Scientists say foot fossil confirms two human ancestor species co-existed

The partial foot fossil indicates a creature that walked upright but that still had an opposable toe, which made it good at climbing trees.

Partial foot fossil found in Ethiopia. Image courtesy Cleveland Museum of Natural History.

A 3.4 million-year-old partial foot fossil – one that did not belong to the same species as Lucy, the most famous early human relation, according to scientists – has come to light in Ethiopia. These scientists say this new specimen suggests that more than one species of early human ancestor lived between 3 and 4 million years ago. The scientists – from the Cleveland Museum of Natural History and Case Western Reserve University – published their results in the March 29, 2012 issue of the journal Nature.

They found the partial foot in February 2009 in an area locally known as Burtele in Ethiopia.

The Burtele partial foot fossil from 2009 and the Lucy fossils from 1974 were found in the same general location. Examination of the new fossils suggests this new species also walked upright, as Lucy did. But, unlike Lucy, the owner of this ancient foot retained an opposable big toe, which made it good at climbing trees. Yohannes Haile-Selassie, lead author of the Nature study and curator of physical anthropology at The Cleveland Museum of Natural History, said:

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.

The video below is six minutes long, but fascinating, if you have time to watch.

The partial foot has not yet been assigned to a species due to the lack of associated skull and dental elements.

Co-author of the Nature paper, Dr. Beverly Saylor of Case Western Reserve University, said:

Nearby fossils of fish, crocodiles and turtles, and physical and chemical characteristics of sediments show the environment was a mosaic of river and delta channels adjacent to an open woodland of trees and bushes. This fits with the fossil, which strongly suggests a hominin adapted to living in trees, at the same time Lucy was living on land.

A Lucy replica in a museum in Frankfort, Germany. Lucy walked upright. Image via Wikimedia Commons.

Lucy’s species, Australopithecus afarensis, lived between 3.9 and 2.9 million years ago. Generally speaking, scientists agree that this species was closely related to the genus Homo (which includes Homo sapiens, or “knowing man,” our modern human species). They don’t agree as to whether Lucy was a direct ancestor to humans.

Bottom line: A study led by Yohannes Haile-Selassie of the Cleveland Museum of Nature History, with scientists at Case Western Reserve University, suggests that a recently discovered 3.4 million-year-old partial foot fossil did not belong to the same species as Lucy, the most famous early human relation. The scientists published their results in the March 29, 2012 issue of the journal Nature.

Read more from the Cleveland Museum of Natural History

EarthSky

MORE ARTICLES