termites and more specifically on "Trinervitermes". This genus of termites has different species throughout the aardwolf's range. In East Africa, they eat "Trinervitermes bettonianus", in central Africa, they eat "Trinervitermes rhodesiensis", and in southern Africa, they eat "T. trinervoides". Their technique consists of licking them off the ground as opposed to the aardvark, which digs into the mound. They locate their food by sound and also from the scent secreted by the soldier termites. An aardwolf may consume up to 250,000 termites per night using its long, broad, sticky tongue.
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Unlike other hyenas, aardwolves do not scavenge or kill larger animals. Contrary to popular myths, aardwolves do not eat carrion, and if they are seen eating while hunched over a dead carcass, they are actually eating larvae and beetles. Also, contrary to some sources, they do not like meat, unless it is finely ground or cooked for them. The adult aardwolf was formerly assumed to forage in small groups, but more recent research has shown that they are primarily solitary foragers, necessary because of the scarcity of their insect prey. Their primary source, "Trinervitermes", forages in small but dense patches of . While foraging, the aardwolf can cover about per hour, which translates to per summer night and per winter night.
Breeding.
The breeding season varies depending on location, but normally takes place during autumn or spring. In South Africa, breeding occurs in early July. During the breeding season, unpaired male aardwolves search their own territory, as well as others, for a female to mate with. Dominant males also mate opportunistically with the females of less dominant neighboring aardwolves, which can result in conflict between rival males. Dominant males even go a step further and as the breeding season approaches, they make increasingly greater and greater incursions onto weaker males' territories. As the female comes into oestrus, they add pasting to their tricks inside of the other territories, sometimes doing so more in rivals' territories than their own. Females will also, when given the opportunity, mate with the dominant male, which increases the chances of the dominant male guarding "his" cubs with her. Copulation lasts between 1 and 4.5 hours.
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Gestation lasts between 89 and 92 days, producing two to five cubs (most often two or three) during the rainy season (October–December), when termites are more active. They are born with their eyes open, but initially are helpless, and weigh around . The first six to eight weeks are spent in the den with their parents. The male may spend up to six hours a night watching over the cubs while the mother is out looking for food. After three months, they begin supervised foraging, and by four months are normally independent, though they often share a den with their mother until the next breeding season. By the time the next set of cubs is born, the older cubs have moved on. Aardwolves generally achieve sexual maturity at one and a half to two years of age.
Conservation.
The aardwolf has not seen decreasing numbers and is relatively widespread throughout eastern Africa. They are not common throughout their range, as they maintain a density of no more than 1 per square kilometer, if food is abundant. Because of these factors, the IUCN has rated the aardwolf as least concern. In some areas, they are persecuted because of the mistaken belief that they prey on livestock; however, they are actually beneficial to the farmers because they eat termites that are detrimental. In other areas, the farmers have recognized this, but they are still killed, on occasion, for their fur. Dogs and insecticides are also common killers of the aardwolf.
In captivity.
Frankfurt Zoo in Germany was home to the oldest recorded aardwolf in captivity at 18 years and 11 months.
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Adobe
Adobe ( ; ) is a building material made from earth and organic materials. is Spanish for mudbrick. In some English-speaking regions of Spanish heritage, such as the Southwestern United States, the term is used to refer to any kind of earthen construction, or various architectural styles like Pueblo Revival or Territorial Revival. Most adobe buildings are similar in appearance to cob and rammed earth buildings. Adobe is among the earliest building materials, and is used throughout the world.
Adobe architecture has been dated to before 5,100 BP.
Description.
Adobe bricks are rectangular prisms small enough that they can quickly air dry individually without cracking. They can be subsequently assembled, with the application of adobe mud to bond the individual bricks into a structure. There is no standard size, with substantial variations over the years and in different regions. In some areas a popular size measured weighing about ; in other contexts the size is weighing about . The maximum sizes can reach up to ; above this weight it becomes difficult to move the pieces, and it is preferred to ram the mud "in situ", resulting in a different typology known as rammed earth.
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Strength.
In dry climates, adobe structures are extremely durable, and account for some of the oldest existing buildings in the world. Adobe buildings offer significant advantages due to their greater thermal mass, but they are known to be particularly susceptible to earthquake damage if they are not reinforced. Cases where adobe structures were widely damaged during earthquakes include the 1976 Guatemala earthquake, the 2003 Bam earthquake, and the 2010 Chile earthquake.
Distribution.
