Miami's Hart part of team identifying early Homo sapiens

Miami geologist William K. Hart is part of the team that has identified remains of the first Homo sapiens. The fossils support the hypothesis that modern humans evolved in Africa.

Cover story articles in the June 12 issue of the journal Nature tell of the discovery and identification of the fossilized crania of two adults and a child by the research team in Herto village in Ethiopia's Middle Awash study area. These African fossils, estimated at about 160,000 years old, are the world's oldest near-modern humans, say the researchers.

"This area of Africa was inhabited by a series of human ancestors from Ardipithecus at 6 million years ago, all the way through to the Herto people at 160,000 years ago. We have a great sequence of fossils showing that we evolved in Africa, and not all over the globe," said Tim White of U.C. Berkeley, a lead researcher.

Skull pieces and isolated teeth from seven other individuals were also found.

The research team found the fossils in late 1997 and worked over three years to separate the crania (skulls lacking lower jaw) from hardened sediment around them and to piece together fragments of the crania. Concurrently, geologists and geochronologists including Hart, worked to establish the age of the finds, also a difficult task.

"This has been the most challenging hominid find for us to constrain chronologically," said Hart. "The ultimate time period, between 154,000 to 160,000 years old, is difficult because it's at the edge of young and old sides of different dating techniques.