ATTRACTIVENESS
THE ROLE OF SEXUAL SELECTION IN PHYSICAL ATTRACTIVENESS
Sexual selection explains why humans have evolved preferences for specific physical traits that signal genetic fitness, health, and reproductive viability. If a trait makes an individual more attractive to the opposite sex, it increases their chances of securing a mate and passing on their genes. Over generations, these traits become exaggerated and widespread.
While other factors such as wealth, status, and dominance can influence mate choice, this discussion focuses purely on physical appearance—what we look like and why certain features are attractive.
NATURAL SELECTION VS. SEXUAL SELECTION
Natural selection ensures survival by favouring traits that help individuals stay alive and reproduce.
Sexual selection focuses on attraction, favouring traits that make an individual more desirable to potential mates, even if they do not directly aid survival.
PLEASE NOTE: While other factors such as wealth, status, and dominance can influence mate choice, this discussion focuses purely on physical appearance—what we look like and why certain features are attractive. For a discussion on non-physical traits such as power and resources, see the topic on sexual selection.
PHYSICAL TRAITS PREFERRED IN WOMEN
FACIAL SYMMETRY
Research suggests symmetrical faces are more attractive because symmetry indicates developmental stability. If a person develops symmetrically, it suggests they have not been significantly affected by genetic mutations, disease, or environmental stressors during growth. Asymmetry, on the other hand, can indicate poor health or genetic defects.
HIP-TO-WAIST RATIO (0.7, HOURGLASS FIGURE)
A waist-to-hip ratio of 0.7 is widely recognised as an indicator of fertility and good health. This proportion is linked to higher fertility due to optimal oestrogen levels, a lower risk of diseases such as diabetes and cardiovascular conditions, and an evolutionary advantage in childbirth, as broader hips facilitate labour.
This preference may also function as a natural deterrent against prepubescent females, ensuring men direct reproductive efforts towards women of childbearing age.
YOUTHFUL FEATURES
Signs of youth indicate higher reproductive potential, making them desirable. These include:
clear skin, free from blemishes, wrinkles, or visible signs of ageing, suggesting good health and high oestrogen levels
long, thick hair, associated with youth and fertility, as hair naturally thins with age
bright, white teeth, indicating good health, strong genetics, and proper nutrition
NEONATAL FACIAL FEATURES
Women with big eyes, a small nose, and full lips are often perceived as more attractive because these features are linked to high oestrogen levels and fertility. They also create a more youthful appearance, reinforcing their desirability.
LARGE BREASTS AND FULL BUTTOCKS
Larger breasts and rounded buttocks are often considered attractive because they signal reproductive health and fertility. These features are linked to higher fat stores, which are necessary for pregnancy and lactation, and DHA storage, an essential fatty acid crucial for foetal brain development.
PHYSICAL TRAITS PREFERRED IN MEN
FACIAL SYMMETRY
Just as in women, symmetrical male faces are preferred because they signal genetic stability and resistance to disease.
HEIGHT
A taller stature is generally more attractive in men, potentially because it suggests physical strength and protection, reflects good genetic health and developmental stability and aligns with sexual dimorphism, where males are larger than females in many species.
BROAD SHOULDERS AND V-SHAPED TORSO
Men with broad shoulders and a narrow waist (inverted triangle shape) are often seen as more attractive because this body structure is linked to high testosterone levels, physical strength, and the ability to compete successfully for resources.
STRONG JAWLINE AND PROMINENT BROW RIDGE
Testosterone influences the development of strong facial features, such as a defined jawline and pronounced brow ridge. These traits are associated with high testosterone levels, strong immune function, and good genetics, contributing to masculine attractiveness.
LOW BODY FAT AND MUSCLE DEFINITION
A lean, muscular build is considered attractive as it signals good physical health, lower risk of metabolic diseases, high testosterone levels linked to muscle growth and strength, and the ability to compete successfully in physical confrontations.
PENIS SIZE
Some research suggests that penis size may play a role in physical attraction. A larger size may enhance perceived masculinity, though it is unlikely to have played a significant role in evolutionary fitness beyond a visual cue of virility.
