Scientists suggest that there were more than just one species of prehuman ancestor living between 3 and 4 million years ago, The New York Times reports.
The 3.4 milion-year-old fossil foot that was found in Burtele, Ethiopia, appears to settle the long-disputed question of whether there was only a single line of hominis, which is the species that are more closely related to humans than to chimpanzees.
Dr. Yohannes Hile-Selassie, the lead author of the study and curator and head of physical anthropology at The Cleveland of Museum of Natural History, and Dr. Beverly Saylor of Case Western Reserve University, found the 3.4 million-year-old partial foot fossil in February, 2009. However, the study was recently published in the March 29, 2012, issue in the journal Nature.
The Burtele fossil and the Lucy fossil from 1974 were found in the same location, and the examination of the new fossils suggest this new species also walked upright, just like Lucy. But unlike Lucy, the owner for this ancient foot retained and opposable big toe, which made it great at climbing trees.
The partial foot has not been assigned to a species yet, due to the lack of associated skull and dental elements. But Dr. Saylor said that the environment it lived in was a "mosaic of river and delta channels adjacent to an open woodland of trees and bushes, which is fitting to the fossil that strongly suggest a homini that is adapted to living in trees."
Lucy's species, Australopithecus afarensis, lived between 3.9 million and 2.9 million years ago. Generally speaking, scientists agree that this species was closely related to the genus Homo that includes homo sapiens. However, they still don't agree whether Lucy was a direct ancestor to humans.
Daniel E. Lieberman, a human evolutionary biologist at Harvard, was not involved in the research but wrote in a commentary for the journals that the homini foot and said that it is a valuable addition to the fossil record because it "extends the existence of Ardipithecus-like feet by a million years."
Image courtesy: Cleveland Museum of Natural History