One of the oldest known hominins, ancestor of modern humans, it was already walking on its two legs 7 million years agoshortly after its lineage split from that of chimpanzees, according to a study published Wednesday in the journal Nature.
Analysis of a forearm bone and two femurs of Sahelanthropus tchadensis found in an excavation at Toros Menalla, Chad, in 2001 supports conclusions scientists had previously drawn from a skull unearthed at the same site.
These hominins could stand on the ground, although they still had the bone structures necessary to climb trees, he stresses. the study of the University of Poitiers (France) and Harvard University (United States).
The orientation and position of the occipital foramen in the skull found two decades ago – the hole where the vertebral column is inserted – had already suggested to paleontologists that individuals from Toros Menalla used two legs as a form of locomotion.
Three other bones that were found in the same area and that are also attributed to Sahelantrhopus tchadensis have now been studied, since no other great primates have been detected at the site.
Comparison with other apes
Guillaume Daver and his team have collected a battery of biometric measurements and biomechanical indicators and have compared them with fossils of other current and extinct apes – chimpanzees, gorillas, orangutans, Miocene apes and various members of the human lineage: Ardipithecus, Orrorin, australopithecines and Homo sapiens-.
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Their results indicate that bipedalism coexisted among Sahelantrhopus with quadrupedalism in arboreal environments.
“All the data reinforce the idea of bipedal locomotion in a very early phase of human history, even if other forms of locomotion were also practiced at that stage,” the authors of the work describe in a statement from the University of Poitiers.