Defining the Genus Homo Learning Objectives By the end of this section, you will be able to: Describe the time periods and geological context of the genus Homo . Identify some key differences between the genus Homo and Australopithecus. Define some of the limitations of and challenges in the classification of hominin species in the genus Homo . Explain the concept of encephalization as it relates to early hominin evolutionary development and as a tool for hominin classification. Putting Homo into Context Before learning about the hominin species that make up the category genus Homo , it will be helpful to become familiar with the key archaeological time periods with which Homo is associated. The species and cultural developments mentioned below will be explored in greater detail in the sections that follow. Lower Paleolithic (from roughly 3 million years ago to approximately 300,000 BCE): This period includes H. habilis and the Oldowan tool industry, followed by H. ergaster and the Acheulean tool industry. Middle Paleolithic (approximately 300,000–40,000 BCE): This period includes continued use of Acheulean tools by H. heidelbergensis, followed by H. neanderthalensis and the Mousterian tool industry. Upper Paleolithic (approximately 43,000–26,000 BCE): The Upper Paleolithic saw the emergence of cave art like that found in the famous Chauvet Cave in France ( ), Venus figurines ( ), and an increased use of bone and antler in tools and jewelry. The most recent ice age occurred during this time, with glaciers covering huge parts of the planet. The emergence of Paleoindians and the use of Clovis points, which were used to kill large game such as mastodons and mammoths, occurred near the end of this time period. Epipaleolithic/Mesolithic (approximately 13,000--8,000 BCE, depending on the location): Corresponding with the ending of the last ice age and the extinction of species such as mastodons, this period saw a further transition toward the hunter-gatherer cultures. It is characterized by the development of certain ceramics and especially of microliths, which are smaller, more precise stone tools. The mesolithic is not a defined period in all parts of the world, and its time boundaries vary significantly by geographic region. Neolithic (Agricultural Age) (8,000–3,000 BCE): New innovations appear during the agricultural age, or “Neolithic revolution,” as H. sapiens set up permanent settlements. Humans begin to transition from being hunters and gatherers to growing grow crops, owning land, and domesticating animals. The Challenge of Defining the Genus Homo The previous chapter introduced the australopithecines, who were diverse in their physical characteristics (gracile and robust), with large jaws and teeth and small brain size. A key characteristic shared by both the australopithecines and the genus Homo is bipedalism. The transition to bipedalism is linked with various anatomical changes, including longer legs, changes in spinal curvature, and the development of arches in the feet to conserve energy and increase balance when walking. What criteria other than bipedalism might be used to classify a species under the genus Homo ? Many anthropologists have attempted to establish specific criteria to use in determining a classification of Homo. Paleoanthropologists Mary Leakey , Louis Leakey , and John Napier , as well as primatologist Phillip Tobias , were among the first to extensively study the fossils of Homo habilis , considered to be one of the earliest species in the genus Homo . H. habilis had a brain size of around 661–700 cc, which was larger than the australopithecines’, with hands that were capable of the dexterity needed for making tools, due to bone structure changes and a repositioning of the thumb, which allowed for better grip. The type specimen OH 7 of H. habilis dated between 2 and 1.7 MYA and was found in 1960 at Olduvai Gorge by Jonathan and Mary Leakey. It was described by Louis Leakey in 1964. Type specimen refers to a specimen that serves as the standard for the taxon or classification group for that species. OH 7 is the identification or accession number of this specific specimen and stands for “Olduvai Hominid #7.” The specimen consisted of a partial juvenile skull, hand, and foot bones. It possessed teeth that were much smaller than those of any australopithecine and was possibly in coexistence with the robust australopithecines ( Paranthropus ). Based on an endocranial cast (an imprint of the interior of the brain case), it was determined that H. habilis may have possessed what is called a Broca’s area in the brain. Broca’s area , which includes two Brodmann areas (referred to as 44 and 45), is located in the middle of the left cerebral cortex of the brain and is especially important for speech development ( ). Some scientists have suggested that H. habilis started to develop the neural networks necessary for human speech, while others argue that H. habilis probably already had speech. Position of the Broca’s area in the brain, consisting of Brodmann areas 44 (yellow) and 45 (blue). Broca’s area is associated with speech development and may have been present in the brain of H. habilis . (credit: Fatemeh Geranmayeh, Sonia L. E. Brownsett, Richard J. S. Wise/Wikimedia Commons, CC BY 3.0) The postcranial features (skeletal structures in the body other than the skull) of Homo habilis are not as well established, as is the case for many other early hominin fossils. This can be problematic, as many hominin species coexisted with overlapping traits. Likewise, it can be problematic to have postcranial material and not the cranium or skull. The skull often serves as a diagnostic tool when postcranial materials do not provide enough evidence or provide confusing evidence. Based on their research on H. habilis , Mary Leakey, Louis Leakey, and John Napier proposed the following criteria for classifying Homo : a brain size over 600 cc; a round, globular skull; tool use; reduced prognathism (protrusion of the jaw) and smaller jaws and mandibles; humanlike postcranial features; and feet that are fully adapted for walking (Leakey, Tobias, and Napier 1964). While this list established specific and fairly comprehensive guidance, the diversity of traits and the ways in which they overlapped didn’t always line up with the criteria. H. habilis has been at the center of several debates regarding their taxonomic position and relationship with other early archaic Homo species. For example, H. habilis was initially believed to have been a direct human ancestor through the lineage of Homo erectus and then modern humans . This viewpoint is now debated and has resulted in a scientific divide between those supporting H. habilis and those suggesting another Homo species, H. rudolfensis , as being the ancestor of H. erectus. H. rudolfensis is an archaic Homo dated to about 2 MYA, which coexisted with other Homo species during that time period. A cranium was discovered in 1972 along Lake Turkana in Kenya by Bernard Ngeneo, a local Kenyan. The specimen was later described by paleoanthropologist Richard Leakey. There is a lot that is not known about this species; scientists are missing postcranial materials, and as of yet no tools have been found. There are hypotheses that propose that H. rudolfensis might be a H. habilis male, exhibiting a larger cranium than that seen in a female H. habilis . Others suggest it is a completely different species. Another controversy centers on tool use. While Homo habilis was long regarded as the earliest hominin to use stone tools, it has been determined, based on evidence of cutmarks, that at least one australopithecine ( A. garhi ) used stone tools before H. habilis , at around 2.6 MYA (Semaw et al. 1997). The specimen of H. rudolfensis on the left is noticeably different from that of H. habilis on the right. (credit: Conty/Wikimedia Commons, CC BY 3.0) While there are still questions as to the phylogenetic relationship of H. habilis and H. rudolfensis , there is general agreement that Homo did evolve from Australopithecus . The timing and placement of the split between Australopithecus and Homo , however, is still debated. H. habilis was determined to not be an Australopithecus due to its smaller teeth, a humanlike foot, and hand bones that suggested an ability to manipulate objects with precision. One of the main considerations in classifying H. habilis as a Homo and not an Australopithecus was its cranial capacity , which is a measurement that indicates brain size. With some exceptions, cranial capacity can serve as an indicator of where a hominin fossil might belong in the hominin phylogenetic tree. Encephalization refers to a progressive increase in brain size over time. In human evolution, we can observe encephalization beginning with Homo habilis and progressing more rapidly through H. erectus . Encephalization correlates with an increase in behavioral, cognitive, and cultural complexity. Cognitive developments correspond with our ability to construct and form ideas, including the ability think in and communicate via symbolic and abstract language, such as that used in storytelling, ritual, and art. There are always exceptions, however, such as the island-dwelling, small-brained H. floresiensis , who will be introduced later in this chapter. In spite of having a very small brain, H. floresiensis made and used tools and built fires. This discovery has challenged what we thought we knew about the correlation of brain size and cognitive development in human evolution. The encephalization quotient (EQ) can serve as a good indicator (with some exceptions) of classification within the genus Homo . The encephalization quotient is a calculation arrived at by comparing the ratio between actual brain size (determined with either a mass or volume calculation) and expected brain size. Body size is a factor in these measurements as expected brain size reflects the relationship between brain and body size for a given taxonomic group (Jerison 1973). The larger the brain weight relative to the overall body weight, the more likely that the brain was used for more complex cognitive tasks. Harry J. Jerison (1973) was the first to develop EQ measurements. The formula he used for calculating EQ in birds and mammals is brain mass/0.12 × (body mass) 0.66 . Other formulas have also been proposed, such as EQ = brain mass (11.22 × body mass 0.76) (Martin 1981). While EQ is a strong tool for studying brain size in early hominins, there are always potential margins of error when dealing with fragmentary fossils, and increasingly alternative forms of measurements are being proposed. One study proposes that EQ should no longer be used as a tool in calculating brain size in primates and other vertebrate species, based on the premise that cognitive performance does not depend on body size and so body size should not be included in the formula (Schaik et al. 2021). Other theories consider the number of cortical neurons and neural connections as most important when considering cognitive ability (Roth and Dicke 2012). According to this approach, the density of the cortex is more associated with intelligence than is brain size. These alternate approaches would perhaps better explain those exceptions in the fossil records, such as H. floresiensis . Other interesting research is looking at potential levels of cognition and memory as it relates to levels of tool complexity (Read and van der Leeuw 2008). In spite of these criticisms, many see EQ measurements as providing fairly consistent results. Modern humans ( Homo sapiens ) have an EQ of roughly 6.0–7.0 (meaning that their brain mass is six to seven times greater than what one would expect to find in a comparable mammal of the same body size). H. erectus has an EQ of 4.0, while for an australopithecine EQ is around 2.5 to 3.0 (Fuente 2012, 227). shows increases in average brain sizes for various species over time. After remaining steady for millennia, average brain size increases noticeably in the last two million years. (Xiujie, Wu, and Norton 2007). (credit: Gisselle Garcia, artist (brain images), CC BY 4.0) Broca’s area a region in the frontal lobe of the brain (which includes two Brodmann areas) first found in H. habilis and connected with the production of speech. cranial capacity the volume of the interior of the cranium or skull, providing an approximate size of the brain. encephalization increased brain size over time. encephalization quotient a measurement defined as the ratio between brain and body size. endocranial cast an impression taken from the inside of the cranium (braincase), frequently used by paleoanthropologists to determine the shape and approximate size of the brain in hominids and other primates. postcranial features skeletal material found in the body that is not related to the skull (cranial bones).

