Father of Us All?

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As for the popular perception that human evolution began in East Africa — well, on reflection, that was never as convincing as it was made out to be. Even those who leaned toward that view knew intellectually that a few dozen individuals from a few sites spaced over millions of years constituted a pretty slim line of evidence. After all, even a shambling, apelike hominid could range a few thousand miles — from Chad, say — in a mere generation or two. The fact that so very few hominid fossils have been found, even in East Africa, makes it clear how rarely these ancient bones survived. "If you think of Africa as a giant place where human ancestors existed for the past 7 million years," says Berkeley's White, "you have to get lucky to find places where environmental conditions allowed them to live and where the geological conditions allowed them to be preserved."

But that also means that paleontologists could get lucky in many more places than they have looked so far. White and other old East Africa hands will continue the excavations they have under way in those traditionally fertile fossil fields. Other, less established scientists, though, may now feel emboldened to look in other parts of Africa with greater confidence that there is something important to find.

Brunet, meanwhile, has every reason to keep mining the windswept desert of Chad. "There's still plenty of work to do," he says. He and his team will be looking not only for additional Sahelanthropus bones but also for even older sediments that are between 7.5 million and 10 million years old — rocks that could yield the ancestral species that gave rise to both humans and chimps. Paleontologists often take months or years to announce the existence of discoveries they have in hand, so it is quite possible that he and his team have already found something more.

Indeed, the last sentence of their paper in Nature declares that while Sahelanthropus will be central to illuminating the earliest chapter in evolutionary history, "more surprises can be expected." Given the splash Toumai has made, that could prove to be an understatement.

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