The Origin of Humankind
Richard Leakey

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The Origin of Humankind



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The Origin of Humankind

Copyright © 1994 by Sherma, B. V.

Chapter I
The First Humans

Anthropologists disliked Darwin’s suggestion intensely, not least because tropical Africa was regarded with colonial disdain: the Dark Continent was not viewed as a fit place for the origin of so noble a creature as Homo sapiens. When additional human fossils began to be discovered in Europe and in Asia at the turn of the century, yet more scorn was heaped on the idea of an African origin. This attitude prevailed for decades. [...] The vehemence of anthropologists’ anti-Africa sentiment now seems quaint to us, given the vast numbers of early human fossils that have been recovered in that continent in recent years. The episode is also a reminder that scientists are often guided as much by emotion as by reason.



Scientists such as Wallace and Broom were struggling with conflicting forces, one intellectual, the other emotional. They accepted the fact that Homo sapiens derived ultimately from nature through the process of evolution, but their belief in the essential spirituality, or transcendent essence, of humanity led them to construct explanations for evolution which maintained human distinctiveness. The evolutionary “package” embodied in Darwin’s 1871 description of human origins offered such a rationalization. Although Darwin did not invoke supernatural intervention, his evolutionary scenario made humans distinct from mere apes right from the beginning.

Darwin’s argument remained influential until a little more than a decade ago, and was effectively responsible for a major dispute over when humans first appeared.



The Ramapithecus affair changed anthropology in two ways. First, it demonstrated the perils of inferring a shared evolutionary relationship from shared anatomical features. Second, it exposed the folly of a slavish adherence to the Darwinian “package.” Simons and Pilbeam had imputed a complete lifestyle to Ramapithecus, based on the shape of the canine teeth: if one hominid feature was there, all such features were assumed to be present.

It is interesting that as each new hypothesis gained popularity, it often reflected something of the social climate of the time. For instance, Darwin saw the elaboration of stone weapons as important in initiating the evolutionary package of technology, bipedalism, and expanded brain size. The hypothesis surely reflected the prevailing notion that life was a battle and progress was won by initiative and effort. This Victorian ethos permeated science, and shaped the way the process of evolution, including human evolution, was viewed.

In the early decades of this century, the heyday of Edwardian optimism, the brain and its higher thoughts were said to have made us what we are. Within anthropology, this prevailing social worldview was expressed in the notion that human evolution had been propelled initially not by bipedalism but by an expanding brain. By the 1940s, the world was in thrall to the magic and power of technology, and the “Man the Toolmaker” hypothesis became popular. [...] And when the world was in the shadow of the Second World War, a darker differentiation of humans from apes was emphasized—that of violence against one’s fellows. The notion of “Man the Killer Ape,” first proposed by the Australian anatomist Raymond Dart, gained wide adherence, possibly because it seemed to explain (or even excuse) the horrible events of the war.

Later, in the 1960s, anthropologists turned to the hunter-gatherer way of life as the key to human origins.

This is not to say that the first bipedal ape species possessed a degree of technology, increased intellect, or any of the cultural attributes of humanity. It didn’t. My point is that the adoption of bipedalism was so loaded with evolutionary potential—allowing the upper limbs to be free to become manipulative implements one day—that its importance should be recognized in our nomenclature. These humans were not like us, but without the bipedal adaptation they couldn’t have become like us.
Chapter 2
A Crowded Family

We know from the size of various bones of the skeleton that the males of the australopithecine species were much bigger than the females. They stood more than 5 feet tall, while their mates barely achieved 4 feet. The males must have weighed almost twice as much as the females, a difference of the sort that we see today in some species of savanna baboons. It’s a fair guess, therefore, that the social organization of australopithecines was similar to that of baboons, with dominant males competing for access to mature females [...]

At a meeting of anthropologists in April 1994, Fred Spoor, of the University of Liverpool, described the semicircular canals in humans and apes. The two vertical canals are significantly enlarged in humans compared with those in apes, a difference Spoor interprets as an adaptation to the extra demands of upright balance in a bipedal species. What of early human species?

