Last updated April 5, 2018 at 12:18 pm
It seems early human ancestors were more nimble on their feet than conventional wisdom (the modern human kind) would have it.
Research from the City University of New York suggests hominins were walking upright with straight legs and a more than acceptable gait more than four million years ago, and that this didn’t come at the expense of their tree climbing agility.
It is obvious that humans walk with much greater economy than non-human apes, but it has not been clear how and when this happened.
And there has been significant debate over whether or not the evolutionary adaptations needed for improved walking economy would have required a corresponding reduction in climbing skills. Some argued that it would be impossible to walk with a tree-climber’s fingers, others that natural selection would sort things out.
Evolved changes in pelvis shape allow the hamstrings muscles (red) to hyper-extend the hip in humans, but not in apes. Credit: PNAS
In the latest study, a team led by evolutionary anthropologist Assoc Prof Herman Pontzer first compared how humans and living apes and monkeys use their hips, leg bones and muscles when they walk and climb.
They then used these results to estimate the locomotor capabilities of three different early hominins – Ardipithecus ramidus, Australopithecus afarensis and Australopithecus africanus – based on pelvic morphology.
All three were found to have an estimated range of motion similar to that of humans, and Ardipithecus ramidus also had an estimated maximum force generation similar to that of apes. The authors say this suggests it developed improved walking economy, compared with apes, without sacrificing climbing ability.
Ardipithecus ramidus lived in east Africa about 4.4 million years ago. In 2009, scientists formally announced and published the findings of a partial skeleton – nicknamed Ardi – first found in 1994.
The paper published in Proceedings of the National Academy of Sciences.
