People often set biological instincts against the rules of civilisation, assuming that instinct seeks to satisfy natural desires while civilisation restrains them through morality and institutions. Yet this view overlooks an important fact: civilisation itself is a product of humanity’s long evolutionary history. Its emergence has also been shaped by evolutionary pressures involving survival, reproduction and social cooperation.
Biologically, men and women face markedly different reproductive costs. Women bear the substantial physiological demands of pregnancy, childbirth and breastfeeding, whereas men’s minimum reproductive investment is comparatively low. This difference may influence mating strategies. Buss and Schmitt’s Sexual Strategies Theory (1993) proposes that both men and women may pursue long-term or short-term mating strategies, but with different tendencies. A study by Schmitt and colleagues (2003), involving 16,288 people across 52 countries and regions, found that men, on average, expressed a stronger preference for sexual variety. A 2022 meta-analysis covering 211 studies and more than 620,000 participants also found a higher average sex drive among men, with the difference persisting after adjustment for response bias.
These findings indicate that some average differences in sexual psychology exist between men and women. There are, however, several intervening steps between sexual desire and an extramarital relationship. A stronger sex drive, a preference for sexual variety, mismatched needs within a marriage and opportunities outside it may all affect the likelihood of infidelity. Personal values, marital commitment and self-restraint also matter. A higher average sex drive among men does not mean that men will inevitably be unfaithful, just as women’s higher reproductive costs do not establish that women are naturally monogamous.
Stable pair bonds, enduring attachment and shared parenting also have deep evolutionary roots. Human children’s prolonged dependence gives sustained parental investment, family cooperation and stable relationships important advantages for survival and reproduction. These capacities were not simply imposed on humanity after civilisation appeared; they were already part of human evolution.
The rules of civilisation may themselves reflect this evolutionary foundation. For example, brothers and sisters who grow up together generally find it difficult to feel sexually attracted to one another and are unlikely to experience physiological sexual arousal in response to each other. This tendency may arise partly from evolved mechanisms for avoiding inbreeding, rather than solely from moral education. Social taboos concerning sexual relationships between close relatives further reinforce that constraint. Similarly, marriage, family responsibilities and institutions for social cooperation respond, in varying degrees, to the long-term requirements of human survival and reproduction.
It is therefore misleading to attribute sexual desire and a preference for sexual variety to biology while assigning fidelity, stability and shared parenting entirely to later civilisation. Humans have evolved both tendencies towards sexual variety and capacities for stable relationships and sustained cooperation. Civilisation has gradually emerged through these different tendencies and their interaction.
Civilisation is more than a straightforward rejection of biological instinct. Its development reflects behavioural tendencies, cooperative needs and cultural selection shaped by long-term evolutionary pressures. Once established, civilisational institutions in turn alter the environments in which humans live and the selection pressures they face. Biological and cultural evolution thus form a continuing process of mutual influence.
References and Academic Research
Buss, D. M., & Schmitt, D. P. (1993). Sexual Strategies Theory: An Evolutionary Perspective on Human Mating. Psychological Review, 100(2), 204–232.
Proposes Sexual Strategies Theory to explain the evolutionary foundations of men’s and women’s long-term and short-term mating strategies.
https://doi.org/10.1037/0033-295X.100.2.204
Schmitt, D. P., et al. (2003). Universal Sex Differences in the Desire for Sexual Variety: Tests From 52 Nations, 6 Continents, and 13 Islands. Journal of Personality and Social Psychology, 85(1), 85–104.
A cross-cultural survey of 16,288 people that found relatively consistent average differences between men and women in their preference for sexual variety.
https://doi.org/10.1037/0022-3514.85.1.85
Frankenbach, J., et al. (2022). Sex Drive: Theoretical Conceptualization and Meta-Analytic Review of Gender Differences. Psychological Bulletin, 148(9–10), 621–661.
Combines data from 211 studies involving 621,463 participants. It found a higher average sex drive among men, with a smaller difference after adjustment for response bias.
https://doi.org/10.1037/bul0000366
Selterman, D., Garcia, J. R., & Tsapelas, I. (2019). Motivations for Extradyadic Infidelity Revisited. The Journal of Sex Research, 56(3), 273–286.
Examines multiple motivations for infidelity, including sexual desire, the pursuit of variety, emotional dissatisfaction, low commitment and situational factors. It shows why infidelity cannot be reduced to biological sexual desire.
https://doi.org/10.1080/00224499.2017.1393494
Fletcher, G. J. O., et al. (2015). Pair-Bonding, Romantic Love, and Evolution: The Curious Case of Homo sapiens. Perspectives on Psychological Science, 10(1), 20–36.
Draws on interdisciplinary research to examine the important roles of enduring pair bonds, romantic love and shared parenting in human evolution.
https://doi.org/10.1177/1745691614561683
Gettler, L. T., Boyette, A. H., & Rosenbaum, S. (2020). Broadening Perspectives on the Evolution of Human Paternal Care and Fathers’ Effects on Children. Annual Review of Anthropology, 49, 141–160.
Explores the evolutionary foundations of paternal care and the relationship between human children’s prolonged dependence and cooperative child-rearing.
https://doi.org/10.1146/annurev-anthro-102218-011216
Lieberman, D., Tooby, J., & Cosmides, L. (2007). The Architecture of Human Kin Detection. Nature, 445, 727–731.
Investigates links between early co-residence, kin recognition and sexual avoidance among close relatives, providing evidence for evolved mechanisms of inbreeding avoidance. The study mainly examines sexual aversion and related judgements; it does not directly measure physiological sexual arousal.
https://doi.org/10.1038/nature05510
Boyd, R., & Richerson, P. J. (2008). Gene–Culture Coevolution and the Evolution of Social Institutions. In Better Than Conscious? Decision Making, the Human Mind, and Implications for Institutions, pp. 305–324.
Uses a gene–culture coevolutionary perspective to explain the emergence of social institutions and the interaction between evolved psychological mechanisms and cultural institutions.
https://doi.org/10.7551/mitpress/9780262195805.003.0014
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