Orrorin tugenensis and the unclear origin of bidepalism

Nowadays, we all know that our ancestors began to diverge from the other arboreal neighbors, by developing bipedality which become a great advantage. But analysis carried out in 2013 suggests that bipedality could appear before Australophitecus afarensis. The discovery of a 6 million year old femur carried out by Sergio Almécija and his group of researchers from Stony Brook University in 2000, suggest that bidepality could appear before Lucy, which means 2 million years before.

The bones of these individual belong to the species Orrorin tugenensis, that lived approximately 6 million years ago at the end of the Miocene in eastern Africa (Tugen Hills, central Kenia). To analyze the bone, it was subjected to cutting-edge technology that analyses the 3D morphology. The obtained information was compared with a variety of apes and other hominids, and they concluded that the femur has an intermediate morphology between fully bipedal primates and those that were arboreal or quatrupedal. One comparison was with Australopithecus afarensis (Lucy) and determined that Orrorin´s femur and humerus are about 1,5 times larger.

Although some scientist and researchers do not agree Orrorin tugenensis was a truly hominin, it was likely one of the very first, and this new information brings new hypotheses about how bipedality could have been originated.

For the moment, there is no enough evidence to determine if this individual was the first to develop bidepality, and further study of other ape from the Miocene will be needed, in order to better understand where and when bipedality originated.

For more further information: http://www.newswise.com/articles/early-tree-dwelling-bipedal-human-ancestor-was-similar-to-ancient-apes-and-lucy-but-not-living-apes