Buildings made of sun-dried earth are common throughout the world (Middle East, Western Asia, North Africa, West Africa, South America, Southwestern North America, Southwestern and Eastern Europe.). Adobe had been in use by indigenous peoples of the Americas in the Southwestern United States, Mesoamerica, and the Andes for several thousand years. Puebloan peoples built their adobe structures with handsful or basketsful of adobe, until the Spanish introduced them to making bricks. Adobe bricks were used in Spain from the Late Bronze and Iron Ages (eighth century BCE onwards). Its wide use can be attributed to its simplicity of design and manufacture, and economics.
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Etymology.
The word "adobe" has existed for around 4,000 years with relatively little change in either pronunciation or meaning. The word can be traced from the Middle Egyptian () word "ḏbt" "mud brick" (with vowels unwritten). Middle Egyptian evolved into Late Egyptian and finally to Coptic (), where it appeared as ⲧⲱⲃⲉ "tōbə". This was adopted into Arabic as "aṭ-ṭawbu" or "aṭ-ṭūbu", with the definite article "al-" attached to the root "tuba". This was assimilated into the Old Spanish language as "adobe" , probably via Mozarabic. English borrowed the word from Spanish in the early 18th century, still referring to mudbrick construction.
In more modern English usage, the term "adobe" has come to include a style of architecture popular in the desert climates of North America, especially in New Mexico, regardless of the construction method.
Composition.
An adobe brick is a composite material made of earth mixed with water and an organic material such as straw or dung. The soil composition typically contains sand, silt and clay. Straw is useful in binding the brick together and allowing the brick to dry evenly, thereby preventing cracking due to uneven shrinkage rates through the brick. Dung offers the same advantage. The most desirable soil texture for producing the mud of adobe is 15% clay, 10–30% silt, and 55–75% fine sand. Another source quotes 15–25% clay and the remainder sand and coarser particles up to cobbles , with no deleterious effect. Modern adobe is stabilized with either emulsified asphalt or Portland cement up to 10% by weight.
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No more than half the clay content should be expansive clays, with the remainder non-expansive illite or kaolinite. Too much expansive clay results in uneven drying through the brick, resulting in cracking, while too much kaolinite will make a weak brick. Typically the soils of the Southwest United States, where such construction has been widely used, are an adequate composition.
Material properties.
Adobe walls are load bearing, i.e. they carry their own weight into the foundation rather than by another structure, hence the adobe must have sufficient compressive strength. In the United States, most building codes call for a minimum compressive strength of for the adobe block. Adobe construction should be designed so as to avoid lateral structural loads that would cause bending loads. The building codes require the building sustain a lateral acceleration earthquake load. Such an acceleration will cause lateral loads on the walls, resulting in shear and bending and inducing tensile stresses. To withstand such loads, the codes typically call for a tensile modulus of rupture strength of at least for the finished block.
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In addition to being an inexpensive material with a small resource cost, adobe can serve as a significant heat reservoir due to the thermal properties inherent in the massive walls typical in adobe construction. In climates typified by hot days and cool nights, the high thermal mass of adobe mediates the high and low temperatures of the day, moderating the temperature of the living space. The massive walls require a large and relatively long input of heat from the sun (radiation) and from the surrounding air (convection) before they warm through to the interior. After the sun sets and the temperature drops, the warm wall will continue to transfer heat to the interior for several hours due to the time-lag effect. Thus, a well-planned adobe wall of the appropriate thickness is very effective at controlling inside temperature through the wide daily fluctuations typical of desert climates, a factor which has contributed to its longevity as a building material.
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Uses.
Poured and puddled adobe walls.
Poured and puddled adobe (puddled clay, piled earth), today called "cob", is made by placing soft adobe in layers, rather than by making individual dried bricks or using a form. "Puddle" is a general term for a clay or clay and sand-based material worked into a dense, plastic state. These are the oldest methods of building with adobe in the Americas until holes in the ground were used as forms, and later wooden forms used to make individual bricks were introduced by the Spanish.
Adobe bricks.
Bricks made from adobe are usually made by pressing the mud mixture into an open timber frame. In North America, the brick is typically about in size. The mixture is molded into the frame, which is removed after initial setting. After drying for a few hours, the bricks are turned on edge to finish drying. Slow drying in shade reduces cracking.
The same mixture, without straw, is used to make mortar and often plaster on interior and exterior walls. Some cultures used lime-based cement for the plaster to protect against rain damage.
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Depending on the form into which the mixture is pressed, adobe can encompass nearly any shape or size, provided drying is even and the mixture includes reinforcement for larger bricks. Reinforcement can include manure, straw, cement, rebar, or wooden posts. Straw, cement, or manure added to a standard adobe mixture can produce a stronger, more crack-resistant brick. A test is done on the soil content first. To do so, a sample of the soil is mixed into a clear container with some water, creating an almost completely saturated liquid. The container is shaken vigorously for one minute. It is then allowed to settle for a day until the soil has settled into layers. Heavier particles settle out first, sand above, silt above that, and very fine clay and organic matter will stay in suspension for days. After the water has cleared, percentages of the various particles can be determined. Fifty to 60 percent sand and 35 to 40 percent clay will yield strong bricks. The Cooperative State Research, Education, and Extension Service at New Mexico State University recommends a mix of not more than clay, not less than sand, and never more than silt.
