The discovery of foot bone fossils from an early hominin may help unlock the mystery of how humans learned to walk upright.
Ancient foot bones from a recently discovered pre-human species, which had opposable big toes like a gorilla's, could shed light on how the ancestors of humanity came to walk upright, researchers say.
Humans dominate the planet partly because walking upright frees their hands for tool use. Among the earliest known relatives of humanity to walk upright was Australopithecus afarensis, the species including the famed "Lucy." This hominin is a leading candidate for direct ancestor of the human lineage, living about 2.9 million to 3.8 million years ago in East Africa.
Although Lucy and her kin were bipedal, there is debate about how much they depended on life in trees. Now scientists also have fossils of a hitherto unknown species of hominin that lived about the same time and place as Australopithecus afarensis. Judging by its feet, this newfound relative of humanity was a tree-dweller – which suggests that, in turn, Australopithecus afarensis adapted to life walking on the ground.
"In biology, if you have two closely related species that live close to each other, they may start to diverge in what niches they occupy," said researcher Bruce Latimer, a paleoanthropologist at Case Western Reserve University.
Since this newfound hominin possessed feet good for climbing trees, "it does really hammer home the idea that Australopithecus afarensis might have been a bipedal animal that committed itself to the ground and walking long distances," Latimer told LiveScience. [Photos of New Hominin Species]