Curly hair appears across nearly every ethnicity on Earth, but the tightest, most consistent curl patterns are found in people of Sub-Saharan African descent. Beyond that, curly and wavy hair is common in people of Southern European, Middle Eastern, South Asian, Latin American, and Oceanian (particularly Melanesian) backgrounds. The real story is more nuanced than any single ethnic group, because hair texture is shaped by dozens of genes that vary widely both between and within populations.
Sub-Saharan African Hair
People of Sub-Saharan African descent have the tightest curl patterns of any population. Their hair strands tend to have an elliptical (oval) cross-section rather than a round one, which causes the strand to curve and coil as it grows. Studies of Ghanaian scalp hair, for example, measured average strand diameters around 71 to 72 micrometers, relatively fine compared to some other populations, but with that characteristic flattened shape that produces tight coils.
The curl pattern in African-textured hair is also influenced by the shape of the hair follicle itself. Rather than growing straight out of the scalp, follicles in this population tend to be curved or hooked beneath the skin’s surface, which forces the hair shaft into a spiral as it emerges. This is why the coils often begin right at the root rather than developing further down the strand. Hair types in this group typically fall into what stylists call type 4 (coily to kinky), though there’s significant variation across the continent, from looser curls in parts of East Africa to extremely tight coils in West and Central African populations.
European and Middle Eastern Populations
Curly and wavy hair is surprisingly common in people of European ancestry, particularly those from Mediterranean and Southern European backgrounds. Greeks, Italians, Spaniards, and Portuguese populations all have high rates of wavy to curly hair. The same is true for many Middle Eastern and North African groups, including people of Arab, Jewish, Turkish, and Amazigh (Berber) descent.
In Northern Europeans, a gene called TCHH (trichohyalin), which codes for a structural protein in the hair shaft, plays a major role in determining whether hair is straight or curly. Variations in this gene are strongly associated with hair shape in people of European ancestry. A large genetic meta-analysis found that the most statistically powerful signal for hair shape across all populations was located near the TCHH gene region on chromosome 1. But TCHH is far from the only player. That same study identified 12 distinct gene regions linked to hair shape, eight of which had never been found before, underscoring just how genetically complex curl patterns are.
East Asian and Indigenous American Hair
East Asian populations (Chinese, Japanese, Korean) tend to have the straightest, thickest hair of any group. This is largely driven by a variant in the EDAR gene, which affects hair follicle thickness and shape. The same gene variant also influences sweat gland density and tooth shape, suggesting it was strongly favored by natural selection in ancestral East Asian populations.
What’s fascinating is that straight hair in East Asians and straight hair in Europeans arose through completely different genetic pathways. Europeans who have straight hair typically carry certain TCHH variants, while East Asians with straight hair carry EDAR variants. This means the trait of straight hair evolved independently at least twice in human history, through separate genes in separate populations.
Indigenous peoples of the Americas generally inherited the thick, straight hair pattern associated with their East Asian ancestors who crossed into the Americas thousands of years ago. However, there is more variation than stereotypes suggest, particularly in populations with longer histories of genetic mixing.
Latin American and Mixed-Ancestry Populations
Latin American populations are a natural laboratory for understanding hair texture because of their mixed European, Indigenous American, and African ancestry. A large genome-wide study of admixed Latin Americans, whose average genetic makeup was roughly 48% European, 46% Native American, and 6% African, found enormous individual variation in hair shape. That study identified a new gene, PRSS53, which encodes an enzyme active in the hair follicle and influences curl pattern in these mixed populations.
The practical result is that within a single Latin American family, you can see everything from pin-straight to tightly coiled hair depending on which combination of ancestry-linked gene variants each person inherited. This makes Latin America one of the most hair-diverse regions in the world.
Oceanian and South Asian Populations
Melanesian peoples of Papua New Guinea, Fiji, the Solomon Islands, and Vanuatu often have tightly curled or frizzy hair that looks similar to African-textured hair but arose through a completely independent genetic route. This is one of the most striking examples of convergent evolution in human appearance: two populations on opposite sides of the world developed similar hair textures through different genes, likely in response to similar tropical environments.
South Asian populations show wide variation. Curly and wavy hair is common across the Indian subcontinent, particularly in southern India and Sri Lanka, while straighter hair is more frequently seen in parts of northern India and Nepal. This gradient reflects both the complex genetic history of the region and the influence of local environmental pressures over thousands of years.
Why Curly Hair Evolved
The leading theory for why tightly curled hair became dominant in equatorial Africa involves heat management. Researchers at Penn State tested this by placing different hair textures on a heated, human-shaped mannequin inside a wind tunnel. They simulated conditions matching equatorial Africa: about 86°F with 60% humidity. Tightly curled hair provided the best protection against solar radiation reaching the scalp while also minimizing the amount of sweat the body needed to produce to stay cool.
The key mechanism is the air space within curly hair. Tight coils create a buffer zone between the sun and the scalp, blocking heat before it reaches the skin, almost like natural insulation. Straight hair lies flat against the head and transfers more heat directly to the scalp. For early humans who had lost most of their body hair and were active in open, sun-drenched environments, this passive cooling would have been a meaningful survival advantage, reducing water loss from sweating during the hottest parts of the day.
Hair Texture Is Polygenic
One reason hair curl doesn’t map neatly onto any single ethnicity is that it’s controlled by many genes at once. Current research has identified at least 12 gene regions with strong effects on hair shape, and researchers suspect many more contribute smaller effects. A predictive model using 14 genetic variants from different genes could only achieve moderate accuracy in guessing someone’s hair type, which tells us that a large portion of hair texture variation remains unexplained by the genes we’ve found so far.
Hair texture can also change over a person’s lifetime. Hormonal shifts during puberty, pregnancy, and menopause frequently alter curl patterns, sometimes dramatically. A child with ringlet curls may grow into an adult with wavy hair, or vice versa. This happens because hormones influence the shape of the hair follicle and the proteins that give the hair shaft its structure. So even within one person, hair texture isn’t fixed, which adds another layer of complexity to the relationship between genetics, ethnicity, and curl pattern.