Social Sciences


Tools and Brains: Homo habilis, Homo ergaster, and Homo erectus Learning Objectives By the end of this section, you will be able to: Compare and contrast the anatomy and material culture of H. habilis, H. erectus , and H. ergaster. Define the term “tool industry” and describe the tools typified by the Oldowan and Acheulean industries. Identify possible correlations between the environment, diet, new behaviors, and brain growth. The Toolmakers Archeologists use the word industry to describe a classification or assemblage of stone tools. The Oldowan tool industry is the oldest known stone tool industry. It dates from around 2.5 to 1.5 MYA. Because there were several hominins in Africa during this time, it is unclear whether these tools were created and used by H. habilis or by Paranthropus boisei , or by both (Susman 1991). Oldowan tools are fairly crude and primitive in appearance, which can make it difficult to find and identify them in the field. An Oldowan tool. This chopper is made of quartzite and dated to the lower Paleolithic period. (credit: Locutus Borg/Wikimedia Commons, Public Domain) Mary Leakey was the first to create a system to classify Oldowan assemblages, basing her classification on utility, or how the tools were used. Later efforts were made to classify tools based on how the tools were made. All Oldowan tools were created by using hard hammer percussion , in which flakes are chipped away from a stone, resulting in a “core”. These cores served as basic tool that could have been used for killing game, cutting meat and plants, and possibly woodworking. Oldowan toolmaking is the earliest evidence of “ flint knapping ,” a technique that became more complex over time, resulting in more sophisticated tools ( ). Demonstration of flint knapping, an ancient technique for shaping stones into useful tools. (credit: “Flint-knapping Demonstration” Tonto National Monument/NPS photo/flickr, CC BY 2.0) Handedness , or brain lateralization (i.e., whether one is right-handed or left-handed), is a cognitive development that can be inferred through evidence of the use of a dominant hand in creating and using tools. The use of a dominant hand suggests a possible reorganization of the brain. It is believed that about 90 percent of humans are right-handed, which differs from apes, which are closer to 50 percent. David Frayer (2016), an anthropologist from the University of Kansas, has concluded that the brain lateralization of Homo habilis was more like that of modern human than that of apes. Frayer found striations on the teeth of a 1.8-million-year-old Homo habilis fossil that indicate right-handedness. He concluded that meat was pinched between the teeth and held in place with the left hand, while the right hand cut the meat with a tool. Brain lateralization, increasing brain size, and tool use are just some of the key developments we see in the genus Homo. Homo ergaster Homo ergaster is the first Homo that looks much like H. sapiens . A key difference between H. ergaster and earlier hominins is that H. ergaster exhibits substantially less sexual dimorphism in body size. H. ergaster males were only 20 percent larger than females. Likewise, modern human males are only 15 percent larger than females. This contrasts sharply with all other previous hominins, such as the australopithecines, in which males were 50 percent larger than females. It is well established that in mammals, significant dimorphism is associated with polygyny, and a lack of dimorphism is associated with a monogamous mating system. It has been suggested that the reduction in dimorphism seen in H. ergaster may indicate less male-male competition for access to females and perhaps a shift toward a monogamous mating system, with substantial parental investment in offspring. Other similarities between H. ergaster and modern humans are seen in the teeth and postcranial features. The average cranial capacity of H. ergaster is 1,100 cc, which is just a bit smaller than that of modern humans, who average 1,400 cc. There is a very important specimen of H. ergaster that bears mentioning, the Nariokotome Boy . This specimen was discovered in 1984 by Kenyan paleontologist Kamoya Kimeu near Lake Turkana in Kenya. It is dated to approximately 1.6 MYA. The specimen is believed to represent a boy of about 12 years old, determined by various dental and cranial features. He was about 5 feet 4 inches tall, roughly the same height as a modern boy of the same age ( ). It has been estimated that his adult height would be around 5 feet 10 inches, with an estimated cranial capacity of 900 cc. The Nariokotome Boy looks tremendously modern in appearance despite being 1.6 million years old. This specimen of Homo ergaster is known as the Nariokotome Boy. It is believed to be the remains of a boy who was about 12 years old at the time of death. (credit: “Homo ergaster (fossil hominid) (Lower Pleistocene, 1.5 to 1.6 Ma; Nariokotome, Lake Turkana area, Kenya) 4” by James St. John/flickr, CC BY 2.0) Homo ergaster Technology Homo ergaster continued to use Oldowan stone tools, but they also began to construct much more complex tools, referred to as the Acheulean industry ( ). These tools have been found throughout Africa, Europe, and the Middle East and are first noted as appearing approximately 1.6 MYA to 200,000 years ago. These types of tools are rarely found in Asia. It is currently unclear whether this is because the Acheulean industry had not yet been developed when H. erectus migrated to Asia or because bamboo (a plant found in abundance in Asia) was found to be a more versatile resource than stone. As wood and bamboo are biodegradable, no remains of tools constructed from these materials would exist today. This hand axe, found in the Zamora province, Spain, displays the form and construction techniques typical of the Acheulean industry. (credit: Jose-Manuel Benito/Locutus Borg/Wikimedia Commons, Public Domain) Unlike Oldowan tools, Acheulean tools actually look like tools. Acheulean tools are distinct from Oldowan tools in that they were modified on both sides, resulting in a symmetrical tool with two faces, also known as biface . One end of the tool was tapered, while the other end was rounded. The creation of symmetrical objects from stone materials is believed to represent an increase in cognitive ability as well as motor skills in the tool maker. These bifaces were struck from large flakes, which had themselves been struck from boulder cores. This required a more delicate technique than banging one rock into another. Acheulean tools were typically created used the soft hammer technique . In this technique, hard rock such as flint is chipped by striking it with a softer material such as bone or wood. The gentler blows detach small flakes that leave smooth, shallow scars, creating a straighter and more uniform cutting edge. The main advantage of Acheulean technology is that it allowed hominins to get a better grip on their tools, as they were shaped to fit the hand. This tool type was used primarily as a hunter’s knife but also for chopping, scraping, and even piercing. The most common type of biface tool is a hand axe . Note that even though these tools are called axes, they are held in the palm of the hand. Another type of Acheulean biface used by Homo ergaster is called a cleaver ( ). The cleaver had a wide cutting edge across the end instead of a point and was best suited for hunting or hacking wood. Another Acheulean tool is the side scraper , used to scrape hides that could then be turned into simple clothing. Map of Acheulean cleaver finds dated to the Lower Paleolithic (1.76–0.13 MYA). Note the concentration of artifacts found in certain areas of Africa and in Spain. (attribution: Copyright Rice University, OpenStax,under CC BY 4.0 license) Evidence of an Increase in Meat Eating In 1973, a specimen of H. ergaster known as KNM ER 1808 was found in Koobi Fora, Kenya. Dated to about 1.7 MYA, this is the most complete H. ergaster specimen ever found. Analysis of KNM ER 1808 suggests that H. ergaster may have been eating carnivore liver, which is high in Vitamin A. This may indicate a dietary shift toward increased meat eating by H. ergaster . Homo erectus : A Success Story Homo erectus is the longest-surviving species in the genus Homo . For almost two million years, H. erectus existed and evolved. Also known as the “Upright Man” or Java Man, H. erectus was first found in Indonesia in 1891 by Eugene Dubois , a professor of anatomy at the University of Amsterdam. At a site called Trinil, he found a skull cap and a femur. He named the specimen Pithecanthropus erectus . The most current dates for Homo erectus are 1.2–1.6 million years ago. H. erectus exhibits a cranial capacity averaging 900 cc and several distinguishing characteristics. These characteristics include a slightly projecting nasal spine, shovel-shaped incisors, a nuchal crest (a ridge in the back of the skull that supported strong neck muscles), very thick skull bones, and pronounced brow ridges. They also had longer legs, evidence that they were utilizing energy much more efficiently when walking and becoming effective hunters. We also see a diminishing of the protruding jaw (or prognathism) that was so prominent in the australopithecines. This Homo erectus cranium exhibits a number of defining features, including a projecting nasal spine, thick skull bones, and pronounced brow ridges. (credit: Daderot/Wikimedia Commons, Public Domain) There is evidence that H. erectus was using fire around 1.7–2.0 MYA, which would make it the first or one of the first hominins to do so. Ancient hearths, charcoal, and charred animal bones have been found in Zhoukoudian , China. This evidence suggests that H. erectus was hunting, cooking, and eating meat. Also found at Zhoukoudian are a number of fossil skulls that were once thought to display evidence of cannibalism. However, recent research evidence suggests that the remains of these H. erectus were prey to animal scavengers such as hyenas (Boaz et al. 2004). The Smithsonian Institution has created an interactive tool that visually illustrates the interrelationships between an increasingly variable and colder climate, encephalization, bipedalism, and new technologies and tool use. These correlations align with fossil evidence indicating changes in diet and caloric requirements in response to a colder and changing climate, which ultimately fueled a growing brain. The “ expensive tissue hypothesis ” proposes that maintaining a brain is metabolically expensive and that, in order to meet the energy requirements of a larger brain, our digestive system became smaller and shorter, making it more suited for higher-quality, nutrient-dense food such as meat (Aiello and Wheeler 1995). The list below summarizes some of the key evolutionary changes seen in H. erectus from 2 MYA to possibly as recent as 50,000 years ago, which provide further support for these correlations (Dorey 2020). There is a progressive increase in brain size in H. erectus , from about 550 cc to 1,250 cc. There is evidence of increased use of fire and of eating cooked meat at H. erectus sites. H. erectus would have needed as much as 35 percent more calories than previous hominins (Fuentes 2012). The eating of softer foods as a result of cooking meat and plants alleviated the need for large chewing teeth and jaws. Over time teeth became smaller, which resulted in thicker enamel. There is a gradual decrease in prognathism, and as in H. habilis, skulls provide evidence of smaller teeth and jaws, which would have made room for larger brains. H. erectus is taller than any other previous hominin, with longer legs that provided the ability to run great distances and chase prey. New research is shedding some additional light on the possible benefits of running in early hominins The fossil evidence suggests that endurance running is a derived adaptation of the genus Homo , originating about two million years ago, and may have been instrumental in our evolution (Bramble and Lieberman 2004). The Homo ergaster and Homo erectus Debate There is great debate as to whether Homo ergaster and Homo erectus are one species or two. Some refer to H. ergaster as the “early” H. erectus. Their differences are largely geographical: H. ergaster is associated with Africa and H. erectus with Asia. Yet some researchers have concluded that H. ergaster and even H. habilis should be referred to as H. erectus . Whether to lump or split the diverse species in the genus Homo is an ongoing challenge in the scientific community. While there are some anatomical differences between H. erectus and H. ergaster , they are fairly minimal. Homo erectus (left) has a sagittal keel (ridge on top of head), a shorter forehead, and a different-shaped skull than Homo ergaster, seen on the right. (credit: (left) kevinzim/Wikimedia Commons, CC BY 2.0; (right) Reptonix free Creative Commons licensed photos/Wikimedia Commons, CC BY 3.0) The diversity and number of evolutionary changes seen in H. erectus indicate that H. erectus set the stage for the arrival of the archaic Homo , which we will cover in the next section. biface tools a type of tool characteristic of the Acheulean tool industry, with both sides worked. handedness the use of a dominant hand, suggests lateralization of the brain and cognitive development. Oldowan tool Industry the oldest and most primitive tool industry; production and use are largely in association with H. habilis. sexual dimorphism differences in physical characteristics other than reproductive organs that appear between males and females of the same species.

