The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology Volume 2: Male Sexual Adaptations (2022) is the second entry in a four-part academic series on sexual psychology. This volume offers an in-depth overview of male sexual strategies and adaptations through the lens of evolutionary psychology, exploring both well-established findings and emerging theories.

FULL SUMMARY

About the Author:
Various experts for each chatper, while the volume is edited by Todd K. Shackelford, a leading evolutionary psychologist and active handbook editor.

Chapter 1: Men’s Sexual Preferences

Authors: Daniel J. Miller and Ryan C. Anderson

Despite considerable overlap between men and women, there are also important differences.

Physical attractiveness dominates men’s mate selection criteria, and higher interest for casual sex and sexual variety aligns with men’s lower minimum parental investment compared to women.

Female Youth and Fertility

By responding to indicators of youth, men indirectly increase the likelihood of selecting mates who are biologically more fertile.

These cues can be physical, such as facial features and body characteristics, or behavioral, reflecting energy and vitality:

• Small nose and feet (Barber, 1995)
• Hairless skin (Barber, 1995)
• Full lips
• Lustrous hair
• Good muscle tone
• Physical enthusiasm high activity levle, and spiritely gait (Buss & Barnes, 1986)

Will You Have Sex With a Stranger? Experiments

Across varying experimental designs, men show a higher willingness than women to accept casual sex offers.

The difference can be explained by men’s stronger evolved mating strategies for short-term, but women’s lower acceptance rates are also partly explained by perceived danger, moral considerations, and the need to know the partner better.

Main studies

• Clark & Hatfield (1989) a Florida university campus proposed 3 options: date, go to the apartment, have sex.
  Findings:
  • Date: ~50% of men and women agreed.
  • Apartment: 6% of women, ~67% of men agreed.
  • Sex: 0% of women, ~75% of men agreed.
• Hald & Høgh-Olesen (2010): Replication in sexually liberal Denmark.
  Findings:
  • Date: 30% of men, 20% of women.
  • Apartment: 22% of men, 8% of women.
  • Sex: 38% of men, 2% of women.
  • Among singles: 59% of men, 0% of women agreed to sex.
  • Women’s consent more linked to requester attractiveness; men’s consent largely unaffected.
• Guéguen (2011) Field study in France with confederates of average and high attractiveness.
  • Average attractiveness: 60% of men, 0% of women agreed to sex.
  • High attractiveness: 83% of men, 3% of women agreed.
• Schützwohl et al. (2009) Hypothetical scenario study in Italy, US, and Germany.
  Findings:
  • Sex: 45.8% men, 4.2% women.
  • Men more likely to accept from moderately or very attractive women.
  • Women’s acceptance strongly tied to requester attractiveness.
  • Cultural variation for men: Italy (61%) > US (43%) > Germany (29%).
• Shackelford et al. (2004) Hypothetical one-night stand scenarios with partner relationship status varied.
  • Men less likely to pursue if partner is in a relationship, but still more willing than women in all cases.
  • Suggests evolved preference to avoid sperm competition.
• Tappé et al. (2013) Pencil-and-paper replication in Hawaii using photos of attractive individuals.
  Findings:
  • Men consistently more willing to accept sex request.
  • Women cited “don’t know person/need to know better” most often, followed by “immoral,” then “danger.”
  • Danger cited by 17 women vs. 5 men.

Key concepts:

• Error management theory: Male psychology evolved to minimize the costliest reproductive errors—missing a mating opportunity or raising another man’s offspring.
• Sexual overperception bias: A tendency for men to overestimate women’s sexual interest as a byproduct of error management.

• Priority of physical attributes: Men gravitate toward cues tied to estrogen levels and reproductive potential (Singh, 1993; Jasieńska et al., 2004) like WHR around 0.70, full lips, and symmetrical breasts
• Casual Sex Preference: Men’s permissiveness toward casual sex outpaces women’s, with meta-analyses showing a moderate gender gap (d = 0.45) (Petersen & Hyde, 2010).
• Higher desire for many partners: Across cultures, men desire and report more sexual partners than women. The authors explain how the gap originates, including possible biases of over-reporting for men and under-reporting for women
• Transactional Sex: Men are far more likely to pay for sex (16.7% in Australia vs. 0.3% for women) (Richters et al., 2014).

Interesting Notes

• Men like partners who often change appearances (Hughes, Aung, Harrison, LaFayette, and Gallup, 2021), probably because of men’s preference for novel partners
• Men’s MILF porn explained with men relaxing standards for short term. 🙋🏼‍♂️ Lucio’s note: not a valid explanation, since one should always prioritize the most valuable/fertile partner, even in short term. Instead, I believe that the MILF is attractive for proven fertility, less likely to require extra investment, and for unrelated potentially maladaptive pursuit of better sex through disinhibition/experience and male drive to experiment

Chapter 2: Men’s Extra-Pair Sexual Interest

Authors: Adam C. Davis, Steven Arnocky, Megan Mackinnon, and Larissa McKelvie

Davis and colleagues argue that extra-pair sexual interest stems from a drive to boost reproductive output by siring more offspring with minimal investment, though it’s a balancing act of opportunities and risks (e.g.: partner abandonment, retaliation, social costs).

Many factors influence the likelihood, intention, and behavior of extra-pair mating, including personality, culture, mate value, dissatisfaction in current relationship, availability of mates, etc.

Key Concepts:

• Reproductive Gains: Extra-pair mating can increase offspring without the burdens of provisioning (Buss & Schmitt, 1993).
• Risk Trade-offs: Costs include partner loss or violence, balancing the potential genetic payoff (Kaighobadi et al., 2009).
• Influencing Factors: Sociosexuality, self-assessed mate value, and low relationship satisfaction predict extra-pair pursuits (Schmitt, 2003).

