Is body hair a functionless vestige?

A vestige,certainly, but perhaps not entirely without function.But it's hard to say. Your own post say perhaps this and perhaps that. And then again, perhaps not.Perhaps it serves some minor function. How would we find out? We could forcibly shave off all the body hair of a million men, and compare them to ... what WOULD be the control group? Double-blind testing is right out.

It should be pointed out that there are some ethnic groups of Africans who don't have any body hair at all, not even the fine fuzz that most people have (that is, they have the normal concentrations of hair on the head, armpits, and pubic area, but none on their arms, legs, etc). I write this from memory, so I can't give a reference. I've also seen it for myself.They seem to get by without it.Edited by Dr Adequate, : No reason given.

I think perhaps your confounding cause and effect: that is, the reason that these regions chafed was because they had been so long protected.After all, you didn't chafe in these areas when you were prepubescent, did you?The fact that such hair is acquired at puberty suggests to me that it has something to do with sex; if it had any other purpose it would develop earlier.

I read recently (I think in a book on supernormal stimuli) that the places where we do get hair are also the places where chimps get it first.So the distribution of hair in humans could be the side effect of a (hormonal?) adaptation towards neoteny that had nothing to do with hair as such but was favored for its effect on something else, such as brain plasticity. It would be what Gould called a spandrel.

Well I'm not sure that this is particularly sparse as compared to a human. Sparse compared to the rest of the chimpanzee, perhaps. But to suggest that we "grow hair where apes do not" seems unjustified.

What you said was "humans grow hair where apes do not". Most of those pictures don't look that much different.Edited by Dr Adequate, : No reason given.

Yes. This does not support your claim that "humans grow hair where apes do not". Follow?

You seem to be better at the "random" bit than the "fact" bit.

It seems to me that if it had a sensory function, then the best place for it would be on the fingertips. Its actual distribution doesn't suggest a sensory function, does it?Here's a sensory homunculus. That's how brain function is distributed over the body. It's not how hair's distributed, is it?And chimps and moneys have hands which are naked on the inside. The one place where the sense of touch is most important ... no hair.Edited by Dr Adequate, : No reason given.

Yes, but I can't say that I've ever found this particularly useful. Bare skin would do just as well.To an animal with thick fur, doubtless it is useful that hair follicles are innervated. But in us this too could be a vestige. But no-one has said that the sensory input doesn't exist. Just that it's not particularly functional.

What distinction are you trying to draw between useful and functional?