Why do asians have flat faces

Why do Asians usually have flat faces? from TooAfraidToAsk

In the present study, the frontal and facial features of 112 populations from around the world are compared in terms of frontal and facial flatness measurements. Univariate analyses and canonical correlation analysis were applied to six indices representing flatness of frontal and facial bones. The deep infraglabellar notch, marked prognathism, and flat frontal bone show distinctive Australian/Melanesian characters among recent populations. Very flat faces in the transverse plane are the most common condition in eastern Asians. Some subSaharan Africans share similar characteristics with Australians in terms of marked prognathism and flat frontal bones in the sagittal plane on the one hand, and with eastern Asians on the other hand, for flat nasal and zygomaxillary regions. These results are not necessarily inconsistent with the evidence for regional continuity. The examination of relationships between frontal and facial flatness through canonical correlation analysis reveals a significant association between morphological features such as a deep infraglabellar notch, prognathism, flat frontal bone, and flat faces in the transverse plane. In this context, together with the generalized features of the late Pleistocene fossil record, the features of Australians having transversely projecting faces and of eastern Asians showing weak infraglabellar notches, ortho-/mosognathism, and rounded frontal bones can be interpreted as a differential retention of ancestral traits of anatomically modern humans. This may allow us to suppose that the frontal and facial flatness features treated herein can be explained by the hypothesis of a single origin of anatomically modern humans.

When you look at someone’s face, what part do you concentrate on? Common wisdom has it that the eyes are the focal point of the face and they are the features that draw attention first. But according to a new study, that may not be universally true – while Western cultures do fixate on the eyes, East Asians tend to focus on the nose.

We owe a lot of our knowledge about the way we look at images to a Russian psychologist Alfred Yarbus. He was the first scientist to carefully record the subtle eye movements that people make when they take in a view. Yarbus’s experiments showed that our gaze rapidly flicks back and forth across an image so that our centre of vision focused on the most important parts. For example, while surfing websites, our eyes tend to focus on headings, words at the top of the page and words on the left.

The same thing happens when we look at faces. Previous studies have found that viewers tend to flick their gaze between the eyes and the mouth – an inverted triangle of important features. Some psychologists have taken this to mean that humans have a single, universal and innate strategy for processing faces. But this conclusion has a big snag – it’s only really based on experiments done with Western populations.

To get a more cross-cultural perspective, Caroline Blais and colleagues at the University of Glasgow tracked the eye movements of fourteen white Western students and fourteen East Asians, eight of whom were Chinese and six of whom were Japanese. The East Asian volunteers were all students who had recently enrolled in the university and had never been to a Western country before.

Look into my eyes…

Blais told the students that they had to learn a set of faces, including both Western and East Asian ones. After the learning trials, they were shown a larger set of mugs and had to say which ones they recognised (and the expressions on the familiar faces were changed to make things a bit more challenging). Later, they had to categorise a set of faces according to race, as quickly and accurately as possible. All of these tasks were essentially red herrings. What the researchers were interested in was the features that the students spent most time looking at.

The results were striking – the two groups of students fixed their eyes on distinct facial features. The Western eyes focused heavily on the eyes and the mouth, exactly as predicted by other studies. But the eyes of the East Asian students homed in on the centre of the face, halfway up the nose and right in the middle of the triangle of attention carved out by their Western peers. In the image below, the red areas show where the Westerners fixed their stares, while the blue areas were preferred by the east Asians.

The race of the face itself didn’t matter – the volunteers’ eye movements were dictated by their own culture and not that of the person in the image. And the students also showed the same biases in all three of the tasks they had to do – learn a face, recognise a face and categorise a face. The first two are considerably more complicated than the third but even so, the students always focused on the same features.

While some may criticise the study’s small sample size, the differences are certainly very pronounced and highly statistically significant. Blais’s team also took every precaution to ensure that they were measuring real strategies of perception. For example, they made all the images that popped up on the screen appear at a random corner, to make sure that students had to make a bit of effort to start looking at it.

Analytic vs. holistic?

Why the difference? It certainly isn’t because Western faces are more easily distinguished by their eyes and East Asian faces by their noses – an analysis of the faces didn’t back up that idea. Instead, Blais has two alternative ideas. It could be that it’s impolite in East Asian cultures to make direct or prolonged eye contact, and focusing on the centre of the face is simply a way of avoiding a social faux-pas. The second and more interesting theory, is that these strategies reflect general differences in the way that Westerners and East Asians view the world around them.

Some psychologists have suggested that Westerners view the world in an analytic way, by focusing on key features, while East Asians have a more holistic perspective where an object’s context is just as important as its parts. There’s a wide range of experiments that back up this hypothesis. For example, one group of Japanese and American researchers showed people two squares of different sizes, one of which had a line inside in. They asked their volunteers to draw a line in the empty square that was either exactly the same length as the first line or proportionally as long, relative to the different sizes of the square. They found that Westerners were better at the first, more absolute task, while East Asians were more accurate at the second relative task.

Does this apply here? Possibly, although Blais’s results don’t quite gel with other studies. When it comes to complex scenes, for example, Westerners focus on central objects but East Asians also flit their eyes across the backgrounds. In this study, the East Asians were the ones who focused on the centre but Blais suggests that this could be because they were homing in on the area that gives them the best overall view of the entire face, namely the centre. It’s an interesting idea but at this stage only a possible one.

Regardless, it’s clear that our culture affects the way we look at each others’ faces. It will be interesting to see if this is the case from birth, or whether people develop these varying strategies as they grow and pick up the habits of their countrymen.

