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Beauty

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41czavSUnNL._SY344_BO1,204,203,200_ Beauty matters a lot in our world. The entertainment and fashion industries are based on beauty. Obviously some aspect of beauty is socially constructed and contextual. Beauty standards can change. There was a time when many aspects of European physical appearance, from light hair and eyes, down to the lack of an epicanthic fold, were excluded from idealized canons in East Asia. Obviously that is not the case today, and one can give a very plausible explanation through recourse to recent history as to why those norms shifted. Similarly, there is even a possibility that something as central to evolutionary psychology as preference for a particular waist-to-hip ratio may vary as a function of material conditions. I is clear from the social historical scholarship that the ideal characteristics of a female mate are strongly conditioned on the resources of the male; lower status males put greater emphasis on the direct economic benefits which their partner may bring because they are more on the margin of survival. For much of history lower status males meant most males. That is, peasants.

And yet cross-culturally there does seem to be a certain set of preferences which one might argue are “cultural universals.” People from “small-scale” societies are still able to consistently rank photographs of people from WEIRD societies in facial attractiveness which correlation with results from participants in developed nations. This indicates that there is a strong innate basis. An element of taste deep in our bones, even if we may inflect it on the margins, or increase or decrease its weight in our calculations of what makes an optimal mate. There may be societies where Lena Dunham’s “thick” physique may be preferred to Bar Refaeli‘s svelte profile, but I am skeptical that there would be societies where the former’s facial features would strike individuals as preferable to those of the latter (one might have to correct for Refaeli’s species-atypical hair and eye color, but European norms are pretty widespread outside of small-scale societies now, so that shouldn’t be a major issue). So the question then becomes: is this adaptive?

Evolutionary psychologists have a panoply of ready explanations. They are often grounded in correlations, and then adaptationist logic. For example, women with lower waist to hip ratios (0.7 being the target) have more estrogen, and are more likely to be nubile, and so are more fertile, all things equal. Since being more fertile is going to be a target of selection, a lower waist to hip ratio is going to be a target of selection, because implicitly there is a genetic correlation between estrogen and waist to hip ratio. The problem is that genetic correlations have to be proved, not assumed. Correlations are not necessarily transitive. Just because A has a positive correlation with B and B has a positive correlation with C, does not entail (necessarily) that A has a positive correlation with C.

With that in mind, a new paper looks at facial attractiveness, averageness of facial features, and heritability of both these traits. They use a twin design, with an N of ~1,800. And, they relate it to a comprehensible causal mechanism: mutational load resulting in increased developmentally instability. Basically, the more mutations you have, the more likely you have to exhibit facial asymmetry, and therefore facial averageness is a good proxy for genetic quality. It is well known that average faces tend to be rated better looking than non-average faces. This is part of an argument that Geoffrey Miller put forth in The Mating Mind, a very fertile work. There is an elegance to it. Unfortunately follow up work over the past ten years is suggesting that this simple model is either wrong, or, everything is a whole lot more complicated.

First, the paper, Facial averageness and genetic quality: Testing heritability, genetic correlation with attractiveness, and the paternal age effect. The abstract gives away the game:

Popular theory suggests that facial averageness is preferred in a partner for genetic benefits to offspring. However, whether facial averageness is associated with genetic quality is yet to be established. Here, we computed an objective measure of facial averageness for a large sample (N = 1,823) of identical and nonidentical twins and their siblings to test two predictions from the theory that facial averageness reflects genetic quality. First, we use biometrical modelling to estimate the heritability of facial averageness, which is necessary if it reflects genetic quality. We also test for a genetic association between facial averageness and facial attractiveness. Second, we assess whether paternal age at conception (a proxy of mutation load) is associated with facial averageness and facial attractiveness. Our findings are mixed with respect to our hypotheses. While we found that facial averageness does have a genetic component, and a significant phenotypic correlation exists between facial averageness and attractiveness, we did not find a genetic correlation between facial averageness and attractiveness (therefore, we cannot say that the genes that affect facial averageness also affect facial attractiveness) and paternal age at conception was not negatively associated with facial averageness. These findings support some of the previously untested assumptions of the ‘genetic benefits’ account of facial averageness, but cast doubt on others.

I’m going to reproduce some of the results from Table 4 below.

