Can anyone explain body hair?
Discussion
Obviously I know what it is, of course, but a couple of Insomnia questions that occurred to me last night. It would be great if anyone has an answer, as they're not easily googleable!
1. What is the evolutionary reason for not getting body hair until puberty? As far as I'm aware, it doesn't apply to any other animal species, and I would've thought small kids in caveman days would've benefitted more from the extra warmth than adults?
2. I have two teenaged boys. Both have far hairier legs than I do, but neither need to shave yet, nor show the slightest sign of chest or back hair yet. What's the cause for that?
1. What is the evolutionary reason for not getting body hair until puberty? As far as I'm aware, it doesn't apply to any other animal species, and I would've thought small kids in caveman days would've benefitted more from the extra warmth than adults?
2. I have two teenaged boys. Both have far hairier legs than I do, but neither need to shave yet, nor show the slightest sign of chest or back hair yet. What's the cause for that?
Kermit power said:
Obviously I know what it is, of course, but a couple of Insomnia questions that occurred to me last night. It would be great if anyone has an answer, as they're not easily googleable!
1. What is the evolutionary reason for not getting body hair until puberty? As far as I'm aware, it doesn't apply to any other animal species, and I would've thought small kids in caveman days would've benefitted more from the extra warmth than adults?
Evolution has, via trial and error, decided it was the best option. Growing hair requires energy, raw materials, all derived from food. That energy may be better used actually growing, building bone and muscle.1. What is the evolutionary reason for not getting body hair until puberty? As far as I'm aware, it doesn't apply to any other animal species, and I would've thought small kids in caveman days would've benefitted more from the extra warmth than adults?
I guess originally, children would have been born with hair, some more than others. Those with less hair didn't die as they had their parents warmth, but grew quicker/stronger so survived in bigger numbers. They passed their less hairy genes on more often than hairy kids did. Two less hairy kids, as adults, mated, so their kids had even less hair, and survived better. And so on. Over many generations, less hairy infants became more and more common.
I think some of the smaller mammals, like mice and rats, give birth to naked babies, so it does apply to some other species.
Kermit power said:
1. What is the evolutionary reason for not getting body hair until puberty? As far as I'm aware, it doesn't apply to any other animal species, and I would've thought small kids in caveman days would've benefitted more from the extra warmth than adults?
Body hair at puberty may also have acted as a signifier of sexual maturity - I doubt it's much about warmth.
Worth bearing in mind that evolution has no plan. If you have a trait that does not penalise you or give you an advantage then it is essentially invisible so there is no pressure to get rid of it or make it proliferate.
The idea that all hair is for protection is an old, and quite clearly garbage idea or your elbows and knees would be hairy and not your belly button. Some hair is useful such as on your head (see how a sunburnt bald patch feels) or eyebrows and eyelashes, keeping sweat out of your eyes but we are the 'naked ape' and as long as there is no penalty or advantage then it will stay that way.
The idea that all hair is for protection is an old, and quite clearly garbage idea or your elbows and knees would be hairy and not your belly button. Some hair is useful such as on your head (see how a sunburnt bald patch feels) or eyebrows and eyelashes, keeping sweat out of your eyes but we are the 'naked ape' and as long as there is no penalty or advantage then it will stay that way.
Pedro25 said:
What part of the evolutionary process allows head hair to recede almost to skin length in my case, but hair grows out my ears and continues to creep out of nasal cavities? Millions of years ago why would I have needed to have a cold head but warm toasty ears?
Aural and nasal hair creeping out of said cavities serves a purpose in helping prevent other less pleasant things from creeping in, I belive.gregs656 said:
Evolution hasn't 'done' anything, least of all by trial and error, and definitely not through a decision, nor are the consequences of evolution fixed - there is no 'best option'.
There is “best option out of the variation which occurred”. Which comes to some staggeringly well optimised solutions as well as some where the limitations of the previous solutions are painfully obvious. gregs656 said:
TwigtheWonderkid said:
Evolution has, via trial and error, decided it was the best option.
Evolution hasn't 'done' anything, least of all by trial and error, and definitely not through a decision, nor are the consequences of evolution fixed - there is no 'best option'.BoRED S2upid said:
We evolved worse than animals. We would be screwed if we all went back to day 1.
Animals can do much cooler things than us.
Some of the things that animals can do may well be much cooler than some of the things that we can do, but given that we can film them doing those cool things, beam the pictures live around the world, record them for posterity and then sit down to watch them back with an alcoholic drink of our choice that doesn't purely depend on us finding fruit that is just rotten enough on the floor, I think on balance we can say that some of the things we can do are way cooler than some of the things that animals can do to.Animals can do much cooler things than us.
Kermit power said:
Pedro25 said:
What part of the evolutionary process allows head hair to recede almost to skin length in my case, but hair grows out my ears and continues to creep out of nasal cavities? Millions of years ago why would I have needed to have a cold head but warm toasty ears?
Aural and nasal hair creeping out of said cavities serves a purpose in helping prevent other less pleasant things from creeping in, I belive.Kermit power said:
BoRED S2upid said:
We evolved worse than animals. We would be screwed if we all went back to day 1.
Animals can do much cooler things than us.
Some of the things that animals can do may well be much cooler than some of the things that we can do, but given that we can film them doing those cool things, beam the pictures live around the world, record them for posterity and then sit down to watch them back with an alcoholic drink of our choice that doesn't purely depend on us finding fruit that is just rotten enough on the floor, I think on balance we can say that some of the things we can do are way cooler than some of the things that animals can do to.Animals can do much cooler things than us.
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