Spoor’s observations are truly startling. In all species of the genus Homo, the inner ear structure is indistinguishable from that of modern humans. Similarly, in all species of Australopithecus, the semicircular canals look like those of apes. Does this mean that the australopithecines moved about as apes do—that is, quadrupedally? The structure of the pelvis and lower limbs speaks against this conclusion. So does a remarkable discovery my mother made in 1976: a trail of very humanlike footprints made in a layer of volcanic ash some 3.75 million years ago. Nevertheless, if the structure of the inner ear is at all indicative of habitual posture and mode of locomotion, it suggests that the australopithecines were not just like you and me [...]

For the first time in human prehistory, there is evidence that the toolmakers had a mental template of what they wanted to produce—that they were intentionally imposing its shape on the raw material they used. The implement that suggests this is the so-called handaxe, a teardrop-shaped tool that required remarkable skill and patience to make [...]

The appearance of the handaxe in the archaeological record follows the emergence of Homo erectus, the putative descendant of Homo habilis and ancestor of Homo sapiens.



The australopithecine species and Homo clearly had different specific adaptations, and it is likely that meat eating by Homo was an important part of that difference. Stone toolmaking would have been an important part of a meat eater’s abilities; plant eaters could do without these tools.

In his studies of tools from archeological sites in Kenya, and in his experimental toolmaking exercises, Toth made a fascinating and important discovery. The earliest toolmakers were predominantly right-handed, just as modern humans are. Although individual apes are preferentially right- or left-handed, there is no population preference; modern humans are unique in this respect.

Chapter 3
A Different Kind of Human

Growing children learn better from adults if there is a significant difference in body size, because a student-teacher relationship can be established. If young children were the size they would be on an apelike growth trajectory, physical rivalry rather than a student-teacher relationship might develop. When the learning period is over, the body “catches up,” by means of the adolescent growth spurt.

Humans become human through intense learning not just of survival skills but of customs and social mores, kinship and social laws—that is, culture. [...] Culture can be said to be the human adaptation, and it is made possible by the unusual pattern of childhood and maturation.

The helplessness of newborn human infants is, however, less a cultural adaptation than a biological necessity. Human infants come into the world too early, a consequence of our large brain and the engineering constraints of the human pelvis. [...] A simple calculation based on comparisons with other primates reveals that gestation length in Homo sapiens, whose average brain capacity is 1350 cubic centimeters, should be twenty-one months, not the nine months it actually is. Human infants therefore have a year’s growth to catch up on when they are born, hence their helplessness.



As every biologist knows, brains are metabolically expensive organs. In modern humans, for example, the brain constitutes a mere 2 percent of body weight, yet consumes 20 percent of the energy budget. [...] Only by adding a significant proportion of meat to its diet could early Homo have “afforded” to build a brain beyond australopithecine size.

For all these reasons, I suggest that the major adaptation in the evolutionary package of early Homo was significant meat eating.

Bipedal apes were able to roam more terrain as they foraged for widespread sources of food in open woodland. With the evolution of Homo, a new form of locomotion emerged, still built on bipedalism but with greater agility and activity. [...] The efficient, striding biped represented a central change in hominid adaptation. And that change surely involved some degree of active hunting, as we shall see in the next chapter.

The ability of an active animal to dissipate heat is especially important for the physiology of the brain, a point emphasized by the anthropologist Dean Falk [...] she demonstrated that the structure of the vessels that drain blood from the Homo brain is conducive to efficient cooling, while in australopithecines it is much less so.

Chapter 4
Man the Noble Hunter?

The combination of hunting meat and gathering plant foods is unique to humans as a systematic subsistence strategy. It is also spectacularly successful, having enabled humanity to thrive in virtually every corner of the globe, with the exception of Antarctica.

To Westerners, the eking out of an existence from the natural resources of the environment by means of the simplest of technologies seems a daunting challenge. In reality, it is an extremely efficient mode of subsistence, so that foragers can often collect in three or four hours sufficient food for the day.

Other lines of evidence, however, have been adduced to imply scavenging as the mode of meat acquisition in early Homo. For instance, Shipman examined the distribution of cut marks on ancient bones and made two observations. First, only about half were indicative of dismemberment; second, many were on bones that bore little meat. Furthermore, a high proportion of cut marks crossed over marks left by carnivore teeth, implying the carnivores go to the bones before the hominids did. [...]

