# The Genus Homo and the Emergence of Us

## Tools and Brains: Homo habilis, Homo ergaster, and Homo erectus

### Learning Objectives

By the end of this section, you will be able to:
1. Compare and contrast the anatomy and material culture of H. habilis, H. erectus, and H. ergaster.
2. Define the term “tool industry” and describe the tools typified by the Oldowan and Acheulean industries.
3. 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.
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 ().
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

 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.

### 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.
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.

### 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

 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.
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).
1. There is a progressive increase in brain size in H. erectus, from about 550 cc to 1,250 cc.
2. 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).
3. 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.
4. 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.
5. 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.
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.


# The Genus Homo and the Emergence of Us

## The Emergence of Us: The Archaic Homo

### Learning Objectives

By the end of this section, you will be able to:
1. Describe the context, time frame, and key anatomical characteristics of archaic Homo.
2. Explain the potential environmental conditions that led to evolutionary change in anatomy and material culture seen in archaic Homo.
3. 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  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

 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

 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.
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.

### Late Archaic Homo

### Homo naledi: A Rising Star

The most recently described archaic Homo is known as . 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.

### 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.
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.
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.

### 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 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.

### 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 , 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

, 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 , 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.

### 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  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.
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.
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 , 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.
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.
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  (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.
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.


# The Genus Homo and the Emergence of Us

## Tracking Genomes: Our Human Story Unfolds

### Learning Objectives

By the end of this section, you will be able to:
1. Describe how mtDNA sheds light on early human migrations and explain the Out of Africa model.
2. Explain how studying the genomes and coevolution of lice can fill current gaps in the human fossil record.
3. 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.
 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.

### 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.
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.

### Critical Thinking Questions

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### 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.


# Language and Communication

## Introduction

Talk, talk, talk. As human beings, that is what we do all day (and sometimes all night). Even when we are alone, we might be listening to the radio, watching a video, reading, or texting—all activities that incorporate language. Language is often considered to be one of the quintessential elements of humanity, key to our social interactions and cultural development. No other animal does it the way we do. A few apes have been taught words in sign language, mainly using simple word combinations to ask for particular treats or desired activities. Is that anything compared to what we do with language?
Consider a situation from the author, Jennifer Hasty’s own fieldwork.
What did the proverb mean in that situation? In most cultures, people do not usually explain proverbs, so the listener has to piece together the meaning. In this case, the proverb was used metaphorically to compare the production of words in the mouth and the roles of the people involved in this particular performance of libation. The nimble tongue is central to human speech, while the teeth play a more fixed and supportive role, providing surfaces used by the tongue to make certain sounds. Alone, the teeth can only clash against each other meaninglessly. A tongue is needed to produce speech. Using the proverb, the first speaker was comparing his elder brother to the tongue—he was more central to the gathering and more proficient in the production of ceremonial speech such as libation. The younger man assigned himself the role of a tooth, only able to make noise rather than ceremonial speech.
In humans, language has developed into an extremely complex feature of sociocultural life. Just as the tongue is central to the production of human speech, language is central to the production of human culture. The subfield of linguistic anthropology examines the role of language in sociocultural life. Linguistic anthropologists are interested in how language affects our thinking and our experience of the world around us. Some explore the different categories of formal and informal speech that people have developed to organize rituals and ceremonies as well as everyday activities. Others listen carefully to various kinds of conversation, looking for patterns in the way people interpret and build on one another’s speech acts.
The discipline linguistics is devoted to the study of language. Linguistics is the science of language, including subfields devoted to speech sounds, word forms, word arrangement, meanings, and practical language use. One subfield of linguistics, sociolinguistics, examines the social context of language use, such as how language varies according to age, gender, class, and race. While sociolinguistics and linguistic anthropology share an interest in the social side of language, linguistic anthropologists tend to focus on language as an aspect of larger cultural processes. Rather than looking at language as a sole object of study, linguistic anthropology studies language as one cultural element among many, all interwoven into the sociocultural life of a people.


