Human dispersal
If climate is the context of our story, the experiences of Homo sapiens are its subject. The earliest available archaeological evidence of the existence and original habitat of our species emerged in 2003, in Herto, Ethiopia, where, near the remains of a butchered hippopotamus, three skulls turned up - a child’s and two adults’ - dated to about 154,000 to 160,000 years ago.
They look similar to skulls of humans today, except that they are slightly larger than what is now average. The skulls had been stripped of flesh and polished after death, as if in the culture they belonged to people practised some death-linked ritual.[371]The date ascribed to the find roughly corresponds to inferences about the antiquity of Homo sapiens from genetic evidence. All humans today - as far as we can tell without actually testing everyone - have a component in our cells that a mother in East Africa passed on to her daughters about 150,000 years ago.[372] We nickname her Eve, but of course she was not our first ancestress nor the only woman of her day. By the best available estimates, there were perhaps 20,000 individuals of the species at the time, all living in the same region and presumably practising the same culture - eating the same food, prepared in the same way, with the same technology, sharing whatever might pass for notions of cosmology and transcendence, celebrating the same rites, and communicating by common means. Thanks to the hippopotamus bones and the cherished skulls, we can begin to picture not only the appearance of the African Eve - we can do that by looking in a mirror - but also something of her way of life or, at least, life at a time close to her own.
Eve's homeland of mixed grassland and sparse woodland was no Eden, but it was suitable for the creatures into whom our ancestor and her offspring had evolved.
In this environment they could, like predecessorspecies in the same circumstances, make up for their deficiency as climbers by standing erect to look out around them. Here, too, they could use techniques familiar to earlier hominids: they set fires to manage the grazing of the animals they hunted with fire-hardened spears, and sharpened stones to butcher the carcasses. They could exploit their modest physical advantages over competitor species. Humans are poorly equipped physically, with inferior senses of sight, smell, and hearing, slow movements, unthreatening teeth and nails, poor digestions, and weak bodies that confine us to the ground. But we can sweat profusely over our hairless skins to keep cool during long chases, and we can ward off rival predators with our relatively accurate throwing-arms and well-coordinated eye-arm movements.[373] In short, like most creatures, we are physically well equipped for a particular kind of habitat.Nonetheless, from their beginnings in East Africa, Eve's descendants spread over the world.[374] Such dispersal had happened before - or something like it had. More than a million years before Homo sapiens set out, Homo erectus migrated from a similar region in East Africa and spread over most of what are now Africa and Eurasia, following numerous earlier, somewhat less far-reaching hominins.1° But theirs was a much slower and more selective peopling of the Earth than Homo sapiens achieved, and as far as we know it did not lead to the startling cultural divergence that came to constitute the history of our own species.
At intervals Homo sapiens encountered other less widely dispersed, culturally homogeneous hominids, such as Neanderthals in Europe and southwest Asia, and perhaps the minute but technically well equipped Homo floresien- sis.11 Despite much speculation over the possible interactions that might have followed during various millennia of coexistence, the only incontestable fact about the interactions is that Homo sapiens survived while the other species became extinct.[375] [376] [377] The uniqueness of the experience of Homo sapiens overshadows everything else that we conventionally call history.