WASHINGTON - Early human-like residents of Europe may have arrived out of Asia, rather than just Africa.
An international team of researchers reports in Monday's online edition of Proceedings of the National Academy of Sciences that Asians appear to have played a larger part in the settlement of Europe than did Africans.
The team led by Maria Martinon-Torres of the National Center for the Investigation of Human Evolution, in Burgos, Spain, reached that conclusion after analyzing more than 5,000 fossil teeth from early hominins, an early form of human predecessors.
After studying ancient teeth from Africa, Asia and Europe, the researchers report that early European populations had more Asian features than African ones.
That conclusion also supports the theory that the development of the genus Homo - modern humans are Homo sapiens - occurred both in Africa and Asia.
The teeth studied were from the genera Homo and the earlier Australopithecus.
"The history of human populations in Eurasia may not have been the result of a few high-impact replacement waves of dispersals from Africa, but a much more complex puzzle of dispersals," Martinon-Torres' team wrote.
The differences in tooth formation, dimensions and shapes in Europe and Asia and that of Africa suggest separate evolutionary courses for a long period, they said.
That doesn't mean there was no genetic flow between Africa and Eurasia, but rather that the Eurasians were probably descendants of an ancient out-of-Africa exodus, they said.
Milford Wolpoff, an anthropologist at the University of Michigan, noted that dental evidence is always difficult to work with and said this research team did "a very good job."
The idea that human evolution involved small and relatively isolated populations for much of its history, with a migration out of Africa and other migrations between continents, "is in concordance with the interpretations of paleoanthropologists," he said.
"It may be in different languages, but we are singing the same song," said Wolpoff, who was not part of the research team.
The research was supported by the Spanish Ministry of Science and Education, Fundacion Caja Madrid, Fundacion Atapuerca, Fundacion Duques de Soria and the Georgian National Museum.
