A new type of hominid foot bone has been discovered in the Afar region of Ethiopia,
showing that Lucy, the famous early human ancestor, had company. The 3.4 million-year-old bones have been shown not to belong to Australopithecus afarensis, but instead to a creature that spent much of its time in trees. It hasn’t yet been assigned a species, as no skull or teeth have yet been found. According to Dr. Yohannes Haile-Selassie of the Cleveland Museum of Natural History the Burtele partial foot clearly shows that at 3.4 million years ago, Lucy’s species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia. Her species co-existed with close relatives who were more adept at climbing trees, like Ardi’s species, Ardipithecus ramidus, which lived 4.4 million years ago. The partial foot is the first evidence that at least two pre-human species with different modes of locomotion lived side by side in eastern Africa around 3.4 million years ago. While the big toe of Australopithecus afarensis was aligned with the other four toes for human-like bipedal walking, the Burtele foot has an opposable big toe like the earlier Ardi. The fossils were found below a sandstone layer, and dated using the argon-argon radioactive method. The findings, published in Thursday’s edition of the journal Nature, provide the first good evidence that another bipedal human relative was still climbing trees at the same time that Lucy and her kind had their feet planted on the ground.