Scientists narrow age estimate for fossils of human ancestor
NEW YORK (AP) - Scientists say they have finally calculated the age of the youngest known remains of Homo erectus, which is generally considered an ancestor of our species.
The fossilized skull fragments and other bones were uncovered on the Indonesian island of Java in the 1930s. Determining their age has been a scientific challenge, and a wide range has been proposed by numerous studies.
In a report released Wednesday by the journal Nature, scientists conclude the remains are between 108,000 and 117,000 years old. Researchers used five dating techniques on sediments and fossil animal bones from the area, combining 52 age estimates for the analysis. The project took 13 years to complete.
'œI don't see any way to date this site more thoroughly," said paleoanthropologist Russell Ciochon of the University of Iowa, an author of the study.
H. erectus arose in Africa about 2 million years ago and spread widely there and in Asia, and possibly into Europe. It reached Java more than 1.5 million years ago, and the new dates suggest it died out at least 35,000 years before the arrival there of our own species, Homo sapiens.
H. erectus may have been doomed on Java by climate change that turned its open woodland environment into rain forest, Ciochon said. Still, it evidently existed longer on Earth than any other species on our 'œHomo'ť branch of the evolutionary tree.
Susan Anton, a New York University anthropologist who did not participate in the work, called the dating effort 'œheroic.'ť But she said she considered the reported age range to be too narrow. She said she preferred a span of less than 550,000 years old to more than 100,000 years old.
That's roughly what she and co-authors proposed in a paper published in 2011. The younger end of the range in that paper was as recent as 120,000 years, which she said is virtually the same as the new result.
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