# Language and Communication

## The Emergence and Development of Language

### Learning Outcomes

By the end of this section, you will be able to do the following:
1. Describe the communicative abilities of wild animals such as birds and primates.
2. Distinguish primate communication from human language.
3. Identify the biological features of early hominins that were central to the emergence of language.
4. Identify the archaeological evidence for the emergence of language.
There are some seven thousand languages spoken in the world today. Most people are proficient in at least one of them, possibly more. But people are biologically capable of mastering any of them, and have been since birth. Humans are born language ready. For a human baby, any language will do. With passive exposure to language (simply hearing it without any formal instruction), human toddlers learn the complex rules and vast vocabularies of the language spoken (or signed) around them. This astounding feat is made possible by specific biological features in the brains and bodies of human babies, features designed to help them understand and produce language. The learning of language then triggers further changes in our brains, making possible certain kinds of reasoning and thought as well as communication with others.
Drawing on biological and archaeological evidence, researchers seek to understand how, why, and when humans developed the biological features associated with language and, once language emerged, how the practice of language changed the way of life of early humans. Language became a building block for human culture of increasing complexity. Innovations such as stone tools, hunting, and using fire for heat and cooking were made possible by language. In turn, these new skills enhanced the survival of those who practiced them, increasing the likelihood that those people would live to pass on their genetic makeup to their offspring. This means that certain biological features were key to the invention of human culture and that human culture was key to the biological development of humans. We think of this as a reciprocal system of biocultural coevolution. Put another way, biology and culture developed in tandem, with language as the link between the two.
No one really knows when or how humans invented language. The problem is that language, whether spoken or gestural, leaves no direct trace in the archaeological record. Lacking direct evidence, researchers must be creative, combining various indirect forms of evidence to suggest theories about how language may have begun in humans. Based on such methods, researchers think that language may have emerged between 50,000 and 200,000 years ago. The largeness of this window of possibility is due to the indirect nature of the evidence and a great deal of controversy about which elements may have been most important in the process of language development. In this section, we look at these forms of indirect evidence, starting with communication in the animal kingdom.

### Animal Communication

All animals communicate with each other and even with other species (Tallerman and Gibson 2011). Many use vocalizations like calls, growls, howls, and songs. Many also use gestures such as dances, postures, and facial expressions. Some change the color of their scales, skin, or fur. Some produce strong-smelling body fluids sprayed in their environment or rubbed on their own bodies. All of these activities are used to tell other animals about territory, food sources, predators, and mating opportunities.
Many people might be tempted to think that animals speak to each other just as we do, that their various forms of communication are roughly equivalent to language. Does your dog bark and jump excitedly whenever you pick up the leash? Isn’t that a way of saying, “C’mon! Let’s go for a walk!”
Some forms of animal communication are fairly simple, such as this canine leash mania. Others are far more complex, such as the way an octopus can change the color of and patterns on its skin for hunting, courtship, and camouflage. Fireflies use bioluminescence to attract mates and as a defense mechanism. Some fish generate electric fields to advertise their species and sex. Many animals use a vast lexicon of postures and gestures to communicate messages to one another and even to other species. When a bird issues a predator-alert call, squirrels respond as well. Many mammals pay attention to the predator warnings of birds.
Are these complex forms of communication equivalent to language? Take a closer look at one famous example of complex animal communication and compare it to human language.

### A Waggle is Not a Word: The Complexity of Language

Consider the famous “waggle dance” of the honeybee. Upon finding a good source of nectar such as a grove of wildflowers, a worker bee returns to the hive and performs a special flight pattern consisting of a figure-eight waggle followed by a return loop alternating right and left. The direction and duration of the waggle communicate the direction and distance to the location of the desirable food source (Seeley 2010; Frisch 1993).
The waggle dance is certainly a complex and effective form of communication, but does it qualify as language? Communication refers to the transfer of information from a sender to a receiver. Communication can be voluntary or involuntary, simple or complex. Language is a specific, complex, systematized form of communication involving the use of vocal or gestural units (words or signs) that can be combined and recombined in larger structures (sentences) that can convey an infinite array of complex meanings. Language is a form of communication. Not all communication is language.
Central to the infinite possibilities of language is a set of rules that govern just how sounds, signs, words, and phrases may be combined. These rules structure the order of words, dictating, for example, where to put subjects and actions in an utterance so that listeners will be able to find them. Rules also tell us whether words indicate a single thing or multiple things and whether actions occur in the past, present, or future. Complex forms of animal communication such as the waggle dance do contain some systematic rules governing the sequence, duration, and intensity of certain segments of the communication, but they are highly constrained to very limited contexts. For example, the waggle dance can be used to signal nectar sources near and far, but it cannot be used to discuss the weather or comment on the laziness of the queen. Unlike the relatively “closed” systems of communication common among animals, human language is open-ended. Our languages have the distinctive quality of allowing actors to combine units in an infinite number of ways to produce new meanings.

