The aquisition of bipedalism is one big and important step in the evolution, as we know it. Nevertheless, due to the lack of fossils remains, the scientists are not in consensus about its modality and period. A research team, involving scientists from the CNRS, the University of Poitiers and theey Chadian partners, examined three limb bones from the oldest human reprensentative currently identified, Sahelanthropus tchadensis. They published in Nature, on 22/08/2022, and their study reinforce the idea of bipedalism as a charateristic aquired really early in the hominids history.
Sahelanthropus tchadensis, with his 7 million years old, is considered the oldest reprensative species of humanity. Discovered and analyzed at the beginning of the millenium (2001), the final analysis was published 21 yeas later. Thanks to the well-preserved cranium palaeontologists could have seen the particular orientation and anterior position of the occipital foramen, where the vertebral column is inserted. Comparisons of the position of the foramen magnum in early hominid species are useful to determine how comfortable a particular species was when walking on two limbs (bipedalism) rather than four (quadrupedalism).
As we can see from this two images:
- the first image has the foramen magnum in an almost central position in the skull, suggesting an erection posture
- the second one is more backward, suggesting a more curved posture that indicates more weight placed in front of the body (different center of gravity).
The structure of the femure and the one's from ulnae also confermed the bipedalism theory, indicating that Sahelanthropus was usually bipedal on the ground, but probably also on trees. A difference between this species and gorillas or chimpanzee is also the use of hands, due to different arboreal clambering methods. Sahelanthropus tchadensis had a firm hand grips, clearly differing from the others who lean on the back of their phalanges.
In conclusion all this data and comparison reinforce the concept of avery early bipedal locomotion in human history; humanity in fact separated from the chimpanzee during the recent Miocene, probably between the 10 and 7 millions years ago.
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