Living in the Past

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The emerging genetic picture tells a different story, one that identifies the earliest Europeans as scraggly, persistent foragers who had hunkered down during the glacial age. "This research changes the whole debate about Europe, shifts it back in time from the Neolithic era of farming to the Paleolithic era of hunter-gatherers," says Bryan Sykes, professor of human genetics at the University of Oxford and a pioneer of mitochondrial DNA analysis. "There's now a much clearer sense that the genes we carry lived through the Ice Age, that our ancestors were hunting bison and reindeer with essentially the same genetic makeup we have today."

Like any other scientific innovation, tracing founder lineages through the Y chromosome of men or the mitochondrial DNA of women is open to many questions. Some scientists think, for instance, that even the relatively high number of samples — whether a lock of hair or a dollop of saliva — used in the most recent studies is still too small to give a full picture of genetic variation. Others harbor doubts that the rate of mutation of mitochondrial DNA is constant enough to support conclusions about chronological dating. "Physical anthropology remains the gold standard for dating," says geneticist Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, a member of the team at the University of California, Berkeley that in 1987 identified "Mitochondrial Eve" as the 140,000- to 280,000-year-old ancestor of all living humans. "But we're getting better at genetic dating all the time."

Carbon dating has been recalibrated in recent decades to give archaeologists strong certainties about the ages of key artifacts for Europe's prehistory, from the drawings in France's Chauvet Cave (32,000 years old), to possibly Neanderthal milk teeth found in Cavallo, Italy (31,000 years old), to the Minoan civilization on Crete (3,700 years old). That means there is always the prospect of a physical discovery — an agricultural site that doesn't fit in time or space, say — that can blow existing theories out of the water.

So, though anthropologists of even the most humanist bent can't afford to ignore the precipitous pace of discovery among geneticists, neither can any search for an integrated picture of the past rely on molecular anthropology alone. "Genetics tells us about the travels of human genes — the boy-meets-girl of the story," says Marek Zvelebil, an archaeologist at the University of Sheffield. "But gene exchange is different from language or cultural exchange. Who are we in the long term? There are at least three identities — genetic, linguistic and cultural — and we're all a mix of these."

Take for instance the key question of how agriculture spread in Europe. The genetic evidence of recent years certainly challenges the notion that agriculturalists from the Middle East wiped out previous immigrants to Europe, but it doesn't answer the question of how farming did spread. Zvelebil's reading of archaeological sites suggests that in many parts of Eastern and Northern Europe, there were porous frontiers between foragers and farmers that could last thousands of years.

In the Eastern Baltic, for instance, foragers traded seal fat, amber, slate and flint for the farmers' pottery and grain. In coastal regions where oysters or other shellfish were plentiful, foragers felt no particular compulsion to take up the tasks of horticulture. Where farming did spread, he says, it was often through a process of gradual adoption by hunter-gatherers rather than continual migration of farmers. "Gene flow just doesn't correspond to the cultural patterns," he says.

Nor, most scholars now agree, do they correspond very well to linguistics. Sykes has pointed out that the Basques, who speak a non-Indo-European language amid a sea of Indo-European ones, lack the genetic markers that would indicate they have been in Europe longer than their French and Spanish neighbors (though there are markers — such as a much higher frequency of RH-negative blood types — that point to their distinctiveness). And most speakers of Hungarian, a Finno-Ugric language surrounded by Indo-European tongues, don't appear genetically much different from their Slavic neighbors.

So what? Well, it complicates matters, suggesting that gradual cultural exchange has played a quiet but constant role in human history — and that invasions aren't necessarily all they have been cracked up to be. Thirty years ago the dominant theory was that the precursor of the Indo-European languages came to Europe on the tongues of warrior horsemen from the Pontic steppes of present-day Ukraine, and that the broad dispersal of those languages across the Continent was a tribute to their martial success. Then in 1987 Renfrew made a powerful case that it was the Neolithic farmers who brought the language with them from the Middle East, and that along with their barley and wheat they sowed the overwhelming dominance of their tongue throughout Europe. But as the genetic evidence now suggests, neither warriors nor farmers were able to keep their language to themselves. The Indo-European language family — from Lithuanian and Catalan to Swedish and English — spread far more successfully across Europe than the genes of its original progenitors did.

Linguists have their own ideas about how change occurs; they have managed through a rough philological equivalent of genetic research to work back from modern languages to common roots, thus reconstructing Proto-Indo-European, a purely theoretical tongue. But as Renfrew points out, if the difficulties of dating genetic change are vexing, the ones for dating linguistic change are even harder: though linguists can chart the rate of change from, say, late Latin to early Spanish, they can't prove the same rate applies for other languages before the advent of writing.

Renfrew sees evidence that linguists — like their colleagues in other disciplines when they look at prehistoric developments — are beginning to think outside the box and relate language to "tangible material processes" like floods, the spread of agriculture and demographic developments. Currently the prehistory of language is, as Renfrew puts it, "at the edge of knowability," but that could change in a matter of decades if the feverish pace of cross-fertilization of molecular anthropology and archaeology continues.

And there is no reason why it will not. "Thirty or 40 years ago the story of Europe was basically one of watching the covered wagons roll west, full of pottery, wheat and barley, pushing aside the hunter-gatherers," says Clive Gamble, an archaeologist at the University of Southampton. Further back, archaeology was harnessed to political ends, subsumed in Nazi Germany to the dogma of Aryan man, and in most other places in Europe to a kind of manifest destiny.

The new research is almost certain — like the genome itself — to suggest a more nuanced and complicated idea of what it means to be a human being. We are all more similar than racists or nationalists like to think: the genetic variance throughout the 6 billion humans on earth amounts to less than that in a single troop of chimpanzees. But those genes have afforded us an ability to adapt from foraging for hazelnuts to searching the Web in the evolutionary blink of an eye. What happens in the next blink is anybody's guess.