Genetic Engineering

Physical Attraction

Physical attractiveness refers to the perception (appearance) of an individual as physically beautiful by other people. Some aspects of how a person is judged beautiful are universal to all cultures, whereas others are restricted to particular cultures or time periods. What is at the root of physical attractiveness? It is theorized that people are attracted to people possessing those traits which convey an ability to enhance one's own survival and those traits with which they wish to imbue their offspring. Whether this theoretical root cause occurs consciously or subconsciously (perhaps through evolutionarily development) is also a matter of debate.

Physical attractiveness can have a huge effect on how people are judged people tend to attribute positive characteristics such as intelligence and honesty to attractive people without consciously realizing it. This fact lends credence to the "hard-wiring," evolutionary development theory. Regardless of the origins of the positive attribution, and as methods for altering one's appearance become more common place, there may well be an increasing trend to improve one's lot in life through artificial manipulation. In fact, this trend is already quite apparent in the case of plastic surgery which is now a multi-billion dollar industry. And there is no reason to believe that people will not afford themselves the benefit of such alterations on behalf of their children as germ-line engineering becomes more prevalent.

With which physical characteristics will people choose to imbue their offspring as the genetic engineering technology becomes readily available and inexpensive? Let's examine a few specific concepts around beauty and physical attraction.

Quicklinks on this Page

1 Judgment of physical attractiveness
  1.1 Universal correlates of beauty
  1.2 Facial symmetry and the golden ratio
  1.3 Determinants of male physical attractiveness
  1.4 Determinants of female physical attractiveness
      1.4.1 Waist-to-hip ratio
      1.4.2 Proportion of body mass to body structure
      1.4.3 Prototypicality as beauty
      1.4.4 Other determinants of female beauty
2 Historical variations
3 Social effects of attractiveness
4 Bibliography

Article Scope

This article discusses some possible reasons behind appearance-based physical attraction which do not necessarily relate to the ability or even likelihood of one person developing a relationship with another. Relationship factors (trust, friendship, love, commitment, etc.) are more a matter of personality, compatibility, and behavior than are looks, and are not the subject of this article. Similarly, many studies suggest that there is a chemical component to the overall attractiveness of one person to another in face-to-face interactions. Pheromones and hormones carried aerially and received via the olfactory system may have a compelling effect on two people. This "chemistry" is also outside the scope of this article which focuses solely on personal appearance.

Judgment of physical attractiveness

One's own culture has a strong effect in determining who a person considers as physically attractive. As children grow up, they learn what their culture considers attractive. Movies and cartoons, frequently portray the villain as being ugly, whereas the protagonist is depicted as attractive. Children are shown examples of what is considered as beauty, in the form of dolls and pictures on magazine covers. Perception of what is considered as attractive and appealing is also very heavily influenced by other dominant cultures and the impact of its value system.

Universal correlates of beauty

That said, cultures tend to agree on what is attractive. There is a strong correlation between judgements of attractiveness between cultures. Furthermore, infants, who presumably have not yet been affected by culture, tend to prefer the same faces considered attractive by adults. This implies that a large part of attractiveness is determined by inborn human nature, not nurture. Social and biological norms also play a significant role in our perceptions of attractiveness: any particular attribute of a physical feature too far outside the normal range denotes abnormality and may be seen as unattractive.

Facial symmetry and the golden ratio

Facial symmetry is seen as a universal determinant of health and therefore of beauty. A person of either gender who is considered as attractive in various cultures has been found to have facial symmetry based on the golden ratio of 1:1.618. Plastic surgeon Stephen Marquardt developed an ideal beauty mask marked with various outlines of facial features based on the golden ratio. The faces that are judged as most attractive are found to fit the mask.