Interesting Notes:

• Extra-pair mating is a cross-culturally and historically ubiquitous phenomenon (Betzig, 1989; Fisher, 1992; Huber, Linhartova, & Cope, 2004; Marlowe, 2000; Nowak et al., 2014; Scelza et al., 2020; Schmitt, 2004)
• Men more likely to adhere to a mixed dual mating strategy of commitment + cheating (Buss & Schmitt, 2019; Nowak et al., 2014): men were more likely to conceal their relationship status from a hypothetical extrapair sexual mate, whereas women were more likely to reveal it (Hughes and Harrison, 2019)
• Men cheat more out of opportunity (32.1%), women because they were unhappy (53%) and made to feel attractive by the extra-pair partner (41%) (Brand et al., 2007)
• The most consistent predictor of infidelity is past infidelity: Feldman and Cauffman (1999) found that 80 percent of college-age men that cheated once went on to do so again. Knopp et al. (2017) found that 45 percent of those who had previously engaged in sexual infidelity would do so in the next relationship
• More unrestricted men are more likely to cheat, and low agreeableness and conscientiousness and high extroversion predicted infidelity
• Mate value and infidelity don’t present a clear picture, with mixed results, but…
  • Believing to be higher mate value than one’s partner predicted infidelity intentions
  • Attractive partners decreased men’s intentions of infidelity, possibly suggesting their fear of jeopardizing the relationship
  • High mate value individuals are more indignant and less insecure in case of partner infidelity
• More opportunities = more cheating: Men primed with women’s abundance increased their intention to cheat and embraced more unrestricted sociosexuality
• There is cultural variance for dispositions towards infidelity. When infidelity is more common, people are less harsh about. But…
  • Globally women are judged more harshly for infidelity

Also see:

• Why people cheat

🙋🏼‍♂️ 📩 Lucio’s Suggestions

Great work, just a suggestion: change the description of Tinder, it seems to suggest it’s dedicated to extra-pair sex, but it’s not

Chapter 3: Male Sexual Attraction Tactics

Authors: Mitch Brown, Kaitlyn Boykin, Kelsey M. Drea, Alicia L. Macchione, Mary M. Medlin, and Donald F. Sacco

Male signaling, whether perfectly diagnostic of actual mating qualities, evolved to outcompete at least some other men for at least some access to viable women. In this market, men seek to “sell” themselves, and their genes, to women. Women then act as “buyers”

Brown and his team explore men’s tactics to captivate potential mates and signal genetic quality, status, or commitment.
Physical feats signal health, resource displays promise provisioning, and interpersonal dominance asserts a competitive edge.

These approaches vary by context, with short-term mating (STM) favoring dominance and long-term mating (LTM) emphasizing reliability, all calibrated to women’s mate preferences.

• Physical Displays: Grooming and muscularity broadcast vitality and strength (Dixson et al., 2011).
• Resource Signaling: Wealth or luxury goods attract mates seeking security (Buss, 1989).
• Dominance: Competitive posturing deters rivals and appeals to women valuing protection (Puts, 2010).
• Humor and Creativity: Wit and artistry signal cognitive fitness, versatile across mating contexts (Miller, 2000).

Interpersonal Dominance

The authors suggest that trait dominance sees the largest upregulation from long-term to short-term.

And the preference for interpersonally dominant men converges with research showing that dominance is predictive of reproductive success, and particularly in short-term mating contexts.

Narcissists also seem to use dominance effectively, displaying as boldness upon first meeting, signaling agency and increasing attractiveness in short-term mating (Campbell & Foster, 2007; Jonason, Lyons, & Blanchard, 2015).
Narcissistic individuals tend to create a charming and impressive first impression when introducing themselves to strangers (Back, Schmukle, & Egloff, 2010). This social boldness mediates the link between men’s narcissism and their mate appeal, with dominant men receiving more contact information from interested women (Dufner, Rauthmann, Czarna, & Denissen, 2013). Such appeal is largely specific to short-term mating and is driven by assertive self-enhancement rather than antagonistic traits like rival derogation (Wurst et al., 2017).

The authors also claim that the social boldness peculiar of extroversion is related to interpersonal dominance and mating success.

If dominant men are more successful, especially in the short term, more promiscuous women are also more interested in dominant men, preferring male facial structures suggesting interpersonal dominance (Brown & Sacco, 2017; Lyons & Blanchard, 2016).

Humor

Humor within mating domains shows a degree of sexual dimorphism, suggesting a role in sexual selection (Greengross, 2014).

Research shows humor plays a bigger role for men than women in dating, with women valuing a man’s ability to make them laugh as part of mate choice (Feingold, 1988; Greengross, Silvia, & Nusbaum, 2020).
Funny men tend to have more short-term mating success (Greengross & Miller, 2011), and the pattern is clear: men produce humor, women evaluate it (Wilbur & Campbell, 2011).

The type of humor matters:

• Benevolent humor is attractive in both short- and long-term contexts
• Biting is more for short-term: sophomoric humor lowers trust (Bressler, Martin, & Balshine, 2006), but women are also more tolerant of aggressive humor in short-term scenarios, likely trading off some risk for signs of dominance and “good genes” (DiDonato, Bedminster, & Machel, 2013).

Men aware of this often lean into dominance-signaling humor in short-term contexts (DiDonato & Jakubiak, 2016).
Sexually explicit jokes appeal more to women with permissive sexual attitudes, helping align with like-minded partners, but they’re disliked by women seeking monogamy and are seen as a turn-off for long-term relationships (Medlin, Brown, & Sacco, 2018).

