The toes of one of the world’s most important feet nearly slipped through scientists’ fingers. This past year Ronald Clarke, a paleoanthropologist from the University of the Witwatersrand in South Africa, was going through a series of bones taken from a cave 15 years ago- -and not considered remarkable at the time--when he realized that one was from the ankle of a human forerunner. Then he found another bone that fit with the first, and another, and yet another. When he put the pieces together, Clarke was holding the inner left foot, from ankle to toe, of a 3- to 3.5-million-year-old australopithecine, one of our earliest ancestors. It was the most complete ancient foot ever found.
While the back of the foot looks like that of modern humans, the front, particularly the big toe, resembles the grasping toe of a chimpanzee. Such a foot would be adept at clutching branches and other objects,’’ says paleoanthropologist Phillip Tobias, who works with Clarke. The obvious implication is that our early ancestors were at least partially arboreal. Anthropologists have long debated when and where our lineage left the trees. Some, such as Owen Lovejoy of Kent State University, have contended that ancestors like Australopithecus afarensis--the famous Lucy’’--had made the shift completely by 3 million years ago. But the new South African appendage--taken from a cave called Sterkfontein and dubbed by its finders Little Foot--argues for something of a swinger’s life, say Clarke and Tobias. Its great toe was highly mobile and was set at a wide angle to the other toes, as in apes, not parallel to them as in humans,’’ Tobias says. There would be no reason for such a toe if its owner wasn’t using it to climb.
Lovejoy, meanwhile, says the apelike features are mere evolutionary holdovers. Until faced with more feet, apparently, the walking camp will stand firm.