Social Sciences


The Emergence of Us: The Archaic Homo Learning Objectives By the end of this section, you will be able to: Describe the context, time frame, and key anatomical characteristics of archaic Homo. Explain the potential environmental conditions that led to evolutionary change in anatomy and material culture seen in archaic Homo . Compare and contrast the current hypotheses regarding the extinction of the Neanderthal. Defining the Archaic Homo There is no universal consensus on what is included within the term “archaic Homo .” The term is used as an umbrella category encompassing all the diverse Homo species after H. erectus . Hominin species classified as archaic Homo typically have a brain size averaging 1,200 to 1,400 cc, which overlaps with the range of modern humans. Archaic Homo are distinguished from anatomically modern humans by the characteristics of a thick skull, prominent supraorbital ridges (brow ridges), and lack of a prominent chin. Archaic Homo are viewed as transitional between H. erectus and H. sapiens and display many overlapping and varied traits. It has been proposed that archaic Homo may have been the first species to use language, based on the size of their brains and the fairly large social groups they lived in. Archaic Homo species as presented here will be divided into two groups: the Early Archaic (800–250 KYA) and the Late Archaic (300–30 KYA). Early Archaic Homo Homo antecessor Homo antecessor has been found in Spain, France, and England and dates to around 1.2 MYA to 800 KYA. These specimens represent the oldest fossil evidence for the presence of the genus Homo in Europe. Some scientists have suggested that this species is the ancestor of Homo heidelbergensis , while others suggest that H. antecessor is the descendent of H. ergaster . Homo antecessor was first found at the Sima de los Huesos site of the Sierra de Atapuerca region in Spain. Within this site is a cave known as the Pit of Bones , where more than 1,600 fossils of 28 individuals have been found that date at or before 780,000 years ago. The site is an important one that stretches over a long period of time and displays the emergence and divergence of various Homo physical characteristics that later appear in the Neanderthal. Evidence from nuclear DNA suggests that early hominins at this site were related to the Neanderthal and not the Denisovans , indicating divergence earlier than 430,000 years ago (Meyer et al. 2016). The section on the Neanderthal will explore further the interbreeding and divergences of the Neanderthal, Denisovans, and modern Homo sapiens . Homo antecessor was almost six feet tall and males weighed about 200 pounds, well within the range of variation for modern humans. Other anatomical features of this species include a protruding occipital bun (a bulge found in the occipital area of the skull), a low forehead, no strong chin, and a cranial capacity of about 1,000 cc. It has been suggested that the purpose of the occipital bun is to balance the weight of the anterior portion of the skull and face. One very modern trait exhibited by this species is the presence of a facial depression above the canine tooth called the canine fossa , which is also found in modern humans. The best-preserved fossil is a maxilla (upper jawbone) of a 10-year-old individual. In addition to the fossil bones, 200 stone tools and 300 animal bones were also found at Gran Dolina , another location at the Atapuerca site, along with a carved stone knife. Stone tools at this site were predominantly Oldowan style and constructed from local raw materials. Tools included cutting flakes and hand-held cores. It has been suggested that the absence of retouched tools at this site indicates that these tools were created primarily for processing and eating meat. Cutmarks are present on the majority of animal remains. One of the most intriguing observations about this site is that there are numerous large animal carcasses (mostly deer) that are believed to have been transported to the site rather than consumed where they were killed. Some scientists have suggested that the practice of bringing food back to the site is evidence of social cooperation, suggesting both a division of labor and a custom of food sharing. Many of the bones of Homo antecessor show the same evidence of cutmarks as the animal bones, indicating that flesh was removed from the bones with the goal of dismemberment. Some scientists have taken this to mean that H. antecessor practiced cannibalism. However, humans have also been known to remove the flesh from bones during funerary rites. Whether the cutmarks made by H. antecessor represent cannibalism, a funerary rite, or another yet unknown practice is still being debated. Homo heidelbergensis Homo heidelbergensis is an incredibly variable group. Many archaic Homo species are included in this group because they possess features that can best be described as a mosaic between H. ergaster, H. erectus , and anatomically modern humans (AMH). This section looks at just a few of the specimens that are regularly attributed to Homo heidelbergensis. One of the most important Homo heidelbergensis specimens is known as Mauer . It was found in 1907 in Germany and is represented by a mandible (lower jaw) that is dated to approximately 600,000 years ago. It has a robust mandible and a receding chin like earlier Homo ergaster but has very small molars like anatomically modern H. sapiens . The jaw is so big and the teeth are so small that there is plenty of space for additional teeth to develop behind the wisdom teeth. Given that the third molar (the wisdom tooth) has already erupted, it has been suggested that this individual was between 20 and 30 years at death. This jawbone from a Homo heidelbergensis specimen was found in Germany in 1907 and is dated to approximately 600,000 years ago. (credit: Gerbil/Wikimedia Commons, CC BY 3.0) Another important specimen of Homo heidelbergensis is known as the Petralona cranium. It was found in 1960 in Greece. Dates are uncertain but believed to be in the range of 100,000 to 700,000 years. Animal fossils found with the specimen indicate Petralona is between 350,000 and 200,000 years old. It combines Homo ergaster –like traits, such as massive brow ridges and thick cranial bones, with a cranial capacity of 1,200 cc, which is similar to anatomically modern H. sapiens . A third specimen of Homo heidelbergensis is known as Bodo . It is very possibly the oldest archaic human specimen from Africa and was found in Ethiopia in 1976. It is dated to approximately 600,000 years and has a relatively large cranial capacity of 1,250 cc, which is again within the range of variation for modern humans. It is a robust cranium with very thick bones and two separate brow ridges. Homo heidelbergensis Technology and Culture Bodo is associated with Acheulean bifacial hand axes. Some scientists have suggested that Bodo butchered animals because Acheulean hand axes have been found with animal bones. There are cutmarks on the Bodo cranium that resemble those made by cutting fresh bone with stone tools. It has been suggested that the Bodo cranium is the earliest evidence of the removal of flesh immediately after death using a stone tool. The cutmarks were made symmetrically and with specific patterns on the cranium, which is interpreted as strong evidence that the defleshing was done purposefully for funerary practices. Once again, others have suggested that the cutmarks indicate that Bodo may have been practicing cannibalism. In addition to their use of stone tools from the Acheulean tool industry, Homo heidelbergensis is also believed to have used spears . The earliest known spears have been found in Schöningen, Germany, and are dated to about 400,000 years ago. The spears were made either from spruce or pine wood and are believed to have had a range of about 35 meters. Probably the most important technological achievement evident in these spears is the use of hafting technology. Hafting involves attaching stone points to a handle made of another substance, such as wood, metal, or bone. The spears found at Schöningen represent one of the first known instances in which hominins united separate elements into a single tool. Hafting gives stone tools more utility, as they can now be thrown (as with a spear), shot (as with an arrow), or used with more leverage (like an axe). These hafted stone points are able to be used with increased force and effectiveness, allowing people to hunt and kill animals more efficiently. This increased efficiency in hunting and killing animals is believed to have created a situation in which H. heidelbergensis had regular access to meat and other high-quality foods. Some have suggested that the presence of spears represent evidence that H. heidelbergensis could hunt herd animals that can run faster than a human, and that they had sophisticated hunting strategies requiring cognitive skills like anticipatory planning. Like Homo ergaster and Homo erectus, Homo heidelbergensis occupied both caves and open-air sites. However, they did not just use the sites as is, they modified them. One of the most interesting aspects of the cultural behavior of Homo heidelbergensis is that they are associated with clear archeological evidence for modified dwellings. For example, in the Czech Republic there is a modified dwelling that consists of a stone foundation that is approximately 700,000 years old. Most likely, this dwelling had a roof constructed of thick branches. Other modified dwellings have been found in Germany and France. Evidence of controlled fire has been found at most reasonably preserved Homo heidelbergensis sites. The oldest established continuous fire site for Homo heidelbergensis is from Israel and is dated to around 780,000 years old. Phylogenetic tree and proposed migration routes of genus Homo heidelbergensis and later Denisovans and Neanderthals. (attribution: Copyright Rice University, OpenStax, under CC BY NC-SA 4.0 license) Late Archaic Homo Homo naledi : A Rising Star The most recently described archaic Homo is known as Homo naledi . They were found in the Rising Star cave system in South Africa in 2013 and 2014 (Figures 5.14–5.15) and are dated to approximately 235,000–335,000 years old. Over 1,500 bones from as many as 15 individuals were recovered from the cave, which is possibly the largest assemblage of a single hominin species yet discovered. Despite their relatively recent date, they have exceptionally small cranial capacities, comparable to the robust and gracile australopithecines, which are around 560 cc. The encephalization quotient of H. naledi is estimated at 4.5, which is the same as H. floresiensis but notably smaller than all other Homo (contemporary Homo are all above 6). The presence of this small-brained hominin at the same time that Neanderthals and Homo heidelbergensis were around is further evidence that multiple hominin lineages were coexisting and evolving at the same time. The classification of H. naledi proved to be a challenge, as the specimens presented a mosaic of traits and characteristics associated with an array of other hominin species. Maps showing the location of the Cradle of Humankind World Heritage Site in South Africa, where Homo naledi fossils were found in the Rising Star cave system. (credit: Hawks et al. (2017), eLife , CC BY 4.0) The Rising Star cave system, showing geological features and the location of the excavation area where numerous Homo naledi specimens have been found. (credit: Paul H. G. M. Dirks et al. (2015), eLife /Wikimedia Commons, CC BY 4.0) H. naledi skulls. It is apparent in these images that this species had rather pronounced prognathism (Credit: John Hawks, Marina Elliott, Peter Schmid et al. (2017), eLife/Wikimedia Commons, CC BY 4.0) H. naledi feet were much like those of modern humans. (credit: W. E. H. Harcourt-Smith, Z. Throckmorton, K. A. Congdon, B. Zipfel, A. S. Deane, M. S. M. Drapeau, S. E. Churchill, L. R. Berger & J. M. DeSilva (2015)/Nature Communications/Wikimedia Commons, CC BY 4.0) The hands of H. naledi display curved finger bones and large thumbs, indicating that it still had an adaptation for climbing trees. (credit: Lee R. Berger et al. (2015), eLife/Wikimedia Commons, CC BY 4.0) Comparison of some of the most commonly known Homo species (credit: Chris Stringer, Natural History Museum, United Kingdom (2015), eLife/Wikimedia Commons, CC BY 4.0) Homo naledi : Did They Bury Their Dead? Homo naledi has not yet been found in association with any stone tools. Despite a lack of established tool use, there is fairly convincing evidence that H. naledi may have used the cave system as a place to bury their dead. The hypothesis that H. naledi had a ritualistic mortuary practice is based on several observations, such as the bones appearing to lack evidence of gnawing marks from predators and the lack of evidence of layers of sediment that would suggest the bones were deposited by flooding (Dirks et al. 2015). In 2017 additional fossil remains were found in a second chamber in the Rising Star cave system (Hawks et al. 2017), but these remains don’t as yet appear to offer additional evidence to support the hypothesis of an intentional burial. Some scientists believe that there is insufficient evidence to conclude that H. naledi were involved in funerary ritual practices. They have noted that the preservation of H. naledi specimens are similar to that of cave-dwelling baboons that have died natural deaths. At Sima de los Huesos , remains of about 28 Neanderthal and H. heidelbergensis fossils were found in a cave dated to about 430,000 years ago. Researchers who examined the scattering patterns of the remains at both the Rising Star cave system in Africa and the Sima de los Huesos site in Spain (Egeland et al. 2018) concluded that the sites showed evidence of having been scavenged but that this doesn’t disprove the possibility that they may also be deliberate burials. The verdict is still out on this. Lee Berger and other scientists are conducting further investigations of the H. naledi skeletal deposits to further explore the possibility they might be evidence of something more deliberate than the actions of predators. Rethinking the Neanderthal Homo neanderthalensis The word “Neanderthal” might conjure up stereotypical images of a brutish caveman-like creature holding a club in one hand and dragging supper with the other. No one said entertainment had to be scientifically accurate, but media can create false perceptions and stereotypes about the past. This section takes a closer look at who the Neanderthal people were and the role they played in the human story. Distribution map of Neanderthal sites. The red squares mark locations of Neanderthal remains and the shaded area represents the supposed territory of Neanderthal people in Europe and Asia. (credit: modification of work Neanderthal distribution by Berria/Wikimedia Commons, CC BY-SA 4.0) Neanderthals have been found only in regions of Europe and the Middle East and are dated to between about 400,000 and 40,000 years ago. The first fossils, which were found in the Neander Valley, were believed to be the remains of an extinct kind of human. The Germans called them the Neanderthals, the people of the Neander Valley. The Neanderthal skull on the left is noticeably different from the H. sapiens skull on the right. (credit: (left) Jose-Manuel Benito/Locutus Borg/Wikimedia Commons, Public Domain; (right) “Image from page 27 of “Human physiology” (1907)” by Furneaux, William S/Internet Archive Book Images/flickr, Public Domain) Neanderthals possess several distinctive anatomical characteristics: the skull and brain is larger than that of humans, with an average size in Neanderthals of 1,520 cc compared to modern humans’ 1200–1400 cc. Does the Neanderthal’s larger brain size mean that it was more intelligent than modern humans? As mentioned earlier in this chapter, while there does seem to be a correlation between brain size and complex cognitive skills, the brain in some hominins may have been organized differently than that of modern humans, with different anatomical areas of the brain emphasized. It is believed that in the Neanderthal brain, the frontal region, which is the center of speech and language, was less developed, while the back of the brain, which deals with the senses, was more developed. This greater development in the back area of the brain could be a survival adaptation found in Neanderthals who had to hunt in often harsh and difficult conditions. Philip Lieberman , a cognitive scientist at Brown University, argues that Neanderthals lacked the anatomy necessary for humanlike speech. He drew this conclusion based on a reconstruction of a Neanderthal throat, which indicated that the neck could not accommodate the vocal apparatus of modern humans (Lieberman,P. 2007). While there is evidence of a hyoid bone, a small horseshoe-shaped bone in the front of the neck, that would have been able to anchor the tongue muscles, other anatomical evidence suggests that the larynx in Neanderthals was placed high in the throat. A highly placed larynx limits an animal’s ability to produce many sounds, such as vowels. In humans, the larynx is positioned further down into the throat. The Neanderthal has been determined to have possessed the gene FOXP2 , which is linked to the ability to understand complex language, but the verdict is still out as to whether they were able to produce complex language. It is believed by some researchers that the ability to produce complex speech gave H. sapiens a significant edge over the Neanderthal. Other skull characteristics of the Neanderthal include an occipital bun at the back of the skull (as also seen in H. antecessor and H. erectus ), large brow ridges (which are not solid bone and create an air cavity), a large nasal cavity, and incisors that show a rounded pattern of wear, especially in older individuals. Their large front teeth typically show excessive wear. Chipping and pitting on the incisors are believed to have been caused by chewing on leather. The postcranial bones show that they had a broad scapula, which indicates that their rotator cuff muscles were well developed. They possessed a robust humerus with a massive head and the ability to rotate their arms, which suggests they were capable of throwing projectiles and using spears. Some of the best-known Neanderthal specimens come from a place called Shanidar Cave in Iraq. Within this cave, various skeletal remains of eight individual Neanderthals were found. These remains are identified as Shanidar 1–9 , which were discovered between 1957 and 1961, and Shanidar 10 , which was discovered in 2006. Nearly all the skeletal remains show some evidence of trauma, suggesting that hunting was risky business. At various Neanderthal sites it has been observed that men and women exhibit similar cranial injuries, suggesting that women might have also engaged in hunting activities. However, the number of injuries in women were significantly fewer than those found in men (Beier et al. 2008). In a comparative study, it was established that during the Upper Paleolithic, modern H. sapiens sustained similar injuries as the Neanderthal, but interestingly, these injuries were less likely to result in death (Beier et al. 2008). Shanidar 3 features a 40-to-50-year-old Neanderthal man who suffered a rib injury, potentially as the result of an encounter with an animal, and suggests healing as a result of care from others. Shanidar 1, called the “Old Man” (30–45 years old was old in Neanderthal terms), had multiple traumas to his body, one of which resulted in blindness in one eye. He was also missing the lower part of his right arm and hand, which suggests the earliest amputation on record. Although he did heal from this amputation, it may have left him paralyzed on the right side of his body. He also had no teeth. It is believed he was kept alive by taking food that had been chewed by others for him. There is evidence of many of these individuals healing from their injuries, which suggests that compassion and a sense of social responsibility for disabled members of the community existed. This cave is the site of the Shanidar 4 Neanderthal flower burial site. Evidence found here and at other sites indicates that the Neanderthal practiced intentional burials of their dead. (credit: “Shanidar Cave, Iraqi Kurdistan” by Sammy Six/flickr, CC BY 2.0) The Flower Burial Hypothesis The remains found at Shanidar 4 in Iraq suggest that the Neanderthal practiced intentional burials , or deliberate placing of the dead in a ritualistic manner. At Shanidar 4, the individual is placed on his left side with his legs drawn up in a flexed position. Pollen analysis of the soil surrounding the corpse suggests that spring flowers had been placed in the grave, possibly indicating that the Neanderthal had a belief in an afterlife and established mortuary practices. However, there has been a lot of debate as to whether there is sufficient evidence to conclude that the pollen found at some of the Neanderthal sites was a result of ritualistic placement of flowers. Opposing hypotheses propose that the pollen was brought into the cave and deposited by burrowing rodents (Sommer 1999). In spite of these counterclaims, the consensus supports the theory that the Neanderthal did practice intentional burials. This is largely based on evidence such as the careful placement of bodies in specially dug shallow pits. Recent research at both Shanidar Cave and other sites now support the claim that the Neanderthal did practice ritual and intentional burial. This reconstruction of a Neanderthal grave is housed in the Israel Museum in Jerusalem. (credit: “Neanderthal Burial, Cast” by Gary Todd/flickr, Public Domain) Neanderthal Creativity and Material Culture Neanderthals have been labeled, perhaps unjustly, as a species with a limited ability to communicate in symbolic or abstract forms. Until recently, the Neanderthal had been assumed to lack the cognitive skills associated with the practice of ritual and art. However, cave paintings discovered in Spain in 2012 by Alistair Pike, an archaeologist at the University of Southampton, UK, challenge that assumption. These paintings, which have been dated to around 65,000 years ago, before the arrival of H. sapiens in the region, have been determined to be the creative works of the Neanderthal and are currently considered the oldest cave art ever found. This discovery may change what people have previously thought about Neanderthal cognition and their ability to express symbolic thought. It should be acknowledged that the ability to depict the world evident in these paintings does not compare with that in the artwork from H. sapiens sites like Chauvet and Lascaux in France (to be discussed later in this chapter). Neanderthals created more technologically advanced tools than those produced by H. erectus and seen in the Acheulian tool industry. The tool industry associated with the Neanderthal hominins is called the Mousterian tool industry or the Middle Paleolithic tool industry. Archeological sites that date to the Neanderthal period are dominated by flake tools . This means that the Neanderthal struck flakes from cores and then used the flakes as their tools instead of the core. This resulted in smaller and sharper tools with increased utility. What Happened to the Neanderthal? What Gave Modern Humans the Edge? The Neanderthal went extinct around 35,000 to 50,000 years ago. There have been various hypotheses as to what caused this, many connected to the fact that Neanderthal coexisted with H. sapiens in regions of Europe and Asia for an estimated 2,600–5,400 years. These hypotheses include an inability to adapt to a changing climate and colder temperatures, the spread of disease, competition for food with H. sapiens , and even aggressive takeover by the H. sapiens , who may have been better able to adapt to environmental changes due to more complex