When remains are found, fleshed or skeletonized, the discoverer should:

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Online Chapter: Nanda/Warms, Cultural Anthropology 11e

Human Evolution

Learning Objectives After you have read this chapter, you will be able to:

• Describe the relationship between culture and evolution for human beings. • Explain the basic principles of Darwin’s theory of natural selection. • List some traits that humans have in common with our closest animal relations. • Describe social relations among nonhuman primate species.

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• Describe australopithecines, and tell when and where they lived and what their social lives might have been like.

• Describe Homo habilis, and tell when and where they lived and what their social lives might have been like.

• Describe Homo erectus, and tell when and where they lived and what their social lives might have been like.

• Tell where and when Homo sapiens evolved, and describe their early material culture. • Compare variation among humans to that found among other species. • Explain some of the sources of human variation, particularly variation in skin color.

In its broadest sense, evolution refers to directional change. Biological evolution, however, is something more specific. For biologists, evolution is descent with modification from a single common ancestor or ancestral population. Evolution is a characteristic of populations, not individual organisms. As individuals, we may grow and learn. We may create inventions or alter our lifestyles. But, for a change to be evolutionary in a biological sense, it must affect the genes we pass along to the next generation. Evolution is the primary way we understand the biological history of humanity and, indeed, of all life.

In this chapter, we provide a brief overview of human evolution. We start with a discussion of Darwin and the theory of natural selection, move on to talk about primates, their social lives, and tool usage, before turning to a summary of what we know about human evolution. We talk about the ways that remains are found, and then survey the major fossil finds, including the australopithecines, Homo habilis, Homo erectus, and Homo sapiens. We end with a discussion of human variation. Along the way, we describe some of the experiences of fossil hunters Raymond Dart and Mary Leakey, discuss forensic anthropology, and consider the fate of primates in the world today.

Speculation about human history and the natural world plays an important role in most societies. For example, the notion that human beings came from earlier life forms was well developed among ancient European philosophers. In the 6th century BCE, the Greek thinker Anaximander of Miletus speculated that humans arose from fish. A century later, his disciple, Xenophanes of Colophon, used evidence of fossil fish from numerous places around the Mediterranean to support Anaximander’s theory.

We are often asked why, in a text on cultural anthropology, there should be an extensive chapter on human evolution, normally a part of biological anthropology. We include it because although modern human behavior is almost totally learned and cultural, it rests on a biological base. It is expressed in the brains and bodies of actual human beings. These brains and bodies were shaped by the process of evolution. Evolution has shaped our behavior, our capacity for culture, and the nature of that culture. For example, highly accurate depth perception, hands with opposable

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thumbs, and the ability to manipulate objects with great precision are all parts of our evolutionary heritage. Members of all cultures make and use tools ranging from fishhooks and spears to microprocessors and satellites. The use of such tools is basic to human life. Without them, human culture would be vastly different, if it existed at all. But, the ability to make and use tools effectively is dependent on the evolved traits we just mentioned. For human beings, culture and evolution depend on each other.

Although human cultures are vastly different, human bodies and brains are all very similar. This shared evolutionary heritage shapes our cultures. It means that despite the impressive differences among cultures, there are powerful underlying similarities as well. Understanding our evolutionary history is vital to cultural anthropologists because it informs us about the things that all humans have in common. As we learn about evolution, we gain insight into what it means to be human, the ties that bind us to one another, and our relationship to the nonhuman world.

Darwin and Natural Selection

In the 18th and 19th centuries, scientists in Europe and North America proposed many different theories of evolution. It was Charles Darwin’s theory of evolution by natural selection, however, that proved the most convincing scientific explanation of the variety and history of life on earth.

The Theory of Natural Selection

Darwin’s notion of natural selection is both powerful and elegant. It is a relatively simple set of ideas with profound consequences. Because it is based on things that are easily observable, such as variation among members of a species, most of its elements are easy to verify and extremely difficult to refute. As a result, Darwin’s theory has been highly durable.

