Fellow travellers: walking with hominins

A 3.4-million-year-old partial skeleton of a hominin foot unearthed in Ethiopia offers an intriguing riddle. The only hominin previously known from that date was Australopithecus afarensis (to which 'Lucy' belonged), which was fully bipedal, and had essentially modern feet. The latest specimen, however, shows evidence for an opposable big toe, more like that seen in modern apes or in the hominin Ardipithecus ramidus, which lived one million years earlier. The new find suggests the coexistence of more than one hominin species in the Pliocene epoch, three to four million years ago, each with its own way of getting around.