Spread of modern humans occurred later than previously thought?
(12 January 2007: VIDYYA MEDICAL NEWS SERVICE) -- The spread of modern humans out of Africa occurred 40,000 to 50,000 years later than previously thought, according to researchers including one Texas A&M University anthropologist.
Ted Goebel, associate director of the Center for the Study of the First Americans at Texas A&M, is the author of the paper titled “The Missing Years for Modern Humans” that appears in the Jan. 12 (Friday) issue of Science.
Goebel’s paper is one of three published in the current issue of Science dealing with the origins and dispersals of modern humans during the Ice Age. A fourth paper appeared in a previous issue of the journal.
The other papers are written by human paleontologist Frederick Grine of Stony Brook University, geneticist Annamaria Olivieri from the University of Pavia in Italy, and archeologists Michael Anikovich and Andre Sinitsyn of the Russian Academy of Science and John Hoffecker of the University of Colorado.
“All of them have one thing in common,” says Goebel of the papers. “They are all trying to investigate and demonstrate when it was that modern humans evolved in Africa, left Africa and colonized different areas of the Old World.”
Previous theories held that modern humans spread from Africa 100,000 years ago. New data, however, suggest that their migration occurred only 50,000 to 60,000 years ago, Goebel argues. Additionally, the spread of modern humans in eastern Europe and Russia occurred earlier than previously thought notes Goebel.
The new information, according to Goebel, is based on paleontological evidence of human fossils including a modern human skull from Hofmeyer, South Africa that was discovered in 1952, mitochondrial DNA used to research modern human dispersal from western Asia and archeological evidence from artifacts found at the Kostenki sites along the Don River in Russia.
Using a combination of dating techniques on the skull, Grine and his colleagues determined that sediment in the skull’s endocranial cavity was deposited 36,000 years ago. According to the authors, the Hofmeyer skull is more similar to modern humans of Upper Paleolithic Europe than recent South Africans or Europeans and has little in common with Neanderthals.
“The idea is that modern humans developed around 100,000 years ago or so in east Africa,” says Goebel. “When they developed the physical and behavioral repertoire that we consider to be modern, they then successfully colonized new areas. This new evidence suggests that modern humans spread out of Africa very late in the Pleistocene era.”
The DNA analyzed by Olivieri suggests that two genetic lineages originated simultaneously in western Asia between 40,000 and 45,000 years ago and from there spread into northern Africa. And artifacts found at the Kostenki sites led researchers to believe that part of central Eurasia and Russia were colonized just as early as Europe by modern humans.
“Why is it such a big deal? The big deal is we have these models that we use to explain the origin and dispersal of modern humans,” says Goebel. “But we still don’t have all of the evidence required to test these models – to disprove or prove them.”
“What we have are three pieces of the puzzle and they help us test the new theory and all pretty much support this notion that modern humans evolved in Africa and then they spread from Africa.”
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