A Muscular Male Body: A Result of Female Mate Choice?

This entry was written by Kieran Baughan as part of a project done in BIAN 6133 ‘Human Reproductive Strategies’ at The Australian National University in 2019 Semester 2.


Darwin’s theory of sexual selection explains traits or behaviours which increase an individual’s reproductive success and ultimately their fitness. Female mate choice, through intersexual selection, explains the evolution of certain male traits chosen by the female because they provide honest signals of superior genes. The female is typically searching for indicators of indirect benefits, for example, healthy males with superior genes which will be passed to her offspring, or direct benefits, e.g. high resource availability, protection or good parenting. Whether intersexual selection can explain mate preferences in humans has been hotly debated, yet a relatively new approach called evolutionary psychology attempts to answer such questions.

Evolutionary Psychology

Evolutionary psychologists (EP) suggest as we have spent most of our evolutionary history as hunter-gatherers, humans have evolved mechanisms in the brain for identifying an ideal mate for that environment. A key component of EP is that the trait of interest must be universally selected for, whether in modern foragers or W.E.I.R.D (Western, Educated, Industrialized, Rich, Democratic) societies. Whilst both male and female mate preferences have been studied, females are the “choosy” sex in mammals therefore male traits maybe under more selective pressure. A male masculine body might provide a perfect example of a male trait under sexual selection through mate choice and an ideal example for the EP approach (Barber, 1995).

This paper will explore whether a muscular male body would have been adaptive and selected for through mate choice in our distant past and if it’s universally preferred in modern humans thus providing support for the EP approach.

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Honest signals of a muscular body

For this trait to evolve through mate choice it must first provide honest signals to the female about the quality of the male. Sim (2013) tested the hypothesis that a muscular body conveys information about the underlying physical qualities (genes, developmental health and sex hormone ratios) and provides reliable information of better health (lower risk of heart disease or mortality in general). The author discovered that a “wedge shape” or a high shoulder-waist ratio (SWR) among other features does provide a quality indicator of hormone levels, physical strength and overall health. Therefore, demonstrating honest signals of good genes.

Furthermore, studies on modern hunter-gatherer societies have demonstrated that upper body size or strength are reliable predictors of hunting ability. Stibbard-Hawkes, Attenborough & Marlowe (2018), tested the hypothesis that hunters exhibit certain proxies or indicators of true hunting ability, one of which was draw strength. Their study found, not only that draw strength was the best predictor of hunting ability, but the hunter had a greater reputation of success because of his perceived strength. Thus, if a more muscular physique is a genuine predictor of hunting success, then we can assume that potential females may favour this trait as it provides an honest signal of direct benefits through resource availability.

Another example, although explored on the same society (Hadza), tested which specific traits of a successful hunter may be under selective pressure and proposed upper body strength maybe one (Apicella, 2014). As expected, the author attained the same results as the aforementioned study, with upper body strength acting as a strong predictor of true hunting ability and greater reputation. Yet, the author concluded that a hyper muscular upper body may have been selected for due to contest competition as well as determining hunting ability. This may suggest that a female preference for this trait maybe a secondary sexual selection characteristic. Either way, a muscular male physique provides honest signals of both indirect and direct benefits to the “choosy” female.

A muscular body and reproductive success

It appears likely that a muscular male body does provide honest signals, yet this is irrelevant if the female doesn’t select the male for mating and he doesn’t gain any reproductive success despite expressing the trait. In addition, to determine if this trait is the result of mate choice, the male must gain a reproductive advantage over his rivals. We have established that males with greater upper-body size are more capable hunters and are perceived as such by both males and females, but why is this important? Why is being a better hunter important within foragers? Amongst foraging societies, hunting ability is possibly the most effective pathway to gaining access to mates.

Smith (2004) observed that good hunters appear to have greater reproductive success in several modern foraging societies. His study concluded that better hunters had more high-quality mates and higher offspring survival. Consequently, the author stated that if a better hunter provides better quality resources then female mate choice may be responsible for this relationship (Smith, 2004).