Interesting Notes:

• Short-term mating is easier for high mate value men: “The potential costs of short-term mating for women would only be worth incurring if a selected short-term partner were especially high in putative good genes traits”
• Women outweigh attractiveness for short-term: “Indicating their minimal threshold of attractiveness for a one-night stand, women’s criterion is substantially higher than for LTM (Kenrick, Groth, Trost, & Sadalla, 1993)”
  • But downregulate it for long term: “When selecting mates for LTM, however, women downregulate this interest in attractiveness, particularly for traits related to masculinization, because of its correlation with infidelity (Booth & Dabbs, 1993)”
• Risk-taking is attractive for short-term, not long term (Sylwester & Pawłowski, 2011)
  • Young men are more prone to physical risk-taking in the presence of attractive women (Ronay & von Hippel, 2010)
• Creativity is attractive: Women at peak fertility report greater interest in creative intelligence. Men primed with both STM and LTM displayed considerably greater creativity (Griskevicius, Cialdini, & Kenrick, 2006)
  • Creativity may be linked with short-term mating strategies: because of creativity’s association with subclinical levels of schizotypal traits that are associated with a disinterest in long-term pair-bonds (Nettle & Clegg, 2006). Highly creative men report greater STM success (Beaussart, Kaufman, & Kaufman, 2012), and it’s not the same for female artists, suggesting that creativity may be sexually selected to facilitate men’s reproductive goals (Clegg, Nettle, & Miell, 2011).
    This also explains why the artist has long been a recognized seducer archetype in pop culture
• Altruistic men are highly attractive as potential long-term mates, altruism suggests greater interest in monogamy and willingness to invest in a family (Barclay, 2010; Brown, Keefer, Sacco, & Brown, in press; Farrelly, 2013).
  Altruistic men also report more sexual partner (Arnocky, Piché, Albert, Ouellette, & Barclay, 2016)
• Beards signal positive dominance for long-term: a full beard augments perceptions of a man’s ability as a father (Dixson & Brooks, 2013) and his desirability in LTM (Dixson, Sulikowski, Gouda-Vossos, Rantala, & Brooks, 2016). The inferred dominance in bearded men could suggest capable protection of offspring (Dixson et al., 2017). Though typically not desirable in LTM, beard may be specific to the paternalism and part of the colloquial “DILFs” (i.e., “Dads I’d like to fuck,” Oswald et al., 2020).

Chapter 4: Men’s Intrasexual Competition

Author: Karlijn Massar

Karlijn Massar dissects the competitive arena of male-male rivalry for mating opportunities.

This chapter frames competition as an evolutionary imperative, intensified by skewed sex ratios and modern platforms like social media.

Competition among men ranges from physical showdowns to strategic put-downs, each method designed to elevate one’s own appeal while diminishing rivals’.
The stakes rise in male-heavy environments, as male-biased sex ratios heighten rivalry intensity (Schacht et al., 2014).

Combative Tactics

Throughout history and across cultures, men competed aggressively with other men to gain status, resources, and access to mates.

This form of competition—intrasexual aggression—is rooted in evolutionary pressures.
Men are generally larger, stronger, and more prone to physical aggression than women (Puts, 2010; Archer, 2004), and archaeological records show male-on-male violence has been common (Walker, 2001).

Even in childhood, boys use rough play to assert dominance and gain peer respect (Pellegrini, 1995).
Popular pupils manipulate and use aggressive behavior publicly to assert their superiority over others (Farmer & Cadwallader, 2000)

Aggression solves several male adaptive problems:

• Defend themselves
• Climb social hierarchies
• Keep mates
• Weaken rivals (Buss & Duntley, 2006)

Male aggression is sensitive to context—men become more physically aggressive when status is threatened or when other men are watching (Griskevicius et al., 2009; Vandello et al., 2008).

This pattern continues into adolescence and adulthood. Young, unmarried men—especially those with little status—are more likely to engage in risky violence, a phenomenon called “young male syndrome” (Wilson & Daly, 1985).
In some premodern societies, killing rivals even increases men’s status and reproductive success (Chagnon, 1988).

Modern parallels include gangs, where the most violent men gain respect and more sexual partners (Palmer & Tilly, 1995; Voisin et al., 2004). Even indirect aggression in teen boys (e.g., social manipulation) predicts greater dating success (Arnocky & Vaillancourt, 2012).

Sport As Ritualized Combat

Many cultures developed ritualized forms of male competition, such as stick fighting, wrestling, or team sports.

These allow men to compete safely while showcasing strength and skill (Llaurens et al., 2009; Deaner & Smith, 2012).

Modern sports, especially those requiring explosive power (like football or boxing), likely evolved from training for hunting and warfare (Lombardo, 2012). Athletes gain status, resources, and often more sexual partners (Faurie et al., 2004).
Women even find aggressive male athletes more attractive (Brewer & Howarth, 2012).

Men also compete as spectators—they follow sports more closely, care more about outcomes, and use these events to assess others’ strength, loyalty, or potential as allies (Lombardo, 2012; Winegard & Deaner, 2010). Sport fandom may be a modern expression of an evolved male psychology shaped by coalitional conflict.

Areas of Competition

• Formidability: men’s fighting ability and resource holding potential are referred to as formidability.
  It’s relevant interpersonally, but particularly relevant in the context of between- and within-group male contests (e.g., McDonald, Navarrete, & Van Vugt, 2012; Van Vugt, Cremer, & Janssen, 2007). Research established that ancestral men engaged in coalitional aggression with other groups of men.
  🙋🏼‍♂️ For a related suite of psychological adaptations and how they impact society, also see ‘social dominance theory‘
• Social status is a central domain of male competition with one another. Social status refers to one’s position within the relevant social hierarchy. Intrasexual competition among men includes achieving a higher standing and status than rivals
  • Positional bias: outperforming rivals shaped human psychology for ‘positional bias’, with satisfaction contingent to the position of rivals, regardless of achievement in absolute sense (see also Schmitt & Buss, 1996).
    Envy is emotionally linked to higher standing rivals (Hill & Buss, 2006), and brain imaging studies corroborate: downward comparisons activate reward-related areas, whereas upward comparisons activate brain areas that are associated with social pain and envy (e.g., Swencionis & Fiske, 2014; Yaple & Yu, 2020)
• Conspicuous consumption is for short-term: the purchase and flaunting of expensive goods, services, or leisure activities, is linked to short-term mating.
  For example, men who pursue a mating strategy focused on short-term mating opportunities – that is, a low investment strategy – are particularly likely to conspicuously consume. For men with a high-investment strategy, the salience of mating opportunities did not increase their conspicuous consumption.
• Generosity is a mating signal: studies suggest that men engage in (public) displays of generosity to impress possible mates and compete with other men.
• Indirect Competition: Rival derogation and status displays subtly shift mate perceptions (Buss & Dedden, 1990)

Interesting Notes

• Higher polygyny = more male competition: across species, higher degrees of polygyny are associated with more male–male competition and increased male risk-taking (e.g., Plavcan, 2000; Plavcan, Van Schaik, & Kappeler, 1995), sexual dimorphism (e.g., Clutton-Brock, 1985), and increased male mortality rates (e.g., Promislow, Montgomerie, & Martin, 1992).

