Tuesday, February 01, 2011


Stone Age people apparently took a surprisingly fast track out of Africa via an unexpected route - Arabia. Modern humans reached Arabia's eastern edge as early as 125,000 years ago, according to a report in Science magazine. That's a good 65,000 years earlier than the generally accepted date for the first substantial human migrations beyond Africa.

A cache of stone tools unearthed at an Arabian Peninsula rock shelter called Jebel Faya resemble sharpened points and cutting implements from East African sites of about the same age, says a scientific team led by physical geographer Simon Armitage of the University of London and archaeologist Hans-Peter Uerpmann of the University of Tübingen in Germany. Jebel Faya is located in what's now the United Arab Emirates. "New dates at Jebel Faya reveal that modern humans migrated out of Africa much earlier than previously thought, helped by global fluctuations in sea-level and climate change in the Arabian Peninsula," Armitage says.

The timing and dispersal of modern humans out of Africa has been the source of long-standing debate, though most evidence has pointed to an exodus along the Mediterranean Sea or along the Arabian coast approximately 60,000 years ago. Many advocates of this later African departure suspect that a massive eruption of Indonesia's Mount Toba around 74,000 years ago created a global 'volcanic winter' that decimated modern human populations in Africa and rendered the Indian subcontinent uninhabitable for thousands of years.

Finds at Jebel Faya call that scenario into question, Armitage says. "These 'anatomically modern' humans - like you and me - had evolved in Africa about 200,000 years ago and subsequently populated the rest of the world," said Armitage. "Our findings should stimulate a re-evaluation of the means by which we modern humans became a global species." By about 130,000 years ago, decreased sea levels narrowed the Bab al-Mandab Strait separating East Africa from southwest Arabia to about 4 kilometers, allowing safe passage, the researchers estimate. Travelers could have then moved through a network of Arabian lakes and rivers created by warm, wet conditions at that time.

Initial finds at Jebel Faya came from settlements dating to between about 3,000 and 10,000 years ago. Stone tools from roughly 38,000 years ago then turned up. In March 2006, investigators began to unearth tools from the ancient rock shelter, which was occupied between 100,000 and 125,000 years ago. Finds at Jebel Faya consist of stone points, a few hand axes and a variety of other sharpened rocks. The researchers analyzed these Palaeolithic stone tools using a technique called luminescence dating and discovered that they were technologically similar to tools produced by early modern humans in east Africa, but very different from those produced to the north, in the Levant and the mountains of Iran. Dr Armitage calculated the stone tools at Jebel Faya are 125,000 years old, and they were made immediately after the period in which the Bab al-Mandab seaway and Nejd Plateau were passable. This suggests that early modern humans migrated into Arabia directly from Africa and not via the Nile Valley and the Near East.

"This is a huge milestone, but unfortunately it raises more questions than it answers," said Jeffrey Rose, an archaeologist at the University of Birmingham in England. Richard Klein, a paleoanthropologist at Stanford University, said that the Uerpmann team's case for an earlier out-of-Africa expansion was "provocative, but in the absence of human remains, it's not compelling." Christopher Stringer, a paleoanthropologist at the Natural History Museum in London, said that Arabia had long been a black hole in terms of early human migrations and that the new discovery was an impressive first start. He, like Dr. Klein, said it was hard to say who made the tools without having any fossil bones from the same site. But the tools are 'suggestive' of having been made by people who came out of Africa, Dr. Stringer said.

Edited from EurekAlert!, ScienceNews, The New York Times (27 January 2011), Past Horizons (30 January 2011)
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