PHYSICAL TRAITS BOTH SEXES FIND ATTRACTIVE
Certain physical traits are universally appealing, indicating genetic health and overall fitness. These include:
Symmetrical body and face, which signal stable development and strong genetics
Clear, smooth skin, which suggests youth, strong immunity, and high reproductive potential
Healthy teeth, which reflect good nutrition and strong genetics
Shiny, well-maintained hair, which is a sign of overall vitality
As studies suggest, genetic dissimilarity results from our being drawn to partners with different immune system genes, which enhances offspring survival. This is detected through scent, particularly during sexual arousal.
WHY PHYSICAL ATTRACTION MATTERS
Physical attraction is not just about aesthetics—it is an evolutionary mechanism that helps individuals identify healthy, fertile, and genetically fit mates.
While modern social factors like status and wealth influence attraction, biological instincts still drive a preference for physical traits that historically increased reproductive success. These preferences, shaped over thousands of generations, continue to influence how we perceive beauty today.
RESEARCH STUDIES
Here are key research studies that support the role of physical attractiveness in sexual selection theory:
FACIAL SYMMETRY AND ATTRACTIVENESS
Little, A. C., Jones, B. C., & DeBruine, L. M. (2011) – This study found that facial symmetry is consistently rated as more attractive across cultures. Symmetry is believed to signal developmental stability, meaning fewer genetic mutations or environmental stressors impacted growth.
Thornhill, R., & Gangestad, S. W. (1999) – Their research on facial symmetry showed that women prefer more symmetrical male faces, particularly at peak fertility in their menstrual cycle. This supports the idea that symmetrical features indicate genetic fitness and enhance reproductive success.
HIP-TO-WAIST RATIO AND FEMALE ATTRACTIVENESS
Singh, D. (1993, 2002) – Singh's studies confirmed that a waist-to-hip ratio of 0.7 is consistently perceived as more attractive in women across different cultures. This preference is linked to fertility and health, reflecting optimal oestrogen levels and lower risks of obesity-related diseases.
Zaadstra et al. (1993) – Found that women with a lower waist-to-hip ratio have higher fertility and a greater likelihood of conception, supporting the evolutionary basis for this preference.
HEIGHT AND MALE ATTRACTIVENESS
Pawlowski, B., Dunbar, R. I. M., & Lipowicz, A. (2000) – Found that women overwhelmingly preferred taller men as romantic partners. The study suggested that height correlates with social status and perceived genetic fitness, making it a desirable trait in mate selection.
Stulp, G., Buunk, A. P., Pollet, T. V., Nettle, D., & Verhulst, S. (2013) – Examined over 10,000 couples and found that taller men had higher reproductive success, reinforcing the evolutionary importance of height in male attractiveness.
STRONG JAWLINES, MASCULINE FEATURES, AND TESTOSTERONE
Johnston, V. S., Hagel, R., Franklin, M., Fink, B., & Grammer, K. (2001) – Found that men with strong jawlines and prominent brow ridges were rated more attractive. These features are linked to higher testosterone levels, which may indicate genetic strength and immune system competence.
Penton-Voak, I. S., & Perrett, D. I. (2000) – showed that women prefer more masculine faces when ovulating but shift towards less masculine faces at other times, suggesting that testosterone-linked features signal short-term genetic benefits rather than long-term parental investment.
NEONATAL FEATURES IN FEMALE ATTRACTIVENESS
Perrett, D. I., Lee, K. J., Penton-Voak, I., Rowland, D., & Yoshikawa, S. (1998) – Found that big eyes, full lips, and small noses were universally rated more attractive in women. These features signal high oestrogen levels and fertility.
MUSCULARITY AND MALE ATTRACTIVENESS
Frederick, D. A., & Haselton, M. G. (2007) – Found that women rated muscular men as more attractive for short-term relationships, suggesting that muscle mass signals good genes and physical dominance, advantageous in ancestral environments.