• Testosterone is a ‘social hormone’: testosterone is considered to be a “social hormone” (Eisenegger, Haushofer, & Fehr, 2011) and it is implicated in a range of male behaviors: aggression, dominance, competition, courtship and sexual behavior, and partnerships and paternal care (for a recent review see Gray, Straftis, Bird, McHale, & Zilioli, 2019).
  • Testosterone levels are influenced by paternal involvement in child rearing

Chapter 5: Competitiveness and Fatherhood as Overarching Domains of Female Choice

Author: Gregory Gorelik

Gregory Gorelik says we can’t be sure whether traits and behaviors were selected by intrasexual competition or mate choice.

But he claims that competition was the main driver of human sexual selection, citing several findings in support, including interpersonal dominance outweighing attractiveness (Hill et al., 2013).

🙋‍♂️Lucio’s Take: I’m not fully convinced this holds true in modernity

Lucio:
Although the author addresses the claim that in modern contexts intrasexual competition may matter less, in my opinion he didn’t address some important changes that favor women’s selection: women’s empowerment, more strangers-to-strangers meetings, online dating, and cold approach.

Such as, smart men may approach women invidivually, and as strangers, outside of social hierarchies. In these contexts, mate choice matters more.
Especially as women’s empowerment and safer societies also make them less needy of dominant men’s protection.

For example, I was fortunate to have dated attractive women while I was still a nobody at work or in society—but my status wasn’t salient when I met them.
That wouldn’t have worked back in the days, but it did today.

In brief, I agree that competitiveness, competition, and success and life success matter a lot.
But one, it’s not easy to disentangle it from female choice. And two, the competition isn’t necessarily against nearby men, or based on aggression and intimidation.

Men’s Dual Mating Strategies Mirrors Women’s: Madonna/Whore Complex

It only occurred to me, thanks to the author, that both men and women have specular ‘dual strategies’.

Women have ‘dominant for short term’, and ‘kind provider’ for long-term, while men have ‘easy for short-term’, and ‘pious for long-term’.

He writes:

Although many questions in this area of investigation are not yet settled, and despite its share of methodological hurdles, the picture that is emerging is that women employ a dual mating strategy marked by a preference for (a) dominant and physically attractive men on the one hand and (b) committed providers and carers who are invested in them and their offspring on the other

And later:

Men may likewise employ a dual mating strategy, perhaps regulated by changes in testosterone, by shifting between competition for access to mating opportunities and direct paternal care within the context of a pair-bond.

I believe this dovetails perfectly with what at the maladaptive extremes becomes the Madonna-whore complex.
But it’s more adaptive when it’s more of an idealized, even simplistic dichotomy of ‘marry and commit to the pious woman, and seek sex on the side with unrestricted ones’.

Read more in:

• Lovers vs providers

Chapter 6: Sexual Coercion and Rape

Authors: Andrew M. Holub and Gavin Vance

Holub and Vance tackle the grim topic of sexual coercion and rape.

The adaptation hypothesis suggests rape evolved as a bypass to female choice in mate-scarce contexts, potentially boosting reproductive success for some men. The byproduct view counters that it stems from broader traits like aggression or sexual desire, not a specific strategy.

Ethical note is important: explaining origins isn’t endorsing, and insights here aim to inform prevention, not excuse perpetration.

• Adaptation Hypothesis vs Byproduct Hypothesis: Rape can be a selected strategy for mating access (Thornhill & Palmer, 2000) or a side effect of aggression and variety-seeking (Symons, 1979).
  Genetic technology can help us answer this question in the future
• Ethical Stance: Evolutionary analysis targets understanding, not justification (Holub & Vance, 2022).
• Rapists are neurologically insensitive to consent: Rapists were more indifferent (in terms of erectile response) to sexual stimuli in which the woman expressed active consent or nonconsent, compared to nonrapists (Harris et al., 2010). Rapist don’t differ from controls consensual stimuli arousal, but show greater sexual arousal to rape than do nonoffenders (Barbaree, Marshall, & Lanthier, 1979; Howes, 1998; Seto & Barbaree, 1993). Diminished inhibition of sexual arousal may be a key difference between rapists and nonrapists (Howes, 1998). Rapists also may be neurologically distinguishable by white matter abnormalities in certain areas of the brain
• Sexual coercion may be at least partially heritable
  • Past rape is one of strongest predictors of future rape
• Anti-cuckoldry tool: men pursuing a long-term sexual strategy are hypothesized to employ a range of behaviors to manage their risk of cuckoldry. Accordingly, several studies have observed that men’s use of sexual coercion is positively associated with their use of other mate retention behaviors.
  Coercion is also correlated with perception of partner infidelity

Chapter 7: Mate Poaching by Men

Authors: T. Joel Wade and Maryanne L. Fisher

Wade and Fisher unravel mate poaching—men luring women from existing relationships—as a calculated evolutionary play.

Poaching leverages superior traits—resources, charm, or looks—to outshine a woman’s current partner, exploiting relationship cracks.
Success depends on many variables, including the poacher’s allure and the target’s dissatisfaction.

• Success Factors: High mate value and partner discontent boost outcomes (Davies et al., 2007).
• Risks vs. Rewards: Gains in mate quality offset potential backlash (Wade & Fisher, 2022).
• Poachers and poachees are less agreeable (i.e., less empathetic, gentle, and generous), less conscientious (i.e., less self-discipline, vigilance, carefulness, and empathy), and higher in dark triad traits, especially psychopathy
• Poached relationships have lower satisfaction, including sexual satisfaction, lower commitment, and lower trust

Chapter 8: Sexual Fantasy

Authors: Mariana A. Saramago and Ricardo Ventura Baúto

Men fantasize more often and explicitly than women, emphasizing variety and visual cues over emotional depth—hallmarks of male psychology.

