New hominid species may be link to ape-man
Fossils found in Ethiopia dating back 2.5 million years belong to a new hominid species that could be a direct ancestor of modern humans, an international team of scientists said in a U.S. science weekly released Friday.
Butchered animal remains found at the same geological layer suggest early humans, possibly the same species, used tools to extract meat from large mammals much earlier than previously believed, according to a report in the journal Science.
The scientists said the species, with humanlike leg proportions, "may be a direct human ancestor and an evolutionary link between the apeman, Australopithecus, and the genus Homo."
They also said the species is descended from the more primitive Australopithecus afarensis - commonly known as Lucy, naming the species Australopithecus garhi, from a native word meaning "surprise."
It was identified by examining cranial, tooth and limb remains found between 1996 and late 1998 near the village Bouri in the Middle Awash Desert region, 250 km northeast of Addis Ababa.
"No one predicted garhi," said Tim White, a U.S. biologist at the University of California, Berkeley, and coleader of the team with Berhane Asfaw, an Ethiopian researcher at the Rift Valley Research Service.
The team, which includes Gen Suwa, associate professor at the University of Tokyo, had been looking for an ape-man species known to have inhabited southern Africa 2 to 3 million years ago - the best candidate for an immediate human forebear.
What they found instead were hominid remains possessing intermediate evolutionary characteristics - with forearms as long as Lucy's, found 3.2 million years ago, but with long thigh bones already seen in the remains of early humans found 1.7 million years ago.
Also, garhi had a cranial capacity of about 450 cc, not as well developed as that of early humans. While its face projected forward like other ape-men, it had teeth larger and more advanced than afarensis.
"This combination of features has never been seen before," said White.
Antelope fossils found nearby bear cut marks that could have only been made by stone tools, while other antelope and horse bone fragments from the same layer were bashed open, presumably to extract marrow, the scientists said.
While the site, believed to have been a grassy plain surrounding a freshwater lake long ago, does not feature rocks suitable for tools, a separate dig 100 km north of the Bouri site has yielded nearly 3,000 stone tools dating back 2.5 million years.
The origin and function of those stone tools, the oldest yet found, had been a riddle to scientists, who found them two years ago.
The Bouri fossils make possible the theory that the garhi made the tools and brought them to hunt game in the Middle Awash.
"The development of stone tool technology allowed this dietary revolution," said White. "This is the earliest evidence of a key adaptation that let our ancestors spread beyond Africa."