Darwin began by pointing out the great variety of nature. He observed that no two living things, even those of the same species, are quite alike. As later scientists discovered, variation among members of a species comes from sources including mutation, sexual reproduction, gene flow, and gene drift.

All living things are subject to mutations, random changes in genetic material. These are the ultimate source of all variation. Sexual reproduction and the movement of individuals and groups from place to place (or gene flow) result in the mixing of genetic material and also create new variations. Isolation can play an important role as well. Imagine that a small number of individuals are separated from a larger population. By chance, some members of the small group have a characteristic relatively rare in the larger population—say, a sixth finger on their right hand. The descendants of this small, isolated group will have an unusually large percentage of individuals with six fingers, compared with the larger population from which they were separated. This process is known as genetic drift.

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Darwin went on to observe that most creatures, human and nonhuman, did not survive long enough to have offspring. They fell victim to predators, contracted diseases, or perished through some defect in their biological makeup. Darwin argued that, in most cases, those creatures that survived did so for some reason. That is to say, their survival was not a random occurrence. There was something about them that favored survival. Perhaps they blended well with a background and so were more difficult for predators to see, or they had a bit more resistance to a disease. Perhaps their shape made them a bit more efficient at getting food, or their digestive system a bit better at processing the food they did find.

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Although very few animals survive to reproductive age, with the advent of modern medicine we have become used to the idea that most of our children will survive. However, before the development of sanitation in the 19th century and antibiotics in the 20th century, vast numbers of children died very young. For example, more than 40 percent of all deaths in London between 1813 and 1820 were children under 10 years old (Roberton 1827). Even today, in the world’s poor nations, large numbers of children die before they reach the age of 5. In 2003, for

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example, more than 20 percent of children in 11 African nations died before the age of 5. Around the world, more than 10 percent died in 45 nations (World Bank 2005). In these deaths, the main culprits are surely poverty and lack of access to basics such as clean water, sanitation, and medical care.

Darwin was profoundly affected by the economic and social philosophy of his era, particularly the works of Adam Smith and Thomas Malthus. Both these philosophers emphasized the role of competition in human social life and culture. In the 1770s, Smith had argued that competition among firms increased their productivity and led to social betterment. A quarter century later, Malthus wrote that because human population levels rose much faster than agricultural production, struggles over resources were inevitable. Darwin, synthesizing these two positions, gave competition and struggle prominent roles in his theory. He argued that life involved constant struggle. Creatures competed with many others for food and with members of their own species for mates. Those who had traits that suited them well to their environment tended to win this struggle for nutrition and reproduction. Thus, Darwin combined the struggle-for-food element of Malthus’s work with Smith’s notion that competition leads to betterment.

Darwin further argued that those who won this struggle for survival were able to pass some of these success traits to their offspring. Thus, each subsequent generation would include more and more individuals with these traits, and fewer without. Darwin reasoned that, over the course of millions of years, this process could give rise to new species and all of the tremendous variation of the natural world.

Darwin’s theory of evolution by natural selection is sometimes referred to as “survival of the fittest,” but this phrase was coined by the social theorist Herbert Spencer (1864), not by Darwin himself. Although Darwin approved of Spencer’s phrase, it is misleading for modern readers. When Spencer spoke of fitness, he thought of wealth, power, and physical strength. But when Darwin spoke of fitness, he meant reproductive success: Creatures better adapted to their environment tend to succeed in the struggle for food and mates, passing on their traits, whereas those less well adapted tend to disappear. Modern readers tend to understand fitness the way Spencer did, equating it with strength or intellect. So, it sounds as if Darwin’s theory actually says the strong and smart survive. But this is incorrect. Strength and intelligence do not necessarily guarantee reproductive success. They are not important for all creatures or environments. Consider the tree sloth, the famous South American tree-dwelling mammal. Sloths are neither particularly strong nor intelligent, yet their continually growing teeth, multichambered stomachs, protective coloring, and habit of sleeping most of the day and night adapt them well to their tropical forest environment.

