Does the increase in surface area made possible by the hair have any significant effect on the efficiency of the body’s ability to evaporate moisture?
It seems to me that the hair has an insulating effect. Particularly when one is also wearing clothes. So it probably makes you sweat more. The hair might also retard the ability of air currents to flow over skin even when there are no clothes.
All just guesses.
Hair tends to retain moisture, not help eliminate it. I suspect axillary and pubic hair in particular retain moisture and provide a more suitable environment for the production and retention of smells that are interesting to the brain. (Not my wife’s brain, necessarily, but the more primitive responses of the mammalian brain.) These smells can be a combination of natural chemicals such as pheromones, and bacteria which like to live there.
I’m off to my shower now, since I’m a modern man…at least a man with a modern spouse.
As a Certified Hairy Sweaty Dude, I am convinced that hair helps retain perspiration. This probably cuts down on sweat’s ability to do what it’s supposed to do, cool the skin. This in turn may very well cause you to perspire more.
Hair is definitely an insulator. Normally during the colder months I grow a full beard to help shield my face from the wind. Though it may not seem like much it does the job. During the summer months I normally have a closely cropped mustache and goatee. In either season if the facial hair gets long it holds moisture whether from sweat or the shower. Any time in the past when I’ve taken it completely off I can immediately tell the difference.
Humans evolved in a quite toasty environment. If hair helped cool you down, we wouldn’t be so nearly hairless. Note that the biggest mass of hair is on the tops of our heads which provides shade on the most heat sensitive part of our upright bodies. (Other mammals running around the open areas of Africa are quadrapeds so they kept their body hair. Although not all use the same cooling methods.)
While hair does add surface area from which evaporative cooling can occur, cooling hairs don’t actually cool the skin. Hair doesn’t carry heat away well at all.