Primitive Human Ancestor Shared Lucy’s World
Ann Gibbons, Sciencemag, 28-03-2012
Lucy was not alone. The discovery of a remarkably rare partial foot from an ancient primate suggests that more than one kind of human ancestor walked upright in Africa when Lucy’s species, Australopithecus afarensis, was alive. The primitive traits in this 3.4-million-year-old partial right foot also show that there was more than one way for early human ancestors to walk upright for at least a million years, according to a new study.
Ever since the discovery of Lucy’s species in 1974, she has been considered a prime candidate for a direct human ancestor. Unlike earlier apes, Lucy walked fully upright, even though her brain and body weren’t much bigger than a chimp’s. This showed researchers that bipedal walking was a key trait of humans and our ancestors, the group called hominins—but not of living apes and their ancestors. Researchers have long wondered if other upright walking species shared the Rift Valley of Africa with Lucy, particularly after they discovered that several types of hominins were alive at the same time after A. afarensis disappeared 3 million years ago.