Lehmiller’s (2018) survey of 4,175 adults found that the most common fantasies related to intimate/ romantic themes and, in order, were: “multipartner sex”; “power, control, and rough sex”; “novelty, adventure and variety”; “taboo and forbidden sex”; “swinging, partner sharing, and polyamory”; “intimacy, romance, and passion”; and, lastly, fantasies about “homoeroticism and gender-bending.”

Gender Differences

Men and women are more similar than different in their fantasies, interests, and experiences, and these differences have decreased over time.

However, some patterns persist:

• Men tend to have greater diversity in fantasies and are more aroused by external stimuli, multiple partners, and sexual novelty.
• Women more often prioritize mate quality and long-term benefits, reflecting evolutionary strategies.

Evolutionary theories suggest that these differences arise from sexually dimorphic brain and mind mechanisms, with men generally more inclined toward short-term mating and women toward long-term provisioning and protection.

Specific male-leaning fantasy trends include:

• Voyeurism and frotteurism
• Dominance and power-themed fantasies
• Multipartner scenarios (threesomes, orgies, sex with strangers, polyamory)

These patterns align with evolutionary explanations that men’s sexual psychology evolved to maximize reproductive opportunities, while women’s evolved to prioritize high-quality, resource-capable partners.

Most common ‘deviant’ fantasies

Paraphilic interests—like voyeurism, exhibitionism, or sadomasochism—are often labeled “deviant,” but research shows they are relatively common in the general population.

For example, Joyal & Carpentier (2017) found that 45.6% of participants reported paraphilic desires, and 33.9% had acted on them at least once. Paraphilic fantasies also significantly predict actual behavior (Williams et al., 2009).
In order:

• Voyeurism: 34.9–83%
• Frotteurism: 13.4–72%
• Sadism: 21.8–62%
• Fetishism: 30–44.5%
• Exhibitionism: 30.6–39%
• Masochism: 15.8–23.8%
• Transvestism: 10%
• Pedophilia: 4.1–13%

• Emotionally charged events can impact the development of sexual interests, Lehmiller (2018) further noted that those who reported fetish fantasies explained that the association between the object and the pleasure was learned when they had a very intense orgasm with the object present and from then on found this fetish to be arousing 🙋🏼‍♂️ Lucio’s note: but I have to wonder if the fetish was already present and was the source of the ‘intense orgasm’. Also, as a man, most orgasms feel pretty much the same, so I must wonder

Personality differences

Personality correlates with sexual fantasies, with psychopathy as the strongest predictor of deviant fantasies.
Importantly, criminal offenders had much higher rates of deviant fantasies (12–56.5% vs. 9.1% in controls).

Paraphilic fantasies are also higher among sexual offenders compared other types of crimes (Curnoe & Langevin, 2002; Langevin et al., 1998).

• Neuroticism:
  • Higher overall fantasy frequency (egosyntonic and egodystonic)
  • Submission fantasies
  • Frotteurism and bondage fantasies
• Openness to experience:
  • Higher overall fantasy frequency
  • Frotteurism and pedophilia fantasies
• Extraversion:
  • Transvestism fantasies
• Narcissism:
  • Sadism fantasies
  • More intimate fantasies
• Psychopathy:
  • Bondage and sadism fantasies
  • Strongest predictor of exploratory, impersonal, and sadomasochistic fantasies
  • Interpersonal facet → voyeuristic and exhibitionist interests
  • Affective facet → pedophilic interests
• Self-destructive / high affective personality types:
  • Report more sexual fantasies than self-actualizing / low affective types
• Obsessiveness:
  • Positively predicts overall fantasy frequency

🙋🏼‍♂️ Lucio’s suggestion: would have been great to get the strength of correlation for these studies

Chapter 9: Ejaculation Latency

Authors: Rosa Angélica Lucio, Alonso Fernández-Guasti, and Maria Reyna Fuentes-Morales

Lucio and her team dissect ejaculation latency, particularly the widespread premature ejaculation, as an evolutionary puzzle tied to reproductive efficiency.

They argue that rapid ejaculation may have been favored in high-competition settings.
Short latency could optimize quick insemination amid rival males or fleeting opportunities, enhancing sperm competition odds.

🙋🏼‍♂️ Lucio’s note: while it’s an interesting interpretation and may ultimately be valid, I’m skeptical.
While it may in some cases be adaptive, it’s also maladaptive for seduction and partner retention, which have historically been more important for men’s reproduction.

Chapter 10: Copulatory Thrusting in Males

Authors: Anders Ågmo and Gabriela Moralí

Thrusting enhances fertilization with better sperm positioning and may dislodge competitors’ sperm.

🙋🏼‍♂️ Lucio’s note: While all explanations are plausible and possible, I remain skeptical about the degree to which trust directly contributed to reproductive success. I recommend caution in assigning definitive evolutionary causes.

Chapter 11: Men’s Provisioning of Oral Sex

Author: Gavin Vance

Gavin Vance examines why men perform oral sex on women, first wondering if it’s a byproduct or an adaptation.

Beyond pleasure, it signals commitment, boosts partner satisfactio,n and retains mates, and possibly detects rival sperm.

Cultural norms shape its practice though, as it seems more frequent among caucasians and Westerners.

Chapter 12: Inducing Female Orgasm

Author: Tara DeLecce

Tara DeLecce investigates men’s pursuit of female orgasm, linking it to evolutionary goals like paternity assurance and mate retention.
Men’s efforts aren’t necessarily altruistic—they’re strategic, enhancing bonds and reproductive odds. It’s a deep dive into how male behavior adapts to female physiology.

Variability in women’s responses means that it acts as an indicator of mate quality.
It seems to me that these mate qualities can also be divided into short-term/attractive and long-term/investing.
Indeed says the author:

It could be that male performance of foreplay is another form of investment that signals willingness to invest in a woman, which is important for long-term relationships, and this supports the pair-bond hypothesis for female orgasm.