Averageness Attractiveness
Heritability Non-heritable Heritability Non-heritable Genetic correl Env correl
Female 0.21 0.79 0.6 0.38 0.11 0.21
Male 0.22 0.78 0.62 0.39 0.11 0.08
Overall 0.21 0.79 0.6 0.4 0.11 0.16

What you see is very modest heritability for averageness, and a decent one for attractiveness. But, there’s no statistically significant evidence that the genetic correlation is there (the confidence intervals are huge around 0.11, from 0 to 0.35). Though they state the environmental correlation passes statistical muster (so common environmental variables might be producing attractiveness and facial averageness). Please note that a heritability of 0.6 does no mean a correlation of 0.6. The heritability of height is 0.8 to 0.9, but correlation of the trait across siblings is ~0.5. Heritability is the proportion of variation of the trait explained by variation in genes, in the population.

If you just look at heritabilities, averageness seems to have been under stronger selection than attractiveness all things equal. Usually strong directional selection removes the heritable variation on a trait. The high heritability gives us a clue that there are a lot of ugly people around still, and some of that is just the way they are born. In contrast, there are fewer people with lop-sided faces. These are subjects from a Western society, so I bet the results are going to be different in a high pathogen load environment (my expectation is that heritability will decrease, but perhaps it will actually increase because as genetic factors which allow for one to be robust to disease will become more important in explaining variation in the trait).

Finally, in the near future there will be high coverage genomic sequences from many people. If you hit the same marker more than 30 times you can conclude with decent confidence if it’s a de novo mutation unique to the individual. You can actually check how well mutational load tracks with averageness and attractiveness (each human has <100 de novo mutations, so there’s a lot of inter-sibling variance presumably). At this point I’m moderately skeptical of a lot of the selectionist models, whereas five years ago I’d have thought there would be something there, and it would be easy to discover. And it may be that beauty, like many aspects of culture, is not about adaptation and function in any direct sense, but simply a cognitive side effect. Like what Steve Pinker has stated about music. I don’t really believe that, but we can’t dismiss that position out of hand anymore.

 
• Category: Science • Tags: Beauty, Sexual Selection 
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On occasion it is useful to outline definitions and frameworks. One thing that I often hear (i.e., I am constantly told) is that beauty is a subjective, and culturally defined, construct. In particular it is common for me to listen to explanations of “Eurocentric Western” beauty standards, as if they are sui generis. These views do not emerge in a vacuum. Rather, they grasp upon a real phenomenon: that beauty standards are malleable and vary across time and place. But like Classical Greeks who may have promoted a converse view, that beauty is an objective aesthetic reflection of innate characteristics of human value, modern subjectivists ignore the empirical reality in favor of a clean and simple narrative.

From where I stand it strikes me that Western intellectuals who engage in a discourse which engages the construction of the non-Western Other sometimes forget that the non-Western Other is itself a social construct with only constrained utility. To unpack it in more plain language, non-Western societies are diverse across themselves, and can not be bracketed as singular non-Western Other in a deep sense. And, they exhibit strong similarities to each other, and Western culture. This is all common sense, and I can attest to it personally, since my parents were raised in a non-Western society, and reflect a combination of banal and comprehensible attitudes, as well as shocking and outrageous ones. People are people. Just somewhat different.

When it comes to physical beauty this framework expresses itself in the assumption that Western standards of beauty are peculiar artificialities, with no grounding in human nature. This is an argument taken to too far of an extreme, and leads people astray. So let me outline a model which I think verbally captures the complexities of beauty, without pushing any particular interpretation in a maximal direction (and as a personal matter of fact I think a maximal argument fails).

First, you have to reconceptualize variation in beauty not as a spectrum, but as a multi-dimensional space. Some of the dimensions are deeply biological and “hardwired,” but others are environmental and malleable. There are two primary biological dimensions: symmetry and secondary sexual characteristics. The first is just species typicality, and I suspect this is the primal trait upon which a ‘beauty instinct’ is constructed. Individuals who are not symmetrical or exhibit bodily deformities are generally not considered attractive, though there are deviations from the norm (e.g., those who cultivate peculiar fetishes, and so may seek out maimed individuals to sexual encounters). The second biological dimension has to do with exaggerated sexual characteristics. There are many beautiful children who are highly symmetrical, but these children are not sexually attractive in the least, because they have not manifested this dimension of beauty. Though one would presume the two biological characters would be correlated, the correlation is imperfect. There are individuals who have striking secondary sexual characteristics, who nevertheless are not attractive in their facial features due to sub-average symmetry. Conversely, there are individuals who exhibit attenuated sexual sexual characteristics, but have symmetrical and highly species typical faces. Another issue to consider is that secondary sexual characteristics considered attractive in one sex may not be attractive in the other. This is qualitatively different from the case with symmetry, where both sexes stand to gain.

