Being hairy helps prevent you being bothered by biting insects, according to new research.
Having a lot of hair makes it harder for blood-sucking bugs to feed, the report said. It also increases the chances of them being felt on the skin and swatted away.
Scientists studied 29 volunteers who had one arm shaved before hungry bed bugs were placed on their skin. The results of the experiment showed that people with more hair - both longer hairs and fine, almost invisible "vellus" hairs - were more protected.
Hair covering the arms extended each insect's search for an ideal feeding ground and increased the likelihood of it being detected.
Because of this, bed bugs and other parasites including mosquitoes, midges, ticks and leeches prefer relatively hairless areas such as the wrists and ankles, the report, featured in the Royal Society journal Biology Letters, claimed.
Study leader Professor Michael Siva-Jothy, from the University of Sheffield's Department of Animal and Plant Sciences, said: "Our findings show that more body hairs mean better detection of parasites.
"The hairs have nerves attached to them and provide us with the ability to detect displacement. By forming a barrier and providing detection, these hairs prolong search time and make detection more likely because the bug has to spend more time clambering over them.
"The results have implications for understanding why we look the way we do, what selective forces might have driven us to look the way we do, and may even provide insight for better understanding of how to reduce biting insects' impact on humans."
But Prof Siva-Jothy said it would be wrong to assume women will always be bitten more often than hairier men.
He pointed out: "Men have more body hair than women, which is caused by the action of testosterone at puberty. This does not necessarily mean that women are more likely to be bitten. Blood-sucking insects are likely to have been selected to prefer to bite hosts in relatively hairless areas."