The Human Journey
Out of Africa

Out of Africa


Book Review of Before the Dawn

Recovering the Lost History of Our Ancestors

Penguin Books, 2007

Pages 1234

Stasis and Settlement

Upper Paleolithic art in Europe

The development of settled societies from 50,000 to 15,000 years ago was an important transition, even though the precise road to settlement remains obscure. From about 45,000 years to 10,000 years ago the people of Europe and East Asia followed the same nomadic life and endured the same vicissitudes of climate. The vastness of Eurasia pushed people into separate trajectories. Because Europe’s archaeology, languages, and genetics have so far received more attention that those of any other region of the world, Europe is the best place to follow the history of human foraging societies.

Cave painting of horses
Painting of horses from Chauvet cave

Stone tools differentiate a succession of European cultures. The earliest was the Aurignacion that lasted from 45,000 to 28,000 years ago, with tools found in France, Italy, and much of eastern Europe and in the Levant. Accomplished fighters, they steadily drove back the Neanderthals, although their culture was not purely martial. It included the remarkable artists who decorated the Chauvet cave in the Ardeche Valley of France, the earliest known of the great painted caves of Europe.

The cave was occupied from 32,000 to 30,000, and from 27,000 to 25,000 years ago. Paintings dominate the walls depicting lions, mammoths and rhinoceroses—animals that were rarely hunted—as well as horses, reindeer, and auroch. The beauty and expressiveness of the paintings often speak to contemporary observers, but their meaning and the intent of their makers is unknown. The Aurignacion period came to an end for unknown reasons, and its culture was replaced with that of the Gravettian, also defined by a distinctive set of tools.

Venus figurine
The Gravettian
Venus

Europe and much of the Eurasian steppes were covered in vast grasslands supporting abundant reindeer, mammoth, bison and antelope that provided abundant food for hunters and valuable materials like hide, bone, ivory, and antler. The Gravettian culture, which lasted from 28,000 to 21,000 years ago, stretched east into Russia with southern provinces in Italy and on the French-Spanish border and focused more on hunting mammoth than reindeer. These people produced the well-known Venus figurines recovered from sites that stretch from France to Russia and might have been associated with a fertility cult. Less well known is their invention of the bow.

Solutrean needle and fishing hook
Solutrean tools

The Gravettians were followed by the Solutrean culture, which was centered in France and Spain that lasted from 21,000 to 16,500. The Solutrean toolkit includes the world’s first identifiable needles. These people had abandoned the worsening climate of cold northwestern and central Europe and were living together in larger societies that were crowded into these southern refuges.

Drawing of a Magdalenian tent
Magdalenian tent from Pincevent, France

As quickly as the glaciers had returned, they withdrew and yielded back the rich lands of Eurasia to animals and those who hunted them. People spread out across what is now France and Germany and created the culture of the Magdalenians that existed from 18,000 to 11,000 years ago. Their toolkit, designed for reindeer hunting, was lightweight and portable. Tools were crafted with particular precision and delicacy, such as bone harpoons with a row of barbs on each side, and the practice of cave-art continued at the Magdalenian sites of Lascaux, dated to 17,000 years ago, and Niaux and Altamira.

Map of the distribution of people during the Early Paleo period in america

People were also migrating out of East Asia. Groups from Siberia, crossing a land bridge that existed at the time, entered North America about 12,000 years ago and eventually created the Clovis culture on the Great Plains about 11,500 years ago. Over time they moved down the coast into the areas of Mexico, Central America and South America.

Or did they? Perhaps they entered the tip of South America first or there may have been three distinct migrations. An archeological site in southern Chile turned up artifacts that dated 12,500 years ago, with a deeper site underneath that was dated 33,000 years ago. Mitochondrial DNA analysis gave support to pre-Clovis dates of settlement at approximately 30,000 years ago.

