We can see, that in the rudest state of society, the individuals who were the most sagacious, who invented and used the best weapons or traps, and who were best able to defend themselves, would rear the greatest number of offspring. The tribes, which included the largest number of men thus endowed, would increase in number and supplant other tribes. . . . As a tribe increases and is victorious, it is often still further increased by the absorption of other tribes. The stature and strength of the men of a tribe are likewise of some importance for its success, and these depend in part on the nature and amount of the food which can be obtained. All that we know about savages, or may infer from their traditions and from old monuments, the history of which is quite forgotten by the present inhabitants, show that from the remotest times successful tribes have supplanted other tribes.

WITH THE DEVELOPMENT OF LANGUAGE, the process of human evolution in Africa reached a decisive stage. After 5 million years, the human lineage that split off from apes had emerged into a people quite similar in their form and faculties to those who live today.

This people, which can be called the ancestral human population, was probably the first to have possessed fully modern speech, and the last from which all people on earth are descended. Since it dispersed so quickly after its formation, it may have endured for only a few thousand years.

Not only did the ancestral population probably have a fleeting existence, it seems to have survived by the narrowest of margins. It lived sometime between 50,000 and 100,000 years ago, probably nearer to the 50,000-year mark. Between 60,000 and 40,000 years ago much of Africa was depopulated, and only in East Africa can archaeologists detect a human presence.⁶³ The reason may have been a long period of dry climate that shrank the forests and dried out the savannas. The ancestral population itself, geneticists estimate, shrank to as few as 5,000 people.

From this village-sized population, the world was peopled. And since people in societies around the world behave in much the same way, the principal elements of human nature must already have been present in the ancestral human population before its dispersal into Africa and the world beyond.

It would be of the greatest interest to know everything about the ancestral human population—its way of life, its social structure, the roles of men and women, its religion, the language that its members spoke. Not a trace of these first people has yet been found by archaeologists. Yet despite the total lack of direct evidence, a surprising amount can now be inferred about the ancestral human population.

Geneticists can estimate how large the population was and, by identifying its closest descendants, can point to where in Africa the ancestral population may have lived. They can even say something about the language the ancestral people spoke. And by analyzing the behaviors common to societies around the world, particularly the hunter-gatherers who seem closest to the ancestral people, anthropologists can describe how the ancestral population probably lived and what its people were like.

The Genealogies of Eve and Adam

Because everyone in the world is descended from the ancestral population, geneticists can infer some of its properties by analyzing the DNA of living people, and then working backward.

Two parts of the human genome are particularly useful for this purpose. One is the Y chromosome, the only chromosome possessed by men alone. The other is known as mitochondrial DNA. These are the only two parts of the genome that escape the shuffling of genetic material between generations. The shuffling, an evolutionary mechanism for generating diversity rapidly at each generation, means that almost all other parts of the human genome have a pedigree that is at present too complex to untangle. ^d

Unlike most pairs of chromosomes, the X and Y do not exchange segments of DNA between generations (except at their very tips). This is to ensure that the Y’s most important gene, the one that makes a person male, never gets shuffled into the X chromosome. The Y chromosome is therefore passed down essentially unchanged from father to son, generation after generation. Mitochondrial DNA escapes shuffling through a different process. Mitochondria, cellular components that generate chemical energy, are former bacteria that were enslaved long ago by animal cells. They live in the main body of the cell, outside the nucleus that holds the chromosomes. When the sperm fuses with the egg, all the sperm’s mitochondria are destroyed, leaving the fertilized egg equipped with only the mother’s mitochondria. Because of this arrangement, mitochondria are bequeathed unchanged from mother to child (and a man’s mitochondria are not passed on to his children).⁶⁴

In addition to their exempt status, the Y chromosome and mitochondrial DNA each have a special and surprising property of uniqueness. All men in the world today carry the same Y chromosome, and both men and women carry the same mitochondria. All of today’s Y chromosomes were in herited from the same, single source, a Y chromosome carried by an individual male who belonged to, or lived slightly before, the ancestral human population. The same is true of mitochondrial DNA; everyone carries the same mitochondrial DNA because all are copies of the same original, the mitochondrial DNA belonging to a single woman.

The metaphor is hard to avoid—this is Adam’s Y chromosome, and Eve’s mitochondrial DNA. The ancestral human population, of course, included many Adams and Eves, indeed about 2,500 of each if the geneticists’ calculations are to be believed. So how did it come about that just one man bequeathed his Y chromosome to the whole world and one woman her mitochondria?