Darwin understood evolution by natural selection as a slow, steady, continuous process, and there is evidence that, in many cases, evolution does operate in this way. In the 1970s, Niles Eldridge and Stephen Jay Gould (1972) proposed an alternative model of evolution called punctuated equilibrium. Eldridge and Gould agreed with the basic Darwinian mechanism of

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natural selection. However, they argued that species tend to remain stable for long periods and then, through mutation and natural selection, change quite suddenly. Much of the fossil record, especially for large species, supports punctuated equilibrium.

Evolution, Politics, and Religion

Although virtually all reputable scientists accept Darwin’s theory, some groups in the United States have raised opposition to this theory on religious and politically ideological grounds. The majority of the world’s religions have stories about the ways in which animals and humans came to live on the earth. Evolution challenges a literal reading of these stories, and for this reason, leaders and congregations in some religions have strongly resisted it.

Not all religious people argue against evolution though. The Catholic Church, for example, declared that evolution was compatible with Christian teachings in 1950, more than a half century ago. Pope John Paul II reaffirmed this in 1996, and in 2007, Pope Benedict XVI said the debate between evolution and creationism in the United States was an “absurdity” and that evolution can coexist with faith (Catholic News Agency 2007). Many theologians in a great variety of religions agree that evolution is consistent with the teachings of their tradition. In official publications and conference proceedings, the United Presbyterian Church, the Episcopalian Church, the Unitarian Church, the United Methodist Church, and the Central Conference of American Rabbis have all supported evolution and opposed the teaching of “scientific” creationism in public schools (Lieberman and Kirk 1996).

Despite religion-based disagreement, Darwin’s theory of evolution by natural selection has withstood more than 140 years of intensive scientific scrutiny. Today, there is no meaningful scientific challenge to evolutionary theory. In fact, evolution has become part of the basic framework of all biological sciences. Just as it is impossible to imagine a science of physics without the theory of gravity, so too modern biology, biochemistry, and many other fields of scientific endeavor are grounded in evolution and are all but unthinkable without it.

Although scientists who study biology overwhelmingly agree on the basic principles of evolution and natural selection, there are disputes among them. Scholars argue about the speed of evolution and the precise conditions under which it occurs. There is much discussion about the historic relationships of plants and animals and how they should be classified. Scientists debate the appropriate evolutionary place of specific fossil human ancestors. It is important to understand, however, that all of this debate takes place within the context of evolution. All sides in these arguments agree with the basic principles of natural selection, though they may differ about the specific applications.

Humans and Our Nearest Relatives

When people think about human evolution, they generally associate the idea with the notion that human beings evolved from apes or monkeys. But this is incorrect. Rather, modern-

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day humans and modern-day gorillas and chimpanzees evolved from common ancestors. The distinction is critical. Not only is it biologically inaccurate to say that humans evolved from apes or monkeys, but it also leads to a misunderstanding of evolution.

Saying that humans evolved from gorillas or chimpanzees suggests that humans are more evolved than these animals. However, no creature can be any more evolved than another. We can only imagine that we are more evolved if we believe that intellect or ability to alter the environment is the most important criterion of evolution. However, that is an extremely human- centered way of looking at biology. We could as easily say that producing the greatest number of related species or the greatest number of individuals is the best measure of evolution. If we were to take these criteria seriously, it would be clear that insects are far more “evolved” than humans. For example, there are believed to be more than 8,000 species of ants, comprising countless individuals. By contrast, there is only a single species of humans, comprising a mere 7 billion individuals.

Our Shared Ancestor and Common Characteristics

Given that humans and our nearest relatives evolved from a common ancestor, the next question we should ask is what that ancestor was. The question is not easily answered: Although there are some recent finds that are good candidates for the ancestral fossil (for example, see Moyá-Solá 2004), no agreed-upon common ancestor of humans and chimpanzees or humans and gorillas has been found. However, fossils that we have found and information gained from biochemical dating techniques tell us a good deal about what the creature was probably like.

