Sex Differences in Physical Attractiveness
<p id="p1">This chapter provides an overview of the literature on the sex differences in physical attractiveness, and how it influences mate choice. More specifically, it investigates evolutionary perspectives on men and women’s preferences for physical traits, such as ideal breast features in...
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Human attraction plays a crucial role in mate choice, which can affect reproductive success. From an evolutionary standpoint, attraction is a psychological mechanism used to identify high-quality mates by recognizing cues related to fitness and reproductive potential. Attractiveness is a key factor that both men and women consider in mate selection.
This chapter focuses on sex differences in physical attractiveness and how certain physical features influence mate choice. Women are often attracted to men with traits that suggest high-quality genes and the potential for investment, while men are drawn to features in women that signal reproductive health. These preferences help explain the evolutionary significance behind what each sex finds attractive, while also considering how ecological factors and individual differences shape these preferences.
Sexual Selection explains how traits important for mate choice (intersexual selection) and traits that help individuals compete with others of the same sex (intrasexual selection) evolve. Darwin's theory suggested that mating success is influenced by traits that signal reproductive potential, such as physical cues that indicate fitness. In non-human species, for example, bright colors in guppies and large antlers in ungulates are attractive because they signal good health and condition. In humans, physical traits like facial and bodily characteristics can reflect reproductive fertility, value, and immune health.
Parental Investment Theory further explains human mate choice. According to this theory, the sex that invests more in offspring will be more selective in choosing a mate, while the less investing sex will compete for mating opportunities. In humans, females invest more in parenting (e.g., pregnancy), so they are more selective in mate choice. This has led to evolved mechanisms in females to detect traits in males that suggest protection and investment, which are important for offspring survival. On the other hand, since male investment is minimal and paternity is uncertain, men focus on traits in women that signal fertility and reproductive capacity.
There are clear sex differences in physical attractiveness, as men and women prioritize different traits in potential mates that may contribute to reproductive success. According to Parental Investment Theory, women may prefer traits in men that suggest they can provide protection and invest in offspring care. Since men typically invest less in parenting, it is hypothesized that they are more focused on physical traits in women that signal fertility and reproductive potential. Furthermore, Sexual Strategies Theory helps explain how men and women prioritize different physical characteristics depending on whether they are seeking short-term or long-term relationships. Throughout human evolution, both sexes have faced distinct adaptive challenges that shaped their mating strategies. For example, women have had to evaluate whether a mate will be a good long-term partner for both her and her offspring, while men have had to assess female fertility, leading them to prioritize certain traits in short-term mating contexts. The following sections will explore these differences using both Parental Investment and Sexual Strategies Theory.
Women’s mate preferences are influenced by physical characteristics in men that signal both indirect benefits (such as good genetics) and direct benefits (such as resource acquisition and protection). These traits help women assess the overall quality of a potential mate and his likelihood of investing in her and their offspring. A key factor in female preferences is the role of secondary sexual characteristics, which are influenced by androgens like testosterone. For men, these features include pronounced eyebrows, strong cheekbones, and an elongated jawline. Testosterone is known to suppress the immune system, so only high-quality men are able to maintain masculine features while also withstanding the immunosuppressant effects of testosterone, a concept known as the immunocompetence handicap hypothesis. This suggests that women may prefer men with masculine features because they signal heritable good genes, immune strength, and the potential for protection and resources.
Sexual dimorphism refers to the differences between male and female physical characteristics, and these differences influence attractiveness assessments. During puberty, androgens shape secondary sexual characteristics, such as jaw length, with men typically having longer jawlines. Masculine facial features in men are often preferred by women because they indicate good health and high genetic quality. According to sexual selection, traits that signal health and reproductive quality in males are likely to be selected for through female mate choice, as women may pass on these desirable traits to their offspring.However, research on women’s preferences for facial masculinity has been mixed. Some studies show that women do indeed prefer men with masculine features, possibly due to their association with immunocompetence, disease resistance, and strength. These traits may suggest a mate with "good genes" or the ability to provide protection and resources. On the other hand, other studies find that women do not have a clear preference for masculine or feminine faces. Some research even suggests that women may prefer feminine faces in men, possibly due to negative perceptions of facial masculinity, such as associations with dominance, dishonesty, or low paternal investment. Masculine faces can also be linked to aggressiveness and being perceived as threatening, which might not be desirable traits for a long-term partnership.
For example, one study using eye-tracking found that women spent more time looking at feminine faces, which suggests that cognitive processes may influence mate preferences. As a result, women may have to make trade-offs in their mate choices, balancing between a partner with high-quality features (like facial masculinity) and a partner who might be more likely to provide parental investment (like facial femininity).
Upper-body strength in men provides both indirect and direct benefits in mate choice. Women may prefer men with stronger, more formidable features because these traits signal good genetics and the ability to offer protection and resources, which are vital in parental investment. Research has shown that women consider men who display cues of strength and formidability as physically attractive, as these traits may be associated with the ability to protect, acquire resources, compete with other men, and form coalitions. Additionally, individuals perceive stronger men as more capable of providing protection to children compared to men with weaker physical attributes.