It’s a curious fact of genetics that one version of a gene, especially in small populations, can displace all the other existing versions of the same gene in just a few generations, through a purely random process called genetic drift. Consider how this might work among surnames, which are passed on from father to son just like Y chromosomes. Suppose a hundred families are living on an island, each with a different surname. In the first generation, many of those families will have only daughters or no children at all. So in just one generation, all those families’ surnames (and accompanying Y chromosomes) will go extinct. Assuming no new male settlers arrive on the island, the same unavoidable winnowing will happen each generation until only one surname (and Y chromosome) is left.

This is what has happened with the human Y chromosome. Every Y chromosome that exists today is a copy of the same original, carried by a single individual in the ancestral human population. The Y chromosomes of all the other Adams have perished at some point along the way when their owners had no sons.

But despite all being copies of the same original, Y chromosomes are not identical. Over the generations, mutations—the switch of one of the four kinds of DNA units for another—have built up on the Y. The mutations are harmless but serve the invaluable purpose for geneticists of assigning the owners of Y chromosomes to different male lineages. The reason is that once a man has acquired a novel mutation in his Y chromosome, all his sons will carry that mutation, and no one else will. If one of the sons has a second mutation, all of his descendants will carry the two mutations. Each new muta tion thus creates a fork on the family tree—between those who carry it and those who don’t—and stands at the head of all the lineages beneath it.

FIGURE 4.1. THE UNIVERSAL HUMAN Y CHROMOSOME.

Only men carryaYchromosome. In each generation, some men have no children or only daughters, reducing the number of Y chromosomes in the population, until only one remains. This is why all men in the world carry a Y chromosome inherited from a single individual—the Adam of the Y chromosome—who lived in the ancestral human population. The same is true of mitochondrial DNA and the mitochondrial Eve.

By looking at the most informative of the mutations on the Y chromosome, geneticists can assign every man to one lineage or another. Since there is only one Y chromosome, all these lineages or branches eventually coalesce to a single trunk, the Y chromosome of the original “Adam.”

Mutations get incorporated into the Y chromosome at a fairly steady rate, which enables geneticists to put a date on each branch point by counting the number of mutations down a lineage. And the lineages can be assigned not only a date but a geographical location. This is because human populations were expanding across the globe at the time the mutations of interest occurred but then, to a remarkable extent, people lived and bred in the same place they were born. So geneticists can impose the Y chromosome tree across the map of the world, assigning each of its forks and lineages to specific geographical regions.

Of particular help in defining the ancestral human population is the lineage of men that left Africa. A few men inside Africa, and all men outside it, carry a Y chromosome mutation known as M168. This means that modern humans left Africa sometime shortly after the M168 mutation occurred. Based on the mutation-counting method, one recent estimate is that M168 occurred 44,000 years ago.⁶⁵ Genetic dates, however, generally come with a wide range of possible error. This one, say Peter Underhill and colleagues at Stanford University, could range anywhere between 39,000 and 89,000 years ago. The root of the Y chromosome tree dates to 59,000 years ago, though this too has a wide range of possibilities, from 40,000 to 140,000 years ago. Still, a date around 59,000 years ago seems a reasonable estimate for the time when the Y chromosomal Adam walked the earth. This date fits well with a date of 50,000 years ago for the ancestral human population, because genes tend to have slightly deeper ancestries than do populations.

Estimating the Ancestral Population Size

The Y chromosome is just a small part of the human genome. But it seems likely to represent human population history well enough, not least because its story is corroborated by mitochondrial DNA. Mitochondrial DNA can be used to construct genealogies of women just as the Y chromosome generates lineages of men.

FIGURE 4.2. THE Y CHROMOSOME FAMILY TREE
AND ITS GEOGRAPHICAL DISTRIBUTION.

Although all men carry the same Y chromosome, mutations have gradually built up on it. The mutations allow men to be assigned to different lineages, depending on which set of mutations they carry. Because the mutations accumulated while the ancestral people were spreading through the world, different lineages of men are found in different regions of the world.

All male lineages outside sub-Saharan Africa carry the Y chromosome mutation known as M168. Men who carry the M173 mutation may have been the first modern humans to enter Europe 45,000 years ago, founding what archaeologists call the Aurignacian culture. Bearers of M170 are thought to have brought the Gravettian culture that succeeded the Aurignacian 28,000 years ago. The M242 mutation occurred just before the first humans crossed the Bering land bridge from Siberia to the Americas.

The women’s lineages, like the men’s, have all turned out to be branches from a single root, the mitochondrial DNA possessed by a single woman who lived in or before the ancestral human population. The mitochondrial Eve appears to have lived considerably earlier than the Y chromosomal Adam—about 150,000 years ago—but that may reflect the difficulty of dating mitochondrial DNA, which gathers mutations more rapidly than does the Y chromosome.