technology and language skills. Another theory points to evidence that the Neanderthal tended to live in small, scattered groups with limited genetic diversity and low birth rates, which potentially impacted the ability of the Neanderthal to be competitive. A low gene pool can result from reduced birth rates and low survival rates of young children. New genetic evidence shows that the Neanderthal were genetically less diverse and more isolated than H. sapiens. And then some argue that the Neanderthal didn’t go extinct at all because some people still have Neanderthal genes in them. Are You a Neanderthal? Recent genetic evidence indicates that human-Neanderthal interbreeding was happening as far back as 125,000 years ago. From one Neanderthal toe bone found in the Denisova cave in Siberia Russia, the Max Planck institute has been able to produce a whole genome which revealed evidence of inbreeding amongst the Neanderthal, along with interbreeding with their cousins the Denisovans (discussed further in next section), as well as a mystery yet to be identified species, as well as Homo sapiens (Pennisi, E., 2013). The genetic evidence is most prominent in people of East Asian descent, accounting for between 2.3 percent and 2.6 percent of their DNA. Various mutations and diseases are linked to this Neanderthal DNA , including diabetes, addictions, depression, allergies, and Crohn’s disease. One study suggests that Neanderthal genes gave people some level of protection from getting a severe case of COVID-19 (Huber, J., 2018), although a later study (Zeberg and Pääbo 2020) proposes that Neanderthal genes may have increased the risk of respiratory failure as a result of the COVID-19 virus. Such differences may have to do with different genetic clusters in Neanderthal populations in different geographical regions (Mortazavi et al. 2021). Neanderthal genes are believed to have provided immunity to some viruses that H. sapiens, arriving from Africa, would not have had time to build up an immunity against. On the reverse side, H. sapiens may have brought diseases from Africa that the Neanderthal did not have resistance to, possibly playing a role in their extinction. As Janet Kelso , a computational biologist at the Max Plank Institute for Evolutionary Anthropology, states, “Viral challenges, bacterial challenges are among the strongest selective forces out there” (Akst, 2019). The Denisovans The Denisovans, like Homo naledi , are archaic Homo . There are not a lot of specimens—just one finger bone, three teeth, some long bone fragments, a partial jawbone, and a parietal bone skull fragment. Because of this lack of evidence, very little is known of their anatomical features. Some of the specimens come from Denisova Cave in Siberia, Russia, and are dated to between 500,000 and 30,000 years ago. These dates are arrived at based on the few fossils that exist, inferences made from genetic studies, and sediment analysis. More recently another specimen was found on the Tibetan plateau. In 1980 a jaw and two teeth were uncovered in the Baishiya Karst Cave by a monk, but it wasn’t until 2010 that scientists were able to study the jaw. Dating placed the specimen at approximately 160,000 years ago. Protein analysis determined the jaw to be of Denisovan origin and from a member of a population who were most likely well adapted to living in high altitudes (Chen et al. 2019). Because so few bones have been found, most understanding of this species comes from genetic analyses. According to nuclear DNA studies, Denisovans and Neanderthals were more closely related to each other than they were to modern humans. DNA evidence suggests that the Denisovans interbred with modern humans and with local Neanderthal populations over multiple time periods. Tracing the male Y chromosome, one study indicated that interbreeding between early humans and Neanderthals actually replaced the ancient Denisovan Y chromosome once found in Neanderthals. The time of divergence of the Denisovan is estimated to be around 700,000 years ago, with modern humans diverging from the Neanderthal around 370,000 years ago (Petr et al. 2020). H. heidelbergensis is typically considered to have been the direct ancestor of both Denisovans and Neanderthals, and sometimes also of modern humans. One specimen is a first-generation hybrid, Denisova 11 —nicknamed “ Denny ”—that had a Denisovan father and a Neanderthal mother (Slon et al . 2018). Denisova 11 was found in Denisova Cave in Russia and provides evidence that Late Pleistocene Homo species interbred when the groups met. Comparison of the DNA of these three groups suggest that most modern-day Europeans and Asians inherited about 1–4 percent of their DNA from Neanderthals, with no Denisovan ancestry in Europe and 0.1 percent in China. The genetics found in Tibetans, Melanesians, and Indigenous Australian are currently being challenged; originally, they were thought to be about 3–5 percent Denisovan and 2.74 percent Neanderthal. Statistical geneticist Ryan Bohlender and his team have investigated the percentages of extinct hominin DNA in modern humans. They concluded that Neanderthals and Denisovans are not the whole story and that there could be a third group yet unknown contributing to the Pacific Islander genome (Rogers, Bohlender, and Huff 2017). Statistical and genetic evidence can serve as indicators of the existence of a group for which no fossils have yet been found. These are referred to as ghost populations . For example, there are indications that 2–19 percent of the DNA of four West African populations may have come from an unknown archaic hominin that split from the ancestor of humans and Neanderthals between 360 KYA and 1.02 MYA (Durvasula and Sankararaman 2020). The hypothesis of a third lineage in the genus Homo appears to have received further confirmation with a discovery in China. New Homo Genus Discovery Homo longi, or Dragon Man Recently a new archaic Homo fossil surfaced in Harbin, China, dated to about 146,000 years ago (Ji et al. 2021). Given the name H. longi , it has also been called “ Dragon man ” as its origins were determined to be in the province of the Black Dragon River. The fossil (referred to as the Harbin cranium) was donated to the Hebei GEO University museum after being hidden away in a well in the 1930s during the construction of a railway bridge. The verdict is still out as to whether H. longi represents a lineage of the Denisovans or a new species, but it is clear it was robust and able to adapt to one of the coldest regions of China. It had a large brain, thick brow ridges, and fairly large teeth, similar to what is found in the Denisovans. Regional Evolutionary Adaptations: Homo floresiensis The Hobbit of Flores Homo floresiensis , also known as “the Hobbit” or “Flores Man,” was discovered on the island of Flores in Indonesia in 2003. The species has been dated to approximately 100,000–60,000 years ago. What was surprising about this species is its size. An adult individual stood about 3 feet 7 inches tall. Liang Bua, the cave where H. floresiensis was found, shows evidence of the use of fire for cooking and contains bones with cutmarks. Since the initial discovery, partial skeletons of nine individuals have been found. H. floresiensis , like the earlier hominins, did not possess a chin, and its leg bones are thicker than those of modern humans. They had flat feet that were relatively long in comparison to the rest of their bodies. As a result of these anatomical differences, it is believed that their bipedalism was quite different from that of modern humans, with a high stepping gait and slower walking speed. H. floresiensis also had substantially more mobility in the elbow joint, which suggests that they were tree climbers. Their small brain size is not believed to have affected their intelligence. This challenges the view that larger cranial capacity equals higher cognitive skills. Although H. floresiensis has a brain size of just 380 cc, equal to the size of an orange, evidence indicates that they made tools, used fire, and hunted very much like H. erectus. The brain of H. floresiensis does contain a Brodmann area, which is associated with cognitive abilities, that is the same size as that found in modern humans. Some have suggested that H. floresiensis is a sister species of Homo habilis that branched off before or shortly after the evolution of Homo habilis. Other hypotheses suggest that they were the descendants of H. erectus who became stranded on the island after arriving via water, possibly on bamboo rafts. Another Homo species similar in size to H. floresiensis was H. luzonensis , found on the island of Luzon in the Philippines and dated to at least 50,000–67,000 years ago. H. luzonensis displays a hybrid of australopithecine traits (including curved hands and feet) and Homo characteristics, yet lived alongside modern H. sapiens . Clearly the genus Homo is more diverse and complex than was originally thought, especially within the special evolutionary pressures of island environments. This H. floresiensis skull is on display at the Naturmuseum Senckenberg, a Natural History Museum in Germany. (credit: Daderot/Wikimedia Commons, Public Domain) Island Dwarfism as an Evolutionary Explanation Numerous hypotheses have been proposed to account for the small brain size found in both H. floresiensis and H. luzonensis. One initial theory was that H. floresiensis had microcephaly, which is a genetic condition creating an abnormally small head. This was discounted as an explanation once additional specimens were found exhibiting the same size. Perhaps the most convincing explanation is an evolutionary theory called island dwarfism , which notes that the evolutionary pressures on islands can be very different from those found on the mainland. Island dwarfism posits that mainland small animal species that colonize islands might evolve larger bodies if the island does not contain key predators. On the other hand, larger species may become smaller due to more limited resources in an island environment. According to the island dwarfism hypothesis, H. erectus made its way to Flores, where its descendants became isolated and grew progressively smaller to make the most of limited resources in the island environment. This theory is supported by the fact that there are unique sizes displayed by other animals found with H. floresiensis , including a dwarf species of primitive elephant called a Stegodon . As H. floresiensis ’s body shrank, its brain may have undergone “neurological reorganization” to fit a smaller cranial space while maintaining its brain-to-body ratio. The only potential large predator that may have been a threat to H. floresiensis was the Komodo dragon, which ate most of the large mammals on the island. Nevertheless, predation pressures for the little people were likely quite low—that is, until H. sapiens arrived. The Emergence of Us: Homo sapiens Modern H. sapiens first appeared about 200,000 years ago in Africa. Anthropologists generally classify these people as “anatomically modern H. sapiens ,” which is a way of noting that while their bodies are the same as modern humans, they had not yet developed the cultural traditions, symbolic behaviors, and technologies that are seen among later H. sapiens, including people of today. Probably the most defining feature of anatomically modern H. sapiens is their chin. Modern H. sapiens is the first hominin to exhibit a projecting chin. One of the most common explanations for this anatomical feature is that the chin evolved in response to human speech and protects the jaw against stresses produced by the contraction of certain tongue muscles. Sometime around 40,000 years ago there was an abrupt change in tool technology, subsistence patterns, and symbolic expression among H. sapiens. These changes seem to have occurred almost simultaneously in Africa, Asia, Europe, and Australia. While there is evidence of some creative artistic activity in earlier groups like the