Evolutionary anthropologist Sean McBride discusses our perceptions of ‘the perfect body'.

Sadly, numerous studies have shown that physical attractiveness is a more important predictor of attraction than other attributes (eg, social skills, intelligence and personality), at least in the short term. Researcher Susan Sprecher at Illinois State University, showed that men and women are equally affected by physical attractiveness (although for long-term mating, women are also affected by status). Sprecher states that: the the article is the only

Men are affected by non-physical characteristics [such as personality] in a potential date only if she is attractive, whereas women respond to non-physical characteristics in both a physically attractive and a physically unattractive potential date (and slightly more if he is unattractive). These results suggest that a woman cannot compensate for an unattractive appearance with social status or warmth, at least in romantic situations.

So, for women especially, being attractive will enhance romantic interactions and provide a whole bevy of advantages in life. In previous articles, I have discussed those facial characteristics that are found to be appealing, such as neoteny (juvenile characteristics such as small chin or large eyes carried into adulthood). In this article, I will be discussing aspects of body shape that are found to be attractive and whether or not there is an ideal body from the point of view of attractiveness and human perception.

Over the millennia, we humans have developed a whole range of abilities to determine the acceptability of a mate. Beauty is a cue to fitness (fertility) and the ability to produce healthy children. From a male's perspective, he will want to find a female who is very fertile with many years of reproduction ahead of her. She will have to exhibit traits that indicate health and vitality so that the children will also be healthy and capable of surviving and, in turn, reproducing. If men chose only women who were past their childbearing age, they would be extremely unsuccessful at producing children and passing on their genes to future generations. Between the ages of 30 and 34, female fertility rates decline to 85 percent of the fertility rate of 20- to 24-year-olds, and between the ages of 40 to 44 it is down to 35 percent. This is one reason youth has a universal appeal. One way that males appear to determine fertility is through visually assessing the distribution of body fat on the female body. It is an unconscious mechanism and will be explained later in this article.

Human body shapes can be divided into three categories; ectomorph (thin), mesomorph (muscular, athletic) and endomorph (heavy, fat). Children and adults, irrespective of their own gender, tend to attribute personality traits in varying degrees to these different body types. Generally, mesomorphs are rated to have highly favourable traits, whereas endomorphs are given highly negative stereotypes. Male ectomorphs are generally also evaluated negatively, but female ectomorphs are treated positively due to their association with health-conscious slimness. For women, being an ectomorph is an advantage, but being too thin is also viewed negatively. It is rather tragic that if you are an ectomorph people will judge you to be more likely a smoker and an alcoholic, and more likely to be anti-social and lack leadership abilities based solely on your body shape. A mesomorph on the other hand will be attributed a whole range of positive characteristics such as being social, a leader, and be considered likely to have a wide circle of friends. The endomorph will be considered lazy and lacking in will power, untrustworthy and be thought likely to be incompetent, amongst many other negative qualities.

Children as young as six show biases towards certain body builds. They prefer mesomorphic (average sized and muscular) builds over ectomorphic (thin and unmuscled) and endomorphic (overweight and unmuscled) builds, and children of all ages tend to associate a variety of social stigmas to the endomorphic build. Given that people make value judgements of us simply based on our body build, where does this leave us in terms of the perfect body, especially the female body, when it comes to self-satisfaction and positive perceptions from others?

The waist-to-hip ratio (WHR)

It has been theorised by evolutionary anthropologists and others that when humans were subject to varying periods of famine and plenty, the most reproductively successful females were the ones who were able to store surplus energy as fat. The extra fat, stored on the body, breasts and buttocks, is said therefore to be attractive to males (and also attractive to women since women are in competition with other females for potential mates, and know what is preferred). This is a plausible theory given that it is necessary for women to have a critical amount of body fat in order to initiate and maintain the menstrual cycle. However, just being fat is not an attractive trait. It is the distribution of that fat that enhances or detracts from female beauty.

Fatness is generally only a positive attribute in countries where food is scarce. In these countries it is a sign of health and wealth, and confers high status on those who have this attribute. However, in the western world, a slim, curvy body is preferred. The distribution of body fat, especially on the waist and hips (the waist-to-hip ratio (WHR)) is one of the main features that determine the attractiveness of women (the Body Mass Index, or BMI, is another). The WHR is calculated by measuring the ratio of the circumference of the waist to the circumference of the hips.

