Our hair is more than just a style statement – it has purpose. In particular, tightly curled or afro-textured hair appears to function like a natural sunscreen and insulation layer for the head. In very hot, sunny climates (like equatorial Africa, where humans evolved), this kind of hair would help regulate body heat and protect the scalp from intense solar radiation. In fact, recent studies suggest that textured hair evolved as a specialized adaptation for thermoregulation – keeping the head cool and moist – in a harsh environment. For example, reference works describe how afro-textured hair differs from straight hair in ways that could benefit early humans (EBSCO Research Starters, n.d.). By understanding this, we can appreciate how the evolution of curly hair is tied to climate and survival.
Studies using thermal manikins and human-hair wigs have shown that all hair types provide some protection against the sun, but the effect is strongest with very curly hair. In one experiment, researchers placed wigs on a heated mannequin head and exposed it to simulated sunlight under controlled conditions. They tested baldness, straight hair, wavy hair, and tightly coiled hair. The results were clear: the presence of hair significantly reduced the amount of solar heat reaching the scalp, and tightly curled hair offered the most protection (Lasisi et al., 2023). In other words, spring-like hair threads catch and deflect sunlight before it reaches the skin.
Curls, Cooling, and Conservation
Not only does curly hair block more sun, it also helps conserve water. Hair reduces the need for sweating by limiting heat gain. The same study found that when the scalp had hair – especially tightly curled hair – the amount of sweating (and thus water loss) needed to stay cool was lower than with no hair (Lasisi et al., 2023). As one summary put it, “all hair reduced solar radiation to the scalp, but tightly curled hair provided the best protection… while minimizing the need to sweat to stay cool” (Tutella, 2023). In very hot, dry climates, saving water would have been a major advantage. By keeping the head cooler and more humid under the hair, early humans could dedicate more energy to other demanding needs – like growing a larger brain (Davis, 2023).
Hair Evolution in the African Sun
The evolutionary context makes sense. Early Homo sapiens evolved in East Africa, where intense sun beat down on upright, largely hairless bodies for many hours each day (Tutella, 2023). With the face and scalp exposed, a built-in “sun hat” would be hugely beneficial. Anthropologist Nina Jablonski notes that under that relentless sun, protecting the head was vital (Tutella, 2023). As groups migrated out of Africa into cooler regions, those with less curly hair fared just as well, so straighter and thinner hair became more common in northern populations. In other words, curly, voluminous hair was especially adaptive in equatorial heat and high UV exposure.
How Coils Create Shade and Airflow
Researchers also emphasize the three-dimensional shape of afro-textured hair as key. Tightly coiled hair stands off the scalp and creates insulating air pockets. This architecture both blocks sunlight and allows airflow. PowerYourCurls, a hair care site, explains that coiled hair “traps an insulating layer of air,” shielding the scalp (PowerYourCurls, n.d.). Similarly, New Scientist and other science outlets have described curly hair as a natural sunshade (New Scientist, n.d.). These sources align with the scientific findings: curly hair increases the volume of hair above the scalp, which means more solar rays hit hair first instead of skin. Straight hair lies flat and absorbs more heat, while curly hair’s spirals and loops scatter the rays and reflect them.
Textured Hair, Timeless Design
Taken together, the evidence paints a consistent picture: hair adaptation in humans was not random. Curly and afro-textured hair gave our ancestors a survival edge by improving thermoregulation. The ability to stay cooler, conserve water, and protect sensitive tissues likely helped early humans survive intense heat. This likely contributed to the conditions that allowed bigger brains and more active lifestyles (Davis, 2023). In short, curly hair acted as nature’s built-in sun helmet for early people living on the sun-drenched savannas.
- Reduced heat gain: Curly hair reflects and diffuses sunlight, keeping the scalp cooler (Lasisi et al., 2023).
- Water conservation: By reducing the need for sweating, coiled hair helps retain body moisture in dry heat (Tutella, 2023).
- Brain protection: A cooler head means less risk of overheating the brain, which was important as our brains grew larger (Davis, 2023).
Today, as we celebrate hair diversity, this science offers a hopeful perspective. The very hair textures that many communities cherish have deep roots in human history as a life-saving feature. Recognizing this natural insulation reminds us of human ingenuity and resilience. In cold or mild climates, hair texture matters less; but in our ancestral homelands, textured hair was a genius adaptation. Embracing this trait honors the ways our bodies have evolved to thrive. As one researcher noted, curly hair may have been “an unexpected hero for the brains of early humans” (Davis, 2023) – a fitting tribute to a biological gift shaped by the sun.
References:
Davis, M. (2023, July 18). Early humans evolved to have curly hair as protection from the heat of the sun, research reveals. Science Times. https://www.sciencetimes.com/articles/44922/20230718/early-humans-evolved-curly-hair-protection-heat-sun-research-reveals.htm
EBSCO Research Starters: Social Sciences and Humanities. (n.d.). Afro-textured hair. EBSCO. Retrieved from https://www.ebsco.com/research-starters/social-sciences-and-humanities/afro-textured-hair
Lasisi, T., Smallcombe, J. W., Kenney, W. L., Shriver, M. D., Zydney, B., Jablonski, N. G., & Havenith, G. (2023). Human scalp hair as a thermoregulatory adaptation. Proceedings of the National Academy of Sciences, 120(24), e2301760120. https://doi.org/10.1073/pnas.2301760120
New Scientist. (n.d.). Curly hair may have evolved to protect early humans from the sun. Retrieved from https://www.newscientist.com/article/2359444-curly-hair-may-have-evolved-to-protect-early-humans-from-the-sun/
PowerYourCurls. (n.d.). Curly hair evolutionary advantage. Retrieved from https://www.poweryourcurls.com/curly-hair-evolutionary-advantage/