Neanderthal, they were not on the same scale as that seen during the Upper Paleolithic, which is also referred to as “ the human revolution .” The level of cultural changes associated with this period has been compared to the level of change that occurred during the Industrial Revolution of the 19th century. Among these changes, H. sapiens began assembling a much more elaborate tool kit by constructing tools from a wider variety of materials including antler, ivory, and bone. During the Upper Paleolithic, humans shifted from the manufacture of round flakes to the manufacture of blade tools . This construction method is known as the blade tool industry . Blades are stone flakes that look like a modern knife blades—they are long, thin, and flat, and they have a sharp edge. They have a much longer cutting edge than flakes do and are thus more efficient than older technologies. The prepared-core technique of the Mousterian that provided pre-shaped flakes was refined and extended to create pre-shaped blades. This Upper Paleolithic burin tool has a much longer cutting edge than anything that came before it and was much more efficient than previous technologies. (credit: “Large Knife Upper Paleolithic or later 35000-3900 BCE Africa” by Mary Harrsch/flickr, CC BY 2.0) Over the 23,000 years of the Upper Paleolithic, there were many distinctive tool industries within the larger category of the blade tool industry, including the Aurignacian, Gravettian, Solutrean, and Magdalenian. The most significant tool during the Upper Paleolithic was the burin . The burin is a narrow-bladed flint capable of scraping narrow grooves in bone. Scraping two parallel grooves would allow a sliver of bone to be detached as stock for a needle, pin, or awl. The Gravettian tool industry lasted from approximately 33,000 to 22,000 years ago. During this tool industry, there are many instances of animal remains being used for both decorative and traditional tool purposes. For example, the teeth of arctic foxes were used for decoration, while their arm bones were used as awls and barbs. Some animal bones such as mammoth tusks and bones were used to not only create tools, but also to make art, as seen in the Lion figurine in . This figurine could be the earliest example of a figure having both human and animal characteristics, a form often associated with shamans or priests. Some have proposed that the “lion man” is actually a woman due to the lack of a lion mane. An ancient figurine of a lion sculpted from a mammoth’s tusk. This figure was discovered in a German cave in 1939 and dated to around 40,000 years ago, making it one of the oldest figurative sculptures yet discovered and the earliest example of an animal-shaped figurine. (credit: JDuckeck/Wikimedia Commons, Public Domain) The Solutrean tool industry utilized tool-making techniques not seen before. It produced finely worked bifacial points made with lithic reduction percussion rather than flint knapping. Lithic reduction is the process of fashioning stones or rocks into tools or weapons by removing some parts. The lithic core, such as a partially formed tool or naturally formed rock, is held in one hand and struck with a hammer or percussor with the other hand. As flakes are detached, the original mass of stone or lithic core is reduced. In addition to stone tool innovations, the Solutrean is characterized by the appearance of the atlatl , or spear thrower. An atlatl is a long stick used to propel a spear or dart. Functioning as an extension of the arm, this stick of wood or antler added kinetic energy, and therefore range, to a short spear tipped with flint or bone. The earliest archeological evidence for this tool innovation comes from France, where a 17,500-year-old atlatl was found constructed out of reindeer antler. It is believed that the atlatl was used by humans to hunt large fauna. Contemporary man using an atlatl, a tool for launching a spear or a dart that is at least 17,500 years old. (credit: “Atlatl throwing demonstration” by Hannah Schwalbe/NPS/flickr, Public Domain) By 17,000 years ago, the Solutrean tool industry was replaced by a new tool industry known as the Magdalenian tool industry . During this period, bone and ivory continue to be used, as well as stone. Unlike Mousterian tools, Solutrean tools are made not only from nearby rocks, but also from rocks that have been transported over relatively long distances. Keep in mind that this required not only transporting the selected rocks, but also finding and extracting them. The Gravettian tool industry is best known for carved Venus figurines portraying a woman, typically made from ivory or limestone. Most figurines have small heads, wide hips, and large breasts. Most researchers believe that they served a ritual or symbolic function. Some have suggested that they represent an expression of health and fertility. Venus of Hohle Fels figurine. This figurine is considered to be the earliest known depiction of a human being in prehistoric art. (credit: Anagoria/Wikimedia Commons, CC BY 3.0) During the Upper Paleolithic, H. sapiens created a great deal of cave art. More than 350 cave painting sites have been discovered, the majority located in France and Spain. Cave art seems to have been created continually from 40,000 to 10,000 years ago and then disappeared around 10,000 years ago, likely due to climate change. As temperatures increased, underground shelters were gradually replaced by surface settlements. The most well-known cave sites in France are the Chauvet (32,400 years ago) ( ) and Lascaux Caves (17,000 years ago). The art in both caves features common subjects, such as bison, horses, and deer, as well as tracings of human hands. Most of the animals depicted were commonly hunted but were not always found with associated deposits of bones. The cave art produced during the Upper Paleolithic show a level of sophistication and even sacredness not seen previously in human history. These drawings of lions from the Chauvet Cave in France are dated to 32,400 years ago. (credit: HTO/Wikimedia Commons, Public Domain) Handprints found in the Cuevas de las Manos upon Río Pinturas, near the town of Perito Argentina. Hand stencils on cave walls have been found in many locations around the world. (credit: “SantaCruz-CuevaManos-P2210651b” by Golan Levin/flickr, CC BY 2.0) Cave paintings were made with natural pigments created by mixing ground-up elements, such as dirt, red ochre, hematite, manganese oxide, and animal blood, with animal fat and saliva. Paint was applied using twigs formed into brushes and blow pipes made from bird bones, through which paint was sprayed onto the cave wall. Hand stencils on cave walls can be found in many locations around the world including Africa, Argentina, Europe, and Australia. Anthropologist Dean Snow (2013) conducted research at eight cave sites in France and Spain to determine who the artists might be. Based on calculated measurements of the handprints, he concluded that 75 percent of the ochre stenciled handprints in the Paleolithic caves were made by women. Acheulean tool industry the production of more complex tools, including hand axes, by H. erectus from 1.6 million to 200,000 years ago. archaic Homo the period of time that precedes the emergence of the earliest early modern humans ( Homo sapiens ) around 300,000 years ago. canine fossa a facial depression above the canine tooth found in modern humans. ghost population proposed group for which no fossil evidence has yet been found. hafting the process of attaching stone points to a handle, which increases a tool’s effectiveness for hunting. intentional burials evidence of placing the dead in a specific manner, suggesting ritualistic practice. island dwarfism mainland small animal species that colonize islands might evolve larger bodies if the island does not contain key predators. On the other hand, larger species may become smaller due to more limited resources in an island environment. lithic reduction the process of fashioning stones or rocks into tools or weapons by removing some parts. Mousterian tool industry a complex stone tool technology largely associated with the Neanderthal. occipital bun an anatomical feature seen in the Neanderthal skull that appears in the rear of the skull.

Social Sciences


Tracking Genomes: Our Human Story Unfolds Learning Objectives By the end of this section, you will be able to: Describe how mtDNA sheds light on early human migrations and explain the Out of Africa model. Explain how studying the genomes and coevolution of lice can fill current gaps in the human fossil record. Describe the origin of human variation from an evolutionary perspective. Mitochondrial Eve Begun in 1990 and concluding in 2003, the Human Genome Project was an ambitious international effort that sequenced about 99 percent of the human genome with an accuracy of 99.99 percent. Genetics has thus far largely confirmed the Out of Africa theory , which proposes that early humans left Africa around 100,000 years ago and migrated to diverse areas of the world. When early humans left Africa and moved into Europe, they not only lived alongside but also interbred with non-African species such as the Neanderthal, who were already inhabiting the region. Molecular anthropologists have an interest in determining when living human populations began diverging from one another. This has been difficult to do using nuclear DNA because it mutates much too slowly for measurable accumulations to occur in 200,000 years. Many of the genetic studies that have been conducted are thus based on genetic material carried in the mitochondria (mtDNA) , which are passed on maternally. There is no recombination in mtDNA, so unless the mitochondria carries a novel mutation, a child has exactly the same mitochondrial genes as its female genetic contributor (which may be its mother, egg donor, or someone in a similar genetic relationship). The mitochondria of every living person is a copy, modified only by rare mutations, of the mitochondria passed down via matrilineal descent from a population in our ancient past. This population is referred to as Mitochondrial Eve or mtMRCA (mitochondrial most recent common ancestor), believed to have lived in southern Africa 100,000–200,000 years ago. As discussed in Chapter 4, the longer ago two populations share a common ancestor, the more time there is for mutations to occur and for adaptations and change to take place. Although genetic variation is small among the world’s human populations, it is greatest in Africa. This indicates that the human populations in Africa have the longest established genetic lineage. While multiple hypotheses exist as to human origins and new evidence could change the current views, the consensus is an Out of Africa model traced back to the matrilineal descent of a population living in Africa about 200,000 years ago. How the Genome of Lice Can Fill in the Gaps While perhaps not a pleasant thought, lice have long been a part of human history. Studying the coevolution relationship between humans and lice has shed much light on human story. Dr. David Reed , the Curator of Mammals and Associate Director of Research and Collections at the University of Florida Museum, has been studying the coevolution of humans and lice, an area of research that has developed only within the last 20 years. Reed’s groundbreaking research has the potential to fill in some big gaps in humans’ rather sketchy fossil record and provides important data that might have applications in medicine and biology. Two questions that this research has already begun to ask are when did we become less hairy and when did we start wearing clothes. There are three types of lice associated with humans: (a) crab or pubic louse; (b) body louse; (c)) head louse. The coevolution of humans and lice is a developing area of research. (credit: (a) Noizyboy1961/Wikimedia Commons, CC BY 4.0; (b) Janice Harney Carr, Centers for Disease Control and Prevention/Wikimedia Commons, Public