Humans were already bipedal 7 million years ago

The recent analysis of bones belonging to members of Sahelanthropus chadensis puts an end to a decades-old debate: this hominid who lived 7 million years ago was indeed bipedal, but not all the time.

The origin of bipedalism is still debated today. It was still thought, not long ago, that the Australopithecines, who lived more than three million years ago, were the very first to be endowed with this faculty. But, in 2001, when Toumaï, the very first representative of the species Sahelanthropus tchadensisdating to between 6.96 million and 7.43 million years ago, was discovered, the question was reopened: the shape of its skull suggested bipedal locomotion. When did humans start walking? A new study published in Nature thus seems to trace its origin back more than 7 million years!

To obtain these results, the team of French and Chadian researchers has been analyzing since 2004 three bones from the limbs of Sahelanthropus tchadensis, of them ulna and one femur. According to the scientists, however, it is impossible to know if these three remains belong to the same individual.

Sahelanthropus tchardensis was bipedal… but not only!

Thanks to numerous analyses, both on the external morphology and internal structure, the scientists obtained a large amount of data for each bone. This information was then compared to that of many living great apes, including “chimpanzees, gorillas, orangutans, apes of the Miocene[mais aussi] members of the human group (Orrorin, ArdipithecusAustralopithecines, Homo old, Homo sapiens)”details a CNRS press release.

The researchers found, based on the characteristics of the femurthat Sahelanthropus was mostly bipedwhether on the ground, or even in the trees ! The ulna show that this hominid was sometimes quadrupedal, they indicate in particular firm grips of the hand. In this, Sahelanthropus tchadensis differed from gorillas and chimpanzees, which move by leaning on the back of their phalanges.