Geneticists track Indo-European languages.

Linguistic tongues may soon wag over a study that correlates genetic traits with native languages throughout Europe, giving a new twist to old disagreements about the origins and distribution of the first Indo-Europeans.

Researchers have long debated the exact beginnings of different Indo-European languages, which include such diverse tongues as English, Greek, Russian, and Iranian.

These and 140 other modern languages are generally believed to have diverged from one ancestral language spoken more than 6,000 years ago, says linguist Merritt Ruhlen, an independent researcher in Palo Alto, Calif.

Currently two main theories, based primarily upon archaeological evidence, attempt to trace the spread of these languages into Europe.

Most experts favor the theory that the first Indo-European speakers invaded Europe f rom the Pontic Steppes - an area north of the Black Sea in what is now the southern Ukraine-starting around 4,500 B.C.

An alternative theory gives Indo-Europeans a longer European history suggesting that early farmers brought agriculture and their language from ancient Turkey beginning approximately 7,000 B.C.

Because none of these early cultures had yet developed writing, such debates remain difficult to resolve with traditional archaeological methods. However, if biological divergence mirrors linguistic branchings, then researchers can look for evidence of ancient migrations in the genetic patterns of modern populations (SN: 6/9/90, p.360).

In the first such attempt focused specifically on Europe, geneticist Robert R. Sokal and his co-workers from the State University of New York at Stony Brook have now compared genetic traits with linguistic patterns.

The team analyzed existing data on the relative abundance of 25 genetic traits (such as blood proteins) examined in 2,111 studies from across Europe. In all, the Stony Brook researchers compiled data from more than 250,000 individuals, estimates Sokal. Results from the study appear in the Aug. 15 Proceedings of the National Academy of Sciences.

European genetic traits clearly correlate with language patterns, the researchers found. Geographic distribution can account for most of this correlation, but a "highly significant" partial correlation - 15 percent of the total - remained after the researchers factored out the geographic distance between populations.

Sokal and his co-workers had hoped to find a genetic-linguistic pattern clearly associated with one or the other of the early migration routes, but they saw "not even the slightest indication that genetic evidence supports" either of these theories, Sokal says. Their results indicate that ancestral groups of the modern Indo-Europeans divided several times, but do not show whether they divided before or after the settlement of Europe.

While these results do not disprove traditional theories, they indicate that scientists should reevaluate the current theories, says Sokal. He refuses to speculate on other possible origins for the Indo-Europeans, preferring to "leave that to the archaeologists."

In a study published last year, researchers led by Sokal found a genetic pattern consistent with a migration of early farmers, but did not look for a correlation with languages. The current lack of regional data complicates any similar study of genetic patterns associated with possible invaders from the Pontic Steppes, Sokal says.

He plans a more detailed study of the relationships between modern language patterns and archaeological data from Europe, without reference to genetic traits.