Sunday, October 04, 2009

Ardi! Ardi! Ardi! Ardipithecus ramidus finally revealed

You would have to be away from all electronic and print sources of news to miss the furor about Ardipithecus ramidus this week. The press releases and conferences hit the news cycle on Thursday followed by the publication of eleven (!) Ar. ramidus related papers in the weekly journal Science.

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.
I have one complaint about Science's handling of the general interest articles -- the introductory article prefacing the eleven scientific articles is entitled "Light on the Origin of Man" written by Brooks Hanson. The use of such sexist language in a major science journal in the year 2009 (and introducing such a major scientific discovery) is unbelievably crass. The language choice may have been unconscious, but it's stupid. I expect dumb headlines like the ones from the Los Angeles Times and the New York Times and we got them ("New Discovery Turns Evolution on its Head") at first, and then they were changed soon after. But Science? Ironically, the partial skeleton described (like "Lucy" before her) is female.


rikijo81 said...

love it!

Margaret said...

I read the article on CNN last week and was fascinated. I need to get the issue of Science.