A subject of considerable debate, a hominid species that inhabited the Earth approximately 7 million years ago may indeed have achieved habitual locomotion on two limbs, according to a recent examination of its fossilized skeletal remains.
Upon its unearthing in 2001, Sahelanthropus tchadensis, affectionately known as Toumai, was posited as one of the earliest progenitors of the human lineage. However, a segment of the scientific community maintains that it represents a more distantly related cousin rather than a direct human ancestor.
A substantial portion of this scholarly contention revolves around whether this ancient primate routinely ambulated on its lower limbs or if it employed its upper limbs for support during movement, akin to modern-day chimpanzees and gorillas.
Current research, spearheaded by investigators from New York University, purportedly provides a definitive resolution to this longstanding discussion: consider S. tchadensis a foundational figure in your extensive ancestral tree.
“Our comprehensive analysis of these paleontological specimens furnishes unequivocal evidence that Sahelanthropus tchadensis was capable of bipedal locomotion. This demonstrates that the evolution of upright walking occurred early in our evolutionary trajectory, originating from an ancestor exhibiting traits closely resembling contemporary chimpanzees and bonobos,” states Scott Williams, an anthropologist affiliated with New York University.
The investigative team arrived at this conclusion through the application of three-dimensional geometric analyses to the creature’s brachial and crural bones, subsequently comparing these with homologous elements from both extant and extinct related species.
They assert the identification of three critical anatomical characteristics indicative of bipedalism. Firstly, a discernible torsion was observed in the femur, a feature that facilitates forward limb projection and enhances ambulatory efficiency. Secondly, S. tchadensis appears to have possessed robust gluteal musculature, essential for maintaining pelvic stability during upright posture.
While these two attributes have been previously highlighted by other researchers, the researchers consider the identification of a femoral tubercle to be the pivotal discovery of their current investigation.
This specific osseous prominence functions as an attachment point for a potent ligament connecting the pelvis and the femur—a crucial adaptation for bipedalism and a feature identified exclusively within hominins.
Nevertheless, this finding does not imply that S. tchadensis had entirely relinquished its arboreal tendencies.
“Sahelanthropus tchadensis was fundamentally a bipedal ape with a brain volume comparable to that of a chimpanzee, and it very likely dedicated a considerable portion of its time to arboreal activities, including foraging and seeking refuge,” explains Williams.
The findings of this research have been formally published in the esteemed journal Science Advances.
