A 10-year study of ancient human skulls from Brazil provides new evidence that two distinct populations of prehistoric people settled the Americas more than 12,000 years ago — a finding that raises new questions about the identity and origins of the first Americans. Brazilian researchers say physical features of the skulls excavated from several limestone caves near Lagoa Santa in central Brazil differ sharply from the ancestors of today's Native Americans, who are thought to have migrated from Siberia to North America at the end of the last Ice Age.
     "These earliest South Americans tend to be more similar to present-day Australians, Melanesians and sub-Saharan Africans," Brazilian anthropologist Walter Neves reported Monday in the Proceedings of the National Academy of Sciences. Neves said the findings suggest a "complex scenario in regards to the influx of humans to the New World," but he skirted controversial new theories that the first people to reach the Americas came by boat from Asia, the South Pacific or perhaps even Europe, rather than crossing a land bridge spanning the Bering Strait, as most archaeologists believe. "No transoceanic migration is necessary to explain our findings," he said. Instead, he said the South American population might have come by the same route used by the ancestors of modern Native Americans.
     The age of the Lagoa Santa skulls does not clearly establish which of the two populations entered the Americas first — or when — but Neves said it is plausible to think that the South American population arrived first and then moved, or was pushed southward by the Asian ancestors of present-day Native Americans, whose genetic makeup and linguistic patterns today are dominant in both continents' native peoples. Some genetic studies comparing ancient remains and modern humans have suggested there might have been anywhere from one to four separate migrations of prehistoric peoples to the Americas.
     Human skeletal remains older than 8,000 years are rare in the Americas, but isolated examples of skulls with seemingly "un-Asian" features have been found and reported in Chile, Colombia, Mexico, Florida and California. But the analysis by Neves, of the University of Sao Paulo's Laboratory of Human Evolution, and his colleague Mark Hubbe is the first to look comprehensively at a large number of remains from a single location. Neves says individual skulls may vary widely, but in the aggregate, the 81 South American skulls show a clear pattern that differs markedly from the features of modern Native Americans. He says today's Native Americans and their ancestors have narrow and long skulls, squarish jaws, and relatively high noses and eye sockets. The South American skulls tend to have short and wide skulls, jutting jaws, and relatively low noses and eye sockets.

Source: The Atlanta Journal-Constitution (13 December 2005)