A Brazilian study involving a large collection of South American skulls suggests at least two distinct groups of early humans colonized the Americas.

Anthropologists Walter Neves and Mark Hubbe of the University of Sao Paulo studied 81 skulls of early humans and found them to be different from both modern and ancient Native Americans, National Geographic News reported Tuesday.

The 7,500- to 11,000-year-old remains suggest the oldest settlers of the Americas came from different genetic stock than more recent Native Americans.

Modern Native Americans share traits with Mongoloid peoples of Mongolia, China, and Siberia, the researchers said. But they found dozens of skulls from Brazil appear much more similar to modern Australians, Melanesians, and Sub-Saharan Africans.

The study is described in this week's online edition of the Proceedings of the National Academy of Sciences.

Copyright 2005 by United Press International