Despite humans having abandoned life in the trees long ago our feet have retained a surprising amount of flexibility similar to that in the feet of great apes such as orangutans and chimpanzees that have remained largely tree-dwelling, scientists at the University of Liverpool reported Wednesday.
Previously it had been though human feet function very differently from those of other apes due to the development of arches in the mid-foot region and the supposed rigidity of the arch on the outside edge of the foot.
"Our ancestors probably first developed flexibility in their feet when they were primarily tree-dwelling and moving on bendy branches, but as time passed and we became more and more ground-dwelling animals, some new features evolved to enable us to move quickly on the ground," Liverpool researcher Karl Bates said.
"Our limbs, however, did not adapt to life on the ground anywhere near as much as those of other ground-dwelling animals such as horses, hares and dogs," he said.
The researchers studied more than 25,000 human steps made on a pressure-sensitive treadmill in a university lab.
"Our tests showed that our feet are not as stiff as originally thought and actually form part of a continuum of variation with those of other great apes."
"We hypothesize that despite becoming nearly exclusively ground dwelling we have retained flexibility in the feet to allow us to cope effectively with the differences in hard and soft ground surfaces which we encounter in long distance walking and running," he said.