Our hominid ancestors may have adapted to living on trees and on land

Our hominid ancestors may have adapted to living on trees and on land

Much has been made of the ability of our ancestors from "come down from the trees", And many researchers see in terrestrial bipedalism a trace of"humanity”. After all, most of our relatives, the primatesThey still spend their time in the trees. Humans are the only family member to spend their life on land, rather than in the trees, but this was not always the case.

The fossil record shows that our ancestors habitually lived in trees, until Lucy appeared. 3.5 million years ago this new creature, the Australopithecus afarensis. Anthropologists agree that A.afarensis was bipedal, but it is not known for sure if Lucy and her group had abandoned life in the trees.

Australopithecus afarensis had a stiff ankle and an arched foot that was not prepared to grasp objects. These traits are functionally incompatible with climbing”Wrote Nathaniel Dominy, Dartmouth associate professor of anthropology and his co-authors at PNAS (Proceedings of the National Academy of Science).

However, this interpretation may be a bit hasty considering the new evidence revealed by Dominy and his companions: modern humans, as well as Lucy, they have adapted to bipedalism terrestrial but can also climb trees effectively.

The studies conducted in Uganda and the Philippines have revealed it is possible to climb in a way that has been described as "walk”To low trees. The technique consists of “walk”Upwards placing the soles of the feet directly on the trunk, advancing with the hands and the feet simultaneously.

Dominy and his team documented climbers flexing their feet up to an extraordinary degree, beyond the anatomical possibility of human beings. Assuming that the bones of the leg and ankle are normal, the hypothesis is that they could have a soft tissue mechanism that allowed extreme flexion of the foot upwards.

They tested their hypothesis using ultrasound imaging to measure and compare the length of the muscle fibers of the gastrocnemius muscle, and in two of the selected groups of men (the Agta and the Twa) it was found that these muscle fibers were significantly longer.

The results suggest that the habitual climbing of these groups changed the muscular architecture associated with the dorsiflexion of the ankle.”Wrote the scientists, showing that a foot and ankle adapted to living on land does not preclude the possibility of climbing in the Australopithecus afarensis behavioral repertoire.

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Video: Rick Barker - Paleoanthropology: Early Human Evolution