The flatter facial profile common among East Asian populations is the result of specific bone structures, particularly a wider and more prominent cheekbone and a less projecting midface. These features developed over tens of thousands of years, shaped by genetics and likely by adaptation to cold climates. Far from being a single trait, facial flatness involves the coordinated shape of several bones, from the nose bridge to the upper jaw to the eye sockets.
What “Flat Face” Actually Means in Anatomy
When anthropologists describe a face as “flat,” they’re talking about how much the middle portion of the face projects forward when viewed from the side. The midface is the region between the lower edge of the eye sockets and the base of the nose, formed primarily by the upper jawbone (maxilla) and the cheekbone (zygoma). A flatter face means these bones sit further back relative to the forehead and chin, creating less forward projection in profile.
A large study comparing 112 populations worldwide found that very flat faces in the transverse plane (side to side) are the most common condition in eastern Asian groups. This flatness is measured using standardized indices that capture how much the nose, cheekbones, and upper jaw project outward. In East Asians, the cheekbones tend to be higher-arched and wider, while the nasal bridge and upper jaw project less. This combination creates the appearance of a broad, smooth facial contour rather than a sharply angled profile.
It’s worth noting that this is distinct from “midface retrusion,” a clinical term for abnormal underdevelopment of the upper jaw. Population-level facial flatness is a normal anatomical variation, not a developmental problem.
The Role of Cold Climate Adaptation
The leading evolutionary explanation centers on adaptation to extremely cold environments. Populations that lived in northern Asia for thousands of years faced severe cold, and facial features that minimized exposed surface area offered a survival advantage. This follows a well-established biological principle called Allen’s rule: organisms in cold climates tend to have shorter, more compact body parts to reduce heat loss.
A 2024 study in the Journal of Anatomy examined native populations across Asia, North America, and South America and found a clear pattern. People from cold climates shared a set of facial features: increased facial height and width, reduced forward projection of the nose and midface, and larger, longer, lower cranial vaults. These traits appeared independently in separate cold-climate populations on different continents, suggesting the same environmental pressure produced similar results.
The nasal cavity plays a central role in this story. In cold, dry air, a taller and narrower nasal passage slows airflow and increases contact with the warm, moist lining inside the nose. This heats and humidifies air before it reaches the lungs, protecting delicate tissue from cold damage. Populations in cold climates showed increased nasal and facial height while keeping nasal width relatively stable, a configuration that improves the nose’s ability to condition frigid air. The wider cheekbones and reduced nasal projection that contribute to a flatter appearance may be, in part, a byproduct of this respiratory adaptation.
Genetics Behind the Shape
One of the most studied genetic contributors is a variant of the EDAR gene, known as EDARV370A. This variant is extremely common in East Asian and Native American populations but rare in African and European groups. The EDAR gene controls the development of tissues that originate from the outer embryonic layer, which includes hair, sweat glands, teeth, and parts of the facial skeleton.
People carrying this variant tend to have thicker, straighter hair, more sweat glands, distinctive shovel-shaped front teeth, and measurable differences in facial structure. A study of 715 Uyghur individuals (a population with mixed East Asian and European ancestry, making them useful for isolating genetic effects) found that the EDARV370A variant was significantly associated with eight distinct facial measurements, chin shape, and three ear features. The variant’s effects on facial bone development help explain why certain facial proportions cluster together in East Asian populations.
This gene variant is estimated to have become common through natural selection, though researchers still debate whether it was selected for its effects on sweat glands (useful in hot, humid environments), facial structure (useful in cold environments), or some combination. Either way, its high frequency in East Asian populations means it contributes meaningfully to the facial features typical of the region.
Bone Structure Differences in Detail
Several specific skeletal features work together to create a flatter facial profile. The zygomatic bones (cheekbones) in East Asian populations tend to be higher-arched and laterally prominent, meaning they flare outward more. This creates facial width. At the same time, the maxilla, the bone forming the upper jaw and floor of the nose, projects less forward than in populations with more convex profiles. The nasal bones that form the bridge of the nose are often lower and less prominent.
Research on Korean subjects found that these midfacial bones continue to change throughout life. In men, the maxillary angle decreased by about 2.9 degrees with aging, and the angle around the nasal opening decreased by 3.3 degrees. These changes were statistically significant in men but less pronounced in women, suggesting that the midface actually becomes flatter over time in East Asian males. Because the cheekbones are already high-arched, age-related bone changes in the upper jaw become more visible, contributing to the flattening effect.
The relationship between dental structure and facial profile adds another layer. Chinese subjects generally have more protrusive lips relative to the chin compared to European norms, partly because of the natural forward tilt of the lower front teeth. This means that standard Western measurements for an “ideal” facial profile don’t apply across populations. What looks balanced in one facial skeleton would look quite different in another, because the underlying bones set different proportions for soft tissue.
How These Traits Fit Into Human Variation
The comparative study of 112 populations found that facial flatness is not a single trait that either exists or doesn’t. Different populations show flatness in different planes and regions. Australian and Melanesian populations, for example, tend to have faces that project strongly forward but are flat across the forehead, with a deep notch above the nose. Sub-Saharan African populations share some features with Australians (forward-projecting faces, flat foreheads) and some with East Asians (flat nasal and cheekbone regions).
East Asian populations are distinctive because their flatness is concentrated in the transverse plane, meaning the face is smooth and broad when viewed from below or from the front. At the same time, they tend to have rounded foreheads without a deep notch above the nose, and the jaw sits in a relatively straight vertical alignment rather than projecting forward. This particular combination, wide and smooth across the cheekbones, minimal forward push of the midface, rounded forehead, is what gives East Asian faces their characteristic appearance.
Researchers have interpreted this pattern as representing different populations retaining different ancestral features from early modern humans, while also developing new adaptations to local environments. The flat transverse face of East Asians and the projecting face of Australians may both derive from variations present in late Pleistocene humans, with climate and genetic drift shaping which features became dominant in each region over the past 30,000 to 50,000 years.