The discovery of a set of 2-million-year-old fossils could be a gamechanger in understanding human evolution, providing a key link in the process that led to modern human beings, scientists say.
The fossils of an apelike creature with human features were recently found in a South African cave. The discoverer of the fossils, Lee Berger of the University of Witwatersrand in Johannesburg, says the news species, known as Australopithecus sediba, is the most plausible known ancestor of archaic and modern humans, The New York Times reported.
This is what evolutionary theory would predict, this mixture of Australopithecine and Homo, said Darryl J. DeRuiter of Texas A&M University. It's strong confirmation of evolutionary theory.
The bones have been extensively examined since they were first discovered in the South African cave in 2008, and are described in full in five separate studies in this week's edition of the journal Science.
The team says the new species may be the best candidate yet for the immediate ancestor of our genus, Homo, wrote Michael Balter of the Science staff in an overview. That last claim is a big one, and few scientists are ready to believe it themselves just yet.
According to the research, while the skull, long arms and diminutive bodies are chimp-like, the ankles, hands and pelvis are surprisingly modern.
This mix of morphology suggests to us that sediba likely still used it hands for climbing in trees, but it was likely also capable of making the precision grips that we believe are necessary for making stone tools, said co-author Tracy Kivell from the Max Planck Institute for Evolutionary Anthropology in Lepizig, Germany.
The mixture of apelike and humanlike qualities suggests that the new species was transitional between the australopithecines and humans, the researchers said at a Wednesday news conference. That is not something seen before in direct human ancestors.
While not all scientists agree to the species' tie to human ancestry, the fossils remain invaluable in the years of discovery and debate on human origins to come.
Just because it shares a bit of anatomical morphology with Homo does not mean it is Homo or ancestral to Homo, anthropologist Bernard Wood of George Washington University told The Wall Street Journal. It looks increasingly that these bits of morphology are appearing more than once, independently, in the tree of life.