Before the Dawn

Hunter-gatherers own almost no personal property and, without differences of wealth, everyone is more or less equal. The first settled communities show evidence of a quite different social order. Houses and storage facilities seem to have been privately owned. With personal property allowed, some people quickly acquired more of it than others, along with greater status. The old egalitarianism disappeared and in its place there emerged a hierarchical society, with chiefs and commoners, rich families and poor, specializations of labor, and the beginnings of formal religion in the form of an ancestor cult.

“Daily life in a village that is larger than a forager’s band heralds the restructuring of the social organization, as it imposes more limits on the individual as well as on entire households,” writes Bar-Yosef. “To ensure the long-term predictability of habitable conditions in a village, members accept certain rules of conduct that include, among other things, the role of leaders or headmen (possibly the richest members of the community), active or passive participation in ceremonies (conducted publicly in an open space) and the like.”¹⁴⁸

Sedentism must also have included a response to the most pressing of human social needs, defense against other human groups. For hunter-gatherers, the essence of security is mobility. For the first settlers, defense must have rested on some other basis, which was presumably that of population size. Because the settlers had learned to live together in larger groups, they would have outnumbered the attackers. With greater manpower than the usual foraging group, together with fortifications and perhaps the guard dogs that first became available 15,000 years ago, settlers would have been able to even the odds against the raiding parties after their food and women.

This new form of social organization preceded and perhaps prompted such innovations as the cultivation of wild cereals, and the penning and herding of wild animals like sheep and goats. These steps led in turn, perhaps more by accident than design, to the domestication of plants and animals and to the beginnings of agriculture. Settled life and the new hierarchical form of society paved the way for complex societies, cities, civilization and, in rudimentary form, the institutions of today’s urban life. Almost all subsequent human history and development seems in one sense a consequence of the pivotal transition from the foraging lifestyle to a settled, structured society.

The innovations of settled life and agriculture started to spread through Europe 10,000 years ago, a date that marks the beginning of the Neolithic age. Because the two inventions became so visible in the Neolithic, archaeologists long assumed that the improving climate made agriculture possible, which in turn opened the gateway to settled living. But in part because of improved dating techniques, they have come to see that the reverse is true: it was not agriculture that led to settlement, but rather sedentary life came first, well before the Neolithic age began, and agriculture followed in its train.

“Until recently, the beginning of the Neolithic was thought to occur with the inception of village farming,” write the archaeologists Peter Akkermans, of Leiden University in Holland, and Glenn Schwartz of Johns Hop-kins University. “We are now aware, however, that sedentary village life began several millennia before the end of the late glacial period, and the full-scale adoption of agriculture and stock rearing occurred much later, in the late ninth and eighth millennia BC. It is now evident that agriculture was not a necessary prerequisite for sedentary life, nor were sedentary settlers always farmers.”¹⁴⁹

Some signs of sedentary life can be seen as early as the Gravettian mammoth bone houses of 18,000 years ago, and it may be that sedentary systems were attempted when people came across an abundant food source, such as hazelnuts or salmon, together with a method of storing it. But these early instances of settlement were sporadic and may not have required any deep behavioral changes. True sedentism did not catch on as a permanent way of life until toward the end of the Upper Paleolithic. The first clear evidence of a successful and long term settled community comes from people called the Natufians, who lived in the Near East from about 15,000 to 11,500 years ago. They occupied lands on the eastern side of the Mediterranean, in the region that is now Israel, Jordan and Syria. The early Natufians gathered the wild emmer wheat and barley that grew there. They made stone sickles to cut the cereal grasses, and the sickles bear signs of the characteristic polish caused by the silica in cereal stalks.¹⁵⁰

Bar-Yosef suggests that the Natufians may have started to cultivate these wild cereals, including einkorn and emmer wheats, rice and barley, during the Younger Dryas when the natural yields of these cereal grasses would have been reduced. There is little evidence on the point, and in any event the Natufians did not develop the domesticated forms of the cereals. But in gathering, preparing and storing these grains, they were laying the technical basis for their successors to do so.

