Scientists take huge step in understanding feet evolution with muscle discovery

15 Jan 2019

Image: © drimafilm/

A muscle in our feet long believed to allow us to walk upright has been shown to actually play a major part in how we run.

Our ancestors’ ability to walk and run great distances helped spread our species across the globe, and now new findings from a team of researchers from the University of Exeter and the University of Queensland has helped us better understand how our feet evolved.

Publishing its findings in Proceedings of the National Academy of Sciences, the research team looked at the concept that arches in our feet – which differentiate us from species such as chimpanzees – help us walk upright due to plantar intrinsic muscles (PIMs). However, this latest study showed that PIMs have a “minimal impact” on it.

Rather, the findings show that foot muscles are crucial for helping us to push against the ground when walking or running, suggesting the evolution of strong foot muscles has led to where we are today.

To test the theory, researchers compared foot and lower limb movement with and without nerve block, preventing contraction of these muscles. As the study participants made contact with the ground during walking and running, the stiffness of the foot arch wasn’t altered by the nerve block, showing the muscle’s role to be minimal in arch support. However, during this nerve block, the distal joints in the foot could not be stiffened enough to prove normal push-off against the ground.

“This could have implications for understanding conditions such as flat feet, the value of training foot muscles and ideas around potential benefits of running barefoot,” said Dr Dominic Farris, lead author of the study.

“It turns out these muscles aren’t important for supporting the arch of the foot, but they are important for propelling us forwards when we walk or run.”

In August of last year, another discovery was made about the human foot, showing that our big toe was the last part of our foot to evolve. As our distant ancestors transitioned from a largely tree-dwelling life to staying on the ground, our big toe could have still been used for grasping in this in-between existence.

Colm Gorey was a senior journalist with Silicon Republic