Biological anthropologists use the fossil record and a variety of techniques based on the study of DNA, blood protein, blood-clotting agents, and immunology to try and determine when the animals that were the common ancestors of humans and other primate species lived. Evidence from a variety of sources yields similar dates (see Figure 2). It shows that the creatures that became humans and apes split from those that gave rise to the monkeys of Europe, Africa, and Asia between 25 and 20 million years ago. We last had a common ancestor with gorillas about 8 million years ago and with orangutans about 13 million years ago. Human ancestors diverged from the ancestors of chimpanzees around 7 million years ago (Begun 2004; Brunet et al. 2002; Holmquist, Miyamoto, and Goodman 1988; Marks, Schmidt, and Sarich 1988; Pilbeam 1996; Sibley and Ahlquist 1987; Sibley, Comstock, and Ahlquist 1990; Spuhler 1989; Templeton 1985, 1986).

All primates originated as tree-dwelling mammals, and many of our commonalities come from this arboreal ancestry. To survive in the three-dimensional world of trees, primates needed grasping hands and feet that could be used to climb and hold. This meant that hands and feet often had fully opposable thumbs. To live in trees, primates developed very acute eyesight; most see in great detail and in color. Additionally, tree dwellers need very accurate depth perception. Misjudging the precise location of an object, such as a branch or a piece of fruit, can easily lead

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to a fall and death. In primates, accurate depth perception comes from stereoscopic vision. Primates have eyes that face forward, near the front of their heads. Reliance on hand–eye coordination developed along with the expansion of the areas of the brain involved in vision, motor skills, and the integration of the two.

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Primate Social Life

Most primates have complicated social lives. By examining the characteristics of primate social lives, we may be able to find basic patterns shared by all primates, including humans. We may also learn the ways in which humans are fundamentally different from our primate relatives.

Almost all primates live in social groups, and these are arranged in several different ways. Gorillas live in groups consisting of a single adult male and numerous adult females and their offspring. Chimpanzees, on the other hand, live in groups that include several adult males and several adult females and their offspring. Gibbons, as well as several species of monkey, live in monogamous pairs, and some monkeys from Central and South America live in groupings with one female and two males (Jolly 1985).

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The core of primate societies is the bond between mothers and their infants. With the possible exception of elephants, the mother–infant bond is stronger among primates than any other animals. The intense bonding between mother and offspring is an ideal ground for teaching and learning. Primates have an enormous ability and need to learn. Young primates learn initially by imitating their mother’s actions. In this way, they discover where to find food and water as well as which other animals are dangerous and which can be approached safely.

As primates grow older, play becomes central to their interaction with their age-mates, and they may spend most of their waking hours in intense, repetitive, and physical play. By playing, primates refine their physical skills, explore their world, and practice solving problems.

In most primate societies, both males and females develop dominance hierarchies; that is, they are ranked as superior or inferior to one another. These hierarchies exist both within and between genders. Although such hierarchies, particularly among males, are created and maintained by shows of aggression, anthropologists believe that overall hierarchies serve to limit the amount of aggression within societies; once the hierarchy is established, lower-ranking individuals are less likely to challenge those with more status than might otherwise be the case.

The critical benefits of high rank include greater access to food and other resources. There is some evidence that high-ranking individuals reproduce more frequently than those of low rank. However, although such individuals are frequently seen having sex, there is evidence that low- ranking males also have frequent sex—they just do it covertly. Thus, they are not effectively prevented from fathering offspring (Constable et al. 2001).

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Among most primates, dominance hierarchies result from a great many individual encounters. Though hierarchy prevents constant conflict, rankings are not absolutely fixed. Aggression among animals does occur, and patterns of dominance within the group may change. Furthermore, rank may be context specific. For example, a low-ranking female might give way to higher rank in competition for food but will defend her baby against all others, regardless of rank.