### Simple Signs and Pant-Hoots: Language in Primates

Biological anthropologists posit that we share a common ancestor with the other great apes (gorillas, chimpanzees, bonobos, and orangutans) about five to eight million years ago. As nonhuman primates do not produce language in the wild, the biological and cultural features that promoted language must have emerged after that. However, studies aimed at teaching human language to nonhuman primates have revealed that individuals of these species are able to master basic vocabulary and use simple words and word combinations to obtain the things they want. So the great apes must have some biological features that enable them to learn human language in a partial and limited way.
You may have heard of Koko, the gorilla famous for learning to use sign language. Sign language is used in such studies because nonhuman primates lack the distinctive vocal tract required to make the sounds of human language. Researcher Penny Patterson taught Koko to use about a thousand signs, roughly the vocabulary of a three-year-old child (Patterson and Linden 1981). Patterson reported that Koko could comment on things that were not currently present in her environment, such as personal memories. According to Patterson, Koko could joke and lie and teach other gorillas to sign. She could even invent new signs. Many of these claims are disputed by other researchers. Some point out that the evidence is largely anecdotal and relies on the interpretation of Patterson herself, hardly an objective observer. Though controversial, Patterson’s path-breaking work with Koko provided a wealth of data and opened up new possibilities for understanding the language abilities of nonhuman primates.
Human-reared chimps, gorillas, bonobos, and orangutans have all been taught to use gestures or tokens to refer to things in the world around them, often combining those signs in a rule-based way to make comments and requests. Even though many linguists are skeptical of these studies, the use of symbolic systems in cooperative interactions to achieve goals does seem to indicate that great apes have the basic capacity to generate some sort of protolanguage. Protolanguage refers to a very simple set of gestures or utterances that may have preceded the development of human language. But do apes display these abilities due to some innate capacity or because we have taught them symbolic systems? Perhaps learning a symbolic system has changed the brains of these individual animals in distinctive ways.
Many primatologists conduct research on the vocal and gestural forms of communication used by primates in the wild, looking for those biological features that might underpin the human capacity for language. Wild chimpanzees, for instance, produce a wide range of calls, including hoots, pant-hoots, pant-grunts, pant-barks, rough-grunts, nest-grunts, alarm barks, waa-barks, wraas, screams, and soft panting play sounds (Acoustical Society of America 2018). Primatologists have listened closely to these calls. Some argue that chimp vocalizations are not much like human language, as calls are fairly fixed and limited in their meanings. Chimps may use a rough grunt to indicate a food source, but they do not seem to have specific grunts for specific food types. Monogamous pairs of gibbons, a smaller species of ape, are known to perform elaborate morning duets. Gibbons have an array of predator calls as well. Research comparing duets with predator calls suggests that gibbons compose their songs to convey specific information, each note carrying a certain meaning (Clark et al. 2006). While impressive, the ability to manipulate notes to convey a limited range of meanings is still a far cry from the infinite productivity of human language. The limitless recombination of signs that produces the flexible, open-ended quality of language is missing in the communication systems of wild primates.

### Human Biology and the Emergence of Language

There must be something special about us to make possible the distinctively flexible and open-ended communication system of language. Research has focused on our throats, our brains, and our genes, looking for the biological features that allowed for the emergence of language.

### The Vocal Tract

Humans have evolved a very unusual vocal tract with a descended larynx (otherwise known as the “voice box”) and a large and rounded tongue positioned in the mouth to enable a remarkable array of sounds (Lim and Snyder 2015). Some researchers suggest that our throats may have evolved in response to walking upright or changes in diet or a combination of those two factors. Humans also have more deliberate control over breathing than nonhuman primates. In order to better understand when hominins developed this distinct vocal apparatus, researchers examine the hyoid bones of hominins to see if they resemble those of modern humans. The hyoid is a U-shaped bone in the human throat that helps us swallow and move our tongues. The few hyoids that have been found in the fossil record suggest that our distinctive vocal tract may have been developed around 500,000 years ago. This means that Neanderthals likely had the same vocal abilities as modern humans.

### Brain Structure

Several features of the human brain are considered prerequisites to language, including the overall (large) size, the division into specialized hemispheres, and certain structures like Broca’s and Wernicke’s areas. Broca’s area is a region of the brain associated with the production of speech. Wernicke’s area is essential to the comprehension of language. Both are most often located in the left hemisphere of the human brain (for left-handed people, both can be located on the right side). How did we acquire these brain features so essential to language? A great deal of controversy surrounds this question, as researchers debate when and how these structures evolved.
Most recently, research has focused on “mirror neurons,” special brain cells that seem to enable mimicry (Lim and Snyder 2015). Many researchers think that the ability to understand the actions of others and recreate those actions ourselves is a fundamental prerequisite for language. That is, in order to be able to talk to each other, early hominins must have been able to evaluate and interpret each other’s actions and reproduce them in similar contexts. In primates like monkeys, scientists have discovered a system of specialized neurons called the “mirror neuron system” that enables primates to recognize and imitate actions. Monkeys and apes cannot talk, but they can recognize, interpret, and imitate actions performed by other primates. The neurological studies that revealed mirror neurons are too invasive to perform on humans, but neuroimaging studies suggest that a similar mirror neuron system does exist in humans.
Brain imaging studies on humans have located evidence for the mirror neuron system in a region of the brain close to Broca’s area. So it is possible that the mirror neuron system inherited from primates provided a foundation for the later emergence of a brain structure devoted to language production in hominins. If imitation and language are in fact connected in this way, then a system of gestures may have paved the way for the development of language. Some researchers now hypothesize exactly this: that hominin language evolved from a system of gestures to a system of vocalizations.

