The First Americans

Science  23 Dec 2005:
Vol. 310, Issue 5756, pp. 1900b
DOI: 10.1126/science.310.5756.1900b

An analysis of ancient Brazilian skulls has lent new weight to the controversial theory that not one but two distinct populations from Asia colonized the Americas.

Scientists have long believed that starting about 12,000 years ago, the ancestors of present-day American Indians migrated from northeast Asia across the Bering land bridge. But in recent years, Walter Neves of the University of Säo Paolo in Brazil has argued that these immigrants were preceded by people from Southeast Asia who came from the same stock that settled Australia and Melanesia.

Last week, Neves and his colleague Mark Hubbe claimed new support for this idea from an analysis of 81 skulls, ranging in age from 7500 to 11,500 years, found in the Lagoa Santa region of southeast Brazil. Detailed comparisons revealed that the skulls did not resemble people from northeast Asia, who tend to have short, wide skulls with relatively flat faces, but rather took after present-day people from Australia and Melanesia, whose skulls tend to be long and narrow with projecting faces. Because other, similar ancient skulls have been found in North and South America, Neves and Hubbe concluded in a paper published online in the Proceedings of the National Academy of Sciences that two distinct populations probably colonized the New World.

Physical anthropologist Clark Larsen of Ohio State University in Columbus cautions that changes in diet over time can modify the jaw muscles in ways that also alter skull shape, without major genetic changes. Nonetheless, says archaeologist Tom Dillehay of Vanderbilt University in Nashville, Tennessee, “Neves is building a more solid case.”

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