Discovery of 4.4 million-year-old "Ardi" named Breakthrough of the Year

The discovery, reported in the journal's Oct. 2 issue by an international team co-led by Tim White, a University of California, Berkeley, professor of integrative biology, surprised scientists because Ardi doesn't look like a human or our presumed relative, the chimpanzee. Short for Ardipithecus ramidus, Ardi was a female who lived 4.4 million years ago in what is now the Afar region of Ethiopia. The team took 17 years to assemble and analyze the skeleton and thousands of other fossils found with it, but the analysis, summarized in 11 papers, revolutionizes our understanding of the earliest human ancestors – those that appeared not long after the human lineage diverged from that of chimps, White said. "From the response we've gotten from our colleagues, people are impressed by the diversity of the data sets," White said. "It's not just a skeleton, it's the context of the many other individuals of that species and ecological information from all the other plants and animals and sediments that really lets you understand – in a way often not possible for these fossil discoveries – what that ancient world was like." Ardi's skeleton was unique in having pelvic and foot bones that allowed the scientists to reconstruct how it walked, part of the cranium to judge its brain size, and parts of the jaw and a full set of teeth to ascertain its diet. Nineteen of the publications' 47 authors trace their roots to UC Berkeley in some way, White said, and many UC Berkeley students were involved in the field and laboratory research.