The mitochondrial genealogy of humankind has three main branches, known as L1, L2 and L3. L1 and L2 are confined to Africans who live south of the Sahara. The L3 branch gave rise to a lineage known as M, and it was the descendants of M who left Africa.

The Y and mitochondrial data can be made to yield another vital piece of information—the “effective” size of the ancestral population. The effective population is a statistical concept inferred by population geneticists from the amount of variation seen in samples of DNA. It is a large fraction of the real population size—for humans, often considered to be about half.⁶⁶ The effective size of the ancestral human population has long been estimated to have been around 10,000 individuals, but recent calculations, which mitigate a confounding factor in the earlier estimates, suggest the actual number may have been even smaller. An estimate based on the Y chromosome suggests an effective population size of just 1,000 men of reproductive age.⁶⁷ Assuming the same number of women, this implies an “effective population” of 2,000, which is equivalent to a census-size population of a mere 4,000 individuals, or say 5,000 in round numbers.

The first two branches of the Y chromosome genealogy, whose bearers are found only in Africa, have many sub-branches. This suggests the ancestral human population soon became quite spread out and diverse. There are other hints in the pattern of mutation that many Y chromosome lineages that once existed are now extinct. The ancestral population, in other words, may have suffered several calamities with widespread loss of male life.⁶⁸

Because foragers lived in groups, generally of 150 people or so who may have liked to trade with neighboring groups, a population as small as 4,000 or 5,000 people is unlikely to have been distributed over the whole continent of Africa. It would probably have had a much smaller range—“perhaps the size of Swaziland or Rhode Island” according to one estimate.⁶⁹ The smaller the area, the more possible that at one time a single language was spoken. Archaeologists have not yet located this ancestral homeland. Given that its inhabitants would have been hunters and gatherers, they may have left little sign of their presence.

FIGURE 4.3. THE MITOCHONDRIAL DNA FAMILY TREE
AND ITS GEOGRAPHICAL DISTRIBUTION.

All men and women carry the same mitochondrial DNA, derived from a mitochondrial Eve. Like the Y chromosome, this single version of mitochondrial DNA has over time collected mutations which can be used to assign women to lineages (mitochondrial DNA is inherited only through the female line).

All women in sub-Saharan Africa belong to one of the first three branches of the mitochondrial DNA tree, known as L1, L2 and L3. All women outside Africa belong to M or N, the two daughter lineages of L3. Women in the western part of the Eurasian continent are all daughters of N; those of the eastern part descend from M or N. The daughter lineages A, B, C, D and X reached the Americas.

But geneticists have figured out where in Africa this ancient homeland may have been located. The clues lie not just in genes but also in tongues, specifically the click languages of Africa and the San people who speak them.

The Click Language Echo from the Mother Tongue

The Dutch settlers who first arrived in southern Africa in 1652 found the country inhabited by two groups of click language speakers—cattle herders, whom they called Hottentots, and foraging peoples whom they referred to as either bushmen or San, a Hottentot word for “original settlers.” The Hottentots called themselves Khoi-Khoi but are now known as Khwe. From these two words, Khoi and San, is derived the word Khoisan, which is used to describe the linguistic family of click languages.

The southern San of the Cape were largely driven to extinction by the Dutch settlers. Anthropologists have studied the northern San, who live in a large area from southern Angola to Botswana that includes the Kalahari desert. Until the 1970s, when settlement became widespread, many of the San lived as hunters and gatherers, one of the few remaining peoples to follow this ancient way of life. The main language of the northern San is !Kung, a name that seems to have been invented by German missionaries and means “they” in the Angola !Kung dialect.⁷⁰ These northern San are often referred to as the !Kung or the !Kung San. The “!” represents one of the many click sounds in their language.

To add to the confusion, anthropologists have recently started to refer to the !Kung San by their name for themselves, the Ju|’hoansi, which means “the Real People.” The Real People’s name for both Europeans and non-San Africans is !ohm, a category that includes predators and other inedible beasts.

The “|” in Ju|’hoansi designates one of the click sounds that are used as extra consonants in click languages. There are 5 kinds of click made by sucking air in, and a larger number made by expelling it. The “|” is an in-coming dental click, made by sucking the tongue in smartly from the upper front teeth, like the “tsk, tsk” sound used to indicate disapproval to children. The sound systems of Khoisan are said to be among the most complex in the world.⁷¹

About 30 different click languages are still spoken in southern Africa. They fall into three groups that, apart from their clicks, bear little evident relationship to each other. Speakers of another two click languages, known as Hadza and Sandawe, live far away in Tanzania. Hadza and Sandawe are both isolates, meaning they have no known relationship to each other or to the !Kung language of the San.

