Scientists from Pennsylvania State University conducted an experiment that showed that the appearance of curly hair in the human species may be related to thermoregulation problems. The study has been published in the bioRxiv preprint catalog.
Humans are the only primate species without fur, but our heads are covered with hair, which some humans also have in curls. No other animal in nature has truly curly hair. Scientists have long assumed that this feature makes people sweat less in extreme heat.
In a new study, scientists set up an experiment. They tested various types of wigs on a mannequin, including straight, wavy, and curly wigs. It turns out that any hairline allows the scalp to absorb less heat, but curly hair is particularly effective.
Sweating is an energy-intensive process that requires moisture. The results of the experiment mean that head hair appears to be a tool for cooling the big brain, especially in hot, arid regions where drinking water is scarce.
Results are considered preliminary until published in a peer-reviewed scientific journal.