Sahelanthropus fossils (centre) compared with a chimpanzee (left) and a human (right)
Wiliams et al., Sci. Adv. 12, eadv0130
A recent study led by Scott Williams from New York University has shed new light on the debate surrounding the locomotion of the earliest known hominin, Sahelanthropus tchadensis. The study suggests that Sahelanthropus had key anatomical features indicating bipedalism, challenging previous theories suggesting a knuckle-walking gait similar to chimpanzees.
The fossil remains of Sahelanthropus, dating back 7 million years, were initially discovered in Chad in 2002. With distinct features such as a pronounced brow ridge and small canines, Sahelanthropus was distinguished from great apes. The skull anatomy suggested an upright posture, characteristic of bipedal hominins.
Further analysis in 2004 identified a femur and ulna alongside the skull fossils, with debates arising on the bipedalism of Sahelanthropus. In 2020, researchers argued that the curved femur resembled that of a non-bipedal great ape, fueling the ongoing controversy.
Williams and his team revisited the evidence, focusing on the femur’s attachment point for the gluteus maximus muscle, size, shape, and a previously unnoticed feature called the femoral tubercle. These findings supported the hypothesis of Sahelanthropus being an early bipedal hominin.
While Williams is convinced of their findings, he acknowledges that the debate is far from over. Franck Guy and Guillaume Daver, who previously argued for bipedalism in Sahelanthropus, supported the new study’s conclusions. However, ClĂ©ment Zanolli remains skeptical, suggesting similarities with African great apes rather than early hominins.
John Hawks from the University of Wisconsin-Madison sees Sahelanthropus as a transitional species, showcasing the complex evolution of bipedalism. The debate continues, with Zanolli emphasizing the need for new discoveries to settle the argument definitively.
Human origins and gentle walking in prehistoric south-west England
Immerse yourself in the early human periods of the Neolithic, Bronze Age and Iron Age on this gentle walking tour.
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