A new analysis of the dental fossils of human ancestors suggests that Asian populations played a larger role than Africans in colonizing Europe millions of years ago, a study released on Monday said.
The findings challenge the prevailing "out of Africa" theory, which holds that anatomically modern man first arose from one point in Africa and fanned out to conquer the globe.
The study also bolsters the notion that Homo sapiens evolved from different populations in different parts of the globe.
The "out of Africa" scenario has been underpinned since 1987 by genetic studies based mainly on the rate of mutations in mitochondrial DNA, a cell material that is inherited from the maternal line of ancestry.
But for this study, European researchers opted to study the tooth fossil record of modern man's ancestors because of their high component of genetic expression.
The investigators examined the shapes of more than 5,000 teeth from human ancestors from Africa, Asia and Europe dating back millions of years.
They found that European teeth had more Asian features than African ones.
They also noted the continuity of the Eurasian dental pattern from the Early Pleistocene until the appearance of Upper Pleistocene Neanderthals suggests the evolutionary courses of the Eurasian and African continents were independent for a long period.
"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 and contacts among populations within and outside continents," the researchers wrote.
"In the light of these results, we propose that Asia has played an important role in the colonization of Europe, and that future studies on this issue are obliged to pay serious attention to the `unknown' continent."
The paper was written by researchers at Spain's national center for research into human evolution in Burgos and appears in the journal Proceedings of the National Academy of Sciences.