Domain; (c) Dr. Dennis D. Juranek, Centers for Disease Control and Prevention/Wikimedia Commons, Public Domain) shows three types of lice associated with humans: the head louse ( Pediculus humanus capitis ), the body louse ( Pediculus humanus corporis ), and the crab louse or pubic louse ( Pthirus pubis ). Body lice infest clothing and lay their eggs on fibers in the fabric. Head and pubic lice infest hair, laying their eggs at the base of hair fibers. The human head and body lice (genus Pediculus ) share a common ancestor with chimpanzee lice, while crab lice (genus Pthirus ) share a common ancestor with gorilla lice. By tracking louse variations, scientists have been able to determine when the head louse and pubic louse diverged, enabling estimates as to when we lost our extra hair and when we started to wear clothes. It is interesting to note that the divergence of the genus Pediculus (head and body lice) correlates with the divergence of the human lineage from chimpanzees about six million years ago. Research on lice also provides further support for the Out of Africa model of human migration. Reed has observed that the genome of African lice shows a higher degree of genetic diversity than that of lice found elsewhere in the world, supporting the hypothesis that both humans and lice existed in Africa first. Many hypotheses about what may have triggered the loss of hair in humans point to thermoregulation , the need to control body temperature in extreme conditions. Living in the heat of the savanna, humans needed a cooling mechanism to enable them to be better hunters. Other evidence of adaptation to the heat includes the appearance of sweat glands, which are more numerous in humans than in other primates. Another theory about the cause of the loss of hair among humans suggests that it was an adaptation to control parasites on the body. Did people immediately throw on clothes after losing all of that extra body hair? Reed’s research suggests that the wearing of clothes was not something that happened quickly. Humans lost body hair about a million years ago and didn’t start wearing clothes until around 170,000 to 190,000 years ago. That’s about 830,000 years living in their birthday suits! When humans began to wear clothes, the body louse adapted structures that enabled them to attach to clothes instead of hair. Humans lost most of their body hair about a million years ago. (credit: “Neanderthal” by Eden, Janine and Jim/flickr, CC BY 2.0) Molly Selba Molly Selba (holding skull) leading a study session. (credit: Molly Selba, Public Domain) Personal History: From the time Molly was young, she knew she wanted to be an anthropologist. She took an archaeology class at the local community college when she was a high school student and went to field school over the summer. In college, she completed a double major in archaeology and anthropology, with a minor in Museums and Society. She later gained experience working with different museum collections and held internships at the Baltimore City Medical Examiner’s Office and the Smithsonian Museum of Natural History. After completing her undergraduate degrees, she knew that she wanted to pursue anthropology as a full-time career and began working towards her master’s and doctorate in biological anthropology. Area of Anthropology: For Molly the most interesting thing about biological anthropology is the information that bones can tell us. Initially she was interested in what the history of disease could tell us about the lives of people in the past, but as she worked with biological anthropologists, her focus shifted to understanding how evolution can impact the shape of different bones. She received her undergraduate degree from Johns Hopkins University in Baltimore, Maryland, and her Master’s degree from the University of Florida, where she is currently a PhD candidate. Her research interests include comparative anatomy, cranial morphology, and anatomical sciences education. She is most interested in how cranial morphology varies within and between species and how it is impacted by factors such as evolution and selective breeding practices. Her earlier research focused on the differences in cranial morphology in dogs created by artificial selection for facial reduction. Her dissertation research currently focuses on a comparative study of facial reduction across bats, primates, and dogs. Accomplishments in the Field: For Molly her most important accomplishment in the field of anthropology has been in education and outreach. Throughout her time in graduate school, she was involved in school visits, working with teachers to facilitate the inclusion of human evolution into existing science curricula. She has specifically focused on helping educators find teaching materials that are culturally inclusive and responsive. She has led multiple professional development workshops for teachers on the same topic and has visited over two dozen classrooms and interacted with over 1,200 students in the last four years. Making science accessible to K-12 educators is an extremely important part of being a researcher, and she believes everyone in academia should strive to be effective science communicators. “Studying biological anthropology helps us better understand our origin story as a species. It helps us recognize why our anatomy is the way that it is, how morphological changes over time can take place, and why we have such a diversity of life on earth. Just being able to recognize and identify our anatomy is only half the challenge—more important is our understanding why various traits are adaptive, how structure relates to function, or why leftover anatomical traits still persist in our body to this day.” Natural Selection and Human Variation: Are Humans Still Evolving? Human variability is attributed to a combination of environmental and genetic factors, including social status, ethnicity, age, nutrition, quality of life, access to healthcare, work and occupation, etc. As mentioned in Chapter 1, anthropology contributes many insights into both the social construct of race and the impacts racial categories have on people’s lives. The focus in this chapter is the role of natural selection in human variation. A number of changes are associated with the Neolithic era and the rise of agriculture around 10,000 to 8,000 years ago. Many have noted that changes during this time period did not have positive effects on human and environmental health. The evolutionary mismatch hypothesis proposes that our bodies are best suited to the environments we have spent much of our evolutionary history in, which are very different from the environments we inhabit today (Li, van Vugt, and Colarelli 2018). Humans evolved for one million years as hunter-gatherers. Today, human bodies are still trying to adapt to the largely grain-based diet brought about by agriculture, a diet characterized by less diversity and lower levels of nutrition than that of a typical hunter-gatherer. Incomplete adaptation to this change has made people susceptible to a number of diseases and nutritional deficiencies. Lactose intolerance is a prime example. The domestication of cattle and the drinking of cow’s milk began during the agricultural age, not very long ago in evolutionary history. Currently 65 percent of humans are unable to digest cow’s milk. Dental caries (cavities) are another problem linked to the change in diet associated with agriculture. The grain-based and high-sugar diets associated with agriculture are very different from the diet of hunter-gatherers. Neither our bodies nor the bacteria in our mouths have had time to fully adapt to this change. Another adaptation that took place during the Neolithic era is related to variation in skin pigmentation. Humans who left Africa and settled in Europe about 40,000 years most likely had dark skin with high levels of melanin , which provides protection against ultraviolet radiation New data confirms that about 8,500 years ago, early hunter-gatherers in Spain, Luxembourg, and Hungary also had darker skin. Skin pigmentation is an adaptation to ultraviolet radiation, with different tones offering different advantages, depending on one’s distance from the equator. As humans migrated to the Northern Hemisphere, they were exposed to less ultraviolet radiation, which also meant less absorption of the Vitamin D needed for strong bones and other important immune functions. In order to compensate for this loss and to allow for greater exposure to ultraviolet radiation, skin pigmentation became lighter. Another example of human variation as a result of adaptation to the environment can be seen in Indigenous populations in the Andes, Tibet, and the Ethiopian highlands. Each of these three groups faces the same environmental challenge, living in a low-oxygen environment, and they have responded with unique adaptations. Tibetans compensate for low oxygen levels by taking more breaths per minute than people who live at sea level. Those living at high altitudes in the Andes have been found to have higher concentrations of hemoglobin in their blood than other people. Ethiopians living at altitudes of 9,800 to 11,580 feet have neither of these adaptations. The explanation as to how the Ethiopian highlanders thrive in their environment is still a mystery. A valley in the Andes near Ollantaytambo, Peru. Indigenous peoples living at high altitudes in the Andes have been found to have higher concentrations of hemoglobin in their blood than other people. (credit: “Snows of the Andes” by David Stanley/flickr, CC BY 2.0) This chapter has explored just some of the immense biological and cultural diversity of the genus Homo . This diversity has emerged in response to highly complex and variable environments connected to factors such as exposure to UV radiation, low oxygen levels at high altitude, changes in diet as a result of hunting or agricultural practices, geographic isolation in island populations, and climate variability and temperature. The genus Homo has proven to be resilient and adaptive in response to whatever environment or challenge it has faced. Variation is the key to survival. While scientists recognize that biological and cultural variation has greatly contributed to our human evolution, the human species is now facing a moment in which we must contemplate a difficult question: To what extent has our success as a species jeopardized the survival of other species and the health of the planet we all call home? Summary In this chapter we have explored our human journey as a member of the genus Homo , following a trail of adaptations and change that ultimately led to us . First on the scene were the australopithecines, who were already walking on two feet and paved the way for the evolutionary changes and cultural achievements that were to follow. A colder climate with drastic changes in climate were associated with an increased reliance on cooked meat, which may have contributed to a growing brain. A brain with highly developed cognitive skills gave humans the capacity to solve problems and create tools that enabled better hunting and survival skills. Adaptations provided H. ergaster and H. erectus the ability to walk and run longer distances, to more effectively track and follow game, and to explore nearby continents. Genetic information provided by mtDNA indicates that all humans shared common ancestors who lived in Africa 200,000 years ago. Studies of genetics shows examples of coevolution and how even small organisms such as lice can shed light on the human story. The rise of agriculture created new challenges for humanity, with evolutionary mismatch still impacting people today. From the earliest toolmakers to the cave art of the Upper Paleolithic to the modern computer age, the predominant theme of human history has always been about change. The ability to adapt to this change is why humans are still here. Humans’ evolutionary story, however, does not end with the emergence of the species. Today