In addition to displays of aggression, primates have many means of reconciliation. One of the best known, grooming, is common among members of the same sex as well as members of different sexes. Inferior-rank animals groom their superiors, and friends groom friends. Among chimpanzees, baboons, and others, friends may hug, pat each other, or hold hands. A variety of other behaviors, including lip smacking and male–male mounting are used to establish, reestablish, or maintain friendly relations between individuals and cohesion within the group.

Tool Use among Primates

The use of tools is fairly common among nonhuman animals. Many different animals build nests; some use rocks, twigs, or leaves to get at their prey. Sea otters, for example, use stones to crack open abalone shells. However, these capacities seem qualitatively different from the extremely complex and varied tool manufacture and use among humans. Nonhuman primates also use tools, but in ways that seem different both from the behavior of animals such as sea otters and from humans.

Jane Goodall recorded the first tool use among nonhuman primates in 1960 (Goodall 1971). Since then, many additional discoveries have been made. Monkeys use sticks and branches to threaten others or defend themselves when they are threatened. Some Japanese macaques wash their food and use water to separate grains of wheat from sand (Huffman and Quiatt 1986; Strier 2000). However, the most sophisticated tool use is found among chimpanzees and bonobos. For example, Pruetz and Bertolani (2007) reported chimpanzees fashioning sticks into spears and using them to hunt bush babies (squirrel-sized nocturnal primates). Mercader, Panger, and Boesch (2002) reported that chimpanzees in Ivory Coast used hammer stones to break nuts, and that stone piles and stone chips left by this process are very similar to the remains of early hominin tools found by archaeologists have found.

Two particularly well-documented examples of chimpanzee and bonobo tool use are termite fishing and the use of leaf sponges. Termite fishing involves the use of a stick or blade of grass. Chimpanzees modify sticks by stripping off leaves, then place the sticks in termite mounds and wait until the termites begin to feed on it, and then withdraw it to eat the termites. Chimps make leaf sponges by taking leaves, chewing them, and then using the resulting wad of material to soak up water from tree hollows. Both termite fishing and the use of leaf sponges are complex actions requiring foresight and planning. It is interesting that among all primates who use tools, it

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is females who first develop tool-using skills. Further, females generally become more adept at tool use than males (Strier 2000).

Tool use behavior among sea otters, woodpecker finches, and other nonprimates seems largely instinctive. All members of the species exhibit these behaviors. Among chimpanzees, however, behaviors such as spear use, termite fishing, and leaf chewing do not appear throughout the entire species. Rather, some groups exhibit the behaviors and others do not. Almost 40 different behavior patterns, including tool use, grooming, and courtship behavior, are present in some chimp communities but absent in others (Whiten et al. 1999). This implies that such practices are learned behavior passed along as part of the knowledge of the social group, very much like human culture.

The Evolution of Humans

Human beings and our nearest ape relations have been following separate courses of evolution for the past 5 to 8 million years. In this time, our species has developed in systematic ways. Our early ancestors were relatively few in number and geographically confined to Africa. In 2011, the world’s population was approximately 7 billion, and humans lived on every continent. The history of human evolution is thus a narrative of growth and movement. For this movement to take place, humans have had to adapt to living in many different climates and ecosystems.

Our early ancestors did not depend heavily on tools, and their cultures left few material remains. They were certainly able to learn, and depended on this ability for their survival. However, the range of their learning was probably small. Today, our ability to learn is vastly greater than that of our early ancestors. To live in many different ecosystems, humans had to innovate, applying our learning in new and original ways, adapting by changing our behavior. The spread of humans and our ancestors reflects our gradual acquisition of increasingly sophisticated, learned, cultural behavior.