You can do this at home - the waist is measured as the distance around the smallest area below the rib cage and above the belly button. The hip measurement is taken as the distance around the largest extension of the buttocks. For instance, if your waist measurement is 28cm and your hip measurement is 40cm, your WHR is 28/40 which is a ratio of 0.7. Studies show that men and women between the ages of 18 and 85 regard normal-weight female figures with a low WHR (e.g. 0.7) as more attractive and healthy than other women with a higher WHR who had the same or lower body weight. The WHR for healthy, pre-menopausal women is generally between 0.67 and 0.80. All of these ranges are found to be attractive but the ideal is about 0.7 (a BMI of 20 or less is also maximally sexually attractive. You can calculate your own BMI at http://www.halls.md/body-mass-index/bmi.htm.).

The beauty of this (pardon the pun) is that even though you may be carrying excess weight you can still have a WHR of 0.7. It is the distribution of the weight that is attractive. If your waist is 42cm in circumference and your hips are 60cm, you will still have a WHR of 0.7 and still be considered attractive. An overweight woman with a low WHR is judged to be more attractive than a slim woman with a high WHR which shows that it is the distribution of body fat that is primarily correlated with attractiveness.

Men's average WHR is between 0.85 and 0.95. If you are female and your WHR is in the male range, you will be considered less attractive than women who are on the female side of this range. In fact, you will be viewed as less and less attractive as the ratio of your waist to your hip approaches 1.0. If you have a high WHR, you will also be judged to be older than those women with a low WHR.

In my next article, I will discuss body builds, shapes and parts, and the way we make value judgements based on these aspects.

(part 2)

Body shape

Due to a high level of oestrogen, it is common for women to begin to deposit fat cells on the lower regions of the body (eg, thighs and buttocks) after they enter puberty. This is because it is necessary for women to have a critical amount of body fat in order to maintain their menstrual cycle and therefore be able to conceive. The extra fat stored on the body is considered attractive when it creates the classic curved female or gynoid shape. The waist-to-hip ratio (WHR), as discussed in part 1, is a measure of this gynoid shape. Research from the Netherlands has shown that females who have a WHR of 0.9 are 30 percent less likely to become pregnant than females with a WHR of 0.8. From an evolutionary perspective, it is no wonder then that researcher Devendra Singh found that women with a WHR of 0.7 were perceived as more attractive than women with a WHR of 0.8 and a WHR of 0.8 was seen as more attractive than a WHR of 0.9. A WHR of 1.0 was seen as the least attractive.

Singh also found that normal-size figures (mesomorphs) were preferred over underweight (ectomorphs), which were in turn preferred over overweight (endomorph) figures. Support for the idea that the distribution of body weight determines attractiveness can be shown from the fact that overweight women with low WHRs are considered more attractive than slim women with high WHRs.

Studies of Playboy Magazine centrefolds from 1955 to 1965 and Miss America contest winners dating back to 1923 have shown that their WHR has remained within a range that is quite narrow. This is despite the fact that the actual body weight of these models has been dropping over the years, suggesting that the preference for a low WHR continues across generations.

In research conducted in Queensland, a large number of Brisbane school children, aged six to eleven, were shown male and female figures with varying waist-to-hip ratios and asked to give their preferences. It was found that the preference for a WHR of 0.7 for women and 0.9 for men emerged strongly around the age of ten and eleven. This seems to indicate that these preferences are inbuilt but only triggered as humans approach puberty and hormones begin to flood the body.

As humans age their WHR ratio gradually increases. This is one of the reasons that older women are generally found to be less attractive than younger women. By maintaining a youthful, low WHR a female can maintain bodily attractiveness. Aiming for a WHR of between 0.67 and 0.8 will generally be considered attractive but 0.7 is the ideal that both men and women find the most attractive. A WHR of 1.0 (waist and hip the same measurement) is considered the least attractive. Anything beyond this will indicate a protruding abdomen which is definitely found to be unattractive by both sexes.

Breasts

Studies have found that female figures with slender bodies, a low WHR, and large breasts are rated as the most attractive, healthy, feminine looking and desirable for both casual and long-term romantic relationships. Large breasts consistently enhance the attractiveness rating of both slender and heavy figures, so long as they have a low WHR.

