蜜芽传媒

Hannah Monteith from Edinburgh in Scotland asked: "How does leg hair know it has been cut? It doesn't seem to grow continuously but if you shave it, it somehow knows to grow back." Dr Adam Rutherford and Dr Hannah Fry consult dermatologist Dr Susan Holmes to discover why the hairs on your legs don't grow as long as the hairs on your head.

First broadcast on The Curious Cases of Rutherford & Fry, 2 June 2016.