Naming Names

Human ancestors, like those of other species, are generally referred to by their scientific names. All human ancestors, all current-day humans, as well as gorillas, chimpanzees, and orangutans, are members of the biological family Hominidae. Within this family, individual ancestors are known by the names of their genus and species. A genus is a group of similar species.

Among living creatures, a relatively simple guideline is used to determine if similar animals are members of the same or different species. If a male and female are capable of producing fertile offspring, they are members of the same species. If they can produce no offspring at all, or if the offspring are infertile, they are members of different species. For example, dogs and cats cannot mate at all and are therefore members of different species. Horses and donkeys are similar and

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can mate, but their offspring, mules, are infertile. Therefore, horses and donkeys also belong to different species. With extinct creatures, such as our fossil ancestors, no such test can be performed. Therefore, determining species membership is much more speculative.

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Most human ancestors and modern-day people fall into two genera (the plural of genus): Australopithecus and Homo. Each of these genera includes numerous fossil species. Modern people, Homo sapiens, are members of the genus Homo. Many of our ancient ancestors are assigned to the genus Australopithecus. In the past decade there have been several exciting discoveries of extremely ancient human relatives. Some anthropologists argue that these represent new genera, but their precise place in the evolution of humanity is still debated. (See Figure 3)

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The Earliest Human Ancestors

From an anatomical perspective, the critical thing that differentiates humans and our ancestors from modern-day apes and their ancestors is bipedal stance and locomotion. Unlike any other primate, humans and our ancestors habitually walk on two legs. Although chimpanzees, gorillas, and some other primates are capable of walking or running on two legs for short distances, their habitual stance is on all fours. Bipedalism involved substantial anatomical changes (see Figure 4). The skulls and pelvises of bipeds are shaped differently than those of animals that walk on all fours. In addition, the feet of human ancestors are specialized for walking, whereas their hands are generalized and able to perform many different tasks. When anthropologists are able to find fossils of these bones, bipedalism is easily inferred.

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Among human ancestors, bipedalism appeared far earlier in the fossil record than increased brain size or the use of stone tools. In fact, bipedalism played a critical role in the development of these features of humanity. Bipedal locomotion freed the hands, allowing our ancestors to carry things for long distances and to make tools.

The earliest evidence currently available for a creature generally considered ancestral to humans is a fossil skull between 6 and 7 million years old found in the summer of 2002. This fossil, popularly called Toumai, is far older than any previously known (Brunet et al. 2002; Vignaud et

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al. 2002), and is unusual not only in its age but because it was found in Chad, 1,500 miles west of Africa’s Great Rift Valley, where almost all other extremely ancient human ancestor fossils have been found.

The earliest, most substantial evidence for human ancestors comes from the Awash River in northeastern Ethiopia. In the early and mid-1990s, teams of anthropologists led by Tim White of the University of California discovered the remains of more than 40 individuals who lived approximately 4.4 million years ago. They named these creatures Ardipithecus ramidus (White, Suwa, and Asfaw 1995). These ancestors had large jaws and small brains compared with modern humans. Many of their teeth and other aspects of their jaw shape were similar to those of modern-day chimpanzees. Despite this, evidence from their pelvic bones, skulls, and forelimbs indicate that they were bipedal. Reconstructions of the environment they lived in shows a flat plain covered with open woodland and dense forests. This suggests that these ancestors may have spent much of their time living in the trees (Wolde-Gabriel, White, and Suwa 1994).

The Australopithecines

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Perhaps the best known and best described of the early hominid fossils are the australopithecines. Beginning with Raymond Dart’s discovery of “Taung Child” in 1924 (described in the “Ethnography” section in this chapter), more than 10,000 individual australopithecine fossil bones have been found, comprising several hundred individuals. The earliest australopithecine fossils are from northern Kenya and are between 3.9 and 4.2 million years old. The most recent, from South Africa, are only about 1 million years old. Although australopithecines are found only in Africa, they were a diverse and complex group of creatures.

