Study Revealed That Ancient Human Ancestor Walked On Two Legs Since 7 Million Years Ago
Update: 2022-08-25 14:00 IST
A representation of the modes of locomotion practiced by Sahelanthropus
A new study estimates that the adaptation to walking on two legs instead of four occurred around 7 million years ago. This is a critical point in the evolution of our species and one that scientists are keen to date precisely. The study was based on a thorough examination of fossilised bones from the forearm and thigh of Sahelanthropus tchadensis, the earliest representative species of humans. The Toros-Menalla region of Chad is where these fossils were initially found in 2001.
In addition, it's possible that these early hominins engaged in some tree climbing utilising all four limbs, as would be expected if the species gradually transitioned from four to two legs. The researchers explained that they revealed postcranial evidence of S. tchadensis's locomotor behaviour, providing fresh understanding of early human evolution's transition to bipedalism.
The researchers were able to determine how this animal moved by comparing the fossilised thigh and forearm bones with the corresponding bones from humans, chimps, and gorillas. The fossilised bones' 20 different characteristics, including their external shape and their internal structures as determined by microtomography imaging, were all used to determine whether S. tchadensis walked on two legs or four.
They came to the conclusion that the most likely scenario was "habitual bipedality" with some tree climbing. According to the research team, the species used solid hand grips to climb trees rather of leaning back on their finger and toe bones like modern gorillas and chimps do.
The investigation expands on earlier research on a skull fossil believed to be from S. tchadensis that was discovered at the same location. There is now more complete evidence that these ape-like species were bipedal, contrary to what the skull research had previously revealed.
The fossils are from a pivotal period, which has already sparked a lot of scholarly controversy, when humans genetically diverged from chimpanzees and bonobos, between 6 and 8 million years ago. These early hominins most likely lived in a setting with a mix of grasslands, palm groves, and forests, and they would have had the option of climbing trees or walking on two legs to find food and water.