It is of interest that the Natufians, as the earliest known settled people, were no strangers to war or to religion, two characteristic human activities that shaped societies before and since. The Natufians have consistently been portrayed as peaceful but closer examination of remains from one site has recently shown evidence of violent conflict between Natufian groups.¹⁵¹

Natufian society is interesting for its burial practices, which indicate the emergence both of social inequality and of a disconcertingly intimate form of ancestor worship. Some 10% of early Natufian burials include decorations of marine shells and pendants made of animal teeth, suggesting the presence of a richer elite. In the later Natufian period, as the rigors of the Younger Dryas began, the society was forced to become more mobile, and their mortuary practices reflect a shift back toward a more egalitarian society. The early Natufians also began a practice that became common in the ensuing Neolithic period, that of separating the skull from the body before burial. The corpses were buried but the skulls were covered with plaster, given new faces, and kept in the houses to serve as a close bond between living and dead.¹⁵²

The Natufians built settlements on the east coast of the Mediterranean some 15,000 years ago. Later, they began to harvest wild stands of wheat and barley, laying the basis for others to develop domesticated forms of those cereals several thousand years after them.

Though it is impossible to reconstruct what was happening in the minds of late Upper Paleolithic people, it seems likely that settled life required developing mental concepts that were largely unfamiliar or alien to foragers. “The slow transformation of the foraging society into a Neolithic world of agriculturalists and herdsmen was associated with the creation of a new set of social and economic values centering around the house, the dead buried in and around the house, and the production and storage of staples,” write Akkermans and Schwartz.

It is hard not to admire the fortitude and intelligence that hunter-gatherers bring to the problems of survival. But the set of intellectual skills required for survival in the wild seem quite different from those needed to prosper in the jungle of urban life. Even if a hunter-gatherer were born with the innate intellectual ability of a Newton, Darwin or Einstein, it is difficult to see how he would profit from his gift or, in evolution’s cold calculus, be able to turn it into the reproductive advantage of raising more children. But in an urban setting, gifts of calculation or abstract thought would translate much more easily into extra children, and the genes underlying such abilities would spread.

The reason is that settled societies permit individuals to acquire extra property or status, both of which barely exist in hunter-gatherer societies and are in any case frowned on by their egalitarian ethos. Property, in turn, is a way of securing survival for oneself and one’s family. For long periods of human history possession of excess property probably helped people raise more children, even though a direct relationship between wealth and progeny is not so evident in modern societies. Settlement, in other words, would have created a quite novel environment, to which people probably adapted by developing a different set of behaviors, including a range of intellectual skills for which there was no demand in hunter-gatherer societies.

Property, value, number, weight, measurement, quantification, commodity, money, capital, economy—these concepts, however natural to the modern mind, would rarely have come into play in the life of mobile foragers. Could it be that the modern mind, the one capable of abstract thought, symbolic notation and writing, is indeed a quite recent development? Perhaps the process by which the modern mind emerged “has to be regarded as a more gradual one, operating in several phases and stages, and perhaps independently in different parts of the world,” writes the Cambridge archaeologist Colin Renfrew.¹⁵³

That, in his view, might explain why human societies apparently accomplished so little for so long. “If human societies of the early Upper Paleolithic had this new capacity for innovation and creativity which notionally accompanies our species, why do we not hear more about them?” he asks. There is a 45,000-year delay between the time of the ancestral human population and the first great urban civilizations, such as those of Babylon, Egypt, the Harap pan cultures of India and the Shang period of China. If “behaviorally modern” humans evolved 50,000 years ago, why did it take so long for this modernity to be put into practice? Renfrew calls this gap the “sapient paradox.”

One possibility is that some evolutionary adaptation had first to occur in human social behavior. That would explain why it took so many generations for people to settle down. The adaptation, probably mediated by a suite of genetic changes, would have been new behaviors, perhaps ones that made people readier to live together in larger groups, to coexist without constant fighting and to accept the imposition of chieftains and hierarchy. This first change, of lesser aggressiveness, would have created the novel environment of a settled society, which in turn prompted a sequence of further adaptations, including perhaps the different set of intellectual capacities that is rewarded by the institution of property.

A striking change that preceded settlement is a worldwide thinning or gracilization of the human skull. This change, discussed further in the next chapter, was probably accompanied by a taming or greater sociability, doubtless a necessary step toward settling down in larger groups.

If such a change occurred, it evidently evolved independently in different regions of the world, just as have other human adaptations like pygmy stature and lactose tolerance. Direct evidence for such a change may emerge in time from the human genome once the genes that influence human social organization are identified.