[...] But I suspect that the recent intellectual revolution in archeology has gone too far, as often happens in science. The rejection of hunting in early Homo has been too assiduous. I find it significant that Shipman’s analysis of the distribution of cut marks shows so many on bones with little meat. What can be obtained here? Tendons and skin. With these materials it is very easy to make effective snares for catching quite large prey.

Chapter 5
The Origin of Modern Humans

If we look back into history beyond the origin of writing, some 6000 years ago, we can still see evidence of the modern human mind at work. Beginning about 10,000 years ago, nomadic bands of hunter-gatherers throughout the world independently invented various agricultural techniques. This, too, was the consequence of cultural or technological, not biological, evolution. Go back beyond that time of social and economic transformation and you find the paintings, engravings, and carvings of Ice Age Europe and of Africa, which evoke the mental worlds of people like us. Go back beyond this, however—beyond about 35,000 years ago—and these beacons of the modern human mind gutter out. No longer can we see in the archeological record cogent evidence of the work of people with mental capacities like our own.

For a long time, anthropologists believed that the sudden appearance of artistic expression and finely crafted technology in the archeological record some 35,000 years ago was a clear signal of the evolution of modern humans. The British anthropologist Kenneth Oakley was among the first to suggest, in 1951, that this efflorescence of modern human behavior was associated with the first appearance of fully modern language.

The two models could hardly be more different: the multiregional-evolution model describes an evolutionary trend throughout the Old World toward modern Homo sapiens, with little population migration and no population replacement, whereas the “Out of Africa” model calls for the evolution of Homo sapiens in one location only, followed by extensive population migration across the Old World, resulting in the replacement of existing premodern populations.

Chapter 6
The Language of Art
The ancient images we have today are fragments of an ancient story, and although the urge to know what they mean is great, it is wise to accept the probable limits of our understanding. Moreover, there has been a strong, and probably inevitable, Western bias in the perception of prehistoric art. One consequence has been a lack of attention to prehistoric art of equal and sometimes greater antiquity in eastern and southern Africa. Another has been to view the art in the Western way: as though it consisted of pictures hung on a museum wall, as objects simply to view.



Known as the Unicorn, the creature may be meant as a human disguised as an animal or may be a chimera. Many such drawings are sufficient to convince us that we are seeing images greatly mediated by cognitive reflection.

An obvious problem with the hunting-magic hypothesis was that the images depicted very often did not, as noted, reflect the diet of the Upper Paleolithic painters. The French anthropologist Claude Léve-Strauss once noted that in the art of the Kalahari San and the Australian aborigines certain animals were depicted most frequently not because they were “good to eat” but because they were “good to think.”

Using notes spanning three octaves, they drew up a resonance map of each cave and discovered that those areas with highest resonance were also those most likely to harbor a painting or engraving. In their report, which they published at the end of 1988, Reznikoff and Dauvois commented on the stunning impact of cave resonance, an experience that would have surely been enhanced in the flickering light of simple lamps back in the Ice Age.

It requires little imagination to think of Upper Paleolithic people chanting incantations in front of cave paintings. The unusual nature of the images, and the fact that they are often deep in the most inaccessible parts of caves, begs the suggestion of ritual.



Chapter 7
The Art of Language

Anthropologists can be certain of only two issues relating to language, one direct, the other indirect. First, spoken language clearly differentiates Homo sapiens from all other creatures. None but humankind produces a complex spoken language, a medium for communication and a medium for introspective reflection. Second, the brain of Homo sapiens is three times the size of the brain of our nearest evolutionary relatives, the African great apes. There is certain to be a relationship between these two observations, but its nature is fiercely debated.

To Chomskians, who represent the majority of linguists, there is little utility in looking for evidence of language capacity early in the human record, and still less in seeking it in our simian cousins. As a result, tremendous antagonism has been expressed toward those who try to teach apes some form of symbolic communication, usually via a computer device and arbitrary lexigrams. One of the themes of this book is the philosophical divide between those who see humans as special and separate from the rest of nature and those who accept a close link. Nowhere does this emerge more passionately than in the debate on the nature and origin of language. The vitriol hurled by linguists at ape-language researchers undoubtedly reflects this divide.

