The oldest ancestor of humans: a tiny bump on a bone confirmed bipedalism.

According to ТСН: Scientists discovered a small bump on the thigh bone of a fossil primate that lived 7 million years ago. This confirms that Sahelanthropus tchadensis could walk upright on two legs, indicating its connection to the human lineage.

Research and Findings

The new discovery was reported by a journalist citing research conducted by Scott Williams, an associate professor of paleoanthropology. This research was published in the journal Science Advances.

Through the analysis of the bump, known as the femoral tubercle, scientists assert that this primate species walked upright when on the ground. This bump, which is now found only in members of the human lineage, allows scientists to consider S. tchadensis the earliest known hominin.

“This (bump) truly convinced us,” said lead researcher Scott Williams. “We determined that this is a bipedal primate, and therefore it belongs to the hominins.”

Anatomical Features and Traits

The analysis of the thigh bone of S. tchadensis also revealed two additional anatomical features similar to those of humans. Firstly, the bone has an inward curve, allowing the knees to be closer together than the hips — just like modern humans. Secondly, on the side of the bone, there is a pronounced bump for the attachment of the largest gluteal muscle, which is absent in living non-human primates.

However, the bent arm bones indicate that S. tchadensis could still climb trees, like modern chimpanzees and bonobos. But its hips and knees functioned like those of hominins, suggesting frequent use of bipedalism on the ground.

“It probably spent a lot of time on the ground to develop bipedalism,” added Williams.

Controversies and New Findings

The fossils of S. tchadensis were first described in 2002, but continue to stir controversy. Researchers previously thought that the position of the hole in the skull indicated upright walking, but other scientists have questioned this.

The latest research utilized 3D scanning of the bones, enabling clearer definitions of the thigh bone characteristics and comparisons with the bones of other known primates.

“It’s a very small bump that I initially didn’t notice, but felt when I ran my finger along the bone,” said Williams.

A biological anthropology researcher noted that the discovery is significant as it raises new questions about the appearance of the common ancestor of humans and chimpanzees. If S. tchadensis is indeed a hominoid, it suggests that this ancestor resembled chimpanzees more than humans.

“Now our key scientific task is to understand: can one be bipedal and not be a hominin?” summarized DeSilva.

Currently, it is noteworthy that scientists from Cambridge University recently discovered new data suggesting that modern humans descend from not one, but at least two ancestral populations, which could further complicate fundamental notions about human evolution.