Despite the fact that many of the click languages apparently have nothing in common save their clicks, Joseph Greenberg, the great classifier of the world’s languages, assigned them all to a single family, known as Khoisan. Linguists grumbled that it was illogical to define a group of unrelated languages as a family, but went along with the idea because no one knew what else to do with the click languages. Greenberg is at present reviled by most historical linguists, but his classification of the Khoisan languages seems a stroke of genius in light of a surprising new link that has now emerged among them.

The link is the finding from genetics that the Hadza speakers and the !Kung are two of the most ancient populations in the world. All peoples are of course the same age in the sense that everyone is descended from the ancestral human population. But some populations are viewed as older than others because they lie on longer branches of the human family tree. In a recent survey of African populations, Douglas Wallace of the University of California at Irvine found that three of the most ancient peoples in the world were the Biaka pygmies of the Central African Republic, the Mbuti pygmies of the Congo, and the !Kung San.

The !Kung possess several lineages of mitochondrial DNA, Wallace and his colleagues found, but their principal lineage forms the first branch of L1, the oldest of the three divisions of the human mitochondrial tree. This lineage, Wallace notes, “is positioned at the deepest root of the African phylogenetic tree, suggesting that the !Kung San became differentiated very early during human radiation.”⁷² In other words, the !Kung San split off from the ancestral population at an early date, and have remained a reasonably distinct population ever since.

Two Stanford researchers, Alec Knight and Joanna Mountain, recently compared the genetics of the !Kung with that of the Hadzabe, as the speakers of Hadza click language are known, a foraging people who live near Lake Eyasi in Tanzania. They discovered that the Hadzabe too are an extremely ancient people. However, the Hadzabe belong not to the L1 division of the mitochondrial DNA tree but to L2. Because L2 and L1 mark two of the first forks in the tree, the !Kung of L1 and the Hadzabe of L2 are two populations that separated almost at the dawn of human time. The split between the ancestors of the two groups “appears to be among the earliest of human population divergences,” the Stanford researchers say. Based on measurements of their Y chromosomes, the two populations are more distant from each other than any other known pair of African populations.⁷³

This genetic discovery provided a plausible reason why the two click languages, !Kung and Hadza, are also so different. Because the two peoples have been separate for so long, both their genetics have become very different and their languages have lost any resemblance to each other, save for the clicks.

The !Kung and the Hadzabe are both hunter-gatherers, and their nomadic lifestyle in the wilderness may explain how they have preserved their isolation from other groups for millennia. But that leaves the puzzle of why, when everything else in their language has changed, they have still retained the clicks.

Some linguists see this as a case of independent invention. They argue that there is nothing special about clicks, since a child can learn them, and that click sounds may have been lost and reinvented many times in language history just like the other features of language.

But on that theory clicks should be used in languages all over the world. In fact they are spoken only in Africa, with the exception of Damin, an extinct Australian language, of limited vocabulary, used for ceremonial purposes by the men of the Lardil tribe of Queensland. Clicks do not seem to have spread beyond their original speakers, with the exception that some click sounds have been borrowed by the San’s Bantu-speaking neighbors. They are used for special purposes, such as in hlonipha, a respect language practiced by Nguni women to avoid the syllables of their in-laws’ names; one way to avoid these taboo syllables is to substitute a click for one the consonants.

Though speakers of non-San languages may occasionally borrow or invent clicks, Anthony Traill, a click language expert at the University of Wit watersrand in South Africa, believes that “it is highly improbable that a fully fledged click system could arise from non-click precursors.”⁷⁴ One reason is the difficulty of attaining fluency with multiple clicks. A single click is easy enough, but rattling off a whole series is another matter. Like double consonants, clicks are easy to stumble over. “Fluent articulation of clicks in running speech is by any measure difficult. It requires more articulatory work, like taking two stairs at a time,” Traill says.

Another reason is that clicks seem easier to lose than to gain. In the ordinary process of language change, certain kinds of click can be replaced by non-click consonants, but Traill has never seen the reverse occur.

Given the laziness of the human tongue, why have clicks been retained by click speakers? “That is a major problem,” Traill says. “All the expectations would be that they would have succumbed to the pressures of change that affect all languages. I do not know the answer.”

If clicks are generally only lost, not invented, and if two of the oldest known populations in the world, the Hadzabe and the !Kung San, speak click languages, then it’s possible that clicks were part of the first language spoken by the ancestral human population. “The divergence of those genetic lineages is among the oldest on earth,” says Knight, the anthropologist on the Stanford team. “So one could certainly make the inference that clicks were present in the mother tongue.”

