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Ancient skull may fill gap in the development of man

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A million-year-old skull discovered in east Africa suggests human facial features began appearing 300,000 years earlier than previously believed, researchers say.

The well-preserved fossil, lodged in silt and clay in Eritrea, is the only skull found in Africa from between 1.4 million and 600,000 years ago and thus fills in a gap in the fossil record, the researchers said.It combines features of both the human ancestor Homo erectus and modern man, or Homo sapiens, the researchers said. As a result, they aren't ready yet to assign it to one species or the other.

The analysis was done by Ernesto Abbate of the University of Florence in Italy and colleagues from South Africa, Switzerland and Eritrea. It was published in Wednesday's issue of the journal Nature.

Scientists have long debated when, where and how Homo sapiens emerged from more primitive species. Some anthropologists believe that human facial features - that is, Homo sapiens features - did not begin appearing until about 700,000 years ago.

Homo erectus had a flat skull, a sloping forehead and a thicker brow and smaller brain than Homo sapiens.

The skull unearthed in Eritrea bears some of the primitive characteristics of Homo erectus, such as the large brow ridge.

But it is like Homo sapiens in one important aspect: The skull is widest at a higher point than skulls of Homo erectus, which are widest near ear level. That could indicate a larger brain.

Because the fossil has not yet been fully cleaned, reconstructed and studied, the authors cautioned that their assessment is preliminary.

The skull, two lower teeth and two fragments of a pelvis were found in 1995 to 1997 near remains of animals that roamed the African savannah at the time, including three-toed horses.

Scientists generally believe Homo sapiens evolved in Africa, then moved toward Europe and Asia. Abbate said the fossil's location in Eritrea, which borders the Red Sea and lies between Ethiopia and Sudan, fits with that theory of northward migration.

Outside experts said that if the skull's estimated age is accurate, it fills a gap in the fossil history of Africa. But they questioned the accuracy of the dating method, which relies on variations in magnetic properties of the surrounding rocks.

In addition, Richard Sherwood, an anthropologist at the University of Wisconsin at Madison, said it would be hard to draw many conclusions from the preliminary analysis.