By

Franck Guy/Université de Poitie

AFTER more than a decade in limbo, a crucial fossil of an early human relative has finally been scientifically described. The leg bone suggests that Sahelanthropus tchadensis, the earliest species generally regarded as an early human, or hominin, didn’t walk on two legs, and therefore may not have been a hominin at all, but rather was more closely related to other apes like chimps.

A paper from a rival group, not yet peer-reviewed, disputes this. The studies are the latest twist in …