for National Geographic News
Tanzania's Olduvai Gorge has yielded an impressive pile of fossilized bones and stone tools that may reshuffle the evolutionary tree of the early hominids and shed light on the behavior of some of human kind's earliest ancestors.
The gorge is most noted for the abundant fossil discoveries of esteemed anthropologists Louis and Mary Leakey from 1959 to 1976 which helped shape modern understanding of human origins.
The new find reported by Robert Blumenschine, an anthropologist at Rutgers University in New Brunswick, New Jersey, and an international team of colleagues includes an exquisitely-preserved 1.8 million-year-old fossilized hominid upper jaw, hundreds of stone tools, and butchered animal bones.
Blumenschine and colleagues describe the find in the February 21 issue of the journal Science.
The jaw bone is intact with all its upper teeth and the lower face, giving the scientists a unique opportunity to advance theories on the evolution of early humans.
"These things are so darn rare," said Blumenschine. "For early genus Homo there are maybe 50 specimens known. This one is complete enough to be ranked in the top ten, if not top five, of fossils of earliest genus Homo."
The scientists assign the fossil, simply known as Olduvai Hominid (OH) 65, to Homo habilis, the earliest member of the genus Homo, the genus of humans. H. habilis was the first hominid to display traits such as tool technology, larger brain size, and a taste for large animals.
"These are all unusual traits and fundamental to what modern humans are all about," said Blumenschine.
The hominid fossil provides what Blumenschine calls an anatomical link between the two earliest members of the genus Homo, H. habilis, and H. rudolfensis, thus providing evidence that H. rudolfensis is not a separate species as some anthropologists claim.
The link is between a cranium known as ER 1470 found by Richard Leakey in northern Kenya in 1972 and described as H. rudolfensis and the original H. habilis specimen OH 7, a mandible or lower jaw, Mary and Louis Leakey's team found in 1960 at Olduvai Gorge.
"What we are arguing is that the ER 1470 cranium would fit nicely on the OH 7 mandible, and OH 65 provides the anatomical link," said Blumenschine. "We are suggesting that H. rudolfensis is not a valid taxonomic name, just a junior synonym of Homo habilis."
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