We’re in it now, people! The hottest months of the year are upon us and you are either feeling dry heat or intense humid heat. No matter which heat is making you sweat, you’ve probably thought of different ways to keep cool. Wearing the right clothes, drinking plenty of fluids, and limiting outdoor activities during hot weather are common ways to stay cool. Have you thought about how your hair may protect you from dehydration and overheating?
According to new research that was published on June 6, 2023, scientists evaluated different hair types and found that curly hair provided the most protection for the sun’s heat. Researchers and anthropologists state that humans evolved in equatorial Africa, where the sun beams down overhead for most days of the year. Investigators behind the study wanted to understand how the heat generated hour after hour from intense sunshine affected the evolution of hair. Anthropologists found that tightly curled hair helped humans stay cooler and conserve more water.
Curls Have Air Pockets That Aid Cooling
In order to simulate the extreme elements that our ancestors faced, researchers used a thermal manikin. This human-shaped model employed electric power to simulate body heat, allowing scientists to study heat transfer between human skin and the environment. Scientists also used human hair wigs of diverse textures to help get a better understanding of which hair type kept the body cool.
Scientists program the manikin to maintain a constant surface temperature of 95 degrees Fahrenheit (F), which is similar to the average surface temperature of human skin. The manikin was then placed in a climate-controlled wind tunnel. Scientists took baseline measurements of body heat loss by monitoring the amount of electricity required by the manikin to maintain a constant body temperature. The researchers then shined lamps on the manikin’s head to mimic solar radiation under four scalp and hair conditions. These conditions were as follows:
- Completely bald
- Moderately curled
- Tightly curled
The scientists had to calculate heat loss in a high-heat, high-humidity scenario, mimicking equatorial Africa, on all of the hair types. They found that all hair types reduced solar radiation to the scalp. Tightly curled hair, however, provided the best protection from the sun’s radiative heat while minimizing the need to sweat in order to stay cool. Scientists suspect that the tight curls allow for air pockets between hair strands. That means that you can have a lot of depth, from the top of the hair to the scalp, without a lot of density.
Moderately Curled Hair Can Be Cooling
Although tightly curled hair provided the most cooling protection, moderately curled hair offered some benefits as well. The exact level of curl that can pass some threshold of heat tolerance is not entirely clear and more research is necessary. Researchers also need to factor in length and style, as they may come into play. All of the wigs in the study had hair fibers that were eight inches long and loosely worn without any styling. It is very unlikely that differences in hair texture affect survival in modern populations, but some findings still have relevance today. For example, the research highlights the importance of some hair types forming a barrier that reduces the risk of overheating in the sun.
Earlier Studies Not That Brains Don’t Function As Well In Heat
A small study from 2020 found that too much sun on the head can impact a person’s ability to perform functions that require coordination and thinking. The authors behind the study noted that heat affects thinking because it undermines the way the nervous system works. Athletes with tight curls who flatten or straight their hair may want to consider these results. Styling the hair in those ways may actually decrease their ability to stay cool in the heat. The reason for that is because the sun’s rays can more easily penetrate the scalp.