February 18, 2005
Fossil Study Adds 35,000 Years to Age of Mankind
Thoroughly modern man just became more ancient.
New fossil evidence from Ethiopia shows that anatomically modern humans roamed Africa about 195,000 years ago, at least 35,000 years earlier than previously thought."These are the oldest well-dated fossils of modern humans known anywhere in the world," an international team of scientists reported Wednesday in the British journal Nature.
Fossils of early human ancestors, the hominids, go back more than 6 million years. The first primitive human species have been dated to 1.8 million years ago. But until now, Homo sapiens - with the large brain case, sharply rising forehead and prominent chin of today's humans - was thought to have emerged in Africa no earlier than 160,000 years ago.
The discovery is the result of a new look at the rock formations along the Omo River in southern Ethiopia, where famed anthropologist Richard Leaky found the partial skeleton of an individual he called Omo I in 1967.
Leaky used the radioactive decay rate in ancient oyster shells to peg the age of the fossil at 130,000 years. Subsequent discoveries in Ethiopia pushed the dawn of the modern human back to around 160,000 years ago.
Now, using a new technique to pinpoint the age of mineral crystals in volcanic ash at Leaky's site, U.S. and Australian scientists have revised the age of the fossils found there to 195,000 years.