Marlowe (2004) went one step further and explored female mate preference in the Hadza, a hunter-gatherer society from Tanzania. The results of his study found that the most sought-after traits for a potential mate are foraging ability, character and looks (Marlowe, 2004). According the author, 85% of females expressed a “good hunter” as their most important value. As food is dispersed amongst the group, Marlowe (2004) doubted whether females would gain any additional direct benefits from mating with a good hunter but concluded that the trait may express underlying good genes and parental investment. More recent studies have also concluded that good hunters gain greater social status of which females, or at least her offspring may benefit.

Cross-cultural research

We have established that a muscular body may have been adaptive in both modern foragers and ancestral humans resulting from female mate choice. However, to support an EP approach to human mate preference, this trait must be universally attractive despite cultural differences or environment. Several cross-cultural studies have tested whether a muscular body is widely regarded as an attractive trait by females in W.E.I.R.D (Western, Educated, Industrialized, Rich, Democratic) societies.

Braun & Bryan (2006) studied the effects of male body shape (SWR) on the desirability of a potential romantic partner, with the prediction that females would be most attracted to males which expressed dominance and the ability to provide. The authors had stated a male upper body which express a desirable SWR and muscular arms are traits which females would target (Braun & Bryan, 2006). The authors sampled undergraduate students from an American University, which included predominantly Caucasian (86%) males and females. Their findings supported two outcomes; the first, that females declared the high SWR to be the most desirable for a one-time sexual partner and second, that the “V-shape” body is clearly more attractive to females (Braun & Bryan, 2006). Interestingly, the authors concluded that whilst this body shape was most desirable for a sexual partner, the male rivals with an equal SWR are more desirable for a long-term mate.

A similar study was conducted by Dixon et al (2003) who tested whether SWR and body somatotype (ectomorph, mesomorph, endomorph) would have consistent effects on men’s attractiveness to females. Respondents were comprised of 685 women; the majority were university students between the ages of 21 and 30yrs. Whilst the authors declared that other demographic details weren’t recorded, comparisons were made between British and Sri-Lankan woman. Their results demonstrated that both groups of women rated the mesomorph (most muscular) somatotype the most attractive and a SWR of 0.6 was significantly more attractive overall. It’s important to note this study and others have demonstrated that females don’t appear to be overly attracted to large, bodybuilder-like physiques suggesting that a run-away selection event is not involved.

These examples of cross-cultural studies offer some support that females within W.E.I.R.D societies show a preference for a masculine male body, seemingly demonstrating some universality to the trait. Further research is still required, preferably on other societies and females of different ethnicity, to offer more support to an EP approach to human mate choice.


Darwin’s theory of sexual selection through female mate choice explains the evolution of male traits which express honest signals of superior genes. Evolutionary psychologists suggest human’s possess mechanisms in the brain for determining an ideal mate in our distant past. A male masculine physique has demonstrated honest signals of indirect and direct benefits to a potential female in modern forager societies. In addition, a muscular upper body with a high SWR has proven to be universally more attractive. This proves there is strong evidence this trait may have been selected through female mate choice and can be explained through evolutionary psychology.


Apicella, C. L. (2014). Upper-body strength predicts hunting reputation and reproductive success in Hadza hunter–gatherers. Evolution and Human Behavior, 35(6), 508-518.

Barber, N. (1995). The evolutionary psychology of physical attractiveness: Sexual selection and human morphology. Ethology and Sociobiology, 16(5), 395-424.

Braun, M. F., & Bryan, A. (2006). Female waist-to-hip and male waist-to-shoulder ratios as determinants of romantic partner desirability. Journal of Social and Personal Relationships, 23(5), 805-819.

Dixson, A. F., Halliwell, G., East, R., Wignarajah, P., & Anderson, M. J. (2003). Masculine somatotype and hirsuteness as determinants of sexual attractiveness to women. Archives of sexual behavior, 32(1), 29-39.

Marlowe, F. W. (2004). Mate preferences among Hadza hunter-gatherers. Human nature, 15(4), 365-376.
Sim, K. (2013). The relationship between sex-typical body shape and quality indicators. Journal of Social, Evolutionary, and Cultural Psychology, 7(2), 97.

Smith, E. A. (2004). Why do good hunters have higher reproductive success?. Human Nature, 15(4), 343-364.

Stibbard-Hawkes, D. N., Attenborough, R. D., & Marlowe, F. W. (2018). A noisy signal: To what extent are Hadza hunting reputations predictive of actual hunting skills?. Evolution and Human Behavior, 39(6), 639-651.

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