A new study led by the University of Kent has found evidence that human ancestors as recent as two million years ago may have regularly climbed trees.
© the university of kent | Research identifies regular climbing behavior in a human ancestor

Walking on two legs has long been a defining feature to differentiate
 , as well as  on our lineage (aka hominins), from our closest living ape relatives: chimpanzees, gorillas, and orangutans. This new research, based on analysis of fossil leg bones, provides evidence that a hominin species (believed to be either Paranthropus robustus or early Homo) regularly adopted highly flexed hip joints; a posture that in other non-human apes is associated with climbing trees.
These findings came from analyzing and comparing the internal  structures of two fossil leg bones from South Africa, discovered over 60 years ago and believed to have lived between 1 and 3 million years ago. For both fossils, the external shape of the bones was very similar showing a more human-like than the ape-like hip joint, suggesting they were both walking on two legs. The researchers examined the internal bone structure because it remodels during life based on how individuals use their limbs. Unexpectedly, when the team analyzed the inside of the spherical head of the femur, it showed that they were loading their  in different ways.
The research project was led by Dr. Leoni Georgiou, Dr. Matthew Skinner and Professor Tracy Kivell at the University of Kent's School of Anthropology and Conservation, and included a large international team of biomechanical engineers and paleontologists. These results demonstrate that novel information about  can be hidden within fossil bones that can alter our understanding of when, where and how we became the humans we are today.

Research identifies regular climbing behavior in a human ancestor
Sterkfontein site. Credit: University of Kent
Dr. Georgiou said: "It is very exciting to be able to reconstruct the actual behavior of these individuals who lived millions of years ago and every time we CT scan a new fossil it is a chance to learn something new about our evolutionary history."
Dr. Skinner said: "It has been challenging to resolve debates regarding the degree to which climbing remained an important behavior in our past. Evidence has been sparse, controversial and not widely accepted, and as we have shown in this study the external shape of bones can be misleading. Further analysis of the internal structure of other bones of the skeleton may reveal exciting findings of the evolution of other key human behaviors such as stone tool making and tool use. Our research team is now expanding our work to look at hands, feet, knees, shoulders and the spine."
This article was originally published by the University of Kent. 
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