Does Kelly Brook have ‘the perfect body’?

“This is What the Ideal Woman’s Body Looks Like, According to Science” 

proclaimed the headline that popped up in my Facebook feed.

I was intrigued.

What was meant by ‘ideal’? Healthiest, most attractive to men, most attainable for women? Or some other metric?

To satiate my curiosity I clicked on the link and found myself looking at photographs of Kelly Brook on the beach. After some scrolling past these photos I eventually found the text which declared that according to researchers at the University of Texas,

“the perfect female body measures 1.68 meters in height [and] the bust/weight/hip measurements are 99-63-91”

What is the source of these figures? And what is meant by ‘perfect’? Luckily the article links to their source. Surely the scientific paper, or at the very least a press release from the university about this earth-shattering research? Unfortunately not. Instead it’s a link to that august publication, the Curaçao Chronicle (no, I’ve never heard of it either).

This article again credits the University of Texas as being the source of the research but fails to name any of the researchers, the journal the work was published in, or any context other than the fact that Kelly Brook is now the ‘perfect’ woman. However, a reading between the lines did provide some useful information. Both articles note that Kelly Brook is 34 (when she is now 37) and it dawned on me that this was not a new study, but an old one just doing the rounds again – on the internet stories do not die, they just lie dormant for a while. This still didn’t help me with sourcing the ‘science’ behind all this but finally one article linked to the university press release… Ahah! Now I have you!

It began,

“A psychology study from The University of Texas at Austin sheds new light on today's standards of beauty, attributing modern men's preferences for women with a curvy backside to prehistoric influences. The study, published online in Evolution and Human Behavior, investigated men's mate preference for women with a "theoretically optimal angle of lumbar curvature," a 45.5 degree curve from back to buttocks allowing ancestral women to better support, provide for, and carry out multiple pregnancies.”

Er, what? How on earth do we get from lumbar curvature to Kelly Brooks being the epitome of womanhood? Clearly I need to find the journal article, which, again, is not linked to in the article.

[Side note – university PR departments for goodness sake link to the journal articles your promoting. Researchers want people to read their research and the point of you promoting their research is so it gets more widely read, so that they get more citations and the university gets more status. That can’t happen if people don’t know where to find the research!!!!]

ahem…

So let’s look at the journal article, titled “Lumbar curvature: a previously undiscovered standard of attractiveness”. It’s behind a paywall but the in-press version is helpfully available for free as a PDF. The article begins by saying that while it is commonly held that “human standards of beauty are arbitrary and dependent on sociocultural processes alone” [p1 – page refs are for the freely available version], this contrasts with our biological understanding of mate attractiveness whereby specific sexual traits are used as indicators of fitness. So far, so good.

They then describe how the female spine has evolved a unique morphology to counter the problems of being pregnant while bipedal, termed ‘vertebral wedging’ and that while this spinal morphology cannot be directly seen by men, they propose that posture of women during pregnancy could be a sexually selected proxy and women with a good posture would appear ‘more attractive’ to men: 

“Men who preferred and selected these women as mates would have gained several key fitness benefits, including having a mate who was less vulnerable to spinal injuries, better at foraging during pregnancy, and better able to sustain multiple pregnancies without debilitating injury.” [p2]

To test this they recruited male psychology students from the University of Texas at Austin to participate in two studies. The first was to look at profile pictures of women with varying lumbar curvatures and rate their attractiveness. They found that, as hypothesized, 

“women's attractiveness increased as their lumbar curvature approached the proposed theoretically optimal angle, β = −.48, SE = .01, p b .0001”… [data which] “support the hypothesis that men possess an evolved mate preference for angles of lumbar curvature that facilitate the solution of the female-specific adaptive challenge of a bipedal fetal load.” [p3]

To confirm that it is vertebral wedging that is causing the change in attractiveness and not the size of the buttocks, the second study looked at images of identical women who varies either in vertebral wedging or in buttock mass and the men then chose which they found the most attractive. They found that vertebral wedging was more attractive than those with greater buttock mass.

The authors therefore conclude that the,

“transition to bipedalism introduced novel selective pressures that favored (a) female lumbar vertebral wedging and (b) male mate preferences for women exhibiting cues to such wedging. Precisely because of this dual (natural and sexual) selective advantage of vertebral wedging over the ancestral average, the new, wedged optimum gradually would have come to characterize the center of reproductive-aged women's distribution.” [p5]

So, let’s ignore the fact that nowhere in the article was Kelly Brook mentioned, nor the “99-63-91” measures that were described in multiple articles, what about the research?