Tracing the Boundaries of Eden

Since the San, on the basis of both genetics and language, seem to be among the earliest human populations, it’s of considerable interest that they once occupied a much larger area of Africa than they do today. In the seventeenth century they inhabited all of southern Africa. Archaeologists believe that much earlier, in Paleolithic times, the San occupied the eastern half of Africa, with their domain stretching up through Ethiopia to the northern tip of the Red Sea.

In support of the archaeologists’ view, geneticists have found that the DNA of Ethiopians living today retains evidence of the San’s ancient presence in their country. Men of the Oromo and Amhara peoples have a small proportion of Y chromosomes that belong to the first branch of the Y chromosome family tree. This branch is rare elsewhere in Africa except among the San, 44% of whom carry it. The Oromo and Amhara must share an ancestral paternity with the San, and the first branch must have been “part of the proto-African Y-chromosome gene pool,” writes Ornella Semino of the University of Pavia in Italy.⁷⁵ The mitochondrial DNA from women of the Oromo and Amhara peoples also indicates that Ethiopia, or at least east Africa, is the place from which the first modern humans left Africa.

Three major events in modern human evolution—the perfection of language, the formation of the ancestral human population and the exit from Africa—seem to have happened quite close to each other in time, around 50,000 years ago. The closer in time, the more likely that they happened in the same place and if so, Ethiopia seems at present the best candidate for being the birthplace of modern humans, the real world’s counterpart of Eden’s mythical garden.

Between the Universal People and the Real People

What were the people of the ancestral human population really like? Archaeologists describe them as “behaviorally modern humans,” in contrast with the anatomically modern humans who first evolved nearly 200,000 years ago. But the term “behaviorally modern” refers to people whose traces in the archaeological record are not appreciably different from those left by contemporary hunter-gatherers. Foraging people of very different natures could leave much the same archaeological record.

It seems unlikely that the ancestral people closely resembled contemporary populations in behavior. The human skull and frame were then much heavier than those of people alive today, suggesting that the ancestral human population was physically aggressive, more accustomed to violence and warfare. Its members did not settle or build, perhaps because the social adaptations required for settled life were not yet part of their behavioral equipment. If fully modern language had evolved only recently, it is unlikely that all the other elements of contemporary social behavior emerged simultaneously with it. More probably they fell into place one by one as part of the continuing evolution of human behavior.

Yet the ancestral population, even if generally more inclined to aggression, presumably possessed all the major elements of human behavior that occur in its descendant populations around the world, since otherwise all of these behaviors would have had to evolve or be invented independently in each of thousands of societies.

There are two ways of developing a portrait of the ancestral human population; one is through the Universal People, the other through the Real People.

The Universal People is a concept of the anthropologist Donald Brown, who devised it as a counterpart to Chomsky’s Universal Grammar. Though most anthropologists emphasize the particularity of the societies they study, Brown is interested in the many aspects of human behavior that are found in societies around the world. These universal human behaviors range from cooking, dance and divination to fear of snakes. Many, such as the facial expressions used to express emotion, seem likely to have a strong genetic basis. Others, like language, may result from the interaction of genetically shaped behaviors with universal features of the environment. Whatever the genesis of these universal behaviors, the fact that they are found in societies throughout the world suggests strongly that they would have been possessed by the ancestral human population before its dispersal.

These ubiquitously shared behaviors define the nature of what Brown calls the Universal People. Among the Universal People, families are the basic unit of social groups, and groups are defined by the territory they claim. Men dominate political life, with women and children expected to be submissive. Some groups are ordered on the basis of kinship, sex and age.

The core of a family is a mother and her children. Marriage, in the sense of a man’s publicly recognized right of sexual access to a woman deemed eligible for childbearing, is institutionalized. Society is organized along kinship lines, with one’s own kin being distinguished from more distant relatives and generally favored over those who are not kin. Sexual regulations constrain or eliminate mating between genetically close kin.

Reciprocity is important in the daily life of the Universal People, in the form of direct exchange of goods or labor. There are sanctions, ranging from ostracism to execution, for offenses such as rape, violence and murder.

The Universal People have supernatural beliefs and practice magic, designed for such purposes as sustaining life and winning the attention of the opposite sex. “They have theories of fortune and misfortune. They have ideas about how to explain disease and death. They see a connection between sickness and death. They try to heal the sick and have medicines for this purpose. The UP practice divination. And they try to control the weather,” Brown writes.⁷⁶

The Universal People have a sense of dress and fashion. They adorn their bodies, however little clothing they may wear, and maintain distinctive hair-styles. They have standards of sexual attractiveness. They dance and sing.

