Psychologist Kimberley Wilson and Dr Xand van Tulleken continue their journey around the human body, asking what our insides can reveal about our lives and the world around us.

This time, Xand and Kimberley marvel at the imperfect feats of engineering that are the arches of our feet, exploring how these arches are the key to our capacity to run, whether we should ditch our shoes for good, and finding out which animal has the ultimate foot.

Producer: Georgia Mills