Why Do Asians Have Smaller Eyes? Full Evolutionary Explanation

One of the most distinctive features of Asian people, especially East Asians, is their small eyes. So many theories and statements have been made regarding this peculiar physical trait, but not everything you’ll find out there is correct.

So, why do Asians have smaller eyes? In this article, we will set the record straight by offering a complete evolutionary explanation of how this trait came to be.

Why Do Asians Have Smaller Eyes?


Many Asians, especially those from East Asia (China, Japan, Thailand, Korea, etc.), have smaller eyes than other people. The “Asian eyes” are described in many ways, including “slanted eyes”, almond-shaped eyes, and “tired eyes”, among other offensive phrases. Some people even consider them as physical defects.

The truth is that these Asian eyes do not indicate any physical defect. Different human species have diverse physical attributes that are passed down through genes. These attributes include skin color, height, eyes, and hair type among others. For Asians, their most distinctive feature is their small eyes.

Unfortunately, the stereotypical descriptions and discriminations have compelled many Asians to undergo expensive and risky plastic surgeries to avoid ridicule, especially when they are outside their countries.

A Chinese TV personality, Julie Chen, underwent plastic surgery to reconstruct her eyes so that she could look appear “less Chinese”, while during the Second World War, Fred Korematsu, a Japanese-American, tried to reconstruct his eyes to look “less Japanese” to avoid captivity.

The main question that everyone asks about these eyes is what makes them appear smaller than other typical human eyes. The lack of a conclusive answer to this question only fuels further speculation and stereotypes. Therefore, the best way to end the unwarranted discrimination and ridicule of Asian people because of their eyes is to offer a complete evolutionary explanation of why these eyes exist and the particular class of people who have them.

How Asian Eyes Evolved

Since humans have diverse physical traits, scientists have always worked hard to explain how exactly these traits developed. According to scholars, the small Asian eyes are a type of mutation that follows this specific racial group. This evolution continues to influence the shape and size of their eyelids.

This mutation is the natural process of selecting and deselecting several characters through time. It’s a random change in a gene that causes inheritable physical characteristics. These traits can be useful, harmful, or neutral, depending on many factors like which part of the body they affect, the degree of deficiency they cause, personal appreciation, etc.

A favorable gene mutation can be chosen and deliberately spread across a population for medical reasons and adaptability to specific environmental conditions. For instance, the Mongoloid slit eyes are believed to have evolved to help this particular population endure cold temperatures experienced in East Asia. Originally, Eastern Siberia was inhabited by a Mongoloid racial group known as the Tungus.

This region experiences very low temperatures, especially during winter. Temperatures can drop to as low as minus 96 degrees Fahrenheit. Since the facial structure of the Mongoloid race lacks protuberance, it reduces the surface area of the face that’s exposed to the cold.

Apart from the flattened face, this group of people also has reduced brow bridges and a nasal skeleton that is the same height as the eye’s cornea. To accommodate the extra size of their nasal resonance chamber, these people have wider faces than Caucasians and other human races. This chamber is necessary for speech.

Furthermore, their cavity is deeper than in other human races because it helps them to heat the cold air they inhale. Therefore, their molars and cheekbones are larger and extended forward to create the necessary depth. The other most distinctive facial feature in Mongoloid is their eyes.

Their monolid or epicanthic fold tends to be smaller than in other humans because it’s designed to adapt to snow glare and snow blindness. Their eyelids are a bit slit to allow the least reception to excess light. In the Mongoloid race, this slit develops naturally during the entire process of human development.

This design was replicated in artificial goggles by the Arctic Eskimo, signifying the engineer-like part of natural selection. The slit monolid offers further protection against extreme cold and snow. The fatty layer that forms above and under the eye causes the slit to form.

Since fat is a poor heat conductor, it effectively insulates the eye from extreme cold. This fat is spread throughout the face to offer complete insulation. The eye orbitals in the Mongoloid race are spread vertically to offer extra space for more fat. Recently, scientists discovered new genetic proof of other Asian phenotypes that offer the same benefits as the small eyes.

For instance, a variant of the Ectodysplasin receptor has been found in Asians and is believed to make their hair thicker and increase their eccrine glands that increase sweating. This receptor is also known to reduce mammary glands, causing small breasts. In short, the epicanthic fold in the people of East Asian and Southeast Asia is believed to have been passed down from their cold-adapted descendants.

However, this explanation doesn’t apply to the African races with this trait, especially the Nilotic people and Khoisans. Scientists claim that the epicanthic fold in African people is meant to protect their eyes from the extremely bright ultraviolet light that’s prevalent in arid and semi-arid areas.

Nevertheless, the exact evolutionary function and origin of the epicanthic fold are still not completely clear. Most scientific explanations are based on random variations and selections, especially sexual selections, or potential adaptation to extreme environments like deserts and/or extremely high ultraviolet light that’s prevalent in high-altitude environments like the Himalayas.

These writers https://eduwriter.ai/, who create AI essays to correct human writings, dissect complex evolutionary theories with chapters referring to genetic mutations and environment adaptations for different diversity among human populations; specifically the East Asian slit eyes (Mongoloid), which deepen appreciation of difference.


Ethnogeographic Distribution of the Epicanthic Fold

This racial group includes Mongols, Amerindians, Siberians, Polynesians, Indonesians, and Inuits. However, the continuing migration from these areas has led to the spread of this trait to other parts of the world, including America, Europe, and Africa. Despite the ongoing intermarriages and intermixing between Asians and other people who don’t have this anatomical trait, many Asians continue to get small eyes.

This fold is predominantly present in specific populations living in Asia, including the ethnic groups in East Asia, Southeast Asia, North Asia, and Central Asia. It’s also very prevalent among Micronesians, indigenous people of the Americas, Mestizos, and a few Africans, especially the Nilotic and Khoisan people. In South Asia, this physical trait is commonly found among Bhutanese, Kirati People, Adivasi, and Northeast Indians.

The epicanthic fold is practically universal in most of these populations, especially in East and Southeast Asia. In the two regions, almost 90 percent of the natives have this trait. It also occurs, albeit at a significantly lower rate, in other ethnic groups like Scandinavians, Irish, Hungarians, Poles, Estonians, Samis, Lithuanians, Finns, Russians, Latvians, etc.

The degree of visibility of the epicanthic fold varies between individuals. Furthermore, the attribution of the presence or absence of this trait is subjective. In most cases, the degree of attribution of this characteristic is relative to its occurrence within a specific community. Similarly, its frequency varies clinically across Eurasia.

Therefore, the use of this physical trait as a phenotypic marker in the definition of biological populations is still contentious. Other possible causes of epicanthic fold include age and medical conditions. Most fetuses have this physical feature but lose it after the sixth month of gestation. Medical conditions like Down syndrome, Zellweger syndrome, and Noonan syndrome are known to cause epicanthic folds.