Of the many australopithecine finds, two are among the most famous in the history of anthropology. In 1974, at Hadar in Ethiopia, a team led by Donald Johanson found an australopithecine skeleton they dubbed “Lucy.” “Lucy” is unusually complete; more than 40 percent of her bones are present. With such a full skeleton, anthropologists were able to answer many questions about the way australopithecines looked, stood, and moved.

The second remarkable discovery was made by Mary Leakey, at Laetoli in Tanzania. In a well- preserved 3.5-million-year-old bed of volcanic ash, she and her team found two footprint trails clearly made by australopithecines. One of the trails was made by two individuals who were probably walking together. The second trail was made by three individuals; two of these were walking together and the third, a smaller individual, was walking in the footprints left by the larger of the first two.

Ethnography

Fossil Hunters

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Raymond A. Dart (1893–1988) was the discoverer of “Taungs Child” (sic), the first Australopithecus skull to be identified. Dart was trained in England and became a professor at University of the Witwatersrand in Johannesburg, South Africa. Living in what was then an academic backwater, Dart was isolated and frequently depressed. He taught anatomy, but partly to pursue his interest in anthropology and perhaps partly to relieve his boredom, he began to develop a fossil collection for the university. One way he did this was to ask his students to bring in any fossils they found. He offered a significant financial reward to whomever found the best fossil.

In early summer 1924, his only female student, Josephine Salmons, brought him the fossil skull of a baboon that had been found by a family friend in a mine at Taungs in Botswana. Although she did not win the prize (Dart had awarded it to another student earlier), Dart was thrilled by the fossil because no primate fossils had yet been discovered south of the Sahara in Africa.

Dart rushed to see a friend who had connections at the Taungs mines and learned that the mine manager, A. E. Spires, had a collection of fossils in his office. Spires, learning of Dart’s interest, had the fossils sent to him. They arrived during a wedding held at Dart’s house. Dart, dressing for the wedding, was unable to restrain himself. He tore off his fancy dress collar and ran out to take possession of the boxes of fossils. The first box yielded nothing very interesting, but when Dart opened the second box:

. . . A thrill of excitement shot through me. On the very top of the rock heap was what was undoubtably . . . the mold of the interior of [a] skull. Had it been only the fossilized brain cast of any species of ape it would have ranked as a great discovery, for such a thing had never before been reported. But I knew at a glance that what lay in my hands was no ordinary anthropoidal brain. Here in lime-consolidated sand was the [fossil] of a brain three times as large as that of a baboon and considerably bigger than that of any adult chimpanzee. (1996/1959:42)

It took Dart 73 days, chipping away at the rock with a small hammer and his wife’s knitting needles, to expose the full fossil. When he could view the fossil from the front, he wrote:

The creature which had contained this massive brain was no giant anthropoid such as a gorilla. What emerged was a baby’s face, an infant with a full set of milk teeth and its first permanent molars just in the process of erupting. I doubt if there was any parent prouder of his offspring than I was of my “Taungs baby” on that Christmas of 1924. (1996/1959:44)

Dart’s discovery came to be called “Taungs Child” (today, Taung Child is the more common usage). He gave it the scientific name Australopithecus africanus, and claimed that it was a human ancestor. His assertion, however, was met with ridicule by his colleagues in Europe who were deeply committed to the authenticity of the Piltdown Man fossils, which looked nothing like Taungs Child. Piltdown Man had been “found” by Charles Dawson between 1908 and 1912. It seemed to be half ape and half human and

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was widely regarded as the “missing link.” Piltdown, however, proved to be a fraud, and Dart lived to see his discovery vindicated.

Mary Leakey (1913–1996) was perhaps the greatest single fossil hunter of the 20th century. Among her numerous finds were the 1959 discovery of the australopithecine fossil “Zinjanthropus” and the “Laetoli footprints,” the fossilized footprints of two or three ancient hominids, probably Australopithecus africanus.

