Human body hair, once thought to be an evolutionary relic, has a real job to do

Another plausible theory is that humans lost their hair in order to dump heat more quickly. Humans are the only fully bipedal mammalian species. Bipedalism is more efficient than quadrapedalism, about 30% more efficient according to what I've read. That allows humans to be great long distance runners, but to fully exploit this advantage, humans also had to evolve the ability to dump heat more quickly, hence specially efficient sweat glands coupled with hairlessness.

Did you know that a human can actually outrun a horse on a hot day at medium to longer distances? The horse has to stop after a short while because it overheats.

Bed bugs are the disease of the week with epidemics in big city hotels....but in truth no one has ever died from being eaten alive by bed bugs. They are a nuisance, less dangerous than driving while texting. And mostly they bite when you are asleep, oblivious to stimulation, whether we are hairy or hairless.

In comparison, more people have died from Malaria in the past year then from all natural disasters COMBINED.

Africans are most afflicted by malaria due to geography. However if hairy backs to prevent mosquito bites was a protective evolutionary mechanism, then the Africans would be selected for hirsute bodies. But black Africans are far from the hairiest people.

Hairiness also promotes certain types of human parasites like lice, fleas, and mites. Look at the rates of infestations of the dog compared to their human master. Hairlessness can be more hygienic. decrease infections and promote survival.

Lastly men are far more hirsute than women. And their survival rates fall short by up to a decade compared to their female cohorts. If anything hairiness results in higher rates of death!

There is no "evolutionary scale" upon which creatures may be assigned higher or lower places.

I always assumed the main use of hair is protection from the sun. Explains why men have more than women, why most of it is on the head, why blacks don't have excessive hair (being better protected anyway), and why southern Europeans have more than northern Europeans.

Classic Just-So story, dressed up with faux 'data.' First, "bugs on hairy skin took about a fifth longer than those on shaved skin to attempt to bite their hosts." So about a fifth longer would mean what? People HAVE hair on their bodies, and they get bitten by bed bugs during sleep. Malarial mosquitos in Africa are the same. And the male/female difference cited goes directly against the hypothesis - why would men be favored over the more reproductively important women?

This is right up there with the 'aquatic ape' silliness that was foisted on anthropology. ALL mammals suffer from ectoparasites - how are humans different?

Silly idea, obviously the evolutionary cost of shaving was too high. Ever tried to nap a decent shaver from flint? The savings on stone resources must have been worth water buffalo alone.

(humor)

One preliminary and very limited study by less than leading researchers does not a well confirmed story make.

A disgusting experiment

"Lastly men are far more hirsute than women. And their survival rates fall short by up to a decade compared to their female cohorts. If anything hairiness results in higher rates of death!"

Correlation of two parameters does not prove causation. Males live shorter lives on average not because of denser hair but due to myriads of other reasons. For example, in some countries alcohol consumption and alcohol induced or aggravated illnesses is one of the main causes for such discrepancy. It would be kinda stretch to assume that poor males drink so much vodka just because they are so hairy.

I don't know why the experimenters were so squeamish. Bed bugs haven't been shown to transmit any form of disease at all.

There might be a simple reason we're so naked, the extreme immaturity of the human new born, neotony, and the effects of self domestication. The latter, as demonstrated by the records of foxes domesticated for the fur trade, caused all sorts of variation, associated with domesticated dogs.

A human child is born in an extremely immature state relative to other primates, because an infants head must be able to pass the birth canal. I might suspect that other species at a similar level of foetal development are almost hairless.

Um havent you just undermined your own argument? Seems like high melanin skin is protection from the sun, this is why Northerners are pasty faced.

It was only in the last 1000 years or so that women might be more cloistered indoors in ---some--- cultures. In any case, Asian, and Native American populations dont show so much sexual dimorphism with respect to hair.

And men go bald.

^^ That doesn't seem to be true:

http://men.webmd.com/features/why-mens-lives-are-shorter-than-women

That's an interesting theory and compelling experiment. That's believable that standoff with parasites could produce such a drastic hair loss. At the same time is it not clear why chimpanzees and gorillas, our closest genetic relatives, did not develop similar fining of hair - are they not combating creepy crawlers at all?

Another detail that asks for more explanation is that many people who live in colder climates (not all though) do have fine hair indeed. And you would assume that parasites issue is more pressing in warmer climates. So the question is why would those people need to have such a property in the environment with less parasites?

It may turn out that fine hair of humans in relation to those bugs is no more that exaptation. Meaning that the property was developed in the process of evolution for some reason not yet known and coincidentally become useful for repelling parasites.

To suggest there is causation by this experiment seems pretty ridiculous. It probably would have taken a lot of pressure to breed the hair follicles completely out of our genomes than for them to just gradually thin from lack of significance. If anything, men kept hair as it served some intimidation factor (beards and chest hair) and it may have stayed with women the same way that nipples have stayed with men since it serves an important purpose in the female.

And another plausible theory is that humans lost body hair after they began to ornament themselves with clothes, perhaps in conjunction with one of the two major cooling periods in modern human history. As sesonal temperature variations increased and spread closer to the equator, humans needed the ability to stay warm in winter and cool in summer. Since you can't take off your fur, clothes fit that bill nicely.

Clothes eventually replaced fur as humans became better at making efficient insulation; however, fine hairs remain, because - as they did under our thick mammalian coats - they create dead air space under clothes where heat is trapped.

And yet another theory as to why humans lost their body hair is because they began to ornament themselves with clothes, which replaced the need for body hair - to a degree. Fine hairs create dead air space under clothes, which is essential to proper insulation.

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Women are more highly evolved than men in the evolutionary scale

(1) women have higher body temperatures

(2) They have less body hair--- apes have the most hairs

(3) they have a higher tolerance for pain and hardship

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Unbelievable!

Body hair can protect human form the invasion of insects, I think it's true.