They always have a shelter of some kind. They are quintessential tool-makers, creating cutters, pounders, string to tie things together or make nets, and weapons.

The ancestral human population presumably possessed many, if not all, of the behaviors of the Universal People. It may also have had much in common with the San, who as members of the L1 branch of the mitochondrial tree may be the closest living approximation to the ancestral human population. Just how close is a matter of disagreement among social anthropologists. Some believe that little resemblance should be assumed between contemporary hunter-gatherers and those who lived thousands of years ago—people are always adapting genetically to their environment and there has been plenty of time for change. But foragers have presumably had much the same environment for the last 50,000 years. Chimpanzees seem to have changed very little in the last million years, so periods of evolutionary stability are not out of the question for human societies too. The lives of contemporary foragers are certainly not identical to those of early humans, but probably they overlap in many ways.

It was explicitly to help explore early human evolution that a group of Harvard anthropologists and others began, in the 1960s, a thorough study of the San, who still followed a foraging way of life. The choice of the San would have seemed even better had their ancient genealogy been known at the time. Unlike early hunter-gatherers, the San may have been confined to the less desirable regions of their former range, but even so they have little difficulty gathering enough food for their needs. They practice a foraging way of life that may have been typical of human existence ever since the days of the ancestral population.

Although the San’s mitochondrial L1 lineage makes them only cousins to the people who left Africa for Asia (a sub-branch of mitochondrial L3), they bear some striking physical resemblances to Asian populations, suggesting that both lineages may have inherited these features from the ancestral human population. Many Khoisan speakers have yellowish skin, the epicanthic folds above the eyes that give some Asian eyes their characteristic shape, shovel-shaped incisors (front teeth hollowed out on the tongue side of the mouth, found commonly in Asians and Native Americans), and mongoloid spots—a bluish mark on the lower back of young infants. The !Kung San themselves apparently recognize this similarity since they assign Asians to the category of Real People like themselves, as distinct from !ohm, the category of non-San Africans and Europeans.⁷⁷

As foragers, the San live off the land. Their principal food is mongongo nuts, but they are excellent botanists and recognize more than 200 species of plant, many of which they consider edible. According to Richard Borshay Lee’s classic study of the !Kung San, some 60 to 70 percent of their food comes from plants they gather and 30 to 40 percent from meat gained by hunting. The !Kung are expert trackers. They can tell the species of animal that made a track and how many hours ago it passed; they can even identify individual people from their tracks. Their hunting bows are lightweight because they poison their arrow shafts with a lethal toxin. They obtain it from the pupae of any of three species of chrysomelid beetle that they dig up from beneath the bushes where the larvae have fed. The pupae stay in arrested development for several months, enabling hunters to carry them around and freshen up the toxicity of their arrows when needed. A well placed arrow will kill a 200-kilogram antelope in 6 to 24 hours.⁷⁸ In the laboratory, 25 trillionths of a gram of the arrow poison extracted from one of the beetle species, Diamphidia nigro-ornata, is enough to kill a mouse.⁷⁹

Foraging life is neither as precarious nor as arduous as it might seem. Because of the diversity of resources the !Kung know how to tap, they cope easily with failures of supply by shifting from one source to another. Archaeological records suggest that their way of life in the Kalahari has persisted for thousands of years without a break.

It takes the !Kung 12 to 21 hours a week to gather all the food they need, according to Lee. Including other work activities like tool-making and maintenance, their total work week is 40 to 44 hours.⁸⁰

The !Kung live in small groups that move camp whenever the surrounding food sources have been eaten out. A family’s total possessions—tools, ostrich shell canteens, children’s toys, musical instruments—pack into two bags. Nothing is stored, since everything they need is obtainable from the environment. Portability imbues !Kung life so thoroughly that it affects even the spacing of children. A woman can carry one child easily along with all her possessions, but two are a burden. !Kung women tend not to have a second child until the first can walk well. Children are not weaned until the age of four and before that age are carried almost everywhere, whether on foraging trips or when moving camp. Lee calculates that !Kung women walk about 1,500 miles a year, at least half of this distance carrying substantial burdens of food, water or possessions. A !Kung mother carries her child a total of 4,900 miles before it walks by itself.

Perhaps because a woman must invest so much care and labor in raising a child, she examines her newborn carefully for signs of defects. “If it is deformed, it is the mother’s duty to smother it,” writes the demographer Nancy Howell.⁸¹ Infanticide is not the same as murder, in the !Kung’s view, because life begins not with birth but when the baby is taken back to camp, given a name and accepted as a Real Person. “Before that time, infanticide is part of the mother’s prerogatives and responsibilities, culturally prescribed for birth defects and for one of each set of twins born,” Howell says. Women give birth outside the camp and men are excluded by taboo from the birth site; the reason for the taboo is doubtless that the father’s absence makes easier the mother’s decision as to whether to keep the newborn.

