How humans behaved before they behaved like humans
- African Exodus: The Origins of Modern Humanity by Chris Stringer and Robin McKie
Cape, 267 pp, £18.99, March 1996, ISBN 0 224 03771 4
- Humans before Humanity by Robert Foley
Blackwell, 238 pp, £25.00, December 1995, ISBN 0 631 17087 1
- The Day before Yesterday: Five Million Years of Human History by Colin Tudge
Cape, 390 pp, £18.99, January 1996, ISBN 0 224 03772 2
- The Wisdom of Bones: In Search of Human Origins by Alan Walker and Pat Shipman
Weidenfeld, 270 pp, £18.99, April 1996, ISBN 0 297 81670 5
- The Neanderthal Enigma: Solving the Mystery of Modern Human Origins by James Shreeve
Viking, 369 pp, £20.00, May 1996, ISBN 0 670 86638 5
Humanity is fissile: everywhere it goes, it forms clans, Yoruba and Yanomamo, Mods and Rockers; so powerful is the urge to diverge, even shared ethnicity is optional. No wonder humanity is so hard to define. Taxonomy, designed to resolve such issues, is helpless where it matters most. Every species of animal and plant is uniquely defined as such on the basis of an objective description of its form and habits. All, that is, except one, Homo sapiens. Our entry in the Systema Naturae, devised by Linnaeus, says (more or less) ‘reader, know thyself,’ thus admitting the impossibility of seeing ourselves as others see us.
Thanks to the discovery of fossils of extinct relatives of humanity, and the application of Darwinian evolution, the boundary between humanity and the animal world, once thought unbridgeable, has been all but erased. The Darwinian emphasis has become a weapon in physical anthropology against the Post-Modernist tendency that sees the scientific worldview as one myth among many. That this is nonsense is self-evident: when one set of fashionable posturings has given way to another, the fossils will still exist.
The story the fossils have to tell is that our ancestry split from that of other African apes around five million years ago. These early hominids, best thought of as bipedal chimps, evolved into a multiplicity of specialised forms. Which, if any, can be described as the first representative of Homo is debatable. The first that was recognisably human was Homo erectus. This species appeared around two million years ago in Africa, and was the first of its kind to spread beyond that continent into Eurasia. Local populations evolved to give a number of distinct regional forms. The European variant became Neanderthal Man. The earliest Neanderthal-like creatures appeared around 300,000 years ago, and the last died out sometime after 30,000 years ago, a few thousand years after modern humans appeared in Europe.
The migration of Homo erectus out of Africa is accompanied by a sharp divergence of scientific opinion about what happened next. Some believe that the racial diversity in modern human form can be traced back to the regional variants of Homo erectus, more than a million years ago. For example, modern Europeans evolved from Neanderthals; modern Chinese from Asiatic Homo erectus. This ‘multiregionalist’ school is challenged by the so-called ‘Noah’s Ark’ school, whose adherents contend that all modern humans descend from a small population of fully modern humans living in Africa around 200,000 years ago. These people spread throughout the world, reaching the Levant 90,000 years ago, Australia around 60,000 years ago, and Europe 40,000 years ago. Indigenous populations were quickly replaced, and contributed no genes to modern humanity. Neanderthal blood courses in no one’s veins.
At the moment, the evidence favours the ‘Noah’s Ark’ school. Genetics, as well as examination of the fossils, points to a recent common origin in Africa. Physical differences between races are superficial, and any human can, in principle, mate with any other to produce viable offspring. ‘Noah’s Ark’ accords with current thinking in zoology, that new species arise in small populations which then spread more widely, competing with similar forms and often replacing them.
The multiregionalist view supposes that several distinct lineages evolved in parallel for a long time. A small amount of exchange between neighbouring populations would keep the entire species inter-fertile. This, not the recent common ancestry, is why the Yoruba and Yanomamo are capable of intermarriage, despite hundreds of thousands of years of separate evolution. Although this may be possible in principle, it is unlikely in practice, because of the zoological observation that species with extensive ranges tend to fray at the edges. There are several examples of animals which belong to the same species, but to opposite ends of its range, proving incapable of interbreeding should they meet, and behaving as members of distinct species. That this is not the case among humans speaks against multiregionalism, but in favour of a recent common ancestry.
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Vol. 18 No. 21 · 31 October 1996 » Henry Gee » How humans behaved before they behaved like humans
pages 36-38 | 2881 words