If the purpose of head hair is to keep your head warm why does it grow fast in summer when not needed, and slower in winter, when it may be actually needed?

I thought it was total temperature modification for us? It helps cool And warm us I thought? And protect us, direct sun on the top of the head, nose hairs for foreign objects, pubic hairs for lubrication... that kind of stuffs... I thought? It's multipurpose. Come to think of it, I've never noticed if my head hair growth was seasonal or not... cool. Something I don't think about much, neat.

Hair growth is influenced by androgens (a form of hormone), and the levels of this hormone increase and peak during summer, causing hair to grow slightly faster in some people. It's not something I think that is done purposefully, but hair does protect a lot of your skin from UV rays which are most intense during summer, so it makes some sense to have more hair.

i never thought of pubes as lube but when u think of it it actually does work but its gross so ill stick with the females shaved tacos.