Well, to be blunt, it’s a complete crock of shit.

Let’s break this study down. It claims that, 

1) there are evolutionarily-based ideas of what makes a woman attractive that transcend culture;

2) that men pick their mates based on these evolutionarily-based traits;

3) these traits indicate reproductive fitness as they hold a reproductive benefit to women.

The study cannot, by its very design, answer point 1 and it completely misunderstands sexual selection in points 2 and 3. I'll also add that all their descriptions of posture relate to pregnant women, and they haven't provided any evidence that women carry themselves in the same way when not pregnant. As they claim that it is all about controlling the centre of mass, I would be very surprised if they did.

Let’s tackle point one first as it’s the easiest to dismiss. When you make a claim that attractiveness is not based on culture, you need to test your hypothesis on multiple cultures. 102 male students from one department from one campus of one university is not a culturally diverse sample group. The only way this study could claim to find a universally attractive trait is to test it on a range of cultures, from all around the world. To take results from 102 students in the same department at the same university and claim that these results will hold across all men is hubristic in the extreme.

The other two points require a little bit of background in sexual selection. Most of this will be pretty obvious when you think about it, but not everyone will have done. Firstly, let’s look at the claim in point 3, that sexually selected traits are beneficial traits. This is patently incorrect. The whole point of sexually selected traits is that they carry a cost. They are dangerous. The aim of sexually selected traits is to say ‘hey member of the opposite sex, I’m so cool and successful that even when I’m handicapped I’m still totally awesome so just think how amazing our kids will be!’ 

A peacock’s tail may look amazing when you see them wandering around the grounds of a stately home but remember that these are jungle animals. Can you imagine getting around a jungle with one of those things? Escaping predators? To be able to do all that while still keeping such an impressive tail is what tells you that peacock is worth having sex with (when you're a peahen). Characteristics which help an animal to stay alive and reproduce aren’t sexually selected for, and not just because there’s no need for them to be – natural selection will do that job. Characteristics that keep you alive aren’t sexually selected for because they tell you nothing about the impressiveness of that individual. You don’t want to mate with someone who’s ‘just getting by’, you want to mate with someone who’s got the most impressive set of genes, and the only way to determine that is to make life as hard as possible for them and only if they still succeed will you know they’re worth your time. So for the study to claim that the vertebral wedging is a sexually selected trait because it benefits the woman completely misunderstands the nature of sexually selected traits. If the trait actively harmed the woman but was seen as attractive, then it could be termed a sexually selected trait. As it stands, it is just a trait that is beneficial for the woman and given its close link with reproduction it will undoubtedly be strongly selected for, regardless of whether or not men find it attractive. (Which isn't to say that is can't be an attractive trait to men, just not that it is a sexually selected trait and men are the ones who are driving its evolution).

All of which leads of to point 2: vertebral wedging is a sexually dimorphic trait. The peacock’s tail is also a sexually dimorphic trait. This just means that only one sex has it (dimorphic means 'two forms' so a trait that is 'sexually dimorphic' has two forms, one for each sex). Some sexually dimorphic traits are, like the vertebral wedging, there to solve a problem present in only one sex. Others, like the bills of the extinct huia, are there to reduce competition between the sexes. But the vast majority of sexually dimorphic traits are there to attract members of the opposite sex, through bright colours, adornments or behaviours. The bright colours and complex songs of many male birds, the antlers of deer, the noses of elephant and hooded seals are examples of sexually dimorphic traits that are sexually selected. In all but a few cases it is the male who takes on these traits, while the females remain relatively unadorned and unobtrusive. This is because for most species females endure the bulk of reproductive costs – in many cases the males leave the female to raise the offspring alone – and as such she is the one that needs to be careful about her mate choice. Males of many species can reproduce far more frequently, far more cheaply and with far more partners than females, and as such it is the females who must guard access to their bodies and carefully chose their partners. 

While sexual dimorphism in humans is not as obvious as in many animals, it is still present and women are still the sex who endure the majority of the physical costs of reproduction and thus it is women who need to be the choosy ones (on a genetic level). It is therefore rather ironic that all the research I have seen on the evolutionary basis attractiveness in humans focuses on the attractiveness of women to men. I think it is clear that this is, indeed, due to the same socio-cultural processes so derided by the authors of this ridiculous ‘research’.