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During the Great Depression, designer and builder Hugh W. Comstock used cheaper materials and made a specialized adobe brick called "Bitudobe." His first adobe house was built in 1936. In 1948, he published the book "Post-Adobe; Simplified Adobe Construction Combining A Rugged Timber Frame And Modern Stabilized Adobe," which described his method of construction, including how to make "Bitudobe." In 1938, he served as an adviser to the architects Franklin & Kump Associates, who built the Carmel High School, which used his Post-adobe system.
Adobe wall construction.
The ground supporting an adobe structure should be compressed, as the weight of adobe wall is significant and foundation settling may cause cracking of the wall. Footing depth is to be below the ground frost level. The footing and stem wall are commonly thick, respectively. Modern construction codes call for the use of reinforcing steel in the footing and stem wall. Adobe bricks are laid by course. Adobe walls usually never rise above two stories as they are load bearing and adobe has low structural strength. When creating window and door openings, a lintel is placed on top of the opening to support the bricks above. Atop the last courses of brick, bond beams made of heavy wood beams or modern reinforced concrete are laid to provide a horizontal bearing plate for the roof beams and to redistribute lateral earthquake loads to shear walls more able to carry the forces. To protect the interior and exterior adobe walls, finishes such as mud plaster, whitewash or stucco can be applied. These protect the adobe wall from water damage, but need to be reapplied periodically. Alternatively, the walls can be finished with other nontraditional plasters that provide longer protection. Bricks made with stabilized adobe generally do not need protection of plasters.
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Adobe roof.
The traditional adobe roof has been constructed using a mixture of soil/clay, water, sand and organic materials. The mixture was then formed and pressed into wood forms, producing rows of dried earth bricks that would then be laid across a support structure of wood and plastered into place with more adobe.
Depending on the materials available, a roof may be assembled using wood or metal beams to create a framework to begin layering adobe bricks. Depending on the thickness of the adobe bricks, the framework has been preformed using a steel framing and a layering of a metal fencing or wiring over the framework to allow an even load as masses of adobe are spread across the metal fencing like cob and allowed to air dry accordingly. This method was demonstrated with an adobe blend heavily impregnated with cement to allow even drying and prevent cracking.
The more traditional flat adobe roofs are functional only in dry climates that are not exposed to snow loads. The heaviest wooden beams, called vigas, lie atop the wall. Across the vigas lie smaller members called latillas and upon those brush is then laid. Finally, the adobe layer is applied.
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To construct a flat adobe roof, beams of wood were laid to span the building, the ends of which were attached to the tops of the walls. Once the vigas, latillas and brush are laid, adobe bricks are placed. An adobe roof is often laid with bricks slightly larger in width to ensure a greater expanse is covered when placing the bricks onto the roof. Following each individual brick should be a layer of adobe mortar, recommended to be at least thick to make certain there is ample strength between the brick's edges and also to provide a relative moisture barrier during rain.
Roof design evolved around 1850 in the American Southwest. of adobe mud was applied on top of the latillas, then of dry adobe dirt applied to the roof. The dirt was contoured into a low slope to a downspout aka a 'canal'. When moisture was applied to the roof the clay particles expanded to create a waterproof membrane. Once a year it was necessary to pull the weeds from the roof and re-slope the dirt as needed.
Depending on the materials, adobe roofs can be inherently fire-proof. The construction of a chimney can greatly influence the construction of the roof supports, creating an extra need for care in choosing the materials. The builders can make an adobe chimney by stacking simple adobe bricks in a similar fashion as the surrounding walls.
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In 1927, the Uniform Building Code (UBC) was adopted in the United States. Local ordinances, referencing the UBC added requirements to building with adobe. These included: restriction of building height of adobe structures to 1-story, requirements for adobe mix (compressive and shear strength) and new requirements which stated that every building shall be designed to withstand seismic activity, specifically lateral forces. By the 1980s however, seismic related changes in the California Building Code effectively ended solid wall adobe construction in California; however Post-and-Beam adobe and veneers are still being used.
Adobe around the world.
The largest structure ever made from adobe is the Arg-é Bam built by the Achaemenid Empire. Other large adobe structures are the Huaca del Sol in Peru, with 100 million signed bricks and the "ciudellas" of Chan Chan and Tambo Colorado, both in Peru.
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