Land is owned collectively. Almost everything is shared, starting with the meat a hunter kills. Two character traits strongly discouraged by the !Kung are boasting and stinginess. Hunters are expected not just to distribute their kill but also to be extremely diffident about their success. This is central to the egalitarian ethos of !Kung society. Men in fact vary widely in their hunting skills, Lee found, but because they do not get to keep the extra meat or put on airs, not even the mightiest hunter can raise his social standing above others.

In the nineteenth century the !Kung used to live in groups with names like The Giraffes, The Big Talkers, The Scorpions, and even The Lice. One could only marry outside one’s group. By the time of Lee’s study, in the 1960s, the !Kung lived in more informal groups based around families and their near kin and in-laws. But the groups were small, around 30 or so people, and their size seems to have been limited by the nature of their sociality.

During the winter dry season, many groups would come together, to share goods, arrange marriages, hold feasts and do trance dancing. “But this intense social life also had its disadvantages,” Lee writes. “The large size of the group required people to work harder to bring in food and fights were much more likely to break out in large camps than in small camps.”

Because !Kung groups are strictly egalitarian, there is no authority to resolve conflicts and keep order. !Kung groups do have leaders, but they are informal, with no authority other than personal persuasion. The usual method of expressing disagreement is to vote with one’s feet and leave camp along with one’s family and followers. Lee noticed that large groups of !Kung stayed together for long periods only at the cattle camps of their Herero neighbors. The reason was in part “the legal umbrella provided by the Herero to maintain order among such a large number of feisty !Kung”—in other words, the Herero maintained a social order that the !Kung apparently had difficulty providing for themselves.

Attractive as an egalitarian foraging society may seem, it has certain drawbacks. Both private property and privacy are kept to a minimum. Without authority or a headman, individuals must resolve, by themselves or with the aid of kin, any disputes they cannot walk away from. And without specialized roles and some kind of hierarchy, a human society cannot grow beyond a certain level of size or complexity.

An early study of the !Kung, by Elizabeth Marshall Thomas, was titled The Harmless People.³⁵² The !Kung have many attractive qualities but harmless they are not. Fighting had been suppressed by the time of Lee’s study, but rock art and historical accounts attest to its prevalence in the past.⁸² The San fought regularly with their pastoralist Bantu neighbors, often raiding their stock and fending off counterattacks with their poisoned arrows. The Cape San in the Sneeuwburg mountains halted the expansion of the better armed and mounted Boers for 30 years until overwhelmed by the Boers’ greater numbers.⁸³ As to internal violence, the !Kung’s homicide rate, Lee found, is 29.3 per 100,000 person years, some three times that of even the United States.

Disagreements in !Kung groups escalate through the three recognized levels of talk, fighting and deadly fighting. The talk stage also has three sub-levels. It starts as argument, moves up to verbal anger, and ends in za, a mode of pungent and personal sexual insult. These fighting words lead quickly to physical aggression. At that point, or shortly after, the poison arrows come out.

When hit with an arrow, the !Kung quickly cut around the wound and suck out the poisoned blood and lymph; chances of survival are 50-50. Puzzled at the high risks of this kind of conflict, Lee asked the naïve question of why men didn’t use ordinary arrows instead. “To this question,” he reports, “one informant offered an instructive response: ‘We shoot poisoned arrows,’ he said, ‘be cause our hearts are hot and we really want to kill somebody with them.’”

The anthropologist gained another insight into !Kung methods of conflict resolution while conducting interviews about hunting success. Having asked four !Kung hunters how many giraffe and deer they had killed, Lee reports, “it suddenly occurred to me to pose the question: ‘And how many men have you killed?’

“Without batting an eye, ≠ Toma, the first man, held up three fingers; ticking off the names on his fingers, he responded, ‘I have killed Debe from N≠amchoha, and N⁄⁄u, and N!eisi from /Gam.’

“I duly recorded the names and turned to Bo, the next man. ‘And how many have you killed?’

“Bo replied, ‘I shot //Kushe in the back, but she lived.’

“Next was Bo’s younger brother, Samk”xau: ‘I shot old Kan//a in the foot, but he lived.’

“I turned to the fourth man, Old Kashe, a kindly grandfather in his late sixties, and asked: ‘And how many men have you killed?’

“‘I have never killed anyone,’ he replied.

“Pressing him, I asked, ‘Well then, how many men have you shot?’

