Why do black people have different hair? Science explains the genetics and evolution behind curly hair

Hair texture is one of the most visible examples of human diversity. Scientists say the tightly curled or coiled hair commonly found among people of African ancestry is the result of genetics, hair follicle structure and possibly an evolutionary adaptation that helped early humans cope with hot environments.

According to a study by anthropologists Nina G. Jablonski and George Chaplin, published in Dermatologic Clinics in 2014, Afro-textured hair is a characteristic shared by most African populations and is likely the ancestral hair type of modern humans.

What Makes Afro-Textured Hair Different?

The study notes that sub-Saharan Africans generally exhibit tightly curled or Afro-textured hair, while some northern African populations tend to have looser curls. Researchers found that the hair shaft in African populations is typically elliptical in cross-section, unlike the rounder shafts often associated with straight hair.


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Jablonski and Chaplin explain that the curliness is caused by the shape of the hair follicle. The hair bulb has a "retrocurvature" that produces an asymmetrical S-shaped follicle, causing hair to grow in tight curls or coils.

An Evolutionary Advantage?

One of the most interesting findings from the study is the theory that Afro-textured hair may have evolved to help regulate body temperature.

The researchers write that hair form is "almost certainly related to thermoregulation" and may have played a role in keeping the head cool during physical activity in hot climates. They suggest that short, tightly curled hair could create a layer of cooler and drier air close to the scalp, helping protect the brain from excessive heat.

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The study states that "short, curly, Afro-textured hair evolved because it can maintain a boundary layer of cooler, dryer air near the scalp, and thereby protect the thermogenic and thermosensitive brain."

Genetics Also Play a Key Role

While scientists have identified several genes associated with hair texture, the authors note that the complete genetic basis of hair form remains only partially understood. The study points out that hair texture is likely influenced by multiple genes rather than a single genetic factor.

Researchers also note that the widespread presence of Afro-textured hair across the African continent suggests it represents the ancestral condition for modern humans.

Recent Research Supports the Theory

More recent research published in the journal Proceedings of the National Academy of Sciences (PNAS) in 2023 found that tightly curled hair offers superior protection against solar heat, reducing the amount of heat reaching the scalp. The findings support the long-standing theory that curly hair may have evolved as an adaptation to intense sunlight and high temperatures.

The Bottom Line

Scientists believe that the distinctive hair texture commonly seen among people of African ancestry developed through a combination of genetics and evolutionary adaptation. According to the 2014 study by Jablonski and Chaplin, Afro-textured hair likely helped early humans stay cooler in hot environments by shielding the scalp and brain from heat stress while also reflecting the rich genetic diversity of human populations.