The New York Times > Oldest Remains of Human Beings Are Identified

This has interesting implications in relation to the previous article about the possible mating of Homo Sapiens and Neanderthals.

"By JOHN NOBLE WILFORD

Scientists have determined that human fossils found in Ethiopia in 1967 are 65,000 years older than first thought, from about 195,000 years ago. The revised date, they said, makes the skulls and bones the earliest known remains of modern Homo sapiens.

The research reinforces the theories of an African origin for modern humans, and the earlier date gives the species more time to have evolved the cultural attributes that probably supported its spread to Asia and Europe from Africa. The new date appears to be near the early boundary for modern human emergence, as suggested in recent genetic studies.

The findings were announced today by a research team led by Dr. Ian McDougall of the Australian National University in Canberra and are being described in detail in Thursday's issue of the journal Nature.

Dr. McDougall, a geologist, and his colleagues reported that a re-examination of the sediments in which the fossils were found and the use of more reliable dating methods showed that the two individuals lived 195,000 years ago, give or take 5,000 years, "making them the earliest well-dated anatomically modern humans yet described."

An expedition led by Richard E. Leakey, the Kenyan paleontologist, excavated the two fossil specimens 38 years ago along the Omo River in southern Ethiopia, near the town of Kibish. The fossil-bearing sediments were dated at 130,000 years, though many researchers, even the discoverers, were never sure this was a valid age for the specimens. Scientists at the time thought it unlikely that modern humans could be more that 100,000 years old.

Two years ago, scientists announced a discovery in northeast Ethiopia, at the village of Herto, that pushed back the earliest fossil evidence for modern humans to 160,000 years ago. Dr. Tim D. White of the University of California, Berkeley, and collaborators said the skulls of two adults and a child "represent the probable immediate ancestors of anatomically modern humans."

Meanwhile, biomolecular research on the genetic diversity among human populations pointed to a common maternal ancestor in Africa, which inevitably became known as the African Eve. This genetic evidence put the origin of modern humans at 150,000 to 200,000 years ago.

Now the revised dates for the Omo fossils not only appear to push back modern human origins even further, Dr. John G. Fleagle of Stony Brook University on Long Island said in an interview, but also "bring the bones and genes into concordance."

Dr. Fleagle, an anatomist who specializes in human origin studies, and Dr. Francis H. Brown, a geologist at the University of Utah, were co-authors of the journal report.

Dr. Brown said the new research confirmed that the two Omo specimens are essentially the same age and lived within a few hundred years of each other at the same site.

Although other scientists accepted the new geological dating, there continued to be controversy over the nature of the two specimens. The skull and bones identified as Omo I are modern in nearly all respects. But Omo II, a partial skull but no limb bones, appears to be more primitive than the first modern Homo sapiens.

Dr. Richard G. Klein of Stanford University, who was not involved in the research, said the differences between the two individuals were sharp enough to suggest that "one or both are intrusions in the deposits" where the fossils were excavated. That is, Omo I could be a more recent specimen.

Dr. Fleagle acknowledged that there were several possible explanations, including that the fossils may have come higher and lower sedimentary levels. "I don't really know what to make of the dissimilar specimens," he said.

It is likely, Dr. Fleagle continued, that several populations of separate but related human groups may have lived in the area, such as the Neanderthals and Homo sapiens at a later time, or they could be examples of diversity within a single species.

"It's not neat," he said, "but there was a lot of morphological diversity in species at this time of evolution."