Growth of Hair

Millions of years of evolution have reduced the hair we carry because we no longer need it to keep warm. We have cars now.

A small experiment, lad. Shave your head and your arm. Walk about in -20°C weather for an hour with both uncovered. Then, we'll talk some more.

Nice response!

Haricool, If you look at hair through a purely geometric lense, you will see that it increases surface area tremendously while remaining in a compact area.

Increasing surface area is important for both increasing evaporation (cooling) and for slowing down heat loss (insulation) to prevent heat loss.

In certain areas on the body this increased surface area also increases the tactile or haptic sensation of contact/movement/ assuring stimuation of nerves , increasing the area of sensation felt, thus improving signal to noise ratio...

milo

And besides, look at all the unemployed barbers there would be if we had no hair.

Then they could all become hatters and go mad from mercury.

Quite simply you lose the most body heat thru your head (assuming you are wearing clothes). Hair acts as an insulator (like a hat), hence lots of hair on your head.

This is also one of the reasons the toupee was invented, because it looks silly walking around the office with a knitted wool hat on your head. I am sure there are other reasons also

Uh, slight correction. Currently, it has been found that you lose no more heat through your head than you do through any other place on your body. Yes, I was surprised, too.

Yes I was also aware of that when I posted my comment, hence included this little gem.

Quite simply you lose the most body heat thru your head (assuming you are wearing clothes).

Clothes act as a good heat insulator, hence most of the heat loss thru the head is due to the fact that it is the largest part of the body exposed (and the heat has to leave somehow, hence the slight misconception). This can quite clearly be demonstrated when you climb a snow-covered mountain wearing only a shirt and shorts, then at the top of the mountain put on a full set of warm clothes.

http://cr4.globalspec.com/comment/146465

What doesn't make you stronger kills you....No wait, other way around.

Cheer up.

Barbers work to make you look alright.

Girls like guys that are bald, and then they like hairy guys too.

All will be revealed.

Be thankful that is okay for you to be hairy, since for girls this is a real turn off to be a hairy girl, while for a guy, it is not so bad.

As an evolutionary event it would appear that hair on the head prevented over heating.

Two hands is Menge` a Trois.

You have a plan, and God has a plan, and barbers live to cut hair.

Be cheery.

Obviously there was an evolutionary reason why our ancestors had hair, probably for insulation reasons, as already discussed. But that may not explain why we still have head hair.

If having (or not having) head hair improved the chances of having offspring, then it would quickly become a feature of the population. But, if there is little survival value or it's swamped by other factors then there isn't mechanism to either select for or against it.

Some people have lots of hair, some little, some have hairy backs (so I've heard), some don't, some have full beards, some don't etc.

I suspect the reason we have hair on our heads is because that's where the hair follicles are.

Are you Haricool or Haircool?

I think, the hair on the head has nothing to do with insulation etc. But, they grow because there is o friction of cloths as it is on almost all body.

If we assume that hair are protective insulation, why ladies do not have hair on almost whole of the body except certain portions. The temder skin of ladies should need more protection!

Besides, there are hair at locations, where no protection is needed after human invented cloths, still hair are there. Still evolution has not reduced the hair in those regions.

_{We are waiting for comments by hairy cat with hair all over.}

This sounds like my first ever question on CR4 and I was not disappointed on what was commented. It was a bit different but you will find a lot of information here:

http://cr4.globalspec.com/thread/2537#newcomments

Have a look and take your pick, Ky.

This reminds me of a question I've been wondering about for ages. Did we lose the hair on the rest of our bodies before or after we started wearing clothes?

The original premise that we no longer need body hair to keep warm is close, but in fact it goes a bit deeper than that.

We have lost our body hair as a result of our development of a method of cooling that surpassed any previous method. We sweat! Moisture evaporates on our skin surface much more efficiently without body hair. Those who keep dogs, especially in summer, will observe the not so attractive alternative!

As we migrated from the tropics we found some areas of the world to be a bit colder so started wearing clothes to keep warm.

Thats all great! Do you know how to grow it on a bald head?

Exactly! And why; if we have hair on our heads for insulation, do we loose it as we grow older and more susceptible to the cold? Shouldn't our hair get thicker the older we get?

Hair would cushion the blows to the head from anger cave women.

We ran this topic once before, and the #3 reply about increased sensitivity is a new take on the crop, that wasn't addressed in the original topic thread. Agreed a good answer, Milo