Now we move to the environmental dimensions. Here you have a distinction between the dimension which spans cultures, and the dimension which does not. Good hygiene for example is a cultural universe. But what constitutes good hygiene is not. In some ways attractive traits which are amenable to environmental intervention and are universal across cultures are innate at a remove, in that there are strong biological functional reasons why people across all societies tend to rate those with sweet breath more attractive than those with foul breath.

Finally, you have the dimension of temporally and culturally variant standards of beauty. This is the dimension which gets a great deal of attention, to the point where some assert that all standards of beauty are culturally contingent. There is famously variation in preferences as to the ideal figure of women, but this is not the really interesting case. Foot-binding, neck-elongation, and other sorts of body modifications which exhibit no rhyme or reason are much stranger illustrations of the fact that signalling driven by cultural aesthetics can move in radically strange directions.

In sum, one can conceive of beauty as a weighted function like so:

Attractiveness = Aw + B x + Cy + Dz, where w, y, x, and z are the dimensions outlined above, and A, B, C, and D are weights.

If an alien only understood human standards of beauty through pornography, they might presume that only secondary sexual characteristics mattered. In contrast, if their understanding of beauty was obtained via reading some feminist scholarship, they might presume cultural variables reign supreme. Reading through catalogs of beauty product supplies might suggest the universal malleability of beauty, and cross-cultural preferences driving personal behavior change. As for symmetry, it is such a fundamental aspect of beauty that I have a difficult time imagining a situation where it is separated from the other variables, but some of the illustrations of the “uncanny valley” actually come close.

Addendum: Modern cosmetic surgery allows us to modify secondary sexual characteristics quite a bit, so it is more under environmental control than in the past.

Image credit: Wikipedia

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Anthropology, Beauty 
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Several people have inquired as to my opinion on the OKCupid post The Mathematics Of Beauty. I’ve blogged data from this dating website in the past, in particular, the differential race consciousness of women vs. men. But that material is a different class than the current post. As I have noted before, there is a robust result in the social science research over the past decade which suggests that women express & reveal more race consciousness than men when it comes dating & mating. The previous OKCupid analysis wasn’t ground-breaking, it simply added some wrinkles into a series of patterns which were replicated in the literature. The current results are different insofar as I haven’t followed the academic literature which relates to this in detail. This matters because unlike most of my peers I’ve done very little online dating (basically 2 weeks in the summer of 2002), and so can’t bring a personal familiarity with the topic to the discussion. To be sure, plenty of my friends have discussed their issues with online dating with me, so I’m not ignorant of the phenomenon. My male friends routinely complain how difficult it is to get the attention of women who are bombarded by messages from all directions. A female friend who is in her mid-30s chronologically, but physically resembles a women in her 20s, has complained how men clearly have automatic age filters set for searches which are working against her.

Let’s start at the beginning. To the left you see a scatter plot of # of messages received by women per month as a function of their rated attractiveness. They controlled for background variables (e.g., race). On the one hand, the results aren’t surprising. You see that more attractive women receive more messages. But on the other hand, the residual (noise) around the trend line is enormous, especially in the top half the distribution. I am personally rather surprised at the enormous variance of message # at the higher ratings. But here’s an important point: this is the mean rating of attractiveness. It turns out there’s a substantial variance around the means of attractiveness for any given mean value. There are two ways to look at this. It seems there is a general consensus about a mean of a distribution as to someone’s attractiveness level. In other words, you don’t have a preponderance of uniform distributions, suggesting that attractiveness is extremely plastic. This is in line with what evolutionary psychologists have found: people from “small scale” societies can ascertain who is, or isn’t, attractive in a set of photos of Europeans. But there’s another part of the story: differences in opinions about physical attractiveness of the same person from the vantage point of outsiders.