Update: Want a different take on this story? Check out Scicurious’s excellent work at Neurotic Physiology.

Reference: PLoS ONE doi:10.1371/journal.pone.0003022

 In our lifetime, we’ve met thousands of individuals and have peered at even more faces. Whether referring to brow bridges or cheekbones, each and every face has its own distinctive structure. This prompts us to question how these differences in facial features came to be. Examining the factors responsible for change, especially using different races as points of comparison, helps us piece together the puzzle of why and how.

The disparity between the Mongoloid and the Caucasian are quite evident. The most prominent Mongoloid facial features— the flat face and slit eyes— evolved to accommodate cold temperatures. Eastern Siberia, was originally inhabited by the Tungus, a Mongoloid race. In temperatures as low as the recorded minus 96 degrees Fahrenheit, a facial structure lacking protuberances minimizes the surface area exposed to the cold. This flattening can be seen in reduced browbridges and the nasal skeleton that is the same altitude as the eye’s cornea. A widened face allows some compensation for the size of the nasal resonance chamber needed for speech, but this cavity needs to be more deeply set in order to heat inhaled air. Thus, to create this required depth, the malars, or cheekbones, are enlarged and extended forward.

Perhaps most striking of the Mongoloid characteristics are the eyes. The monolid, or epicanthic fold, is an adaptation to snow glare and snow blindness: the slit allows minimal reception to bright light. Where this slit occurs naturally on the Mongoloid, its effective design was emulated in man-made goggles created by the Arctic Eskimo, showing the engineer-like role of natural selection. Moreover, this monolid allows further protection from low temperatures. It is the fatty layer molded above and under the eye that creates the slit. Fat, a poor conductor of heat and thus an effective insulator, is distributed throughout the face. This facial fat is so crucial that the eye orbitals are extended vertically to provide additional space for fat.

Recent studies have uncovered new genetic evidence to explain other Asian phenotypes beyond the eyes and facial structure.

The EDARV370A (370A) allele, or a variant of the Ectodysplasin receptor, has been traced as the cause of Eastern Asian thickness of hair, an increase of eccrine glands (more sweat) and a decrease in mammary glands (small breasts).

But in further discussion of the potential selective forces causing 370A, the temperature again is a strong candidate— but in this case, the warm temperatures that followed the cold. A large number of eccrine glands supports efficient evapotranspiration, which due to water’s high heat of vaporization, shows a strong homeostatic effect in relieving body heat. As geographical records indicate a warm and humid Central Asia between 40,000 and 32,000years ago, excessive sweating is a selective advantage. Although this heated climate seems to imply there would no longer be a need for slit eyes and flat faces (and while it is true that eyes have become less epicanthic in some areas), the flat facial structures continue due to a lack of a more advantageous gene to replace it.

In contrasting the defined, thin Caucasian face structure with its flattened, insulated Mongoloid counterpart, the effects of adaptation and natural selection are unmistakable.

But it is the nuances between Asia itself, and more specifically, between the Korean, Japanese, Chinese, that are often mistaken as a singular entity.

“The only thing that all these [Asian] people have in common is the habit of eating rice,” states Carleton Coon, author of Races; a study of the problems of race formation in man. In fact, because rice was commonly used to ferment and preserve foods, and alcohol can lead to bodily damages, genes involved in the ethanol metabolic pathway became a target of selection. As the ethanol is metabolized, by product accumulates in the body, creating the flushed cheeks. For it is the ADH1B*47His allele, passed on 10,000 years ago and now nearly universal to East Asians, that causes the modern Asian to flush red after alcohol consumption.

Archaeological evidence supports that the Koreans were a Tungusic race that migrated from Central Asia to what is now the Korean peninsula in the third millennium BC. The Paleo Asians who were driven out of the peninsula by the Koreans are thought to be ancestors to the Ainu, an important ethnic group in Japan. This supports a study researching the allelic frequency of blood markers that found that Koreans are genetically nearest to Mongolians (Central Asia) and are related to the Japanese (Ainu). This is compatible with linguistic evidence that shows the Korean, Mongolian, Tungusic and Japanese language all share a common origin.

Despite the geographical proximity, there is not a demonstrably close genetic relation between the Korean and Han Chinese. This is supported by the fact that the Korean minority living in China for centuries haven’t received much genetic contribution from the Han Chinese.

The Korean population is said to lack most of a sizable ethnic minority compared to Japan and China. Perhaps due to nationalistic pride, Koreans have maintained their cultural and linguistic identity throughout historical migrations. Contrastingly, modern China, with over 3.7 million square miles, is comprised of 92 percent Han- Chinese and another 56 prominent minorities, including the Uyghurs, Tibetans and Hui.

The modern Japanese genotype is a result of an admixture of the Jomon and Yayoi farmers. Characterized with more wide-set eyes and a more pronounced facial topography, the Jomon were the primary inhabitants of Japan until circa 300 BC. As Japan transitioned from being hunter-gatherers to farmers, the period raised the carrying capacity that increased the population and promoted more movement and a dilution of the gene pool.

“The peoples of eastern Asian are quite diverse, and the national boundaries [between ] China, Korea and Japan are relatively recent political compositions that contain a range of different ethnic and cultural groups,” notes Agustin Fuentes, an anthropology professor at the University of Notre Dame.

Even within these nations, the “Japanese, Korean and Chinese are not biological units or even homogeneous populations.”

The differences between the Caucasian and Mongoloid are prominent, but it is the differences within the Mongoloid that lacks recognition. Whether it is their complex social history or evolutionary genetics, the Chinese, Japanese and Korean are significantly different.