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From Ethiopia, Fossils of a Possible Forebear

Discovery by Yohannes Haile-Selassie of an Ardipithecus ramidus kadabba canine tooth
Yohannes Haile-Selassie holds a tooth he says belonged to a subspecies of hominid that lived more than 5.5 million years ago.
© 1999 Tim D. White\Brill Atlanta
 

July 11, 2001 -- Scientists working in a dry-as-bones desert in Ethiopia have uncovered what they say may be the oldest human ancestor. The evidence consists of a small boxful of bone fragments and teeth culled from a site that's been explored for several years. The creature they belonged to is a newly named species of Ardipithecus, a mysterious chimp-like animal that lived about five-and-a-half million years ago. On All Things Considered, NPR's Christopher Joyce reports.

Yohannes Haile-Selassie, a doctoral candidate at the University of California at Berkeley, found the fossils at a site about 140 miles northeast of Ethiopia's capital Addis Ababa -- and about 50 miles south of Hadar, where fossils of the 3.2 million-year-old hominid nicknamed "Lucy" were found nearly 30 years ago.

1997-1999 hominid fossils belonging to Ardipithecus ramidus kadabba
Haile-Selassi says these fossils belonged to Ardipithecus ramidus kadabba. (Click photo to enlarge)
© 1999 Tim D. White\Brill Atlanta

Haile-Selassie's discovery is likely to spark controversy: there's another contender for the title of oldest human ancestor, found recently in Kenya. Much of the scientific community doubts that the Kenyan fossil really was on the evolutionary line that led to humans. This latest Ethiopian find is already meeting similar skepticism. Some say it looks more like a chimp than a human ancestor. Then again, it could have been one of the animals that lived before the evolutionary split between humans and chimps -- that is, a precursor to both humans and chimps.

The discovery appears in this week's issue of the journal Nature. It will be months if not years before a consensus forms on just where in the primate evolutionary tree this particular limb sprouted. In the meantime, what is clear is that there were indeed many types of evolutionary "experiments" taking place during that crucial period when the characteristics that make us human -- notably, walking on two legs -- first started to appear among the primates.