h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Interesting... I hadn't thought of that one...

It leaves the question, though... why did we lose most of the rest of our body hair?

Replaced it with clothes, I guess.

I remember hearing somewhere that at some stage proto-humans became semi-aquatic, which is where we get our aptitude for swimming from; our slightly webbed fingers, flat hands and babies' natural reaction to hold their breath underwater.
Water-logged hair is bad for all sorts of reasons, including hydro-dynamics, so the theory goes that we lost most of our hair to aid swimming. The hir on the head is an exception because it is where most body heat is lost and the area most exposed to sunlight. Apparently, what body hair we have is either in places that do not affect hydro-dynamics or follows the flow of water across a swimming person.

So, that would account for armpits, but pubic hair? Somebody had to ask.

Here's one theory behind the evolution of pubic hair -- you've seen the nature programmes on the telly about nymphomaniac monkeys, right? You know the ones: when they greet each other they have sex, when they leave each other they have sex, when they're sad ... you get the idea. So sex is an important social behaviour in many primates; also this trait will be increased through natural selection because the more sex a monkey has the more likely he is to have lots of monkey babies

This might give you a clue as to why homo sapiens has retained the short 'n' curlies. Look at a naked person, and where is the eye naturally drawn? The sexual organs! It's not just becauase we're all perverts, the whole area is signalled with striking hair that says "Look at me!" - just the sort of thing which can encourage sex as a social behaviour like with our hormone-crazed monkey cousins.

Hmm, that seems to make sense. It could be much worse - we could all have bright red sexual organs!

I think we just started to go bold all over and just adapted to it, I don't think there was any "reason" for it, but if we did not adapt, ( learn to make clothes ) we would have gone extinct

manda

We still have the same number of hairs on our bodies!

I read in a biology book many years ago that humans have the same number of hairs per square inch as apes, but the individual hairs are just shorter and finer. One of their primary uses is to help determine the direction of air movement over the body; after all, hunter or hunted, it's a big aid to survival to be able to tell easily what direction is "downwind"...

There is a lot of presumptions in this text. Can any of it be backed up at all?

Well, I'm about to do Anthropology at Durham so have spent the last year studying this subject. Most of what you guys are saying is right, (at least it agrees with the cambridge encyclopedia of Human Evolution, yes i did have to be sad enough to read it cover to cover!!) Except human's short and curly's are also there not just as a visual signal but also as a pheremone catcher. Body hair is incredibly good at holding onto your unique smell, this smell is also vital for finding your partner. There is a theory that by smelling your mate you judge their genetic background, and how suitable they are to you as a mate. (perfumes and scents don't confuse this because you are likely to pick a smell that enhances your own body odour. don't believe me, check out perfume websites, they advise you to ear a scent for two or three days before you purchase because the scent will change in reaction to your own body smells!!)

Oh, and there are many theories as to our hair loss, the aquatic ape theory (although as a hairy man I agree with just because I know what it's like swimming!!) is actually the least listened to. The other possibilities include heat control, sexual signalling, and neotony, but I think I've bored you all enough!!

many regards LG

Yeah, hair also gives a larger surface area so more vaporization. Which is good for spreading smell. Though in the case of armpits something probably went wrong.

Swimmers apparently shave arms and legs.

Why did something go wrong in the case of armpits??

And as for the swimmers thing, yes they do, in fact i heard they shave all over, so the streamlining of the hair thing obviously doesn't work as well as no hair at all!! Then again as good as we could get in those days, lacking the modern necessity of razors!

Well, with armpits the smell isn't very pleasant. Primates like to smell each other all over, but they also avoid the armpits.

I don't think they shave all over. They usually have headhair and they wear swimsuits so no reason to shave there either.

Harking back to the initial question about body hair... I heard a theory that didn't really explain it all but it is certainly interesting.
As humans evolved, babies started being born prematurely. The reasons are unknown, however the result was that they had less body hair and in order for babies to survive the mother needed support from other humans. This led to the social structure of a family forming and early man started to communicate more about how to care for other people, particularly helpless ones. A highly significant occurence in human history one could say!

Again, how would you prove that one?

I don't think absolute proof is accessible, or sought exclusively. The theory arose due to the comparative helplessness of human babies to most other animals, in particular apes (our closest relatives). They also take an awful lot of time to rear fully, (comparative once again) The reasons could be random... but the hypothesis is just one that seems to explain something about why we ended up so bald and naked. Seemingly the evolution continued in this direction because youthful traits were retained for longer and social environment that was created is also fairly powerful and useful to survival. Apparently also, we aren't supposed to be sexually promiscuous anymore because of this increased stable setup...

I saw on a kids wildlife programme a woman who raised orphan monkeys and she was saying how needy human babies were, most demanding infants on the planet apparently


Xanatic, we meet again, not stalking you, honest, just chasing you with

Peanut xx

Some religieus persons don't even believe where descendants of the monkeys. Imagine how far in the dark they are..

This is the voice of the author of the article you have all read!

Please read THE AQUATIC APE HYPOTHESIS which I co-wrote, in the H2G2 archives which was featured in the University project.

It may help to answer your questions.

Cheers for the interest!!!!!!!!!!!!!1

A less commonly mentioned possible explanation for the loss of body hair is the advent of fire use by humans. It would be a distinct and potentially fatal disadvantage to have a thick covering of body hair and be playing with fire. I think it would have been a fairly heavy selection pressure for hairlessness once our ancestors started using fire. As for pubic hair and underarm hair, another simple explanation. Hair in those areas is a very effective friction modifier. In other words, the presence of hair, plus sweat, underarms, helps to reduce the adverse effects of skin against skin friction. Same for pubic hair, if anyone has tried sex with pubic hair removed, it can become quite uncomfortable. Definitely an evolutionary disadvantage.

I was surprised to see Richard Dawkins give these theories little or no recognition in one of his recent books. Surely someone has mentioned them before.