So what's the deal with Ardi? She is a partial skeleton of a hominid species ancestral to us and older than Lucy, the famous Australopithecus afarensis partial skeleton by a over a million years. Tim White and his team discovered "Ardi" in 1992, finding a molar and a lower jaw, which they published in 1994. Working on this find and the area where the partial skeleton was found in Aramis, Ethiopia, it took 15 years to complete. Instead of publishing a stream of papers as discoveries were made, White made the decision to hold off until a complete story could be told.
The wait has been worth it, considering the amount of information that the extended international team has been able to provide. Several ideas about human evolution will have to be reconsidered based on this species' attributes.
Ardipithecus ramidus lived in the trees but was also "intermediately" bipedal, based on analysis of pelvis, spine, legs, and feet. For the first time, a hominid species was found with a large opposable big toe, allowing for tree limb grasping. A theory about the development of bipedialism describes the needed walking trait in an African savannah environment, but Ardi walked even though she was also arboreal, living in a woodland environment.
Yet, Ardipithecus ramidus did not knuckle-walk, like chimpanzees or gorillas, the wrist and hand bone structure is not strong enough to support that kind of movement. "Ardi" is not chimpanzee-like, which is how most theorists described our earliest hominid ancestor.
This is the find of a generation and I'm sure there will be much more analysis and commentary in the years to come.
- Great interactive site for general audiences can be found over at the Discovery Channel, which is a companion to the TV special.
- Science has the scientific papers and news articles available with a free registration -- I recommend doing this because you can read the original papers yourself. There is also a good 10-minute video interviewing Tim White and explaining some of the significant features of "Ardi." I also highly recommend science-writer Ann Gibbons' NewsFocus article here entitled "A New Kind of Ancestor: Ardipithecus Unveiled."