the shapers of our habitat.27
Our biological constitution is, for the most part, an echo from the past three million years when the earth was significantly colder than it is today. A factor that contributed to this cooling process was the formation of the Isthmus of Panama three million years ago, which connected North and South America and interrupted the flow of warm water from the Pacific Ocean over to Africa. Atlantic currents were forced northwards, eventually leading to the formation of today’s Gulf Stream. The Himalayan mountain range also continued to rise, which rerouted Asian rivers to flow northward rather than south. Flowing into northern seas diluted their salt concentration: water that is low in salt freezes more quickly, which led to the glaciation of the Arctic region. The sea level sank during these periods to an average of 426 feet because the water froze.
Then the level rose again as subsequent oceanic and atmospheric changes led to warming periods. The Great Rift Valley in East Africa, where early hominids lived, rose slowly but continuously during this epoch, creating a drier habitat and causing forests to change to savannahs—an environment where an upright gait was a significant advantage.28
Early humans lived during times of sweeping change in the natural world that surrounded them. Whereas many species remained unchanged and only reacted to events, our ancestors were more flexible, innovative, and adaptable. Environmental changes even tended to foster flexibility and generalism in early humans. They developed an ability to survive under varied conditions, sustained by a wide variety of foods. The route to today’s world, wherein people can live in Arctic cold or tropical heat, on mountaintops or in river deltas, in Indian slums or in air-conditioned New York stockbrokers’ offices, arose a good two million years ago; omnivorous hominids proving to be very skilled at adapting. Due to genetic changes, brain size increased more rapidly, something that did not occur in close hominoid relatives whose numbers were much greater. These creatures began to use stone tools and began the evolutionary journey towards Homo; our branch on the tree of life.29
That branch spread north two million years ago, from East Africa toward the Mediterranean and from there into Asia, even as far as present day Indonesia and China. These prehistoric peoples wandered only a few miles each generation, eventually reaching Europe where, as far as can be determined, they lit the first fires during the cold era that occurred about four hundred thousand years ago. Neanderthals were one of the first waves of this human expansion.
But a more significant revolution, a human “Big Bang,” also took place in Africa, about 220,000 years ago—a mere instant in geological terms—a lighter, more agile creature called Homo sapiens emerged. Everyone alive today is related to this “new kid on the block.” He is the most social yet egotistical, loving yet cruel, sensible yet emotional, far-sighted and narrow-minded, creative and destructive of all hominids. Our ancestors survived dangers and setbacks, and began a triumphal march out of Africa across the globe, the march Paul Salopek is following with his “Out of Eden Walk” project. A hundred thousand years ago, they settled in what is now the Middle East, seventy thousand years ago they arrived in Australia, about forty-four thousand years ago they came to Europe and entered the habitat of the Neanderthals and about thirty thousand years ago they came from the north, moving into the entire American landmass.30
The spread of Homo sapiens had disastrous consequences for Neanderthals, human beings with artistic, cultural and even religious sensitivities. In their competition for land and resources, Neanderthal humans drew the short straw. Early Homo sapiens had already wiped out countless other species of animals—mostly large predators and some species they most enjoyed eating—a mere foretaste of the Anthropocene wave of extinctions to come, perhaps. According to recent findings, our direct ancestors cannot be held responsible for the extinction of the Neanderthals since there are no signs of massacres or widespread slaughter.31 There are even strong indications that Neanderthals and Homo sapiens had sex and that some Neanderthal genes persist today. But that didn‘t stop Neanderthals from going extinct. It may have been enough for our ancestors to be just a little more efficient at hunting and gathering in shared regions and in using up the resources that Neanderthals needed to survive. Thirty-seven thousand years ago, the trail of this fascinating alternate species of human disappears, whereas the spread of Homo sapiens truly kicked off.
The next decisive point in humanity’s ascent happened about twelve thousand years ago. The end of the last Ice Age and the beginning of a natural global warming created ideal conditions for a truly global expansion. Human ingenuity, fertile soil and a more favorable climate coalesced in a unique way. Independent of one another, human groups abandoned nomadic life and became agriculturalists, settling in fecund regions of the world, like the “Fertile Crescent,” the Andean Altiplano, Mesoamerica, China and New Guinea.
Some of these early farmers settled in an area comprising modern-day Azerbaijan, Iran, Iraq, Turkey and Syria. They discovered that grass seeds are not only edible but can also replicate. Precious calories could be gained from this food source, supplementing the hunting of gazelles and the gathering of nuts and berries. Once under way, the agricultural revolution could not be stopped.
Farming had some grave disadvantages: each calorie yielded from the land took more time and effort compared to hunting for meat.32 Farmers had less free time than hunters and gatherers. Yet, farmers found it worthwhile to work the land since it enabled them to stock up food in case of hard times. Surplus food meant that more children survived their first few months of life but also there were now more mouths to feed.
Layer upon layer, this history is evident at the village of Abu Hureyra, an ancient settlement on the upper reaches of the Euphrates River, in present-day Syria. British archaeologist Andrew Moore examined the village before it disappeared under floodwaters caused by the construction of Syrian president Hafez al-Assad’s massive new dam.33 People of the Natufian culture lived here around twelve thousand years ago. Remains of hundreds of different plants have been discovered beside the residents’ simple homes. Einkorn and emmer wheats, rye, lentils and fava beans play a central role in life. These people were very innovative: they discovered ways of maintaining the fertility of the land, by planting pulses which return nitrogen to the soil, and they domesticated animals such as goats, sheep and later cattle, brought down from the nearby Zagros Mountains. The symbiosis between humans and farm animals had begun to develop.
We have now arrived at a critical moment in our high-speed review of human history. The Holocene is the period of earth’s history in which we currently, officially live, based on geological calculations. Before modern humans were the children of the Holocene, our closest ancestors inhabited the Pliocene, a geological epoch that began 5.3 million years ago and ended 2.6 million years ago when the Pleistocene era began. If the Pleistocene Ice Age had simply continued, it is conceivable that humans would have remained hunters and gatherers. But something “new” happened, which is what “Holocene” means (from the Greek, holos, whole or entire and kainos, new). As far back as seventy thousand years ago, our ancient relatives had already produced paintings on the walls of South African caves, and thirty thousand years ago, they had fashioned pipes from bones, made sculptures, needles, and ceramics. In many places, such as the Chauvet cave in the south of France, they created paintings that would rival those by Picasso or Franz Marc. Humans are artists, masters at imagining, at creating, at reshaping their environment. Embedded in the favorable Holocene climate, these abilities have changed the world.
The start of the warming after the last Ice Age, approximately eleven thousand seven hundred years ago, prepared the conditions for “modern”
