HOW GROWS

Why do we get hair on certain parts of our bodies, and can we get it back once it's gone?

- SCOTT DUTFIELD

From peach fuzz to armpits, there are around 5 million hair follicles dotted all over your body. Around 150,000 of them are found on your head. But why do we have hair, and do we still need it? Homo sapiens have always had hair. As mammals, it's one of our defining features. But over millions of years of evolution, we've shed the furry coats of our ancestors to become the naked mole rats of the ape world, while all of our chest-beating cousins are covered in thick coats of fur. There are countless theories as to why we lost our hair as a species, including thermoregulation, pest control and even streamlining our bodies for swimming. However, the hair on our heads has persisted. Science's best guess as to why we kept our hairy bonnets is because they act as a builtin hat to retain heat during the cold seasons and, as bipedal beings, help protect our scalps from the Sun's harmful ultraviolet rays.