Determinants of male physical attractiveness

According to studies conducted by M.R. Cunningham in the 1990's, sexual attraction for a man by a woman is determined in part by the height of the man. From many women's perspectives, the man should be at least a few inches taller than her in order to be perceived as physically appealing. It would be preferable if the man is at least a little above the average in height in the given population of males. This implies that women look for signs of dominance and power as factors that determine male beauty. Other properties that enhance perception of male attractiveness are a slightly larger chest than the average, and an erect posture. Women seem more receptive to an erect posture than men, though both prefer it as an element of beauty. law.jpg
Jude Law - People Magazine's Sexiest Man Alive, 2004

Today, certain characteristics are generally accepted throughout the Western world as signs of physical attractiveness. These are, of course, far from universal:

1) A muscular physique is a sign of athleticism and good health- heritable characteristics women want their offspring to possess. Today, muscular physiques are generally desired by most men in the West, but extreme over-development can be viewed as undesirable to some women due to a natural aversion to body dimensions grossly outside of a generally accepted norm. Male physiques which are not viewed as attractive by large sectors of society are - obesity (often perceived as a sign that the man is either lazy or in poor health) and overly slim bodies (seen as indicative of the man not engaging in sports or exercise or of being in poor health).

2) A unique hairstyle can signify individuality which presumably sets the male apart in an attractive manner. There is an analogous phenomenon in nature: that of unique plumage in some bird species (i.e. the Peacock) used to attract the female. This factor is still subject to the biological and social range norms, however.

3) A facial structure which accentuates skeletal features. In Western societies, men and women of all races often agree that a face with pronounced cheekbones and often a heavily-set jaw is physically attractive. These are currently viewed as indicative of a masculine personality. These skeletal features in addition to a slightly elongated face can make the masculinity more heightened and the male much more attractive.

Not within the realm of physical attractiveness, but included in the discussion to support the proposed root driver of the attraction phenomenon, are material wealth and social signs of success. Women generally find these characteristics attracive as they indicate the ability of the male to care for the female and her offspring.

Determinants of female physical attractiveness

The determinants of female physical attractiveness include those aspects that display health and fitness for reproduction and sustainance. These include correlates of fertility such as the waist-hip-ratio, mid upper arm circumference, Body mass proportion and facial symmetry.

Waist-Hip Ratio and female attractiveness

Strong correlations between attractiveness and particular physical properties have been found, across cultures. One of the more important properties is symmetry, which is also associated with physical health. Large clear eyes are also important. In women, a waist-to-hip ratio (WHR) of about 0.7 ratio (waist circumference that is 70% of the hips circumference), is typically considered very attractive.

Proportion of body mass to body structure

The Body Mass Index (BMI) is the most important and most universal determinent of the perception of beauty. The BMI refers to the proportion of the body mass to the body structure. However, in various cultures the optimal body proportion is interpreted differently due to cultural learnings and traditions. The Western ideal considers a slim and slender body mass as optimal while many ancient traditions and Asian societies considers an embonpoint or plump body-mass as appealing. In either case the underlying rule applied in determining beauty is the BMI and hence displays how cultural differences of beauty operate on universal principles of human evolution.

Besides, the slim ideal does not consider an anorexic body as attractive just as the full-rounded ideal does not celebrate the over-weight or the obese. The cultural leanings are therefore just social emphasis on specific phenotypes within a parameter of optimal BMI.

The attraction for a proportionate body also influences an appeal for erect posture.

Prototypicality as beauty

Besides biology and culture, there are other factors determining physical attractiveness. The more familiar a face seems, the more highly it is judged, an example of the mere exposure effect. It is seen that when many faces are combined into a composite image (through computer morphing), people find the resultant image as familiar and attractive, and even more beautiful than the faces that went into it. One interpretation is that this shows an inherent human preference for prototypicality. That is, the resultant face emerges with the salient features shared by most faces and hence becomes the prototype. The prototypical face and features is therefore perceived as symmetrical and familiar. This reveals an "underlying preference for the familiar and safe over the unfamiliar and potentially dangerous" (Berscheid and Reis, 1998). However, critics of this interpretation point out that compositing computer images also has the effect of removing skin blemishes such as scars and generally softens sharp facial features.