### The “Language Gene”

In the late 1980s, medical researchers became aware of a particular speech disorder common among members of one family in West London. Many members of this family could not pronounce words. Many stuttered. Many had very limited vocabularies. Geneticists traced the disorder to a genetic mutation on chromosome number 7 of the human genome. (See Biological Evolution and Early Human Evidence for more on chromosomes and genes.) The mutation was located on a gene named FOXP2, prompting some researchers to dub this “the language gene.” Some hypothesize that FOXP2 may have played a role in the development of language in humans (Lim and Snyder 2015).
At first, researchers thought that only humans had the FOXP2 gene, but subsequently a form of this same gene has been identified in many vertebrates, including mice, bats, fish, and songbirds. In mice, the gene appears to be related to vocalizations. In birds, it seems to be linked to birdsong. All primates have FOXP2, but the human copy is slightly different than that of nonhuman primates. Some researchers think this mutation occurred around 260,000 years ago and may have enabled the development of spoken language in Neanderthals and Homo sapiens.
Other researchers are skeptical of the notion that one gene could be responsible for the emergence of spoken language (Tallerman and Gibson 2011). Many anatomical developments and cognitive processes—connected to different parts of the human genome—are involved in human language. These developments and changes would have required mutations in other parts of the genome of early Homo. While the mutation of FOXP2 in Homo may have played a role in language development, other mutations would have been important as well.

### Hominin Material Culture

Evidence from the material culture of hominins such as Homo habilis and Homo erectus is also used to speculate about the emergence of human language. Early hominins developed stone tool technologies and created stunning works of art. The production and use of such tools and artwork must have required a complex set of social and cognitive abilities. Those same types of social and cognitive skills are important to human language. It is possible that language emerged as part of a whole complex of material culture.
Archaeological evidence and linguistic theory come together in a model suggesting that the invention of tools by early hominins was linked to the invention of language. Some linguistic theorists suggest that the evolutionary changes in brain structure that allowed for the development of tool use also support the emergence of language. Furthermore, the innovations of tools and language are entwined in a reciprocal relationship; evolutionary pressure to develop tools stimulated the development of language, and the development of language facilitated increasingly complex tool making and tool use.
There are two theories to explain the connections between advances in tool use and language. The first rests on the assumption that tool making requires a considerable degree of cognitive planning. You cannot make a useful tool by just picking up a rock and randomly chipping away at it. Hominins like Homo habilis and Homo erectus must have known just what kind of rocks would work as base and chipper and how to execute a set of precise chips in a certain sequence to achieve a sharp blade without breaking the core. The mental processes important to this sort of planning are hypothesized to have also enabled hominins to do the sort of quick planning involved in the production of complex speech (Tallerman and Gibson 2011).
A second theory linking tool use and language emphasizes the importance of imitation in passing along the complex set of skills involved in tool making. Neuroscientist Michael Arbib suggests that the ability to imitate may have generated the first gestural language among hominins (2011). And he has developed a model to describe how imitation and tool making may have evolved together over time. About 2.5 million years ago, Homo habilis began making basic stone choppers, cores with flakes removed, used for butchering carcasses. Such choppers are called Oldowan tools, named after the site in Olduvai Gorge in Tanzania where they were first found. Arbib has theorized that the production of Oldowan tools required the ability for hominins to imitate each other’s actions. Simple imitation would make it possible for a learner to reproduce the actions of an accomplished tool maker through observation and mimicry. This ability to imitate is biologically rooted in the system of mirror neurons discussed earlier. As hominin brains acquired the ability of simple imitation involved in tool production, they might also become capable of the kind of gestural communication we see in apes today—not language, but a precursor to it. Investigate this diagram for more about the evolution of language.
The array of action-oriented mirror neurons, tool innovation, and language all progressed together in hominin evolution. As tool technology developed, Homo erectus began making distinctive pear-shaped hand axes about 1.6 million years ago. A more intricate form of imitation would have been necessary to teach this sort of tool making to others, corresponding to the emergence of protolanguage. This protolanguage might have been a set of simple one-word utterances corresponding to concepts such as “yes,” “no,” “here,” or “there.”
We don’t have any hominin brains to examine, but remember that in the human brain, the system of mirror neurons is assumed to be situated near Broca’s area, which is associated with human speech. So very likely, protolanguage emerged in the same part of the brain as the ability to imitate. The explosion of innovations in tool making over the past 100,000 years is linked to the emergence of complex human language. While the development of mirror neurons and the ability to learn tool making required biological changes to the brain, Arbib argues that the last step, the emergence of language, was purely cultural.