To the right you have the top line results. The plot shows the response # as a function of variance of assessments for women at the 80th percentile of attractiveness. As you can see it looks like the number of messages starts to rise as a linear function above the center of the variance range. Below the curve you see an equation which predicts the number of messages as a function of the shape of the distribution. Apparently OKCupid attractiveness measures range from 1 to 5, and the coefficients in front of the values indicate the effect upon the final number of messages. So, if all the men rated a woman a 5, then you’d expect an increase of messages above expectation. The weird thing from the equation is this: according to the model it is better to have everyone evaluate you a 1 than everyone evaluate you a 4. Look at the signs of the coefficient. I don’t personally believe this outcome is valid. In fact, I assume that there’s no one in their data who was rated a 1 by everyone, or, a 4 by everyone. These sorts of models are giving us precise inferences, but the models themselves are only rough correspondences to broader underlying dynamics (which is why people argue over which model better “fits” data and such). Pushing a model to ludicrous extremes doesn’t necessarily give us insight. Rather, it suggests that we should be careful about confusing the model for reality (just as we should be careful about confusing a mean for the totality of the shape of the distribution). I suspect the equation would be different if one constrained the range of attractivenes (e.g., 50th to 100th percentile vs. 25th to 75th percentile), but the qualitative result would hold. The model may be precise, but the inferences we make should be a little less precise.

The authors of the OKCupid post implicitly give a nod to this, illustrating the peculiar pattern of variation in message responses. Their data set indicates that a woman who received more extreme reactions would receive more messages than a woman who received more uniform reactions, even if the latter had a higher average rating than the former. This is certainly counterintuitive. What’s going on here?

First, let’s present the OKCupid explanation:

Suppose you’re a man who’s really into someone. If you suspect other men are uninterested, it means less competition. You therefore have an added incentive to send a message. You might start thinking: maybe she’s lonely. . . maybe she’s just waiting to find a guy who appreciates her. . . at least I won’t get lost in the crowd. . . maybe these small thoughts, plus the fact that you really think she’s hot, prod you to action. You send her the perfectly crafted opening message.

“sup”

On the other hand, a woman with a preponderance of ’4′ votes, someone conventionally cute, but not totally hot, might appear to be more in-demand than she actually is. To the typical man considering her, she’s obviously attractive enough to create the impression that other guys are into her, too. But maybe she’s hot enough for him to throw caution (and grammar) to the wind and send her a message. It’s the curse of being cute.

In some ways this was the model that my college roommate was espousing. His argument was that the key was to find a woman who you found more attractive than the average bear. That way, you were in a better bargaining position to select good mates from this pool of women, who don’t necessarily know their own leverage over you, because they have to assume that you’re the typical male. The “win-win” scenario is where two people perceive each other to be better “catches” than the general population when it comes to looks. There are a lot of such cases presumably because of the residual you see above, but there are plenty of other factors in mates where one can be choosy. By maximizing the disjunction between between population-wide assessment of attractiveness and your own perception of a woman’s attractiveness you can “negotiate” for someone “better” on the other characteristics you value than you otherwise might be able to. If you want to be happy the key isn’t to find a woman you find ugly, it is to find a woman who you value more than the going “market” rate.

Alex Tabarrok has another plausible explanation:

….Rather I think there are certain types of beauty that greatly attract some men but repel others. Analagously, some people will pay hundreds of dollars for an ounce of caviar that other people won’t eat for free. The reason some people love caviar, however, is not that other people dislike it. Instead, it just so happens, that the thing that some people love is the very thing that repels others. We see the same phenomena in art, some people love John Cage, other people would rather listen to nothing at all….

Alex’s model is not totally exclusive of the one OKCupid was espousing. Both of them clearly suggest that distinctiveness matters. Individuals have their own “brands,” and accentuating brands can allow for your “market segment” to target you. Back during my 2 weeks of internet dating I put “atheist” under religion, and indicated that I did not want inquiries from someone who was religious. I was well aware that this was putting me into a “sausage surplus” market, as there seems to be a preponderance of males among those who espouse such frank irreligiosity. But I recall hoping that my honesty about this would at least attract the attention of women who shared a similar disinclination toward religion (this turned out be a good move, a woman who was raised Jehovah’s Witness but had left religion contacted me). That being said, I did have my limits. I did not play up the fact that I was a Republican, as I judged that the pool of atheist Republican women in Portland, Oregon (where I lived at the time), was very small. It must also be admitted that my personal experience is that similar politics is less important in the success of a relationship than a common “metaphysic.” In my case this is partly probably a function of a general weak passion for politics at this stage of my life. But even when I was a very strident libertarian politics was never a litmus test for relationships and friendships.

