Evolution makes some weird choices. Keratin is the stuff fingernails are made of. Bone is. Well. It’s bone.
And yet it’s the keratin horns that are permanent features, and the bone antlers that are temporary.
And I get why, sort of. A keratin structure can steadily renew itself, so if it’s damaged it can heal, sort of. Bone shatters, so it’s ultimately not as durable. But bone is also a major resource investment for an organism! Doing that every year, instead of having some funky oversized toenails on your head, seems kinda wasteful.
But it worked, so many species just stick with it. Because evolution.
