Why does human hair grow longer than animal hair and keep growing?

Answer 1

Answer

Short answer- noone knows exactly what selective advantage long scalp hair has. Most common theories are that it has something to do with sexual selection. This is the answer biologists tend to give when a feature has no obvious useful function. Difference is that human hair has a longer growth period (about 2-6 years) than the hair (fur) of most non-human animals. But again, noone really knows why. Answer An important aspect to keep in mind is that "animal hair" is indeed growing all the time, but it also falls off. Thus an equilibrium is reached where the hair in animal fur stays, on average, at a "constant" length. The same would happen with the hair that remains at a constant length in humans (like hair of the arms).

Answer 2

Human hair grows longer than animal hair due to a longer growth phase in the hair cycle, called anagen phase. This phase allows human hair to continue growing for several years, resulting in longer strands. Additionally, human hair follicles are capable of producing longer hairs compared to most animals.