Mankind stems from African stock

By Gwynne Dyer

This is the first of three articles in a series on the history of the human race.

LONDON (JP): "I've given an introductory lecture on human evolution every year since 1970," remarked Leslie Aiello, professor of biological anthropology at University College, London, "and I've never given the same lecture twice." But the avalanche of new data and new ideas is making it possible, at last, to write a real history of the human race -- or perhaps a "meta-history", because it's a bigger project than that.

Last July, in the far west of England, a team from Glasgow University found a stone with the inscription "Pater Coliavificit Artognov" in post-Roman sixth-century script: a bald statement that Arthur had this built. Moreover, they found it at Tintagel in Cornwall, the traditional birthplace of King Arthur, on the edge of a cliff overlooking a tavern that has been known as Merlin's Cave since time out of mind.

So the old legends were true after all -- although "Artognov" isn't exactly the King Arthur of the Round Table. "There are two Arthurs," explained Geoffrey Wainwright, the chief archaeologist of English Heritage. "King Arthur the myth -- Malory, Tennyson, Excalibur, Guinevere, Lancelot -- I'm afraid is fiction. But the warlord who lived in the Dark Ages, named as Arthur in later texts, who fought and won battles, is real."

That's the problem with oral tradition. It preserves a few names and even a few facts, but it gives us none of the context, the real history of the time. There is just an 'Arthur-shaped hole' in Britain's past, as one historian put it. And that has always been the state of our ancient history and pre-history: a matter of stones and bones and bits of half-remembered lore, open to endless argument and interpretation. We didn't really know who we were, or where we came from. But now the biggest gaps are being closed.

It's not the historians who are doing the work, for they don't have the necessary tools. It's the anthropologists, the geneticists, and the linguists -- even the primatologists -- who are figuring out what really happened. And it's all quite different from what we believed even ten years ago.

In the 1980s, for example, it was still thought that we were descended from primitive humans who migrated out of Africa between one and two million years ago, settled all over Eurasia (the Neanderthals in Europe, Peking Man in East Asia, Java Man further south), and there evolved into the various races of humanity. Now it is all but certain that we are a much more closely knit species who emerged in Africa about 200,000 years ago, and moved out into the rest of the world as recently as 100,000 years ago.

It turns out that DNA differences among different groups of Africans -- and hence the length of time since they ceased to belong to the same inter-marrying tribe -- are far greater than between all other human beings. Even Scots and Japanese are closer to each other genetically than African groups living a couple of hundred kilometers (miles) apart, because their ancestors all left Africa and lost touch with one another only 100,000 years ago.

The so-called "races" of mankind, in other words, are only recent local variations of a common African stock. Indeed, the 90 percent of the human race whose more recent roots are non-African are a rather inbred lot, since they are descended from a very small number of ancestors -- perhaps only a few thousand -- who crossed the Sinai peninsula to populate Europe, Asia, Oceania and the Americas. (The quickest way to re-diversify the human gene pool would be for everybody else to marry Africans, but there aren't enough Africans to go round).

So if anatomically modern humans (Homo sapiens) are all of recent African origin, what became of the earlier breeds of proto-humans that spread across the world a million or so years before us? In Europe, it's clear that our ancestors and the Neanderthals cohabited in the same areas for many thousands of years -- but the Neanderthals, like their cousins in Asia, eventually disappeared.

"I think it was the development of language proper, about 50,000 to 60,000 years ago, that changed the behavior of H. sapiens and caused them to push out the Neanderthals," speculates Ian Tattersall, curator of anatomy at the American Museum of Natural History in New York. But did we kill them off, or did they interbreed with us and get absorbed into the more successful human population, or did they just die of disappointment?

The sentimentalists want to believe we intermarried, but a study last year by Svante Paabo of Munich University knocked that notion on the head. Using a technique known as DNA amplification, he cloned Neanderthal DNA from bone fragments and compared it with human DNA.

There were 27 differences between Homo sapiens and Neanderthals in a 379 base-pair strip of DNA, whereas the entire human population of the world differs by only eight pairs along this strip. "It indicates that Neanderthals had nothing to do with our history," explained Paabo.

We still don't know how the Neanderthals and their relatives met their end, but by 30,000 years ago we were the only hominid species left standing. And over the next 20,000 years little happened that was new and exciting except that we crossed into the Americas and filled up the rest of the world.

It was a time of great conformity: everywhere we lived in hunting-and-gathering groups of only a hundred or so, and hunter- gatherers make their living in essentially the same way no matter what the continent or climate. But it was also the time of maximum diversity, with a new tribe, a new language and new customs every ten kilometers or so.

If the behavior of contemporary hunting-and-gathering groups is any guide, they were often engaged in low-level warfare with their neighbors. Nevertheless it was, in some senses, an idyllic time: the closest that real history has ever come to Rousseau's 'state of nature'. And then the steamrollers began to move.