Image: Dmanisi excavation site in the Republic of Georgia
Reid Ferring via AP
Researchers work at the Dmanisi excavation site in the Republic of Georgia. The worldwide spread of ancient humans has long been depicted as flowing out of Africa, but tantalizing new evidence suggests it may have been a two-way street.
updated 6/6/2011 7:55:50 PM ET 2011-06-06T23:55:50









Wil Roebroeks, a professor of archaeology at Leiden University in the Netherlands, said the new findings suggest a sustained regional population that had successfully adapted to the temperate environment of the southern Caucasus at about 1.8 million years ago.

He called it "an important observation for our views on the earliest colonization of Eurasia."


But he stressed that's a hypothesis that will be tested in future studies. "Possible does not equate with observable, but the Dmanisi evidence has forced us to have a good fresh look at some of our basic assumptions," said Roebroeks.

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Not so sure of Ferring and Lordkipanidze's theory is Richard Potts, director of the human origins program at the Smithsonian's National Museum of Natural History.

"The new evidence at Dmanisi consists of stone tools, not fossil bones. So we don't really know who the toolmaker was in the time range of 1.85 to 1.77 million" years ago, he said. "(We) cannot know this for sure until fossils come from this older level."

Michael D. Petraglia, co-director of the Centre for Asian Archaeology, Art & Culture at England's University of Oxford, said the findings do show that early humans were present in Eurasia between 1.85 million and 1.78 million years ago.

"The stone tool evidence represents the oldest and best-documented case for the presence of early humans in Asia. This means that early forms of humans probably migrated out of Africa at or before 1.85 million years ago, or before, colonizing new regions of the world for the first time," he said.

But Petraglia added, that he thinks the authors "are on less solid ground" with their suggestion that this early group may have migrated back to Africa.


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