Scientists from the Pennsylvania State University conducted an experiment that showed that the appearance of curly hair in the human species could be associated with problems with thermoregulation. The study was published in the bioRxiv preprint catalog.
Humans are the only primate species without a coat, but our heads are covered with hair, which in some people is also curly. No other animal has truly curly hair in nature. Scientists have long assumed that this feature allows people to sweat less in extreme heat.
In a new study, scientists set up an experiment. They tested several types of wigs on a mannequin, including straight, wavy, and curly wigs. It turned out that any hairline allows the scalp to absorb less heat, but curly hair is especially effective.
Sweating is an energy-intensive process that requires moisture. The results of the experiment mean that the hair on the head appeared as a tool for cooling the large brain, especially in hot and arid regions where there was not enough drinking water.
The results are considered preliminary until publication in a peer-reviewed scientific journal.