One way researchers assess upper-body strength in men is by measuring the shoulder-to-hip ratio (SHR), which is the circumference of a man's shoulders compared to his hips. Men with a higher SHR (i.e., a more V-shaped body, with broader shoulders relative to the hips) are considered more attractive by women. Evidence from eye-tracking studies has shown that women spend considerable visual attention on men with formidable features, further suggesting that cognitive processes (like automatic attention) play a significant role in women’s assessments of men’s bodies for mate potential.
Height is another key sexually dimorphic trait that influences mate choice. Taller men are often perceived as stronger, more aggressive, dominant, and higher in social status—all important qualities in success during intrasexual competition (competition with other males). Taller men tend to have higher self-esteem and self-confidence, which are important psychological traits for success in interpersonal relationships. Research indicates that taller men are more successful in acquiring both long-term and short-term partners. Women report that height is an important physical characteristic in selecting a mate, and while both men and women generally prefer mates taller than average, women's preference for height is stronger than men’s preference for taller women.
Facial and body hair are sexually dimorphic traits closely linked to men’s attractiveness. Beards, which are androgen-dependent traits, may serve as an honest cue to a man’s heritable fitness, as per the immunocompetence handicap hypothesis. Beards are the most noticeable secondary sexual trait in men and are often associated with masculinity, dominance, aggressiveness, and even threat. This suggests that beards might function as an intrasexual competitive display, enhancing features like the jawline. The research on how facial hair affects attractiveness is mixed. Some studies show that women rate men with full beards as more attractive, while others find that men with heavy or light stubble or clean-shaven faces are rated more highly in attractiveness.Interestingly, men with beards are often perceived as more capable of parenting and are rated more attractive for long-term relationships. This could be due to perceptions that bearded men appear more mature, ambitious, and capable of providing long-term stability. Regarding body hair, research shows mixed findings. Some studies suggest that women rate men with body hair as more attractive, while others prefer hairless men. The ectoparasite avoidance hypothesissuggests that hairless men may appear healthier and less likely to carry parasites, which could make them more attractive due to these health cues.
Women engage in both short-term and long-term mating strategies, each offering distinct benefits. For short-term strategies, women seek immediate resources, the ability to assess a potential long-term partner, and good genetics. In contrast, for long-term strategies, women focus on obtaining investment, commitment, status transmission, and physical protection. To maximize genetic benefits in a short-term context, women often prioritize physical attractiveness in a mate, such as facial masculinity, body muscularity, and formidability. Women with short-term mating orientations (measured by the sociosexuality orientation inventory, SOI) tend to engage in sexual activity with minimal commitment, aiming to secure genetic benefits from attractive men.
Research indicates that short-term mating-oriented women are more attracted to masculine faces and muscular body types. This aligns with Strategic Pluralism Theory, which suggests women may prioritize certain physical traits for genetic inheritance, provided the costs of short-term mating (e.g., reduced paternal investment, partner desertion) are outweighed by the benefits. Eye-tracking studies support this by showing that women pursuing short-term strategies focus more on upper body regions, which are associated with muscularity. For long-term relationships, however, women may prefer men who signal investment and commitment. Muscular men are often perceived as less committed and more likely to pursue multiple mating opportunities, influencing women to prefer less muscularity in long-term partners.
According to Parental Investment Theory, males, having lower parental investment, are more inclined to pursue short-term mating opportunities. However, pursuing a long-term mating strategy provides the benefit of increasing offspring survivability through investment from both parents. Men assess reproductive value (such as youthfulness) to determine a woman’s fertility, and this trait is considered universally attractive. Additionally, other bodily traits like breast morphology and waist-to-hip ratio are perceived as indicators of youthfulness and fertility, contributing to men’s attraction to women.
Men find facial femininity highly attractive as it signals reproductive health and fertility. Facial femininity correlates with higher estradiol levels, which are crucial for reproduction. Men tend to prioritize facial femininity because it indicates overall reproductive condition, and women with more feminine faces are often seen as more attractive. Research suggests men are more attracted to facial femininity than averageness. Men’s preference for femininity tends to be stronger in younger women, possibly because older men face greater competition from younger males in accessing women with ideal traits.Breasts are a secondary sexual trait in women that are sexually attractive to men. Unlike other mammals, female breasts remain enlarged after puberty, making them a key visual cue. According to the nubility hypothesis, breast size can signal age and reproductive value, as larger breasts are typically associated with younger, more fertile women. Men's preferences for breast size vary across cultures, with some preferring large breasts, others medium-sized, and some small. Additionally, the firmness of breasts is seen as an indicator of fertility, health, and youthfulness, with non-ptotic (firm) breasts rated higher in attractiveness. In contrast, high-ptotic (sagging) breasts are associated with reproductive success(number of children) and are often rated as older in age. Eye-tracking studies also show that men focus a significant amount of visual attention on the chest region, highlighting the importance of breast features in their assessment of attractiveness.