Once people were settled, many new opportunities for human innovation were opened up in technology, trade, warfare and political organization. A salient new technology was that of agriculture, which was invented before the end of the Pleistocene ice age and took off as soon as the climate started to warm up in the Neolithic. The reason for agriculture’s rapid spread, archaeologists believe, was that societies of the Near East had preadapted to it, primarily by sedentism but also with efforts to intensify production by seeding wild grasses.¹⁵⁴ Many previous theories about the invention of agriculture have invoked external forces that allegedly pushed a passive human society into taking up cultivation. None is well supported. One thesis holds that population pressure drove people to agriculture. But the archaeological evidence is that human populations grew after the advent of agriculture, not before it. Another proposal is that the warming of the climate after the end of the Pleistocene ice age was the driving force. But climate improvement was much the same everywhere, yet agriculture emerges at very different times in different regions of the world.

“It is important to realize,” write Akkermans and Schwartz, “that farming was neither the production of food according to an economic rationale nor an inevitability imposed on early Neolithic communities by large-scale events beyond their control. Instead, the adoption of agriculture was part of the profound transformation of the entire forager society and an adjustment to a wholly different set of societal values and meanings.”¹⁵⁵ Sustenance is not the only reason for agriculture. One advantage enjoyed by settled societies, and denied to foragers, is the ability to generate and store surpluses. Surpluses form the basis for trade. They can be exchanged for things considerably more vital than extra food, like weapons, or alliances, or prestige.

The transformation of cultivated wild cereals into their domestic forms could have happened very quickly, in as little as 20 to 30 years. That and other genetic considerations have been taken to mean that domestication of wheat was easy and might have happened several times independently.¹⁵⁷ But a genetic family tree drawn up for domesticated and wild varieties of einkorn wheat shows that the domesticated varieties all cluster on one branch, indicating a single domestication. The same is true for barley.¹⁵⁸

Archaeologists have not so far found any single site where they can trace the progression from the wild form of a cereal to its domesticated versions. But genetics has provided an unexpected helping hand in the case of einkorn wheat. Francesco Salamini, of the Max Planck Institute for Plant Breeding Research in Cologne, Germany, with colleagues in Norway and Italy, analyzed nearly 1,400 strains of wild einkorn wheat from the Near East. Those with a genetic structure closest to the domesticated strains came from the Karacadağ mountains of southeastern Turkey. The region is close to sites in northern Syria, like Abu Hureyra, where domesticated einkorn is known to have been grown some 8,500 years ago. The researchers conclude that “the Karacadağ mountains are very probably the site of einkorn domestication,” a claim disputed by some but endorsed by Daniel Zohary, a leading expert on plant domestication.¹⁵⁹

Einkorn was apparently the first wild cereal to have been domesticated. It was cultivated some 12,500 years ago and the first possible domesticated forms occurred 10,500 years ago; domesticated einkorn becomes abundant in the western half of the Fertile Crescent (from southeastern Turkey down the east Mediterranean coast) from 9,500 years ago. Domesticated emmer wheat, which is easier to harvest, is found at Abu Hureyra from 10,400 years ago. (Einkorn wheat mostly ceased to be planted in the Bronze Age; emmer is still grown in Ethiopia. Modern wheats stem from an accidental cross between a domesticated variety of emmer wheat and a wild grass known as Aegilops squarrosa or tauschii. The hybridization is thought to have occurred in the region of northern Iran some 7,000 years ago.) Rye and barley were two other wild cereals domesticated before 10,000 years ago in the Fertile Crescent.¹⁶⁰

After the dog, the first animals to have been domesticated were sheep and goats, probably between 10,000 and 9,500 years ago. Cattle were domesticated from the aurochs at about the same time, and the pig from wild boar. The aurochs ranged widely across Europe as well as the Near East, but a comparison of British aurochsen (based on mitochondrial DNA extracted from fossil bones) with modern cattle shows that Europe’s cattle too were domesticated in the Near East.¹⁶¹ It may be that these animal species, like the wild cereals, were domesticated unconsciously, in a process that started with wild herds being penned and the tamer animals picked as parents of the next generation. This assumes that people of 10,000 years ago were not aiming at domestication because they had no idea it could be achieved. On the other hand, they had the dog as an example, and a growing number of instances of their own success.