Polish research has shown that women with large breasts and a small waist had larger amounts of female hormones than women with a broad waist and large hips; narrow waist and small breasts; or broad waist and small breasts. No wonder then that they are considered attractive because a low WHR (ie, a curvaceous body) is believed to correspond to the optimal fat distribution for high fertility - they are more fertile and therefore more attractive. They may also be healthier, given that a high WHR resulting from a bloated abdomen can be a sign of parasite infection. A high WHR in a female can also predict menstrual irregularity, hirsutism, elevated plasma tri-glycerides, diabetes, hypertension, cardiovascular disease, gallbladder disease and cancer of the endometrium, ovaries and breast.

A study of Playboy Magazine centrefold models reported the average bust (90.8 cm), waist (58.6 cm) and hip (89.3 cm) measurements. This represents a waist to bust ratio of 0.64, roughly the same as their waist-to hip ratio. This is very close to the 36-24-36 ratio that has been presented to us for years as an ideal - the so-called hourglass figure. The 36-24-36 ideal results in a curvaceously thin female with small waist and hips and large breasts. This is very difficult to achieve naturally. However, evolutionary research shows that a WHR of 0.7 and a WBR (waist-to-breast ratio) of 0.7 are considered the ideal. This can be represented as equivalent to two equal inverted triangles

Unfortunately only a small percentage of women are born with this combination of attributes. For all other women it is a near impossible goal to achieve naturally. Even through dieting and exercise it is impossible to lose body fat without also reducing breast size. This is because the breasts are composed mainly of fat and this fat is reduced in line with other fat loss throughout the body when a diet and exercise regime is followed. From the viewpoint of maximisation of attractiveness it would seem then that large breasts would be optimal - but are they? It is a trade off between attractiveness from a biological perspective and attractiveness from a societal viewpoint. We are influenced by biology but also by societal norms. One of the greatest influences on our expectations is television.

Research has shown that television not only reflects societal preferences but also shapes them. Studies by Kristen Harrison on television viewers' ideal body proportions have shown that the television ‘worldview' of the ideal female waist and hips could be described as relatively extreme: thinner is better. In contrast, the television worldview of the ideal female bust is more moderate: medium is ideal. Harrison's work was the first to empirically link the curvaceously thin female body ideal with media exposure.

Since the achievement of status and the emulation of status-rich people (eg, television and media personalities) seems to be built into the human psyche, and we also have evolutionary pressures to secure mates who demonstrate high fertility and health through ideal waist-to-hip ratios and ideal waist-to-breast ratios, it is no wonder that women seek to achieve the 36-24-36 ideal. This ideal is very close to research findings of the most preferred ratio (34:24:34). Remember though that it is a ratio so you could be 40:28:40 or 53:37:53 and still be attractive (although a thin body with this ratio is the most preferred).

Experimenters have also found that women with smaller breasts were rated as competent, ambitious, intelligent, moral and modest. However, women with large breasts were judged to have the opposite characteristics, by both females and males. So medium breasts combined with a low WHR would appear to be the best option to achieve both physical and social attractiveness.

Unfortunately, for many women searching for this ‘ideal', liposuction and breast augmentation (or reduction, depending on your present size) may be the only ways to achieve this. Not surprisingly liposuction and breast augmentation are the two most popular surgical cosmetic procedures at the present time.

Body, breast and WHR sizes interactively influence judgements of attractiveness, femininity, healthiness and youthfulness, and males and females generally agree in their judgements of bodily beauty. Unfortunately, unless you were lucky enough to have been blessed with 36-24-36 measurements, diet and exercise may not be enough to get you there. The research indicates that a lower figure (34-24-34) may be more attractive and more achievable for some, but for many women liposuction and breast enhancement may be viable options. If you decide to go down this path then discuss the possibilities and aesthetics of your choice thoroughly with your surgeon.
Remember though, our hunter/gatherer ancestors got by happily for millennia without achieving these figures as they were too busy hunting, fishing, gathering, dancing and enjoying their lives. Maybe we just have too much time on our hands.

Sean McBride is an evolutionary anthropologist and lecturer. He has delivered presentations in Sweden, the UK, the US and Australia. He has made numerous appearances on television, radio and in magazines, and was a consultant to Discovery Channel and Channel Nine's Australian Survivor. Sean is available for guest speaking engagements and can be contacted on 0402 084 785.

ACSM #33