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Why do humans still have body hair?
Hairs serve as motion detectors for alerting us to insects, like bedbugs, before they can bite us.
Wed, Dec 14 2011 at 8:20 AM
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Photo: Lee J Haywood/Flickr
Human body hair might seem to be useless on today's modern man, but it could help us detect parasites, researchers suggest, adding there's a chance our female ancestors preferred a bug-free mate, and so opted for hairier guys.
Humans appear relatively hairless compared with our ape relatives, but the density of hair follicles on our skin is actually the same as would be expected of an ape our size. The fine hairs that cover our bodies, which have replaced the thicker ones seen on our close relatives, are thought to be an evolutionary leftover from our hairy ancestors.
Now scientists find these fine hairs are useful after all — people with more of them are better at detecting bedbugs.
"I run a research group that seeks to understand the biology of bloodsucking insects," said researcher Michael Siva-Jothy, an evolutionary ecologist at the University of Sheffield in England. "Our aim is to find ways of controlling these insects effectively and thereby preventing the transmission of insect-vectored disease."
Investigators recruited 29 university student volunteers through Facebook and shaved a patch of hair from one of their arms. The scientists then tested how long it took the volunteers to detect bedbugs placed on each arm and how long it took the parasites to find a good place to feed on. (The bugs were removed before they started feeding.)
The researchers found that body hair significantly enhanced how well people detected the bedbugs, with participants noticing the bugs on the hairy arm quicker than they did when tested on the "hairless" arm, with the hairs serving as motion detectors. The hair also prolonged how long it took the parasites to find places to feed, presumably because they hindered movement, Siva-Jothy told LiveScience.
Men seemed better at detecting parasites — they are generally hairier than women because of higher testosterone levels. This does not necessarily mean that women are more likely to be bitten — blood-sucking insects likely prefer to bite hosts in relatively hairless areas such as ankles.
Although the researchers stress they are not saying that the differences in male and female body hair are due to parasites, they do speculate that in our evolutionary past women might have preferred men with fewer parasites on them — hairier men.
The scientists detailed their findings online Dec. 13 in the journal Biology Letters.
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Even body hair on females varies significantly between different ethnicities... any anthropological or historical reasons for that?
'Still' have body hair? If it takes a university to work out why we have body hair, surely common sense says that random unintelligence could not have produced a design so intelligent.
I have hair on my forearm and noticed, when I get a sun burn it's mostly where there's less hair, and less so on the forearm. I have really sensitive skin, so you could also theorize that body hair protects from the sun. and keeps sweat from rolling off and keeping moisture in place.
What they do not mention in the article that diabetics get neuropathy and can have a loss of hair from that. I know because I am diabetic. That is the reason some of us lose their hair. And even though I don't have hair on my legs I can still detect something on me.
How evolution theory explain the continuing growing hair on our scalp, primates do not have such a thing. also we have hair in places where usually they do not have.
evolution has nothing to do with it. humans are attracted to people with hair on their head more so than their body, and so they choose to breed with such examples and continue this feature. it's the action of humans that decide how we look. better to ask the question why do we like hair and skin, but we want to see hair covering the skin on our heads and not anywhere much else.
Evolution vs. Creationism. I opt for science.
No wonder you are confused.
Thanks for showing the world how little you know.
I didn't read this... O.o
Your'e right we're not related to apes in general. I think I'm closer to a Bonobo myself.
So DNA lies and we arn't 99.99% identical to chimpanzees, which btw are primates... Hm, I guess a lot of court cases are going to get thrown out because DNA isn't accurate.
i think people with hairy skin r realy stronggggggggggg.
I feel proud I went to a University that spends so much time researching something that brings so little benefit to the world
at least your University does ressearchs,mine steals money -_-
I think the bigger question is "why did we lose our hair in the first place?" Think about it, we lost our "fur" and had to wear the fur of other animals to keep warm. Why?
Because our method of hunting our prey back on the African savannah involved running after it until it died of heat stroke. I'm serious. In order for our ancestors to do that, they had to be able to sweat to cool off. In order to sweat, we had to lose our hair.
So why did other hunting mammals (lions, tigers, cheetahs, jaguars, pumas, etc.,) not lose their hair?
We are the only naked land mammal. The only other mammals without body hair are marine mammals. Hence the aquatic ape theory of human evolution, which is strongly repudiated by biologists, mainly because they didn't think of it.
If people are hairy to detect bugs, and bugs like to bite people in non hairy places like the ankles, then that makes no sense. We should have hairy ankles then shouldn't we. And the fact women are less hairy makes no sense either then, why would evolution make men hairier than women if women need bug protection too, we should all be walking hairy mammoths. The ultimate bug protection, this article is a load of hairy bollox
We have hairy ankles, at least I do?
What exactly is the "theory of revolution"?
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