Men’s effort for female orgasm, categorized by short and long term by Lucio Buffalmano

Takeaways

• Paternity Boost: Orgasm may favor sperm uptake (Baker & Bellis, 1993).
• Mate Retention: Pleasure strengthens pair-bonds (Shackelford et al., 2005).
• Signaling Skill: Success reflects mate quality (DeLecce, 2022).
• Attachment styles moderate men’s interest for her orgasms, with anxious men reporting greater interest than secure men, and avoidant men report less interest
• Orgasm is unrelated to reproductive success: In one study of over 8,000 women, there was no significant correlation between rates of orgasm and number of children conceived (Zietsch & Santtila, 2013)

Chapter 13: Copulatory Urgency

Authors: Arial Bloshinsky and Valerie G. Starratt

Bloshinsky and Starratt define copulatory urgency as an intense motivation to pursue sex with a sense of immediacy, insistence, and persistence.

Urgency increases with fertile females or rival threats, pushing men to act fast and secure copulation. It’s a flexible trait, varying by personality and context, but can lead to impulsivity—like pornography binges—when unchecked.

• Triggers: Fertile cues or competition spark urgency (Goetz et al., 2005).
• Adaptive Value: Quick mating maximizes fitness in uncertain contexts (Buss & Schmitt, 1993).
• Variability: Hormones and traits shape intensity (Bloshinsky & Starratt, 2022).

Chapter 14: Postejaculatory Adaptations to Self-Semen Displacement

Authors: Gordon G. Gallup, Jr., and Steven M. Platek

Gallup and Platek explore postejaculatory behaviors—like continued thrusting—as evolved tactics to ensure paternity.

Postejaculatory thrusting may scoop out competitors’ sperm, a mechanism tied to penis morphology and timing precision. Psychological drivers like jealousy fuel these actions, integrating with mate guarding to protect genetic investment.

• Semen Displacement: Thrusting removes rival sperm (Gallup et al., 2003).
• Timing: Men suspecting infidelity seek sex ASAP, while women who believe the extra-pair partner is of higher value should actively avoid sex with their partner
• Psychology: Competition cues trigger adaptive responses (Shackelford et al., 2002).
• Male jealousy accounts for most violence (e.g., spouse and child abuse), more than social class, poverty, alcohol, or drug addiction combined (Burch and Gallup 2019).

Female Hypergamy & Bruce Effect

The Bruce effect—a phenomenon where a recently impregnated female mouse spontaneously aborts after exposure to a new higher quality male, is an adaptation of female hypergamy—the drive to seek and potentially switch to higher-quality mates.

The authors suggest that certain non-phase menstruation (bleeding outside the expected menstrual window) at the start of a new sexual relationship might be a human analog to the Bruce effect.
This bleeding could either:

• signal the termination of a prior pregnancy from a lower-quality mate, or
• serve as a signal to new partners that the woman is not currently pregnant—possibly reducing the chance of male cuckoldry.

From the male perspective, the chapter suggests that men might have evolved to detect unusual menstruation timing in their partners. If detected, this could lead to increased mate guarding behaviors and more vigorous sexual activity, aimed at reducing the risk of losing paternity to another man.

🙋‍♂️Lucio’s Take: Bruce effect needs a stronger frame of speculative theorizing

Lucio:
I was surprised to see the Bruce effect presented as applying to humans.

As expected, the theory is highly speculative, based on limited empirical evidence and with a likely small real-world effect even if it turns out to be true.

Prefacing it with “There is reason to believe…” overstates the case and, in my view, may undermine the authority of the chapter.
A stronger disclaimer of speculation would be more appropriate.

🙋🏼‍♂️ Lucio’s note: male paternity ‘detection system’ is inaccurately biased for safety

The authors write:

for men with low paternal confidence the incidence of nonpaternity was 30 out of 100 (…) an astonishing 15 times higher than those with high paternal assurance.
(…)
while attributions of nonpaternity are far from being failsafe, these data suggest there are some evolved/hardwired and surprisingly accurate paternity assessment mechanisms

Being wrong 70% of the time doesn’t seem ‘surprisingly accurate’ to me.
Instead, it seems a case of perception bias erring on the side of safety.

Chapter 15: Male Mate Retention

Authors: Bruna S. Nascimento, Katia C. Vione, and Renan P. Monteiro

Nascimento and colleagues first explain the many benefits for men in commitment, and then outline how men guard mates to thwart infidelity and secure paternity.
These strategies, flexible to context, balance benefits like pair-bond stability against costs like effort, resource depletion, or partner alienation when they are value-taking.

Mate retention spans direct guarding—like jealousy-fueled monitoring—to indirect boosts like enhancing appeal or providing gifts. High mate value or infidelity risks dial up intensity, while harsh tactics risk backfiring.

• Investing men obtain higher quality mates because women value investment in long-term relationships, which are typically more advantageous for women in comparison to short-term relationships (Buss & Schmitt, 1993)
• Cuckolding undermines social social and interpersonal respect, on top of jeopardizing paternity
• Direct Guarding: Vigilance and control deter rivals (Buss, 1988).
• It’s a strategic dance of controlling, while still retaining a mate.
• Indirect Guarding: Gifts and charm reinforce bonds (Shackelford et al., 2005).
• Anxiously attached men work harder to retain their mates (Barbaro et al. 2019)
• Costly Tactics: Threats can destabilize relationships (Nascimento et al., 2022).
  • Men use more submission tactics than women (Buss & Shackelford, 1997; Kardum, Knežević, & Gračanin, 2006), in what I suspect are cases of emotional manipulation like guilt tripping

Chapter 16: Shifts in Partner Attractiveness: Evolutionary and Social Factors

Authors: Rebecca L. Burch, Maryanne L. Fisher, James B. Moran, Catherine A. Salmon, T. Joel Wade, and David R. Widman

Burch and her team analyze why partner attractiveness waxes and wanes, blending evolutionary cues like fertility with social dynamics like familiarity.
Evolutionary factors tie attractiveness to reproductive status: fertile phases heighten appeal, menopause dims it.

