The Evolutionary Advantage of Commitment

Adaptive Benefits of Commitment and Marriage for Men

• Ancestral women required reliable signs of male commitment before consenting to sex, motivating men to seek marriage for reproductive success.
• Men willing to promise long-term resources, protection, and investment are appealing to women, broadening their range of potential partners.
• Marriage increases the odds of a man being the father of his children and improves their survival in ancestral environments.
• Fathers in many cultures have a strong influence in arranging beneficial marriages for their children.
• Marriage increases a man's status, bringing potential benefits such as better resources and additional mates.
• Married men live longer than single men, especially if married to younger women, potentially due to marriage itself having a causal effect on men's health.
• There are potentially nine powerful adaptive benefits for men willing to commit to marriage, including increased reproductive success, social status, and lifespan.
• Ancestral men would benefit from marrying women with the capacity to bear children for reproductive success.
• Men cannot observe a woman's reproductive value directly, so selection could only fashion preferences in men for observable qualities correlated with reproductive value.
• Human mating differs from chimpanzee mating, as women's ovulation is relatively concealed, unlike the pronounced signs of estrus in female chimpanzees.
• Sexual activity among humans occurs throughout a woman's ovulation cycle, unlike the concentrated activity during the estrus phase in chimpanzees.
• Women's ovulation in humans is not accompanied by pronounced genital swelling or clearly detectable scents, unlike the female chimpanzee's estrus phase.

Cues to Female Attractiveness

• Super-white sclera is universally evaluated as attractive and a key cue to health (Provine, Cabrera, & Nave-Blodgett, 2013).
• Among the Trobriand Islanders, health, strong hair growth, sound teeth, and smooth skin are essential conditions for beauty (Malinowski, 1929).
• Hair length and quality are strong cues to youth and health, with younger women having longer and higher-rated quality hair (Hinsz, Matz, & Patience, 2001).
• Clear, unblemished skin signals absence of parasites and skin-damaging diseases, and is linked with perceived facial attractiveness (Sugiyama, 2005).
• Skin quality is linked with perceived facial attractiveness, with homogeneous skin color distribution receiving higher ratings (Fink & Neave, 2005).
• Facial femininity, linked to estrogen levels and fertility, is a marker of reproductive value and health (Schaefer et al., 2006).
• Feminine voices and high-pitched voices are found to be more attractive in women and provide cues to youth (Collins & Missing, 2003; Feinberg et al., 2005).
• Women who wear high heels are judged to be more feminine and attractive (Morris, White, Morrison, & Fisher, 2013).
• Facial symmetry is positively correlated with judgments of attractiveness and is a cue to developmental stability (Gangestad & Scheyd, 2005).
• Facial averageness is linked with attractiveness, with composite faces being judged more attractive than individual faces (Langlois & Roggman, 1990).
• Leg length, especially long legs relative to torso length, is viewed as maximally attractive in women (Sorokowski & Pawlowski, 2008).
• Relatively longer legs are viewed as more attractive in women, with legs roughly 5 percent longer than average being maximally attractive (Bertamini & Bennett, 2009).

Evolutionary Strategies for Paternity Certainty

• Female primates have concealed ovulation, making it difficult for males to ascertain paternity.
• Cryptic ovulation expanded the window of female attractiveness, posing a unique paternity problem for men.
• Marriage potentially provided a solution by increasing paternity certainty through repeated sexual contact.
• Concealed ovulation may have evolved to facilitate long-term committed mating, promoting marriage as a social tradition.
• Marriage serves as a public signal of mating, reducing conflict within male coalitions.
• Men had to seek assurances of their wife’s sexual fidelity to reap the reproductive benefits of marriage.
• Men sought qualities in a mate that could increase the odds of securing paternity, such as premarital chastity and postmarital fidelity.
• The value of chastity has declined over time, coinciding with the availability of birth control.
• Men globally value chastity more than women as an important trait in a long-term mate.
• There are significant cultural variations in the importance placed on chastity as a desirable trait in a potential mate.
• Countries like China, India, Indonesia, Iran, Taiwan, and Palestinian Arab areas value chastity highly, while Sweden, Norway, Finland, the Netherlands, Germany, and France do not.
• The desire for chastity in a long-term mate varies across cultures and is more valued by men than women globally.

