The Biology of Beauty

When we think about the characteristics that make someone physically attractive most of us probably think that they are purely subjective and culture bound. But recent evidence suggests that this is not true.

In an astonishingly comprehensive study published in the Proceedings of the Royal Society B: Biological Sciences, Devendra Singh from the University of Texas at Austin has analyzed references to fictional beauties from modern times back to early Indian literature. He found that slimness of the waist was the most common term of praise from an author.

I found it very surprising that this association even seemed to hold in times when a more Rubenesque figure was in fashion.

But I think that the key is not the actual number of inches, but the ratio of waist to hips.I have commented several times that the waist to hip ratio is probably a better physical marker of health risk than body mass index (BMI). Though even this needs to be supplemented by other tests.

Professor Singh’s work has nothing to do with making value judgments, but is instead looking at some of the factors involved in mate selection and this work adds to evidence highlighting the role of the ratio between waist and hips in attracting a mate.

All the recent furor over the dangerously shrinking fashion model has again raised the question that although female waist size has become important in modern Western society and culture – and is likely a factor fueling eating disorders – it is not completely clear whether this waist obsession has always been the case.

In what can only be described as a labor of love, Singh has spent years examining representations of women through history, and in one study, he measured the waist-hip ratio of hundreds of statues from different eras.

In the most recent research, he looked at how "attractive" women were depicted in literature, analyzing more than 345,000 texts, mainly from the 16th to 18th centuries. While most of the writings were British and American, there was a small selection of Indian and Chinese romantic and erotic poetry dating from the 1st to the 6th century of the Christian era.

Singh had this to say: "The common historical assumption in the social sciences has been that the standards of beauty are arbitrary, solely culturally determined and in the eye of the beholder. The finding that the writers describe a small waist as beautiful suggests instead that this body part – a known marker of health and fertility – is a core feature of feminine beauty that transcends ethnic differences and cultures."

Other studies have found a link between a woman’s waist to hip ratio and her fertility which may offer some explanation as to why during evolution it became a factor in selecting a mate. The ratio, like breast size and smooth complexion, is partly under the control of estrogen, which is, of course, a key hormone in the maintenance of fertility.

There has been a great deal of work – and even more speculation – about why men and women are found physically attractive. The idea is that beauty is an indicator of genetic and developmental health. There is also some evidence that physically "attractive" people are healthier than less attractive people.

In 2004 Satoshi Kanazawa and Jody Kovar from the London School of Economics published an intriguing study in the journal Intelligence with the controversial title: “Why Beautiful People are More Intelligent."

The basic idea is that evolutionary processes have, both genetically and socially, led to what we call assortative mating, in which partners have been chosen for their strength, good health and even height: all attributes which have given their possessors a high status. I must be honest that even though I’ve seen the data, when I see and hear some of the comments of a few people in the public eye I still question the association between beauty and intelligence.

There appear to be a few features that characterize physically attractive faces: bilateral symmetry, averageness, and secondary sexual characteristics. Attractive faces tend to be more symmetrical than unattractive faces. 

Fluctuating asymmetry (FA) – random differences between the two sides of the face – is usually not found to be attractive. And this may be why: it increases with exposure to parasites, pathogens, and toxins during development. FA also increases with genetic disruptions, such as mutations and inbreeding. Developmentally and genetically, healthy individuals have less FA and more symmetry in their facial and bodily features.

Across many societies around the world, there is a positive correlation between parasite and pathogen prevalence in the environment and the importance placed on physical attractiveness in mate selection. The theory is that in societies where there are a lot of pathogens and parasites it is especially important to avoid individuals who have been afflicted with them when they select mates. 

Facial averageness in another feature that increases physical attractiveness: faces with features close to the population average are more attractive than those with extreme features. The evolutionary reasons for why average faces in the population are more attractive than extreme faces are not as clear as the reasons for why facial symmetry is attractive. Some current speculation is that facial averageness results from the heterogeneity rather than homogeneity of genes so that would mean that individuals with average faces are more resistant to a larger number of parasites. Therefore like FA, facial averageness may be an indicator of genetic health and parasitic resistance.

There is good data that infants as young as 2-3 months gaze longer at a face that adults have judged attractive rather than a face judged unattractive. And other research has shown that 12 month old infants exhibit more observable pleasure, more play involvement, less distress, and less withdrawal when interacting with strangers wearing attractive masks, than with strangers wearing unattractive masks. They also play significantly longer with facially attractive dolls than with unattractive dolls.

2-12 months is not nearly enough time for infants to have learned and internalized the cultural standards of beauty through socialization and media exposure. So the research data seems to suggest that the standards of beauty might be innate, rather than learned.

Even though there is all this evidence for a evolutionary and biological factors in beauty, it is a mistake to use such a simple model  to try and explain away all of our partner preferences.

By the time that they leave high school, most people have grasped that physical attractiveness is an important first step in attraction, but after that becomes highly
subjective: delightful but not essential.

This work also fails to take into account the attractiveness of factors like radiance, humor, attention, attentiveness, energy, self-assurance, movement, grace and gesture.

Neither can it take account curiosity, presence, charisma, compassion and spiritual awareness. All of these can be extremely attractive, but are hard to explain on simple biological and evolutionary models.

And, by the way, all of these additional factors can be learned: whatever your weight and measurements, whether you are tall or less so and whatever your age.

You can learn to develop many of the things that genetics may have forgotten.

“Beauty awakens the soul to act.” –Dante Alighieri (Italian Poet and Philosopher, 1265-1321)

“Beauty is not in the face, beauty is a light in the heart.” –Kahlil Gibran (Lebanese Poet and Philosopher, 1883-1931)