Interesting Notes

• The importance of physical attractiveness decreases with growing familiarity (Hunt, Eastwick, & Finkel, 2015)
• Female youth is most appealing for long-term mating (Buss, 1999)
• Men find ‘nipple erections’ sexy (Burch and Widman, 2021)
• Inducing jealousy may increase attraction: but it’s not been empirically verified yet

Chapter 17: Emotional Commitment in Men

Author: Elizabeth G. Pillsworth

Elizabeth Pillsworth analyzes emotional commitment as an evolved male trait fostering pair-bonds and paternal care, critical for human offspring survival. It’s not just sentiment—it’s strategy, cementing relationships and boosting fitness.

Commitment increases resources and protection for vulnerable young, a hallmark of human biparenting. Attachment styles and satisfaction modulate the strength of pair bonding.

Interesting Notes

• Reproductive success is the goal, not relationship strength: commitment or relationship stability aren’t the purpose or desired outcome, and there is no ‘ideal’ approach to a relationship. Each attachment style, commitment level, and relationship orientation represents a strategy that promotes the greatest reproductive success in a particular context
• Men’s infidelity is less predictive of relationship dissolution than is women’s infidelity (Betzig, 1989), suggesting that sexual infidelity and relationship commitment are not mutually exclusive, particularly among men

Chapter 18: Sexual Jealousy in Males

Author: Tsukasa Kato

Tsukasa Kato argues that sexual jealousy is a tailored male adaptation to guard against cuckoldry, distinct from emotional jealousy.

He delves deep into intercultural studies and finds that the Buss’ original findings that men are more concerned about sexual infidelity and women more by emotional infidelity is more nuanced.
He summarizes the findings in this way:

Following Sagarin’s criterion, the studies using a forced-choice measure found that the (evolutionary jealousy mechanism) EJM hypothesis was corroborated overall.
As claimed by Buss, the sex difference in jealousy was robust and replicable (…) although the effect size was small.

However, the studies using continuous measures presented mixed results.
In contrast, when following Harris’ criterion, the EJM hypothesis was not holistically corroborated by either forced-choice or continuous measures.
(…)
Following Sagarin’s criterion, the studies using a forced-choice measure found that the EJM hypothesis was corroborated overall.
As claimed by Buss, the sex difference in jealousy was robust and replicable, excluding a few samples, such as homosexuals, although the effect size was small.
However, the studies using continuous measures presented mixed results. In contrast, when following Harris’ criterion, the EJM hypothesis was not holistically corroborated by either forced-choice or continuous measures.
(…)

He also adds though that we cannot deny the viability of the EJM based on low effect sizes, but that sociocultural factors and relationship type matter.

Chapter 19: Men’s Attachment-Related Needs in the Sexual Arena

Author: Moran Mizrahi

Moran Mizrahi uses attachment theory to decode how men’s emotional styles shape their sexual lives.

Secure men thrive in committed relationships, anxious ones chase reassurance through frequency, and avoidant ones favor detachment. These patterns, forged in childhood, steer mating strategies—long-term for some, short-term for others—revealing how attachment links to mating strategies and relationship dynamics.

Chapter 20: Paternal Care

Author: Ryan Schacht

Ryan Schacht traces paternal care’s evolutionary arc, explaining why men invest in offspring and how this varies globally.
Paternal care is a fitness booster, enhancing child survival, yet flexible to ecology and culture.

Paternal care—rare among mammals—is particularly useful in humans because of children’s prolonged dependency.

Interesting Notes

• Poverty, low paternity certainty, and polygyny lead to absent fathers: Among Afro-Caribbean households in St. Kitts, offspring investment often comes from extended female kinship networks because men are typically peripheral to family structure due to limited male economic opportunities and lower paternity certainty (reviewed in Gray & Brown, 2015). When men can find new wives, they also look outside the household to invest their resources in new women <— 🙋🏼‍♂️ Bright observation, I had never thought that to increase paternal care one should also ensure a minimum income, paternal certainty, and encourage monogamy

🙋🏼‍♂️ Lucio’s note: paternal investment is expected IF it increases fitness
The author states that paternal investment is expected to evolve if it aids in offspring survival or quality once pair-bonding evolves and paternity certainty is high (Clutton-Brock, 1991; Dunbar, 1976; Perrone & Zaret, 1979; Thornhill, 1976; Westneat & Sherman, 1993). While these elements are indeed crucial milestones, the ultimate driver of evolutionary outcomes remains inclusive fitness. There may be a species where women are more than enough to ensure offspring well being, and hence men still have no benefit in investing.

Chapter 21: Paternal Filicide

Author: Vibeke Ottesen

Vibeke Ottesen confronts the dark paradox of paternal filicide—fathers killing their own—framing it as an extreme response to reproductive conflict and perceived threats like doubted paternity or resource drain.

Filicide emerges when investment in a child clashes with a father’s reproductive interests, a calculus from ancestral scarcity.
Mental health crises or step-parenthood amplify risks.

• Reproductive Conflict: Killing reflects investment trade-offs (Daly & Wilson, 1988).
• Risk Factors: Psychopathology and step-parenting heighten likelihood (Ottesen, 2016).
• Cultural Mitigation: Legal and social shifts curb incidence (Durrant, 1999).

How Northern Europe Tackled The ‘Stepfather Issue’

The Nordic countries reduced stepparental violence by structurally removing the reproductive conflicts that typically arise in stepfather–child relationships.

Indeed, say the authors, the mere lack of genetic relatedness is not determined to motivate men to perform lethal behaviors toward children.
It’s the extra costs of the stepchildren that fuel harm-inflicting strategies.

Key strategies include:

• Shared custody and legal child support obligations ensure that biological fathers retain primary parental duties after separation, relieving stepfathers of those burdens.
• This removal of stepfathers’ investment pressure minimizes the evolutionary incentives for harmful behavior by stepfathers.
• Strict laws banning physical punishment of children, combined with cultural norms against violence, further reduce the behavioral outlets for such conflicts.

