Why do lions have manes?

At the onset of sexual maturity, male lions will start to grow thick manes around their head, neck and underbelly. The hormone testosterone is responsible for this process – interestingly, neutered males usually lose their manes entirely. Studies have shown that females are attracted to bigger, darker manes, so it seems that manes are a signal of sexual fitness. Lions often live in open savannah habitats, so it’s particularly beneficial to have evolved a visual method of communicating strength and status. Manes also provide added protection from injury when males fight with one other.