Extinct tree-climbing human was handy with its feet as well

Washington D.C.: Scientists studying the 1,550 fossil bones of Homo naledi, a newly discovered human relative unearthed in a South African cave, has provided more insight into how modern humans descended from the trees and evolved to walk upright, bearing tools in their hands.

The study suggests that although its feet were the most human-like part of its body, H. naledi didn't use them to walk in the same way we do. Detailed analysis of 107 foot bones indicates that H. naledi was well adapted for standing and walking on two feet, but that it also was likely comfortable climbing trees.

The work provides insight into the skeletal form and function that may have characterized early members of our genus.

Homo naledi's foot is far more advanced than other parts of its body, for instance, its shoulders, skull, or pelvis, said lead author William Harcourt-Smith, adding that quite obviously, having a very human-like foot was advantageous to this creature because it was the foot that lost its primitive, or ape-like, features first. That can tell us a great deal in terms of the selective pressures this species was facing.

Analysis of these bones has shown that the foot bones look much more like human bones than chimpanzee bones, except for two major areas: the toes of H. naledi's foot were more curved and their feet were generally flatter than seen in the average modern human. Despite the close similarity in the foot structure, H. naledi likely did not walk exactly like us, the researchers say.

Clues from other parts of its body--long and curved fingers, and a more ape-like shoulder joint--paint a picture of a creature that was undoubtedly bipedal but also a tree climber.

The study is published in Nature Communications.