The history inside us

ACCOUNTS OF the dawn of human civilization often begin at the riverside settlements in present-day Egypt and Iraq. But the evidence of what happened before that has been far fuzzier - if people evolved in Africa, how did they end up everywhere they did? But as Dr. Spencer Wells and other population geneticists have shown, humans have been carrying that information inside them all along.

Wells will discuss his research tonight at the Museum of Science. As director of the Genographic Project, a five-year effort of the National Geographic Society and IBM, he's been collecting DNA samples, in the form of cheek swabs, from remote villagers and from residents of modern industrial nations. Such research is fascinating, but it's also bittersweet, for it comes at a time when out-of-the-way languages and ethnic groups are being absorbed into a larger, blander global culture.

By looking at genetic markers on certain DNA, scientists can work out where that individual's distant maternal ancestor might have lived. Markers on a man's Y chromosomes provide similar data about his far ancestor on his father's side. With help from archaeology and linguistics, the data indicate when different groups of people moved about, and which languages might be related to which. But not just that. The data blast away the notion of race as an "immutable entity," as Wells put it in an interview yesterday.

Genetic patterns imply epic drama: Maybe newcomers to a region were the first humans to see it, and marveled at the virgin territory before them. Or maybe there were natives, and the newcomers mixed in with them. Or maybe the reality was far grimmer.

Genetic data also reveal something about modern America. The extent to which different populations have mixed here, Wells said, is unique in human history. The nation's melting-pot nature, Wells thinks, only makes its residents wonder more about their origins. "A lot of Americans feel somewhat culturally adrift because of that," Wells says. So the level of public interest in the Genographic Project is hardly surprising.

The pull of ancestry is strong. One always hears that "ancient hatreds" will keep sowing discord in the Middle East and elsewhere. Yet in the long span of human history, centuries-old grievances are recent wounds. Having walked from the valleys of East Africa to the southern tip of South America, humans have endured and survived far worse.