Using a new method for exploring ancient relationships among languages, linguists have found evidence further illuminating the peopling of North America about 14,000 years ago. Their findings follow a recent proposal that the ancestors of Native Americans were marooned for some 15,000 years on a now sunken plain before they reached North America.

This idea, known as the Beringian standstill hypothesis, has been developed by geneticists and archaeologists over the last seven years. It holds that the ancestors of Native Americans did not trek directly across the land bridge that joined Siberia to Alaska until the end of the last ice age, 10,000 years ago. Rather, geneticists say, these ancestors must have lived in isolation for some 15,000 years to accumulate the amount of DNA mutations now seen specifically in Native Americans.

Archaeologists examining deep sea cores from the Bering Strait believe that a special ecological zone known as shrub tundra existed there during the Last Glacial Maximum, an exceptionally cold period that lasted from about 30,000 to 15,000 years ago. Though often referred to as a bridge, the now sunken region, known as Beringia, was in fact a broad plain. It was also relatively warm, and supported trees such as spruce and birch, as well as grazing animals.

Writing in the journal Science last month, John F. Hoffecker, an archaeologist at the University of Colorado, summarized the evidence for thinking the Beringian plain was the refuge for the ancestral Native American population identified by the geneticists. “The shrub tundra zone in central Beringia represents the most plausible home for the isolated standstill population,” he and colleagues wrote.