The dating of the oldest undisputed fossil ofHomo sapiens was estimated 200,000 years ago. Radiometric dating of a volcanic layer in Ethiopia allows us to reassess the age of our species several thousand years earlier.
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How old is the species Homo sapiens ? The emergence of the species in Africa occurred during the Late Pleistocene and the Omo Kibish Formation in southwest Ethiopia contains the remains of Omo I which had so far been dated within 200,000 years ago. In study published in the newspaper Nature, a team of researchers is now reassessing the age of Omo I.
Older than 230,000 years
The Omo Kibish formation is located in the valley of east african rift, which is an area that has experienced and still experiences strong volcanic activity. However, the authors explain that each volcanic eruption has a kind ofdigital print, which makes its identity recognizable and unique. The remains of Omo I lay beneath a thick layer of volcanic ash, the dating of which was uncertain until then because the ashes were too fine for a absolute dating be carried out.
However, the authors of the study used stones pumice from this same layer of ash in order to carry out a radiometric dating. They were thus able to determine that the age of the ash layer above the remains of Omo I was produced by the eruption of the volcano Shala, located 400 kilometers from the site, 230,000 years ago. The authors also indicate that fossils older are sometimes attributed to early stages of the lineage H. sapiens but that Omo I is to date the oldest fossil indisputableHomo sapiens due to anatomical features such as a high cranial vault and globular, as well as a chin.
Homo Sapiens ages 35,000 years
From paleontologists Australians and Americans have reviewed the dating of human fossils found along the Omo River in southern Ethiopia.
Article from France Sciences, published February 28, 2005
Both skulls, dubbed Omo I and II, were unearthed in 1967 and dated according to a first estimate of about 130,000 years by analysis of the rate of thorium and D’uranium oysters found in the sediments (a dating at the time controversial because it was thought that modern man could not be more than 100,000 years old).
But the new methods available led Francis Brown, University of Utah, John Fleagle, Stony Brook University (New York), and Ian MacDougall, Australian National University, to another conclusion: both fossils, contemporary despite morphological differences, date back to nearly 195,000 years (to 5,000 years).
The researchers particularly focused on the decay rate of theargon feldspar crystals from sediments located just below the fossils and ash collected well above (about 50 meters); the former indicated an age of 196,000 years and the latter a lower limit of 104,000 years.
The speed of sedimentation since the Omo river was very important at the time, the age of the remains would therefore be closer to 196,000 years. Until then, the oldest human fossils were considered to be those found at Herto, also in Ethiopia, and estimated to be between 154,000 and 160,000 years old. This work confirms recent paleogenetic analyzes locating the origin ofHomo sapiens between -150,000 and -200,000 years.
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