Textbooks will tell you that the human foot is rigid, which allows more efficient walking. Other apes, in contrast, have flexible feet better suited to grasping branches as they move through the trees. But the textbooks are wrong, say Jeremy DeSilva and Simone Gill at Boston University.
The pair asked 400 adults to walk barefoot around the Boston Museum of Science while they filmed their feet. This revealed that 8 per cent of people have some mid-foot flexibility, rather like that seen in tree-dwelling apes (American Journal of Physical Anthropology, doi.org/mmh). In another, soon-to-be-published analysis, Robin Huw Crompton at the University of Liverpool, UK, found that a flexible mid-foot may be even more common than DeSilva and Gill suggest.