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We "naked apes" aren't as hirsute as our primate cousins. We still have an ape-like density of hair follicles—but we sprout out peach fuzz, instead of a thick coat. Those downy hairs may be more than an evolutionary leftover, though. They may be "hair-trigger" sensors for bedbugs and other parasites. So says a study in the journal Biology Letters. [Isabelle Dean and Michael T. Siva-Jothy, Human fine body hair enhances ectoparasite detection, link to come.]
Researchers shaved one forearm on each of 29 student volunteers, and placed a hungry bedbug there. Without looking, the students counted each time they felt something. The researchers repeated the experiment on each victim's unshaven arm as a control. And don't worry—in each case they plucked off bedbugs just as they prepared to dine.
Turns out students were significantly more likely to sense bedbugs crawling on their unshaven arms. And those tangles of hair slowed down the bug's search for a place to snack, too. The authors say our fine human hair may thus be perfectly evolved: thin enough to eliminate hiding spots for bugs, but thick enough to act as an alarm system for bloodsuckers in the night—enough to make anyone's hair stand on end.
—Christopher Intagliata
[The above text is a transcript of this podcast.]
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3 Comments
Add CommentWhy is this news... 25 years ago when lecturing about the skin I mentioned that body hair served as a signal for parasites and other creepy crawly things. hairs act as levels amplifying the signals.
Reply | Report Abuse | Link to thisInteresting exercise. No doubt that our body hairs help us detect creatures and other encounters at close range. Bed bugs, however, are stealthy villains. They're active mainly when we're not. Although a bed bug might be sensed as it brushes against a hair of a fully awake person, I doubt few sleeping folks, regardless of how hirsute their arms or body, would notice and react to a wandering or feeding bed bug. Whereas the findings are not likely of much relevance to bed bugs, I am confident that the hair-associated sensations do alert us to many other insects, ticks and insults when we're more alert. More insight on the biology of bed bugs and other skin-associated pests may be found at IdentifyUS LLC.
Reply | Report Abuse | Link to thisI am one of those very hirsute individuals and since I sleep with a dog in my bed quite often. I can assure you the random flea that crawls onto me in my sleep is enough to awaken me to deal with the little critter. Never had any experience with bedbugs, I'll leave that to you city folk. Flies, ticks and mosquitoes don't stand a chance when I'm awake. This year was a bad one for ticks here, and I was awoken several times this summer by ticks crawling on me in my sleep as well.
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