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B. A Question of Knuckles

Narrator: This is Science Today. Anthropologist Adrienne Zihlman of the University of California, Santa Cruz has spent many hours dissecting gorillas from zoos. One reason is to gain insight into human evolution, because gorillas and humans diverged from the same ancestor about five million years ago. One question she's asking is, did our ancestors walk on their knuckles?

Zihlman: Humans of course don't use their hands in locomotion, so do not knuckle-walk, and one of the great debates is whether or not human ancestors were knuckle-walkers.

Narrator: However, gorillas and chimpanzees walk on their knuckles all the time. But Zihlman says knuckle-walking is never mentioned in studies of human evolution.

Zihlman: The anatomy of the hand and upper limb is always interpreted in terms of climbing, ignoring the fact that chimpanzees and gorillas, that almost all their locomotion from place to place is on the ground as knuckle-walkers. So what we're doing is looking at some of the anatomy that I think we're going to be able to show correlates with knuckle-walking and not with climbing.

Narrator: For Science Today, I'm Steve Tokar.