PENIS SIZE AND PERCEIVED ATTRACTIVENESS
Dixson, B. J., Grimshaw, G. M., Linklater, W. L., & Dixson, A. F. (2013) – Found that larger penis size was associated with increased attractiveness, particularly when paired with taller height and broad shoulders, supporting the idea that secondary sexual characteristics contribute to mate selection.
UNIVERSAL ATTRACTIVENESS OF SYMMETRY AND CLEAR SKIN
Grammer, K., Fink, B., Møller, A. P., & Thornhill, R. (2003) – Found that clear skin, facial symmetry, and healthy hair are universally preferred traits because they indicate good health and genetic quality.
FEMALES SPEND TIME ON THEIR APPEARANCE TO ATTRACT A MALE
Research on intra-sexual selection, particularly regarding females investing time in their appearance to attract a mate, provides valuable insights into mating strategies and behaviours. Several studies have explored this phenomenon:
Feingold (1990) conducted a meta-analysis examining gender differences in physical attractiveness. The study found that women generally place a higher emphasis on their physical appearance compared to men. This suggests that females invest time and effort in enhancing their attractiveness to attract potential mates.
Buss (1989) carried out a cross-cultural study on mate preferences, finding that physical attractiveness was consistently rated as a highly desirable trait in potential mates across different cultures. This suggests that women may invest time in their appearance to increase their attractiveness and reproductive success.
Cash et al. (1985) researched body image and self-esteem, focusing on how individuals perceive their physical appearance. The study found that women often engage in grooming and cosmetic practices to enhance their physical attractiveness, which may be driven by intrasexual competition and the desire to attract potential mates.
Townsend and Wasserman (2011) investigated mate selection strategies in a speed-dating setting. The study found that women tended to spend more time grooming and dressing up before the speed-dating event than men. This suggests that females may prioritise their appearance as part of intrasexual competition to attract desirable mates.
Hill and Durante (2011) explored how ovulation influences women's mating preferences and behaviours. Their research found that women tend to dress more provocatively and exhibit greater interest in appearance-enhancing behaviours during the ovulatory phase of their menstrual cycle. This suggests that females may strategically invest time in their appearance during peak fertility to attract potential mates.
The significant spending in the beauty and fashion industries also offers strong evidence of mate attraction and selection behaviours.
BEAUTY INDUSTRY
The global beauty industry was valued at approximately $532 billion in 2019, with consumers in the United States alone spending over $80 billion on cosmetics and personal care products in 2020 (Statista).
This industry encompasses various products and services, including skincare, makeup, haircare, fragrances, and spa treatments, catering to both men and women and reflecting a diverse consumer base.
FASHION INDUSTRY
The global fashion industry is valued at over $2.5 trillion, as reported by McKinsey & Company, with consumers in the United States spending approximately $380 billion on apparel and footwear in 2019 (Statista).
This industry encompasses clothing, accessories, footwear, and textiles, spanning a wide range of segments from luxury brands to fast-fashion retailers, catering to different consumer preferences and budgets.
SUMMARY OF EVIDENCE SUPPORTING SEXUAL SELECTION THEORY IN PHYSICAL ATTRACTION
Symmetry signals genetic fitness and resistance to disease (Little et al., 2011; Thornhill & Gangestad, 1999).
A waist-to-hip ratio of 0.7 is linked to female fertility (Singh, 1993, 2002; Zaadstra et al., 1993).
Height in men correlates with reproductive success (Pawlowski et al., 2000; Stulp et al., 2013).
Masculine features signal high testosterone and genetic strength (Johnston et al., 2001; Penton-Voak & Perrett, 2000).
Neonatal features in women indicate high oestrogen levels (Perrett et al., 1998).
Muscularity in men signals physical strength and genetic quality (Frederick & Haselton, 2007).
Penis size may contribute to perceived virility (Dixson et al., 2013).
Clear skin and symmetrical features are universally attractive (Grammer et al., 2003).
This research provides strong empirical evidence that physical attraction is an evolutionary signal of genetic health, fertility, and reproductive success.
