Body hair protects against bedbugs

Body hair protects against insect bites and bed bugs

12/14/2011

A special fashion factor has been spreading for some years: More and more people are shaving their entire body hair, allegedly „hygienic reasons“, although less hair is not human „clean“ makes. The body hair remaining from primeval times have an important function, for example, to protect people from annoying parasites. The remnants of the body coat are by no means annoying, but contribute to the touch sensitivity of our senses, as researchers of the University in the British Sheffield demonstrated.

Search behavior of insects is extended
The body hair, which hardly exists in humans, is by no means an unnecessary remnant of former times. The remaining fine hairs increase the sensory perception of our body and make light touches more noticeable. The natural effect: If there are bed bugs or other insects on the skin, we can recognize and eliminate them faster. This was the result of a study by British biologists „University of Sheffield“. During the course of the study, the scientists examined how quickly subjects can recognize bed bugs. It showed that the stronger a participant was hairy, the faster the subjects noticed the skin parasites on the body. According to researchers, it can therefore be explained why men feel insects on the skin earlier than women. After all, even today men have significantly more body hair than relatively women, as the authors of the study argue in the scientific journal "Biology Letters". The study results showed that the fine hairs „extends the search behavior of bed bugs and facilitates the detection of these parasites, "say Isabelle Dean and Michael T. Siva-Jothy.

Study compared with women and men
The study involved 29 men and women (19 men and 10 women). During the experiment, the researchers placed previously starved bed bugs of the genus Cimex lectularius on hairy and relatively shaved forearms of the subjects of both sexes. It turned out that the bugs needed significantly more time to use their lancing tools when their forearms were hairy. In contrast, the insects could quickly use their sucking mouthparts when the skin was clean shaven. However, to ensure that the participants were not at risk, the bed bugs were quickly removed before they could stab. Since women usually have significantly less hair on the forearm, no significant difference could be detected between shaved and non-shaved skin. Basically, however, the time to insect bite lasted longer, the denser and longer the body hairs were.

In the second part of the experiment, the participants should provide information on when and if they feel crawling of the animals on the skin. For this, the subjects had to avert their eyes from the forearm. Both men and women, whose forearms were unshaven, felt the creatures faster than those whose arms were shaved. The research team summarizes that the body hair fulfills a double protective effect. On the one hand, they hinder the insects when applying stitches and, on the other hand, they sensitize the sensory perception, so that the animals are perceived faster, in order to ultimately ward them off.

Evolution made a compromise on body hair
In prehistoric times people lived in tribes and stayed longer in one place. However, this has also favored the transmission of infectious diseases, as insects are commonly considered carriers of serious diseases. In the course of evolution, people lost more and more of their fur. The less available body hair now had the advantage that the insects are recognized more quickly on the skin. Therefore, the scientists believe that the existing hair is virtually a compromise of human development. On the one hand, the function of the fine hairs is still available to make it difficult for the insects and on the other hand, the animals can be spotted and eliminated faster, because the body hair has become much clearer. Why men, regardless of hormonal influences, have significantly more hair than women, could also be due to the sexual selection of those times. In ancient times, women preferred men with strong hair growth because they were better equipped for insects. Whether the recent findings lead to a rethinking may be doubted. Rather, people today are influenced by fashion influences. But the study shows that everything has a natural purpose. (Sb)