humans are faced with numerous challenges as they adapt to an increasingly changing environment as a result of climate change, loss of habitat, and decreasing biodiversity. In 2020, Darwin’s theory of natural selection played out in real time as people began an arms race with a mutating and evolving COVID virus. Evolutionary change is not something that happened to people just in the past—it is very much still happening today, and it will continue to be part of the future. Identify the Fossil Imagine that you have just discovered a hominin fossil with some of the characteristics listed below. Write each of the characteristics on a card and shuffle them together. Then, working in a group, decide which characteristics belong in the Homo group and which belong in the Australopithecus group. What scientific name (genus/species) would you give it, and what criteria did you use? (Note: This is an actual hominin fossil!) Brain similar in shape and structure to modern human brains Hands suited for tool use Small jaws and teeth Third molar larger than other molars (found in australopithecines and some early Homo species) Skull shaped more like H. erectus or H. habilis A sagittal keel (as seen in H. erectus )—a small raised ridge on top of the skull Bipedal and walked with a human gait Humanlike feet with arches and ankles Flaring blades of the pelvis (primitive) Broad rib cage Lower part of pelvis like modern humans’ Small braincase (EQ 4.5) Skull shows prognathism (protruding face) Primitive shoulder position suggests suitability for climbing and swinging Curved fingers (What would that suggest?) Critical Thinking Questions References Ahern, Jim. 2015. “Archaic Homo.” In Basics in Human Evolution, edited by Michael P. Muehlenbein, 163–76. Cambridge, MA: Academic Press. doi:10.1016/B978-0-12-802652-6.00012-8. Aiello, L., and P. Wheeler. 1995. “The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution.” Current Anthropology 36 (2): 199–221. http://www.jstor.org/stable/2744104. Akst, Jef. 2019. “Neanderthal DNA in Modern Human Genomes Is Not Silent.” The Scientist , September 1, 2019. https://www.the-scientist.com/features/neanderthal-dna-in-modern-human-genomes-is-not-silent-66299. Beier, J., N. Anthes, J. Wahl, and K. Harvati. 2018. “Similar Cranial Trauma Prevalence among Neanderthals and Upper Paleolithic Modern Humans.” Nature 563:686–90. https://doi.org/10.1038/s41586-018-0696-8. Boaz, Noel T., Russell L. Ciochon, Qinqi Xu, and Jinyi Liu. 2004. “Mapping and Taphonomic Analysis of the Homo erectus Loci at Locality 1 Zhoukoudian, China.” Journal of Human Evolution 46 (5): 519–49. doi:10.1016/j.jhevol.2004.01.007. Bramble, D., and D. Lieberman. 2004. “Endurance Running and the Evolution of Homo .” Nature 432:345–52. https://doi.org/10.1038/nature03052. Chen, F., F. Welker, C. C. Shen, S. E. Bailey, I. Bergmann, S. Davis, H. Xia et al. 2019. “A Late Middle Pleistocene Denisovan Mandible from the Tibetan Plateau.” Nature 569:409–12. https://doi.org/10.1038/s41586-019-1139-x. Dirks, Paul HGM, Lee R. Berger, Eric M. Roberts, Jan D. Kramers, John Hawks, Patrick S. Randolph-Quinney, Marina Elliott et al. 2015. “Geological and Taphonomic Context for the New Hominin Species Homo naledi from the Dinaledi Chamber, South Africa.” eLife 4:e09561. doi:10.7554/eLife.0956. Dorey, Fran. 2020. “ Homo erectus .” Australian Museum. https://australian.museum/learn/science/human-evolution/homo-erectus/. Dorey, Fran. 2019. “ Homo naledi .” Australian Museum. https://australian.museum/learn/science/human-evolution/homo-naledi/. Dunsworth, Holly M. 2010. “Origin of the Genus Homo .” Evolution: Education and Outreach 3:353–66. doi:10.1007/s12052-010-0247-8. Durvasula, Arun, and Sriram Sankararaman. 2020. “Recovering Signals of Ghost Archaic Introgression in African Populations.” Science Advances 6 (7): eaax5097. doi:10.1126/sciadv.aax5097. Egeland, Charles P., Manuel Domingues-Rodrigo, Travis R. Pickering, Colin G. Menter, and Jason L. Heaton. 2018. “Hominin Skeletal Part Abundances and Claims of Deliberate Disposal of Corpses in the Middle Pleistocene.” PNAS 115 (18): 4601–06. https://doi.org/10.1073/pnas.1718678115. Fuentes, Agustin. 2019. Biological Anthropology: Concepts and Connections . 3rd edition . New York: McGraw-Hill Education. Frayer, David & Clarke, Ronald & Fiore, Ivana & Blumenschine, Robert & Pérez-Pérez,FF Alejandro & Martínez Martínez, Laura & Estebaranz-Sánchez, Ferran & Holloway, Ralph & Bondioli, Luca. (2016). OH-65: The earliest evidence for right-handedness in the fossil record. Journal of Human Evolution. 100. 10.1016/j.jhevol.2016.07.002. Hawks, John, Marina Elliott, Peter Schmid, Steven E. Churchill, Darryl J. de Ruiter, Eric M. Roberts, Hannah Hilbert-Wolf et al. 2017. “New Fossil Remains of Homo naledi from the Lesedi Chamber, South Africa.” eLife 6:e24232. doi:10.7554/eLife.24232. Holloway, Ralph L. 2018. The International Encyclopedia of Biological Anthropology . Hoboken, NJ: John Wiley and Sons. Huber, J. 2018. “Inherited Neanderthal Genes Protect Us Against Viruses, Study Shows.” Scope , October 5, 2018. https://scopeblog.stanford.edu/2018/10/05/inherited-neanderthal-genes-protect-us-against-viruses-study-shows. Jerison, H. J. 1973. Evolution of Brain and Intelligence . New York: Academic Press. Ji, Qiang, Wensheng Wu, Yannan Ji, Qiang Li, and Xijun Ni. 2021. “Late Middle Pleistocene Harbin Cranium Represents a New Homo Species.” The Innovation 2 (3): 100132. https://www.cell.com/the-innovation/fulltext/S2666-6758(21)00057-6. Leakey, L. S., P. V. Tobias, and J. R. Napier. 1964. “A New Species of the Genus Homo from Olduvai Gorge.” Nature 202:7–9. doi:10.1038/202007a0. Li, Norman P., Mark van Vugt, and Stephen M. Colarelli. 2018. “The Evolutionary Mismatch Hypothesis: Implications for Psychological Science.” Current Directions in Psychological Science 27 (1): 38–44. https://doi.org/10.1177/0963721417731378. Lieberman, P. 2007. “The Evolution of Human Speech: Its Anatomical and Neural Bases.” Current Anthropology , 48 (1): 39-66. doi:10.1086/509092. Meyer, Matthias, Juan-Luis Arsuaga, Cesare de Filippo, Sarah Nagel, Ayinuer Aximu-Petri, Birgit Nickel, Ignacio Martínez et al. 2016. “Nuclear DNA Sequences from the Middle Pleistocene Sima de los Huesos Hominins.” Nature 531 : 504–07. https://doi.org/10.1038/nature17405. Monfils, A., J. Allen, B. W. Goodner, and D. Linton. 2020. “Louse and Human Coevolution.” Biodiversity Literacy in Undergraduate Education , QUBES Educational Resources. doi:10.25334/JJBH-SG27. Mortazavi, S., K. Kaveh-Ahangar, S. Mortazavi, D. Firoozi, and M. Haghani. 2021. “How Our Neanderthal Genes Affect the COVID-19 Mortality: Iran and Mongolia, Two Countries with the Same SARS-CoV-2 Mutation Cluster but Different Mortality Rates.” Journal of Biomedical Physics and Engineering 11 (1): 109–14. https://doi.org/10.31661/jbpe.v0i0.2010-1218. Nielsen, R., J. Akey, M. Jakobsson, J. Pritchard, S. Tishkoff, and E. Willersley. 2017. “Tracing the Peopling of the World through Genomics.” Nature 541: 302–10. https://doi.org/10.1038/nature21347. Petr, Martin, Mateja Hajdinjak, Qiaomei Fu, Elena Essel, Hélène Rougier, Isabelle Crevecoeur, Patrick Semal et al. 2020. “The Evolutionary History of Neanderthal and Denisovan Y Chromosomes.” Science 369 (6511): 1653–56. doi: 10.1126/science.abb6460. Pike, A. W. G., D. L. Hoffmann, M. García-Diez, P. B. Pettitt, J. Alcolea, R. De Balbín, C. González-Sainz, C. De Las Heras, J. A. Lasheras, R. Montes et al. (2012). “U-Series Dating of Paleolithic Art in 11 Caves in Spain.” Science 336 (6087): 1409–13 doi:10.1126/science.1219957. Schaik, Carel P. V., Triki, Zegni, Bshary, R. Heldstab, S.A., (2021) “Farewell to the Encephalization Quotient: A New Brain Size Measure for Comparative Primate Cognition” Brain Behav Evol 96:1–12 van Schaik/Triki/Bshary/Heldstab DOI: 10.1159/000517013 Toups, M.A. Kitchen, A., Light, J.E. Reed, D.L (2011). “Origin of clothing lice indicates early clothing use by anatomically modern humans in Africa” Molecular Biology and Evolution , Volume 28, Issue 1, January 2011, Pages 29–32, https://doi.org/10.1093/molbev/msq234 Read, Dwight, and Sander van der Leeuw. 2008. “Biology Is Only Part of the Story.” Philosophical Transactions of the Royal Society 363 (1499): 1959–68. doi:10.1098/rstb.2008.0002. Rogers, A. R., R. J. Bohlender, and C. D. Huff. 2017. “Early History of Neanderthals and Denisovans.” PNAS 114 (37): 9859–63. doi:10.1073/pnas.1706426114. Roth, G., and U. Dicke. 2012. “Evolution of the Brain and Intelligence in Primates.” Progress in Brain Research 195:413–30. doi:10.1016/B978-0-444-53860-4.00020-9. Semaw, S., P. Renne, J. W. K. Harris, C. S. Feibel, R. L. Bernor, N. Fesseha, and K. Mowbray. 1997. “2.5-Million-Year-Old Stone Tools from Gona, Ethiopia.” Nature 385:333–6. https://doi.org/10.1038/385333a0. Slon, Viviane, Fabrizio Mafessoni, Benjamin Vernot, Cesare de Filippo, Steffi Grote, Bence Viola, Mateja Hajdinjak et al. 2018. “The Genome of the Offspring of a Neanderthal Mother and a Denisovan Father. Nature 561:113–6. https://doi.org/10.1038/s41586-018-0455-x. Snow, Dean. 2013. “Sexual Dimorphism in European Upper Paleolithic Cave Art.” American Antiquity 78 (4): 746–61. doi:10.7183/0002-7316.78.4.746. Sommer, J. D. 1999. “The Shanidar IV Flower Burial: A Re-evaluation of Neanderthal Burial Ritual.” Cambridge Archaeological Journal 9 (1): 127–9. https://doi.org/10.1017/S0959774300015249. “Study Finds Earliest Evidence in Fossil Record for Right-Handedness.” 2016. University of Kansas. https://news.ku.edu/2016/07/21/study-finds-earliest-evidence-fossil-record-right-handedness. Susman, R. 1991. “Who Made the Oldowan Tools? Fossil Evidence for Tool Behavior in Plio-Pleistocene Hominids.” Journal of Anthropological Research , 47 (2), 129–51. http://www.jstor.org/stable/3630322 Xiujie, Wu, Liu Wu, and Christopher J. Norton. 2007. “Endocasts —The Direct Evidence and Recent Advances in the Study of Human Brain Evolution.” Progress in Natural Science 17 (9). Zeberg, H., and S. Pääbo. 2020. “The Major Genetic Risk Factor for Severe COVID-19 Is Inherited from Neanderthals.” Nature 587:610–2. doi:10.1038/s41586-020-2818-3. Additional Resources Visual timelines and maps The Atlas of Human Evolution has put together a user friendly interactive map on the development of Homo sapiens. The Smithsonian Institute's Human Evolution Interactive Timeline provides an interactive overview of major milestones and species ranges. Coevolution of lice and humans David Reed, associate curator of mammals at the Florida Museum of Natural History, offers an explanation of his research for a general audience. The Smithsonian Magazine explores possible causes and benefits of the human loss of hair. coevolution an interaction between different species that influences each species’ evolution; the simplest case of this is predator-prey relationships. evolutionary mismatch a hypothesis that disease and nutritional deficiencies result when people’s bodies are unable to adapt to an environment that they have not spent most of their evolutionary history in. genome the complete set of genes or genetic material present in a cell or organism. melanin substance that determines the color of skin pigmentation and protects people from ultraviolet radiation. Skin will have higher levels of melanin the closer to the equator one lives. mtDNA the DNA located in the mitochondria that can be passed down unchanged from female genetic contributor to child. mtMRCA “mitochondrial most recent common ancestor,” or Mitochondrial Eve, representing the common ancestor of H. sapiens around 200,000 years ago. Mitochondrial Eve genes traced through mitochondrial DNA that represent the female genetic originator of all humans who lived 200,000 years ago in Africa. Out of Africa theory theory that proposes that Homo sapiens developed first in Africa and then spread around the world between 100,000 and 200,000 years ago. thermoregulation an adaptation that allows the body to control and regulate body temperature.

Social Sciences