Classical conceptions of beauty are essentially a celebration of this prototypicality. It celebrates the extra-ordinary (from the latin root meaning over or extremely-ordinary) as the prototype or most beautiful.

The phenotype of ones own mother during the early years of childhood, becomes the basis for the perception of optimal body mass index (BMI). This shows the importance of prototypicality in the judgment of beauty and also explains the emergence of similarity of the perception of attractiveness within a community or society, which shares a gene pool.

Other determinants of female beauty

Although it is said that beauty is in the eye of the beholder, studies have shown that there are many other universal or near-universal qualities which make human females attractive to males. Among these other determinants are:

1. Symmetry of features: an indicator of lack of disease or injury

2. Clear complexion: indicator of health

3. Contrasting colors and features: such as well-delineated eyebrows, dark lashes, dark eyes/light face or light eyes/dark face; these heighten the features of attraction, perhaps a holdover from primitive forebears with less acute vision

4. Large, symmetrical, white teeth: indicator of reproductive vigor and ability to defend young; also health and contrast

5. Prominent zygomas (cheek bones), especially with a blush of color: paired, rounded forms, especially if pigmented, stimulate the same male response as the flushed buttocks of simian females in mating position

6. Thick, vivid lips which may also have an analogous phenomenon in nature (see 5, above)

7. Large, symmetrically spaced eyes: paired, rounded forms

8. Proportionate nose, straight bridge devoid of signs of breakage or physical damage

9. Ovoid face, small chin, lack of facial hair perhaps clearly signally femininity and fertility

10. Thick, lustrous hair: an indicator of health, and perhaps reminiscent of the analogous phenomenon in nature (i.e. the plumage and the perception of uniqueness correlation)

11. Soft, higher pitched voice: indicator of non-maleness and therefore fertility; perhaps suggestive of submissiveness to a degree sufficient to facilitate mating

Historical Variations

Peoples' views of attractiveness have differed from culture to culture throughout history. In Mediterranean societies such as Ancient Egypt, men with muscular physiques were considered attractive as it was thought to be the natural state of the male body. However, being fat was considered more attractive, as it indicated that the person was rich enough to afford a lot of food and avoid physical labour. During the Middle Ages in Europe, having tanned skin was considered deeply unattractive amongst men and women, as it was a sign that the person had to work outside in the fields. Consequently, rich men and women sought to maintain very pale skin (to the extent that they would completely cover their skin when outdoors) as a way of showing that they were wealthy and could avoid working outside. Traditionally, some Japanese people dyed their teeth black (ohaguro). It was thought that the blacker the teeth is, the more beautiful; a view which died out in the early Meiji period. A similar phenomenon occurred in Renaissance Europe - sugar was very expensive and only the rich could afford it, thus serving sugary food become a major status symbol. Contemporary accounts reveal that people were aware of sugar's ability to rot the teeth, and as a result many rich, fashion-conscious Renaissance people (particularly English women) took to deliberately blackening their teeth to prove how much sugar they could afford. In nineteenth-century Germany, it was considered attractive to be fat (again as a symbol of wealth), whilst young men often participated in duels simply in order to gain facial scars, which were viewed as symbols of masculinity.

At certain periods in history, emphasis has been focused on a particular area of the male body. In Renaissance Europe, the codpiece, a popular fashion accessory, led to emphasis on the thighs, and fashion-conscious men strove to maintain muscular thighs. From the sixteenth to the late eighteenth century, the popularity of stockings led to men striving to attain muscular calves. In more recent times, a growing acceptance of displaying large areas of flesh has led to appreciation focusing on developed pectoral muscles, biceps and triceps, and abdominal muscles, which enjoyed popular appreciation in 1990's Western nations. Different societies generally have significantly different perceptions of male beauty:

In pre-industrial societies, having a muscular physique and tanned skin was attractive, but signified that the man had to work in the fields all day, and was consequently likely poor and uneducated. Having pale skin and/or a fatter physique was considered highly attractive, as a symbol that the man was rich or educated enough to avoid manual labour in the field.