“‘I never shot anyone,’ he wistfully replied. ‘I always missed.’”⁸⁴

Ancestral Portrait

It is tempting to suppose that our ancestors were just like us except where there is evidence to the contrary. This is a hazardous assumption. The ancestral human population is separated from people today by some 2,000 generations. In evolutionary time, that is not so long, yet is still time enough for very substantial evolutionary change to have taken place.

Consider that the anatomically modern humans of 100,000 years ago showed no signs of modern behavior. They had no apparent capacity for innovation and may have lacked the faculty of speech. Very significant evolutionary change seems to have occurred in the 50,000-year span that separates them from the behaviorally modern humans of the ancestral population. Yet that is the same span of time that separates the ancestral population from people today, allowing for an equally decisive evolutionary change. And the pace of human evolution may well have accelerated in the last 50,000 years, given the unparalleled changes in environment experienced by the ancestral people as they left their homeland, colonized strange lands and cold climates, and converted from foraging to settled life.

Indeed specific evidence has now emerged suggesting that the human brain has continued to evolve over the last 50,000 years. The evidence, as described in the next chapter, rests on the finding that two new versions of genes that determine the size of the human brain emerged only recently, one around 37,000 years ago and a second at 6,000 years ago. Given the brain’s continued development, the people of 50,000 years ago, despite archaeologists’ tag for them as “behaviorally modern,” may have been less cognitively capable than people today.

The ancestral human population would have lived by hunting and gathering, and its way of life was perhaps not so different from that of foragers like the !Kung San. In its homeland in northeast Africa, the ancestral people were doubtless as skilled at exploiting the plants and animals of their local environment as the San are in theirs. They would have possessed a carefully thought-out suite of tools for hunting, food preparation, and carrying things. To judge by the journey of those who were to leave Africa, they probably knew how to build boats and how to fish.

But their technology would have been considerably less sophisticated than that of the !Kung. The !Kung’s lightweight bows and poisoned arrows represent a high degree of mechanical and biological knowledge. There is no clear evidence that the bow was invented until some 20,000 years ago. It never reached Australia, suggesting it was not known to the ancestral human population.

Without projectile technology, male hunting success in early human societies would have been considerably less spectacular. Large animals would have been hard to kill, so hunters perhaps concentrated on small game that they could run down and spear. “Before effective hunting, males could have focused more on honey and plant foods, so their daily hauls of food did not have to be lower but must have been different,” writes the evolutionary anthropologist Frank Marlowe. But women’s foraging, for plant foods and tubers excavated with digging sticks, may have been much the same as in contemporary foraging societies.⁸⁵

In appearance, the ancestral human population would certainly have had dark skin as protection against the African sun. They had stronger bones and were thicker set than contemporary people. They would have cut and decorated their hair. From the date assigned to the evolution of the human body louse, which lives only in clothing, the ancestral people must have worn clothes that were sewn to fit the contours of the body tightly enough for the lice to feed.

It is tempting to suppose the ancestral people looked like the San, with their lightish skin and slightly Asian cast of features, or perhaps like the aboriginal tribes of Australia, who have dark skin and wavy hair. But these two groups have been evolving independently for 50,000 years and their appearance is unlikely to have remained unchanged. The ancestral people may have been similar to both but would also have possessed their own distinctive appearance, which cannot at present be reconstructed.

The ancestral people spoke a fully articulate language, which may well have included the click sounds still used by their Khoisan-speaking descendants.

As hunters and gatherers, the ancestral people probably lived in small egalitarian societies, without property or leaders or differences of rank. These groups engaged in constant warfare, defending their own territory or raiding that of neighbors. When they grew beyond a certain size, of 150 or so people, disputes became more frequent, and with no chiefs or system of adjudication, a group would break up into smaller ones along lines of kinship.

Yet these quarrelsome little societies would have contained in embryo the principal institutions of the large modern societies of today. They had some form of religion, a practice that seems as old as language and may have coevolved with it. Religion may have served as an extra cohesive force, besides the bonds of kinship, to hold societies together for such purposes as punishing freeloaders and miscreants or uniting in war.

A sense of fairness and reciprocity governed exchange and social relationships. Much later, the idea of reciprocity would be extended to non-kin, allowing strangers to be treated as honorary relatives and creating the framework for societies that transcended the kin-bonded tribe.

Warfare may have been a dominant factor in the ancestral population’s existence. A group could attain respite from conflict by finding new territory. Yet it could not have been easy to travel far from the ancestral homeland. Foragers are adapted to surviving in their local environment by their intimate knowledge of its plants and animals. Only one group of people, a little band maybe only a few hundred strong, succeeded in overcoming the daunting odds and leaving the homeland altogether. But by daring so much, they gained the whole world.