CRITIQUES OF SEXUAL SELECTION THEORY APPLIED TO PHYSICAL ATTRACTIVENESS
While sexual selection theory provides a strong evolutionary explanation for physical attraction, it is not without its criticisms. Several challenges arise when applying this framework to human mate preferences:
CULTURAL AND SOCIAL INFLUENCES
One major critique is that cultural and social factors heavily shape perceptions of attractiveness, challenging the idea that preferences are purely evolutionary. For instance:
Historical variations in beauty standards: Fuller-figured women were considered highly attractive in the Renaissance, contrasting with modern preferences for a slimmer figure. This suggests that attractiveness is not entirely biologically fixed.
Media influence: The modern beauty and fashion industries, mainly through advertising and social media, may reinforce and exaggerate specific beauty standards rather than reflect innate preferences.
Research by Swami and Tovée (2005) found that socioeconomic factors influence preferences for body shape. Men from poorer environments prefer larger body sizes, contradicting the universal appeal of a low waist-to-hip ratio.
INDIVIDUAL DIFFERENCES AND SEXUAL ORIENTATION
Sexual selection theory assumes a one-size-fits-all model of attraction, often overlooking:
Variability in preferences: Some men may prefer different body shapes, facial features, or ages based on personal experience, culture, or environmental influences.
Same-sex attraction: Much of the research focuses on heterosexual attraction, ignoring mate preferences in same-sex relationships. If attraction were purely driven by reproduction, the existence of stable, long-term same-sex relationships would be difficult to explain within this framework.
OVERSIMPLIFICATION OF PHYSICAL ATTRACTIVENESS
Sexual selection theory tends to oversimplify the role of physical attractiveness, often neglecting the impact of:
Personality and intelligence: While physical attractiveness is important, many prioritise qualities like kindness, humour, and intelligence when selecting a long-term partner. Buss and Barnes (1986) found that in mate selection, personality traits ranked higher than physical appearance for both men and women.
Non-visual factors: Preferences are influenced by voice tone, body language, and scent, which are not accounted for in most physical attractiveness research.
EVOLUTIONARY MISMATCH
Modern environments differ drastically from the ancestral environments in which these mate preferences allegedly evolved:
Contraception and medical advancements: Fertility cues like a youthful appearance may no longer be as crucial, as reproductive success is now controlled by medical technology rather than mate choice.
Shifts in gender roles: In societies where women have financial independence, mate preferences may be shifting. Eagly and Wood (1999) found that as gender equality increases, the importance of physical traits in mate selection decreases, suggesting that evolved preferences are not as rigid as sexual selection theory implies.
LACK OF DIRECT CAUSATION
Many studies show correlations rather than causation when linking attractiveness to reproductive success. Just because men prefer symmetrical faces or a low WHR does not mean these traits enhance survival or reproduction.
For example, Pawlowski et al. (2000) found that while taller men are preferred, height does not always correlate with greater reproductive success in modern populations. Similarly, Buss (1989) found a preference for younger women, but lifestyle choices than age-based fertility cues more influence modern birth rates.
CHEATING EVOLUTION THROUGH PLASTIC SURGERY
One significant challenge to the evolutionary perspective on physical attraction is the ability to "cheat" biological signals through plastic surgery and cosmetic enhancements. If physical traits are meant to signal genetic fitness, youth, and fertility, then modern medical advancements allow individuals to artificially mimic these desirable features without possessing the underlying biological advantages.
Breast implants, lip fillers, and Botox create features associated with youth and fertility but do not enhance reproductive potential.
Liposuction and body sculpting can artificially create a low waist-to-hip ratio, bypassing natural fat distribution patterns.
Facial symmetry can be surgically enhanced, undermining the idea that it naturally signals genetic stability.
Research by Russell et al. (2019) found that men rated surgically enhanced faces as more attractive than natural faces, suggesting that attraction is based more on perceived cues than actual biological fitness.
Additionally, modern cosmetic interventions may distort natural mate selection. If individuals select partners based on artificially enhanced traits, this could reduce the evolutionary pressure that originally shaped these preferences. This suggests that, in an era of widespread cosmetic surgery, sexual selection theory may not function as effectively as it did in ancestral environments.
