Thursday, January 6, 2011

Let's walk for sex!

If you want to watch a paleoanthropologist blow a gasket, just ask him about the "missing link."

"The term is wrong in so many ways, it's hard to know where to begin," said Tim
White of the University of California, Berkeley. "Worst of all is the implication that at some point there existed something halfway between a chimp and a human. That's a popular misconception that has plagued evolutionary thought from the beginning, and one Ardi should bury, once and for all."

"Ardi" - short for Ardipithecus ramidus - is the 4.4 million year old adult female fossil White and his team found about 15 years ago that may be the oldest hominid on the books. It's more than a million years older than the famous "Lucy," which was 3.2 million years old. (It certainly is NOT a link to the far-off creature that was an ancestor to both apes and humans.)

But what's ironic is that nowadays, Ardi may be just what many people have in mind when they think about a missing link.

Ardi is a curious mix of ancient traits far older than the apes of its time and modern hominid traaits that lead straight toward humans. For instance, take Ardi's foot. It allowed the creature to walk upright, if not easily, and walking upright is the main definition of a hominid. The foot is built much like Lucy's - who strolled with ease - but it also had a big toe that stuck out to the side - great for climbing trees.

And then there's Ardi's pelvis, which National Geographic author Jamie Shreeve called a perfect example of a "primitive primate caught in the act of becoming human." Lucy had hips made for walking; chimps have hips made for climbing (they walk with a huge lurch); but Ardi's hips are (dare I say it?) half and half.

So why walk at all? Some think it had to do with sex. Apes have giant, sharp canines to fight off other males for mates. Maybe Ardi's menfolk, with their small canines, made sex-for-food deals with females and had to have hands free to carry the food home.

Now, there's the beginning of a human trait!

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