(AP) -- Anthropologists analyzing ancient skulls from around the world say modern humans did not arise from a single migration from Africa, but from small groups that journeyed to every continent and intermingled with archaic humans such as the Neanderthal.

In a study appearing Friday in the journal Science, the researchers say that distinctive features in ancient skulls, some dating to more than 200,000 years, suggest that modern humans descended independently from common ancestors that lived on nearly every continent and mingled with earlier human types.

"There was no single wave of modern humans out of Africa," said Milford H. Wolpoff, a University of Michigan anthropologist and co-author of the study. Modern humans did originate in Africa, but they migrated in small groups over thousands of years and journeyed to Asia, Europe and even as far as Australia, he said.

"It was not a single wave," Wolpoff said. "It was more like a leaky faucet. They moved out in dribbles."

This is contrary to the Eve theory, which holds that modern humans evolved in Africa and moved into the rest of the world in a singular movement of perhaps 10,000 people. Once on the other continents, the theory holds, the moderns supplanted the existing more ancient humans, such as the Neanderthal.

But Wolpoff and his co-authors said that skulls dated 25,000 to 30,000 years from Europe and from Australia share strong characteristics of 40,000 to 200,000-year-old archaic human skulls found in Europe, Indonesia, and Africa.

The more recent skulls from Europe, for instance, showed clear evidence of a Neanderthal influence, along with features of the early modern humans that evolved in Africa. Early modern human skulls from Australia had similarities to the more ancient skulls from Indonesia.

Wolpoff said this suggests modern humans dribbled out of Africa in small numbers and migrated to distant lands where they mingled with a more ancient human type that already lived in those places.

Eventually, he said, the superior genes of modern humans dominated the species through natural selection and the clearly identifiable archaic humans, such as the Neanderthal, disappeared.

"The Neanderthal disappeared as a result of interbreeding," Wolpoff said.

Traces of those archaic humans survive still, in the genes of modern humans, said John Hawks, University of Utah anthropologist and co-author of the study. And these genes produce distinctive markings on modern human skulls.

"There are still Neanderthals today and they are us," Hawks said in a statement released by the University of Utah. "People of European descent are also people of Neanderthal descent."

The conclusion is controversial, and another University of Utah anthropologist, Henry Harpending, said he is unconvinced.

"The genetic evidence is unequivocal in support of the idea that we are all descended from a small group of Africans within the last 100,000 years," Harpending said in a statement. "There is no Neanderthal in us."

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