Evolutionary Theories of Homosexuality and Contextual Influences on Men's Mating Behavior

• A study in Samoa found that male homosexuals (fa’afafne) exhibited greater avuncular tendencies compared to heterosexual men, investing more in nieces and nephews through babysitting, buying toys, and investing in their education.
• Cross-cultural studies of male androphilia expressed in a transgendered form found elevated levels of kin altruism, suggesting a potential evolutionary explanation for homosexual behavior.
• The female fertility hypothesis suggests that genes for male homosexuality can evolve if they produce an increased reproductive rate in the female relatives of male homosexuals, potentially compensating for lower rates of reproduction in gay males.
• Evidence suggests that the maternal female relatives of gay males produce significantly more offspring than those of heterosexual men, supporting the female fertility hypothesis.
• The alliance formation theory proposes that homoerotic behavior by young men with older men provides a strategy for gaining allies and boosting status, ultimately leading to greater sexual access to women.
• Empirical difficulties have been encountered by the alliance formation theory, and it does not seem to explain the majority of cultures where homoerotic behavior is not used as a strategy of alliance formation.
• The kin altruism theory has received mixed empirical support, while the female fertility hypothesis has accrued the strongest empirical support among the three evolutionary theories of homosexuality.
• Social, ecological, and personal contexts influence men’s mating strategies, and desires may not always correspond with actual mating behavior.
• Humans likely evolved in small groups, where a particular man would have encountered only a few dozen attractive women, but in modern environments, they are bombarded with thousands of images of attractive models.
• Men lacking status and resources may have difficulty attracting women, as evidence from historical data suggests that wealthier and high-status men tend to marry younger brides.
• Kings, emperors, and men of high status historically married younger brides, while men lacking wealth and lower-status counterparts married older brides.
• The contextual influences on men's mating behavior highlight the discrepancy between modern environments and ancestral environments in which human mating strategies likely evolved.

Evolutionary Psychology of Mate Preferences

• As people's mating budgets increase, they spend more on "luxuries" like kindness, creativity, and liveliness, with kindness and intelligence being close to necessities.
• Low, medium, and high budgets likely parallel individual differences in mate value, with lower mate value individuals focusing on necessary mating traits, and higher mate value individuals being choosier.
• Men's long-term mate preferences impact their behavior in personal ads, responses to personal ads, actual marriages, vocal patterns, tips in restaurants, money spent on engagement rings, and intrasexual competition.
• Men respond more to women's personal ads than vice versa, with younger women receiving more responses, and mentioning physical attractiveness generating more responses for women than for men.
• Actual marriage decisions confirm men's preference for increasingly younger women as they age, with American grooms being 3 years older at first marriage, 5 years at second, and 8 years at third marriage.
• Men's preference for younger women is a global trend, with men marrying women 10.6 years younger in 1800s Sweden, and average age differences of 3 years in Poland to 5 years in Greece.
• In polygynous cultures, the age difference between brides and grooms is even larger, with high-status men marrying women two decades younger.
• Men who marry younger women tend to have greater reproductive output, with a study showing that men married to women 6 years younger had an average of 2.3 children, while those married to women 6 years older had 1.7 children.
• Physically attractive women, historically, had higher fertility rates, with modern birth control potentially severing the link between female beauty and reproductive output.
• Men's evolved mate preferences for young and attractive women continue to be activated and acted upon in modern environments, regardless of their current reproductive outcomes.
• The data presented in the text supports the idea that men's long-term mate preferences heavily influence their mating behavior and decisions.
• The text provides evidence that men's preference for younger women is a global phenomenon with significant impact on reproductive outcomes.