The horse appears to have been domesticated much later and outside the Near East, probably on the Eurasian steppes. Wild and domesticated horse bones are hard to tell apart, but horse remains with possible bit wear on the teeth occur in archaeological sites of the Ukraine and Kazakhstan, starting from 6,000 years ago. Unlike other animal species so far studied, which appear to have been domesticated only once or twice, horses seem to have been domesticated on many separate occasions, according to a study based on mitochondrial DNA.¹⁶² Possibly it was the technology for capturing, taming and rearing wild horses that spread from one society to another, rather than a strain of domesticated animals. If so, this would suggest that horses were of such high value, perhaps for military purposes, that people rushed to domesticate their own rather than waiting to acquire a breeding pair.³⁶⁰

The people of the Near East, having developed suites of domesticated plant and animal species, expanded their farming activities north and west into Europe. Archaeologists have generally assumed that these farmers could support more people and that their populations must have crowded out the original inhabitants of Europe who had entered as foragers during Upper Paleolithic times. But the founder analysis undertaken by Richards, as mentioned in the previous chapter, shows that only a small percentage of today’s Europeans are descended from those who entered from the Near East in Neolithic times.

Presumably a few farmers from the Near East entered Europe, and perhaps the original inhabitants started to imitate their success, by settling down and adopting the new technology. Or the new farming groups, if composed largely of men in search of new land, may simply have captured women from the indigenous groups. The farmers’ Neolithic genes would have become more diluted, generation by generation, as they and their new culture pushed farther into Europe.³⁶¹

Whatever the mechanism of spread, only 4 of the 10 principal Y chromosome lineages found in today’s Europeans arrived during Neolithic times. These 4 lineages, according to Semino and Underhill, account for 22% of European Y chromosomes, a reasonable match with mitochondrial DNA data suggesting that 13% of Europeans have Neolithic heritage.¹⁶³

It is only a coincidence of timing that associates these Y chromosomes with the Neolithic, and, given the approximate nature of dates derived from genetics, it would be reassuring to have some more direct link. One has emerged from the painted pottery and figurines associated with Neolithic sites. The pottery, known as LBK from the German words for “linear band ceramics,” was made in the Near East, the home of the Neolithic revolution, as well as in Greece, the Balkans and southern Italy. Two Stanford University researchers, Roy King and Peter Underhill, matched the geographical distribution of LBK pottery and figurines with that of the four Y chromosome lineages that entered Europe at the beginning of the Neolithic age. They found that one lineage in particular, marked by the mutation known as M172, was found in almost exactly the same locations as the LBK culture.¹⁶⁴ The present day male population with the highest known frequency of M172 happens to live in Konya, a city near the southern coast of Turkey and some 60 miles from the well known Neolithic site of Çatal Höyük. No less than 40% of men in Konya carry M172 on their Y chromosomes.

The finding supports the idea that Neolithic farmers from the region of Çatal Höyük pushed into Europe, gradually mixing with the local population. Their farming techniques and pottery making became universal, even though their genes did not. The intriguing question of whether they introduced the Indo-European languages into Europe is addressed in chapter 10.

Though cattle were first domesticated in the Near East, Europe became a center of cattle breeding during one of its first farming cultures, known from its pottery as the Funnel Beaker culture. The culture, which lasted from 6,000 to 5,000 years ago, was located in north-central Europe in the region that now includes the Netherlands, northern Germany, Denmark and southern Norway. It has left a lasting mark on the genetics of both the cattle and human populations of the region.

A team of European researchers led by Albano Beja-Pereira recently studied genes that encode the 6 most important milk proteins in 70 breeds of European cattle. From samples taken from 20,000 cattle, they drew up a map showing the degree of genetic diversity in the cattle genes. The greatest diversity—usually the sign of a species’ original homeland—coincided closely with the territory archaeologists have defined for the Funnel Beaker culture.

The researchers then performed the same mapping exercise for the human genetic trait known as lactose tolerance, the ability to digest lactose in adulthood. They found that the highest percentage of people with lactose tolerance occurred among populations in a region that substantially overlapped with the ancient territory of the Funnel Beaker culture. The frequency of lactose tolerance dropped off progressively with distance among populations outside the core area.¹⁶⁵

This finding is remarkable because it shows a human population evolving, in recent times, in response to change created by human culture. Lactose is a special sugar that accounts for most of the caloric content of mother’s milk. The gene for lactase, the enzyme that digests lactose, is switched on just before birth and, in most people, switched off after weaning. Because lactose does not occur naturally in most people’s diet, it would be a waste of the body’s resources to continue making the lactase enzyme. But in people of mostly northern European extraction, and to some extent in African and Bedouin tribes that drink raw milk, the lactase gene remains switched on to early adulthood or throughout life. Among these milk drinkers, the ability to digest the lactose in cow’s, sheep’s or goat’s milk evidently conferred so great a benefit that the genetic mutation conferring the ability became widespread.