Leakey spent much of her childhood in the Dordogne in France, a region particularly rich in human prehistory. From an early age, she was fascinated by these archaeological treasures. Leakey audited courses in archaeology and geology at the University of London, but although she was to receive many honorary degrees later in life, she never earned a university diploma.

In 1933, friends introduced her to Louis Leakey. He was the son of missionaries and had grown up in Kenya. He studied at Cambridge University and had earned a PhD by 1930. Though he was married, with a child and a pregnant wife, Louis and Mary began an affair. In 1935, he returned to Africa, taking Mary with him (and leaving his wife in England). In 1936, he divorced his first wife and married Mary. Mary and Louis eventually had three children. Of these, Richard and his wife, Meave, became important fossil hunters.

Louis had hoped for a job in England, but the scandal surrounding his divorce and remarriage made this impossible. From the mid-1930s until the late 1950s, Louis and Mary searched East Africa for human ancestor fossils with little success. Although Mary found the first fossil skull of an extinct primate called Proconsul, as well as many tools and sites, a truly big find eluded them.

On July 17, 1959, the Leakeys were waiting for their friends Armand and Michaela Denis to arrive. The Denises were naturalists who, along with their cameraman Des Bartlett, made films for British television. The Leakeys had agreed to let them film their Olduvai excavations and had paused in their research to allow them time to come to the site. Louis was sick in bed, and Mary decided to take her two dogs for a walk over to a site they were not actively working. Mary Leakey later wrote:

There was indeed plenty of material lying on the eroded surface. . . . But one scrap of bone that caught and held my eye was not lying loose on the surface but projecting from beneath. It seemed to be part of a skull. . . . It had a hominid look, but the bones seemed enormously thick—too thick, surely. I carefully brushed away a little of the deposit, and then I could see parts of two large teeth in place in the upper jaw. They were hominid. It was a hominid skull, apparently in situ, and there was a lot of it there. I rushed back to camp to tell Louis, who leaped out of bed, and then we were soon back at the site looking at my find together. (Leakey and Leakey 1996/1984:47–48)

Mary had found Zinjanthropus, the first australopithecine found outside of South Africa. When the Leakeys’ naturalist friends and their cameraman arrived, it was the excavation of Zinjanthropus that they filmed.

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Finding Zinjanthropus made the Leakeys’ careers. Whereas before they had struggled along in obscurity with very limited funds, they soon found themselves international celebrities and the recipients of many grants. From the early 1960s to the early 1980s, Mary and Louis (who died in 1972) ran large and very successful projects at Olduvai and other African locations. Mary later wrote:

The reason why “Zinj” was so important to us was that he captured the public imagination. . . . If we had not had Des Bartlett and his film camera on the spot to record the discovery and excavation of the skull, this might have been much harder to achieve. Zinj made good television, and so a very wide public had the vicarious excitement of “being there when he was dug up.” (Leakey and Leakey 1996:48/1984)

Louis Leakey had the academic credentials, and was a charismatic speaker with an eagle eye for outstanding publicity opportunities. Thus, until his death, he was the public face of their projects. However, it was Mary and their children who made most of the fossil finds. Mary’s relationship with Louis was problematic; he had frequent affairs with other women and the couple grew apart. Looking back on their lives, it is clear that Mary was not only the better fossil finder but, despite her lack of an earned degree, her meticulous work and caution probably made her the better scientist as well.

Source: Excerpts from Brian M. Fagan, Quest for the Past: Great Discoveries in Archaeology, 2nd ed. Long Grove, IL: Waveland Press, Inc., 1994. All rights reserved.

The plethora of fossil finds reveals a great deal about the australopithecines and their lifestyles. The australopithecines of Hadar and Laetoli are called “gracile” australopithecines because they are generally small, light, and slender. They were a varied group, standing between 3.5 and 5 feet tall and weighing between 65 and 100 pounds (McHenry 1992). Their brains, at between 400 and 500 cubic centimeters, were only about one-third the size of modern human