[...] As a result of this thinking, anthropological literature has long been littered with behaviors that were considered unique to humans. These include toolmaking, the ability to use symbols, mirror recognition, and, of course, language. Since the 1960s, this wall of uniqueness has steadily crumbled, with the discovery that apes can make and use tools, use symbols, and recognize themselves as individuals in a mirror. Only spoken language remains intact, so that linguists are effectively the last defenders of human uniqueness. They appear to take their job seriously.



Ralph Holloway examined the shape of the brain of skull 1470, a fine example of Homo habilis found east of Lake Turkana in 1972 and determined to be almost 2 million years old [...] He detected not only the presence of Broca’s area, impressed on the inner surface of the cranium, but also a slight assymetry in the left-right configuration of the brain, an indication that Homo habilis communicated with more than the pant-hoot-grunt repertoire of modern chimpanzees.

Humans are able to make a wide range of sounds because the larynx is situated low in the throat, thus creating a large sound-chamber, the pharynx, above the vocal cords. [...] In all mammals except humans the larynx is high in the throat, which allows the animal to breathe and drink at the same time. As a corollary, the small pharyngeal cavity limits the range of sounds that can be produced. Most mammals therefore depend on the shape of the oral cavity and lips to modify the sounds produced in the larynx. Although the low position of the larynx allows humans to produce a great range of sounds, it also means that we cannot drink and breathe simultaneously. We exhibit the dubious liability for choking.

Human babies are born with the larynx high in the throat, like typical mammals, and can simultaneously breathe and drink, as they must during nursing.

Chapter 8
The Origin of Mind

Three major revolutions mark the history of life on earth. The first was the origin of life itself, sometime prior to 3.5 billion years ago. Life, in the form of microorganisms, became a powerful force in a world where previously only chemistry and physics had operated. The second revolution was the origin of multicellular organisms, about half a billion years ago. Life became complex, as plants and animals of myriad forms and sizes evolved and interacted in fertile ecosystems. The origin of human consciousness, some time within the last 2.5 million years, was the third event. Life became aware of itself, and began to transform the world of nature to its own ends.

The world we perceive as individuals is essentially of our own making, governed by our own experience. Similarly, the world we perceive as a species is governed by the nature of the sensory channels we possess. Any dog owner knows that there is a world of olfactory experience to which the canine but not the human is privy. Butterflies are able to see ultraviolet light; we are not. The world inside our heads—whether we are a Homo sapiens, a dog, or a butterfly—is formed, therefore, by the qualitative nature of the information flow from the outside world to the inside world, and the inside world’s ability to process the information. There is a difference between the real world, “out there,” and the one perceived in the mind, “in here.”

There is a large literature, in philosophy and psychology, relating to the issue of whether thought depends on language or language on thought. There’s no question that a lot, perhaps most, of human cognitive processes go on in the absence of language or even consciousness. Any physical activity, such as playing tennis, goes on largely automatically—that is, without a literal running commentary on what to do next. The solution to a problem that pops into the mind while one is thinking of something else is another clear example. To some psychologists, spoken language is merely an afterthought, so to speak, of more fundamental cognition. But language surely shapes elements of thought in a way that a mute mind cannot [...]

Either natural selection has been profligate in making primates—including humans—smarter than they really need to be, or their daily life is more intellectually demanding than it appears to the outside observer. Humphrey came to believe that the second of these alternatives is correct: specifically, that the social nexus of primate life presents a sharp intellectual challenge. The primary role of creative intellect, he suggests, is “to keep society together.”



The challenge for individuals in primate societies is to be able to predict the behavior of others. [...] If, for example, individuals were able to monitor their own behavior, rather than merely operate as computerlike automatons, then they would develop a heuristic sense of what to do under certain circumstances. By extrapolation, they might then be able to predict the behavior of others under the same circumstances. This monitoring ability, which Humphrey calls an Inner Eye, is one definition of consciousness, and it would confer considerable evolutionary advantage in those individuals that possessed it.

Compare to:

Richard Dawkins

text checked (see note) Nov 2009

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