The researchers used a mannequin and several wigs to understand how our hair has evolved.
We are the only primate species that is completely hairless, but for some inexplicable reason, we have a whole tuft of hair growing in seemingly random places, including on the top of the head, Science Alert writes .
Scientists still don’t understand why this is the case, but a new study appears to support the theory that our scalp hair evolved at some point to help keep us cool. For the new experiment, the scientists used a mannequin, several human hair wigs, and a climate-controlled room.
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A wig was put on a thermal mannequin and sent circling around a climate-controlled chamber. The scientists found that the mannequin absorbs much less heat with its hair than when it was bald. Note that the researchers tested several types of wigs in this way, including those with straight hair, loose and gathered in a ponytail, as well as tight curls.
Ultimately, the scientists found that tightly curled hair did the best job of shielding the mannequin from “solar” radiation. According to the authors of the study, the findings suggest that head hair evolved in response to the upright posture of our species, as well as our larger brains. The scientists suggest that the appearance, or retention, of hair on the head probably resulted in an optimal balance between maximizing heat loss over a large surface area of the body and minimizing solar heat gain over a large surface area of the head, directly above our brain.
Curly curls are a trait that no other mammal has, so obviously there is something in our history that made us prefer this type of scalp coverage. The scientists note that their study is, in fact, the first to focus on how scalp hair affects a person’s overall heat load, and not just the body’s response to sweating.
The results of the study suggest that regardless of the structure, the hair is a protective barrier that literally allows our brains to “not boil” from the heat. However, at the same time, scientists have found that curly hair is more effective at this task. Most likely, this is due to the fact that they do not lie flat, and therefore not only protect against “thermal overheating”, but also allow the scalp to “breathe”.
Note that this study has not yet been peer-reviewed, but has become available on the Preliminary Publication Server. Scientists also note that in the future it will be necessary to reproduce this experiment in humans in order to finally dot the “i”.