In industrial societies, having a pale body was considered unattractive, as it was a sign that the person worked in a factory and lived in dense, polluted urban areas with weakened sunlight. Being tanned and muscularly-defined instead of fat or undeveloped muscularly became attractive, as a symbol that the man lived in the countryside, which was far healthier than the cities, and performed "good honest" agricultural labour as opposed to working shifts in a factory.

In post-industrial societies, being pale and/or fat or especially thin is may be viewed as a sign that the person has little regard for his physical state or health. Having tanned skin is viewed as naturally attractive, and as a potential sign that the person takes foreign holidays. False tans, however, can be the subject of humour.

Having a fit or muscular physique is considered highly attractive, as a sign that the person takes care of his body and health, and has both the time and money to frequent a gym. However, having especially large, highly-developed muscles is viewed by some as naturally unattractive, and possibly indicating undesirable aggressiveness or obsession with muscles. In recent decades, a backlash against social stereotypes of male physical attractiveness has increased variation in physiques, hairstyles, fashion trends, etc, often as an expression of individuality in place of conformity to arbitrary stereotypes.

Social effects of attractiveness

When a person is seen as attractive or unattractive, a whole set of assumptions are brought into play. Across cultures, what is beautiful is assumed to be good. Attractive people are assumed to be more extroverted, popular, and happy. There is truth in this attractive people do tend to have these characteristics. However, this is probably due to self-fulfilling prophecy; from a young age attractive people receive more attention that helps them develop positive characteristics.

Physical attractiveness can have very real effects. A survey conducted by London Guildhall University of 11,000 people showed that physically attractive people earn more. Less attractive people earned, on average, 13% less than more attractive people, while the penalty for being overweight was around 5%.

Interestingly, cultures differ in the details of how attractive people are seen. In Western cultures that value individuality, attractive people are seen as assertive and strong. But in some more collectivistic Asian cultures, attractive people are seen as being more sensitive and understanding.

Both men and women use physical attractiveness as a measure of how 'good' another person is. Typically men tend to value attractiveness more than women. But in terms of behavior, most studies have shown very little difference between men and women.


Ellen Berscheid and Harry T. Reis. "Attraction and Close Relationships". In Daniel T. Gilbert, Susan T. Fiske, and Gardner Lindzey, editors, Handbook of Social Psychology, pages 193-281. New York: McGrawHill, 1998.
Harper, B. "Beauty, Statute and the Labour Market: A British Cohort Study", Oxford Bulletin of Economics and Statistics, 62, December 2000, pp773-802. Press release and summary (
Fisher, Helen. "Why We Love : The Nature and Chemistry of Romantic Love", Henry Holt and Co., February 4, 2023
Cash, T.F; Gillen, B; & Burns, D.S; (1977) Sexism and 'beautyism' in personnel consultant decision making. Journal of Applied Psychology, 62, 301-310.
Clark, M.S; & Mills, J. (1979) Interpersonal attraction in exchange and communal relationships. Journal of Personality and social psychology, 37, 12-24.
Cunningham, M.R. (1990) What do women want. Journal of personality & social psychology, 59, 61-72. Singh, D; (1993) "Adaptive significance of female physical attractiveness: role of waist - to - hip ratio". Journal of personality and social psychology, 65, 293 - 307
Cunningham, M.R; Roberts, A.R; Barbee, A. P; Duren P.B; & Wu, C.H; (1995) "Their ideas of beauty are, on the whole, the same as ours: Consistency and Variability in the cross cultural perception of female physical attractiveness". Journal of Personality & social psychology, 68, 261 - 279.
De Santis, A; and Kayson, W. A; (1999) Defendants charactersitics of attractiveness, race, & sex and sentencing decisions. Psychological reports, 81. 679 - 683.

^ Top ^