The waist-to-hip ratio (WHR), which compares the circumference of a woman’s waist to her hips, is a key sexually dimorphic trait associated with attractiveness. Lower WHRs are considered an indicator of reproductive health and fertility, as they are associated with higher levels of estradiol. Research consistently shows that men find women with low WHRs most attractive, perceiving them as more fertile, healthy, and reproductively valuable. In contrast, women with higher WHRs are often rated as less attractive, possibly due to the association with obesity and reduced reproductive health, including irregular menstrual cycles and fewer ovulatory cycles. Studies also show that neuroscientific evidence supports the idea that ideal WHRs activate brain regions associated with reward processingand decision-making, indicating that WHR plays a significant role in mate choice.
Men pursue both short-term and long-term mating strategies, with short-term strategies being characterized by low commitment and a desire for multiple sexual partners. In short-term mating, men prioritize physical attractiveness to maximize reproductive success by identifying signs of reproductive health. Men with short-term mating orientationstend to rate feminine faces, low WHRs, and low BMI as more attractive, as these traits are linked to higher fecundity(fertility). Additionally, studies on breast size preferences show that men pursuing short-term mating strategies often prefer women with larger breasts (especially C and D cup sizes), as these are associated with higher levels of estradioland reproductive success. These preferences reflect men’s drive to assess fertility and reproductive potential when seeking short-term mates.Human mate choice can be influenced by ecological conditions, such as resource availability and mortality risks. In harsh environments, where obtaining resources is unpredictable and survival risks are high, individuals may adopt faster reproductive strategies by prioritizing mates with good genetics. These traits are considered beneficial because they may provide protection and immediate provisioning in unstable conditions.
- Women’s Preferences in Harsh Environments: In environments marked by violence, resource scarcity, or high pathogen prevalence, women are more likely to prefer men with masculine characteristics, as these traits suggest strength, protection, and the ability to provide resources. Masculine men may be viewed as less likely to invest in long-term relationships, but they are valued for their ability to offer immediate support and protection. Research suggests that in resource-scarce conditions, women are more likely to favor stronger body types in men, as these suggest the ability to protect and provide.
- Biparental Care Strategy: Despite the preference for masculine traits in harsh environments, biparental care (i.e., investing in both parents for offspring survival) remains beneficial. Some studies suggest that when women are primed with cues of ecological harshness, they may also show a preference for men who exhibit "good dad" traits—those who are more likely to invest in long-term care for their children, indicating the importance of resources from both parents for offspring survival.
- Preferences in Safer Environments: In safer environments, where survival is less of a concern, women may place greater emphasis on finding partners with high-quality traits, focusing less on the ability to provide immediate protection. Masculine traits may still be preferred in the context of short-term mating, as they signal good genetics and health.
Men’s mate preferences may also be shaped by ecological conditions, particularly regarding women’s breast morphology. In harsh environments, larger breasts may signal fat reserves, which are crucial for pregnancy and lactation. In such environments, men might adopt a faster reproductive strategy, prioritizing women with traits that indicate the ability to carry and nurse offspring effectively.
Men’s preferences for women’s waist-to-hip ratios (WHR) also vary based on resource availability:- In resource-scarce societies, men may prefer women with higher WHRs, as higher fat reserves could indicate better health and reproductive capabilities. For example, research on the Hadza, a hunter-gatherer population from Tanzania, found that men in this population preferred women with higher WHRs, associating them with better health and suitability for marriage.
- In more resource-abundant societies, where food supply is predictable, preferences tend to shift, with men favoring women with lower WHRs, as lower fat levels are often linked to better reproductive health and lower risks of malnutrition. This shift in preference can be seen in contrasting preferences between U.S. men and Hadza men. Similarly, in Peru, men from a village with more stable food supplies preferred lower WHRs in women, while those from a more westernized village preferred higher WHRs.
Mate value refers to an individual’s assessment of their physical attractiveness and mating market value, which can influence their preferences for potential partners. People with higher mate value are typically better positioned to attract high-quality mates, often preferring partners who match or complement their own level of attractiveness.
- Women’s Mate Value: Research suggests that women who rate themselves highly on physical attractiveness tend to prefer men with masculine features, such as a masculine face or broad shoulders relative to the waist. These traits are often associated with high genetic quality. Studies have shown that attractive women tend to focus on high-quality traits in their partners, such as indicators of good genes (e.g., masculinity) and parenting traits(e.g., the ability to provide care for offspring). Additionally, women with high mate value may be more successful at matching their ideal partner preferences with their actual relationship choices and controlling their partner’s behavior to prevent mate desertion.
- Men’s Mate Value: Men also calibrate their mate preferences based on their own mate value and self-perception of attractiveness. Men who perceive themselves as more attractive or better long-term partners are more discriminative in choosing mates, often prioritizing physical attractiveness and other features that align with their self-assessment. For example, men who rate themselves as attractive tend to prefer partners who possess good health, high social status, and good looks, in addition to qualities like a desire for children. This suggests that self-perception of mate value can shape the preferences for specific traits in potential partners.
- Higher Mate Value and Standards: Individuals with higher mate value may set higher standards for their partner choices, seeking mates with qualities that signal genetic health, reproductive success, and parenting ability. This phenomenon is more commonly studied in women, with attractive women often having the ability to "raise their standards" for desirable partner traits, such as masculinity, good health, and parental investment.