Geneticists are still trying to define the exact genetic change that causes the lactase gene to stay active after weaning. The DNA sequence of the lactase gene itself is identical in both lactose tolerant and intolerant people. The difference must lie in some nearby region of DNA that controls the activation of the lactase gene, such as the two mutations recently discovered by Leena Peltonen of the University of Helsinki.¹⁶⁶

What is certain is that lactose tolerant Europeans have inherited unchanged from a common ancestor a huge block of DNA that includes the lactase gene, its neighboring gene and much else. The size of the block is a sign of recent evolutionary change. Big blocks of unchanged DNA are very rare because at each generation pairs of chromosomes swap sections of DNA so as to create individuals with novel combinations of genes. As is easy to envisage, the blocks of original DNA that a chromosome may start off with will get smaller and smaller at each generation as the swapping process whittles them down. So a large block of DNA shared by lots of people is a sign of recent selection. Large blocks are created when some must-have mutation occurs that is greatly favored by natural selection. Nature cannot pick out a specific mutation or gene; it can only favor individuals who have inherited the large block of DNA within which the advantageous gene occurs.

Besides indicating the presence of a gene under natural selection, a block of DNA can also be used to date the time the gene started to be selected, since the larger it is, the more recent the selection. Joel Hirschhorn of the Harvard Medical School has found that the block containing the lactase gene in lactose tolerant Europeans extends for about 1 million DNA units. He and colleagues believe that this is a sign of strong positive selection, and that the block started to become widespread sometime between 2,000 and 21,000 years ago.¹⁶⁷ This date fits with that of the Funnel Beaker culture.

Lactose tolerance occurs in a high percentage of many northern Europeans who live in the former region of the Funnel Beaker culture—in 100% of Dutch people, according to one survey, and 99% of Swedes. The condition also occurs in many other populations, though at generally much lower rates. In Africa, tribes who keep cattle, sheep or goats have higher rates of lactose tolerance than nonpastoralists. Lactose tolerance in some African groups includes as much as 25% of the population. It is presumably less common in these African groups than in northern Europeans because pastoralism got started later in Africa and natural selection has had less time to raise the frequency of the gene.

The phenomenon of lactose tolerance draws attention to three aspects of human evolution. First, it confirms that evolution didn’t stop 50,000 years ago, when modern humans left Africa, as is often assumed, but has continued to reshape the human genome.

Second, it shows the human genome is likely to have responded independently in different populations to the same stimulus, a process known as convergent evolution. Lactose tolerance has arisen independently in northern Europeans and in several African populations. Many other human attributes that have evolved since the African diaspora may also have taken place independently in different populations, such as the probable cognitive advances discussed in chapter 5.

Third, the lactose tolerance phenomenon establishes that genes respond to cultural changes. This is not so surprising because culture is a major part of the human environment, and genomes are mechanisms for responding to the environment. But a feedback of culture on genes is rarely considered by social scientists, many of whom assume that human evolution ended for all practical purposes when cultural development began. The case of lactose tolerance shows that any long lasting human cultural behavior, such as drinking raw milk, can cause genetic changes if there is a way for the genome to respond to it.

Looking back on the years between 50,000 and 5,000 years ago, from the time of the ancestral human population to that of the Funnel Beaker people and their contemporaries, it is clear that wrenching changes in the human environment took place during this period, particularly in the social environment. Hunter-gatherers learned to settle down and cooperate in larger groups with people to whom they had no kin relationship. People who had been egalitarian and generalist joined hierarchical societies in which occupations were increasingly specialized. All these changes probably induced different behaviors, some of them maybe mediated through evolutionary changes to the human genome.

Human nature, in other words, has probably changed significantly in the last 50,000 years. It cannot have changed profoundly, because the principal lineaments of human nature are the same in societies around the world, suggesting that all are inherited from a single source. But any characteristic with a genetic basis can vary, and is very likely to do so, because few genes remain constant for long periods of time. The question of human nature and its evolution is the subject to be considered next.

Settlement and Domestication

The Interaction of Genes and Culture: Lactose Tolerance