Settling down or sedentism as archaeologists call it may sound simple, but for foragers it was not so clear a choice. Sedentism anchored people to a single exposed place, possibly vulnerable to intruders, and disease. But once people were settled, new opportunities for innovation opened up in technology, trade, warfare, and political organization. Agriculture stimulated a transformation of the entire forager society as they adjusted to a totally different set of societal values and meanings. Archaeologists have no hesitation in describing this transformation as a revolution.

Human nature has probably changed in significant ways in the last 50,000 years. But it has not changed profoundly because its principal characteristics are much the same around the world, thus all of us inherit from a single source. Any characteristic with a genetic basis can vary, however, and is likely to do so, because so few genes remain constant for long periods of time.

Sociality
What is it that knits human societies together in the first place? Human social behavior is rooted in a genetic template adapted to prevailing circumstances. It includes a vigorous expansion of the chimpanzee propensity for territorial defense and aggression. But it also includes different behaviors, which enable people to work effectively with others in complex societies. In chimpanzee groups, most of the males are related to one another, a kinship that holds them together. Humans allow strangers to be treated as kin which provides the glue for large and civilized societies.

Chimpanzee mom and baby
Chimpanzees

In chimpanzee groups the male is dominant, and the female tends to live separately with her offspring. A chimpanzee community never assembles together as a whole. They move around in bands of 20 or more with a shifting membership. The females often feed alone with their offspring. Human family units require a higher level of trust among males, enabling them to band together for social purposes like warfare with a reasonable degree of confidence that other males will not steal their wives.

All chimp communities habitually use tools but their use varies in the different communities. For example, in the forests of the Ivory Coast chimps use stones as hammers to open nuts, but Gombe’s chimps have never learned or invented this useful procedure.

Bonobo
Bonobo

No tool use has been observed among bonobos. Some additional differences between bonobos and chimpanzees, who look very much alike in appearance, are the separate female hierarchies that dominate bonobo groups and the penchant of bonobos to use sex, not only for reproduction, but also as a social greeting and reconciliation technique.

It seems more likely that bonobos descended from chimpanzees rather than the other way around. Since both are descended from the joint ancestor of chimps and humans, the joint ancestor presumably had both chimp-like and bonobo-like traits that may indicate where humans came by their contradictory impulses of aggression and conciliation.

Although warfare is a distinctive feature of human history, it tends to overshadow a more remarkable feature of human societies. The unique human ability to cooperate with others, especially unrelated individuals, is the opposite of warfare. This uniquely human blend of sociality that has evolved over time came about through a major shift from ape sociality to the human nuclear family, which gave all males a chance of procreation.

OXYTOCIN molecule

Trust is an essential part of the social glue that binds people together. Exchange and trade depend on trust, treating strangers as if they were family. Without this, human societies would still consist of small family units and cities and civilization couldn’t exist. Two hormones, oxytocin and vasopressin, modulate social behaviors. The hormones are generated in the pituitary gland at the base of the brain and have effects both on the body and the brain. Oxytocin induces labor in childbirth and the production of milk. It specifically affects the willingness to accept social risks in interpersonal relations with others.

Vasopressin molecule

The emergence of the male-female bond changed human societies. The willingness of the male to protect the female and her offspring was based on the female’s willingness to bear only his children and this allowed the necessary behaviors that have developed since then to support the male-female bond.

The evidence that human tribes became less murderously hostile to one another lies in a world-wide thinning, or gracilization, of the human skull that occurred during the Upper Paleolithic age. The fossils of early modern human skulls are large and thick-boned, but early modern skulls began to become more gracile about 40,000 years ago. With our bones more gracile than those of our Upper Paleolithic ancestors, our personalities less aggressive, and our societies more trusting and cohesive, a preference for negotiation over annihilation was injected into the genome.

In parallel with social evolution, the human physical form continued to evolve across the different continents. The distance between the populations as well as a general hostility did not allow for significant gene flow. For these reasons, the people on different continents followed independent evolutionary paths that led over the generations to the emergence of a variety of human adaptations, skin color, eye folds, hair, etc.

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