Stone artifacts unearthed at Georgia’s Dmanisi archaeological site, 90 kilometers southwest of Tbilisi, suggest that early man may have gotten his start in Eurasia and then migrated to Africa, an international team of scientists contends.
The team’s findings, published in the June 6, 2011 print edition of the Washington, DC-based scientific journal PNAS (Proceedings of the National Academy of Sciences), hold that “Eurasia was probably occupied [by early humans] before Homo erectus [the species from which a straight line of evolution to modern humans begins -- ed] appears in the East African fossil record.”
The sediment in which the artifacts, crude stone tools, were found is “almost 70,000 years older “ than the 1.85 million-year-old early human fossils, also found at Dmanisi, that date as Eurasia’s earliest homo erectus, Reid Ferring, a professor of geoarcheology at the University of North Texas and a member of the research team, told EurasiaNet.org. The sediment is located “several meters below” that earlier find, he said.
No human fossils have been found next to the tools, but the researchers believe that the artifacts -- stones sharpened for cutting -- belonged to humans more primitive or from the same era as Dmanisi’s 1.85-million-year-old homo erectus (known as “homo georgicus”). The artifacts will be kept at the Georgian National Museum run by team member Davit Lordkipanidze, a prominent archaeologist-anthropologist who discovered homo georgicus.
The evidence has prompted the Dmanisi researchers to consider the strong possibility that some more primitive form of human evolved in Africa, came to Eurasia, and there evolved into homo erectus.
“For a long time, everyone assumed that homo erectus evolved from homo habilis [1.44 million to 2.3 million years], but later it appeared that homo erectus and homo habilis lived side by side in Africa for hundreds of thousands of years, so one cannot evolve into another and both survive,” Ferring said. “That raises the question where homo erectus came from.”
“Very importantly, the Dmanisi fossils are just barely homo erectus. They are the most primitive of homo erectus . . . very small-brained, very short people,” he continued. “Most of the skulls in Dmanisi have a brain size of 600 cubic centimeters, while the first homo erectus found in Africa is almost 850 cubic centimeters; more than one-third bigger.”
Researchers on the ground in Dmanisi also do not rule out the possibility that Eurasia’s homo erectus may have evolved in parallel with homo erectus in Africa.
Ferring describes homo erectus as the “first cosmopolitan” human, with an apparent penchant to travel. The hominid is believed to have spread quickly from Eurasia to China, Southeast Asia and Europe.
The possible reasons for such a move may not be immediately clear, but, to the homo erectus of the time, territory was territory, one American anthropologist noted.
"Remember, it would not have been obvious to the hominins they were leaving Africa. There were no signs saying 'You are leaving Africa now — come and visit us again!'" George Washington University Professor of Human Origins Bernard Wood joked to the weekly journal Nature.
While few doubt the importance of the Dmanisi find for the study of human evolution, some observers caution that only new human fossils could warrant a conclusion in favor of the hypotheses of the Dmanisi team. Ferring acknowledges that “very aggressive surveys” are needed to find “even older fossils,” but underlines Georgia’s potential role in providing answers to key questions about human evolution.
“Once again the answers may come from the Caucasus, “ he said. “We may even say maybe from Georgia.”
Giorgi Lomsadze is a freelance reporter based in Tbilisi.