When did early humans first leave Africa? If you measure the rate that DNA changes in human bodies over time, then it was between 62,000 and 95,000 years ago — not the 106,000 years ago date which was suggested by recent tools found in the Arabian peninsula.
An international team, led by Johannes Krause of Germany’s Tűbingen University, took samples of mitochondrial DNA, which is passed down through the female line, from a variety of ancient human fossils. According to their calculations, the last common ancestor of every living modern human is a woman who lived around 160,000 years ago — sometimes described in popular science as Eve or the Mitochondrial Eve.
Their findings that humans left Africa around 95,000 years ago at the very earliest are in agreement with earlier genetic studies, which suggested that the migration could have taken place as recently as 40,000 years ago. However, it does conflict with the 2011 announcement that over 100 sites in the Sultanate of Oman contained tools that were made by early humans around 106,000 years ago.
However, oddly enough, there were no animal remains found at those sites — just the flint tools, which were allegedly created by striking flakes off of flint.
A 2005 find of 700,000 year old flint tools in Britain — 200,000 years before the agreed-upon dates before humans arrived in that country — was equally perplexing. Tools this old could not have come from our species, Homo sapiens, and were presumably instead created by the Neanderthals.
In 2012, some 300,000 year old flint tools, also attributed to Neanderthals, were collected in northern France.
The date when early humans left Africa was pretty important to our cousins. We outcompeted the other species in our genus, including both the Neanderthals and Homo erectus and possibly others. We are now, of course, the only humans on the entire planet, with a population of about seven billion and growing.
While the debate will continue, for the moment I tend to feel that flint tool evidence alone doesn’t prove much about early human migration. The DNA study, on the other hand, may be the real deal.
When do you think early humans left Africa?
[photo of skull discovered in South Africa courtesy José Braga, Didier Descouens, and Wikipedia Commons]