"Key" Human Ancestor Found: Fossils Link Apes, First Humans?
An Australopithecus sediba skull bears both human and ape traits.
Ker Than
for National Geographic News
Published April 8, 2010
Identified via two-million-year-old fossils, a new human ancestor dubbed Australopithecus sediba may be the "key transitional species" between the apelike australopithecines—and the first Homo, or human, species, according to a new study.
(See pictures of Australopithecus sediba fossils.)
"We've never seen this combination of traits in any one [early human species]," study leader Lee Berger told the journal Science, where the new study is published today.
Found in the remnants of an underground cave network in South Africa, the partial Australopithecus sediba skeletons are believed to be from a roughly 30-year-old woman and an 8- to 13-year-old boy.
The pre-human pair, who may or may not have been related, apparently fell to their deaths into a chasm littered with corpses of saber-toothed cats and other predators.
The new species may be the wellspring—"sediba" in the local Sotho tribal language—from which our ancestors flowed, the report suggests.
Berger, of the University of the Witwatersrand in Johannesburg, conjures a different metaphor.
"It's the opinion of my colleagues and I that [Australopithecus sediba] may very well be the Rosetta stone that unlocks our understanding of the genus Homo," Berger said in a statement, referring to the artifact that helped decipher ancient Egyptian hieroglyphics.
(Also see "Oldest Skeleton of Human Ancestor Found.")
A. Sediba Fossils Suggest Human-Like Ape
Growing to just over 4 feet (1.2 meters) tall, A. sediba has a number of key traits that some would say mark it as an early human, like Homo habilis, which many consider the first human species.
A. sediba, for example, had long legs and certain humanlike characteristics in its pelvis, which would have made it the first human ancestor to walk—perhaps even run—in an energy-efficient manner, the study says. (Related: "Did Early Humans Start Walking for Sex?")
Also, A. sediba's face had small teeth and a modern—rather than chimpanzee-like—nose, the study says.
And as in humans, the shapes of A. sediba's left and right brain halves—discernible from indentations on a remarkably preserved skull—appear to have been uneven.