At this point I’d like to introduce a stylized model. In Survival of the Prettiest Nancy Etcoff introduced me to two different types of beauty. The first you should be well aware of: more symmetry means that you are more attractive. Composites of a range of individuals are almost always more attractive than the individuals themselves. This is attributed to the asymmetry which is introduced in development due stochastic, environmental, and genetic factors. Being lopsided is not a good sign of health, whether the cause is endogenous or exogenous. But there is another sort of beauty: that focused on secondary sexual characteristics, which are sex specific. Symmetrical beauty is applicable in the same manner to both sexes. This secondary sexual characteristic component is not. A powerful robust chin which may indicate rugged good looks in a man does not do so on a woman. Large eyes, a small nose, and a pert mouth, may be attractive on a woman, but they may seem ludicrous on a man (unless you’re Speed Racer). In the case of symmetry being at the mean is the best. But in the case of secondary sexual characteristics exhibiting some deviation from the mean of your sex in one particular direction is probably ideal. Let’s call this “good” deviation.

Finally, there’s a third component. To some extent this is like “non-shared environment” in many behavior genetic models. It’s a whole host of factors thrown together to explain the residual which can not be accounted for by the two other variables. So that’s why I labelled it “X” factor. Probably the easiest sub-component to pick out here are cultural influences as a function of space and time. To the right you see two photos. One is of the Bollywood actress Karisma Kapoor, while the other is of the Indian actress Freida Pinto. To be honest the photo of Ms. Kapoor is probably more flattering when it comes to the range of her photos than that of Ms. Pinto. A large fraction of the reason that Ms. Kapoor is a Bollywood star is contingent. She’s from a showbiz family, and nepotism seems to count for a lot in the film entertainment industry in India and the USA. But another factor is that Ms. Kapoor is extremely “fair” by Indian standards. In contrast, Ms. Pinto is more conventionally Indian looking. My personal experience is that Westerners, and brown folk raised in the West, have a hard time understanding how someone who is as “conventional” looking as Ms. Kapoor could be a leading lady. But she is very unconventional in complexion in South Asia, and in a good way. In contrast, Ms. Pinto is more conventionally good looking. She is of normal coloring for a South Asian. I am willing to bet that most Westerners would judge Ms. Pinto more attractive than Ms. Kapoor without makeup. Anyone who has encountered 19th century Chinese foot binding literary porn will be rather aware of how cultural expectations and norms can reshape and distort beauty standards. In a Western context the shift toward slimness away from a more ample form is often used to illustrate the principle of variance of tastes and standards over time. But these realities should not allow us to forget that common factors do tend to remain invariant. It is famously observed that though the size of the ideal woman in the West has shifted a great deal, the ideal ratio of proportions have moved far less.

But there may be genuine differences which are not so temporally or cultural sensitive. Another component of the third dimension of assessment of attractiveness is probably just individual differences. The domain of behavior genetics, as opposed to evolutionary psychology. There are after all “legs” and “breasts” and “butt” men. Granted, the proportions vary across cultures, but there nevertheless remains a mix in most cultures of preferences. I believe this aspect is the one that may explain much of the pattern in the OKCupid results. There are men who prefer very small breasts, men who prefer corpulent women, and so forth. Whatever the origin of these preferences, even assuming relative cultural invariance in the sample population (I believe this is so for the middle to upper middle class Western target audience of OKCupid) there will remain individual differences of taste and preference, as noted by Alex Tabarrok. Women sharply deviated from the population norm on many traits may produce an average decline in aggregate attractiveness rating, but still may command a premium among the target audience of men who prefer the deviated traits (e.g., attractiveness drops as the number and extremity of piercings increases for the general population, but increases for a minority who find that attractive). Quite often it is preferable to be a second choice, but in this case women who are blandly “cute” may suffer because of the way in which men allocate their time and energy. Dating sites such as OKCupid have many more potential target matches than not, so why not focus on those individuals with whom one is the best match with, instead of the second best? In this way OKCupid is perhaps very different from the small villages or tribes of yore; you have thousands of “first matches.”

Finally, I want to observe something about the images on the OKCupid post. Quite often it seemed that the women who had higher variance ratings used more salient photos, with harsher or higher key lighting. A woman who uses a classic “MySpace angle” photo that’s a touch on the blurry side may get higher ratings than a woman who uses a more crisp image without makeup, but I suspect that many men would prefer the latter to the former. One can’t rate someone lower just for being clever with lighting and selection biasing, but, one may change one’s behavior explicitly and implicitly taking that into account.

In any case, I’ve gone on long enough. I was asked my opinion, and I gave it. What’s your take? (this is not a call for retarded comments by the way. You know who you are)

Image credit: Xavier449, Bollywood Hungama, Lili Ferraz.

(Republished from Discover/GNXP by permission of author or representative)
 
• Category: Science • Tags: Beauty, Behavior Genetics, Culture, Data Analysis, Dating 
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Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at http://www.razib.com"