As a result, while stepfathers remain overrepresented among rare filicide cases, the overall rates of child abuse and filicide are very low.
Most remaining cases of paternal filicide in these countries are now linked to severe psychopathology, not reproductive conflict.

🙋🏼‍♂️ SHARPEST INSIGHTS

These are the insights that struck us the most.
We use the authors’ quotes and research, but the titles and interpretations are our own—and may not reflect the authors’ intent.
Credit for the insight goes to them; blame for the interpretation is on us.

Lower mate value men should leverage money

Contrary to misguided advice in some male development circles, lower value men should leverage resources to maximize their mating strategies and attract higher quality partners.
From chapter 3:

This desirability of provisioning becomes an especially important attraction strategy for unattractive men because of the reprioritization of resource access over attractiveness in selecting mates, with men demonstrating greater beneficence toward women as a compensatory strategy for their own lack of attractiveness (Buss & Greiling, 1999; Takahashi, Yamagishi, Tanida, Kiyonari, & Kanazawa, 2006).

This also recalls, and confirms, a popular maxim on ‘alphas vs betas’ mating strategies.

Lower-value men are more likely to be abusive

Quoting Nascimento from chapter 15:

Men with higher mate value are more likely to be able to provide the partner with benefits such as good genes, resources, and protection as opposed to men with lower mate value (Miner, Starratt, & Shackelford, 2009).

Men with lower mate value are more likely to perform higher risk, cost-inflicting mate retention, because, unlike men with higher mate value, they may lack the resources to perform benefit-provisioning strategies.
Indeed, Miner et al. (2009) suggested that men’s mate value is a better predictor of men’s mate retention than their partner’s mate value

And:

Mate retention strategies may be grounded in feelings of insecurity and, as such, activated by cues of real or perceived infidelity (Campbell & Ellis, 2015). As the risk of infidelity increases, men also experience more jealousy and allocate more effort to mate retention.

Of course, the answer for committed men is not to pretend all is OK when they doubt their spouses’ infidelity or when someone is hitting on them.
The answer is to be smart and strategic about it so to not appear low value.

Lower status men are better daddies (not because they’re ‘nice’)

Quoting Schacht:

However, how much each individual father invests is flexible and depends on his social status with the group. Poorer, lower status Aka fathers spend more time with their children and provide more childcare than do wealthier, higher status fathers (Hewlett, 1988)

I suspect this is not because they’re ‘nicer’, but a combination of having fewer extra-pair mating options, fewer chances of siring other offpsring (and hence focus on the ones home), less fulfilling lives outside of home, and becaue they’re expected to contribute more with the unwritten deal ‘provisioning in exchange for intimacy’.

Indeed, little later writes the author:

Additionally, where men can marry polygynously (i.e., have more than one wife), excess resources are often targeted toward attempts to gain additional wives rather than additional investments in improving offspring quality (Hedges, Mulder, James, & Lawson, 2016).

QUOTES

The bottom line logic of evolution:

Reproductive success is the ultimate currency in the economy of natural selection” (Frank Marlowe, 2004)

On cold evolutionary investment logic:

paternal investment in a genetically unrelated child is more or less a waste, in strict evolutionary terms. Even worse than a waste, investing paternal care in a stepchild would be aiding the transmission of another man’s genes (i.e., an evolutionary competitor) to the next generation

🙋🏼‍♂️ Lucio’s Analysis

Still unconvinced by semen displacement theory (Chapter 14)

In previous volumes and handbooks I raised my concerns around the semen displacement hypothesis.

I’m glad Gallup and Platek address some of them, and I will respond to their points:

Another common objection to the semen displacement hypothesis concerns the incidence of female infidelity. How often does the frequency of double mating produce instances in which viable sperm from two or more males coexist in a woman’s vagina?
(…)
While it is true that sperm can live in a woman’s reproductive tract for several days, a generous estimate of the amount of time that would be available to displace viable rival male semen from a female’s vagina would be plus or minus twelve hours (Gallup, Finn, & Sammis, 2009)

The authors then note that several women have had sex with different partners within 24 hours.

However, this still does not fully account for biology.
The first hours after insemination are when sperm competition is most intense, and each passing hour reduces the likelihood of effective displacement.
Back-to-back encounters, which would be the most effective, are also likely the rarest.

Most importantly, sexual activity in the cited studies does not equal reproduction.
The study surveyed American college students—an environment dominated by hookup culture—where nearly none of these encounters were aimed at conception.

This context is therefore a poor proxy for ancestral conditions.

Overall, these factors suggest that the evolutionary relevance of semen displacement remains, in my opinion, more marginal than semen competition theories may lead to believe.

The ‘Sperm piggybacking hypothesis’ is too speculative (chapter 14)

Even as an hypothesis, leaving this section as it is risks undermining the book’s authority.
Here’s one passage:

Put another way, if your partner is not circumcised you may be at risk of having sex with the men who had sex with your partner’s previous partner. <— ???
This idea inspired a novel by Robin Baker (2013) who is one of the prime movers behind the concept of sperm competition.
As implied by the title of his book, the sperm of one man may “hitchhike” under the foreskin of another man and lead to fertilization by proxy (see Figure 14.11)

It ‘might’, of course, but how likely and impactful is this be on an handbook of adaptations?

Even if it’s ‘proven’ to have happened a number of times, which over millions of years it probably did, what impact would it have on evolution?

I don’t see how this could be an adaptation.
And even to be a process with any evolutionary effect, you’d have to believe it was common for men to impregnate women with another man’s sperm lodged under their foreskin.

For many reasons, including basic biological constraints on sperm survival, I find that extremely unlikely. And no evidence or logic was provided to suggest otherwise.

At the mention of Baker’s novel though I had my own hypothesis: some of the most out there speculations on sperm competition may be driven less by logic and more by paraphilic fascination.

Suggestion: remove the novel’s book cover, add a clear claim of speculation, or reduce/remove the sub-chapter entirely. May note that modern sperm competition includes sperm banks and donations.

Suggestion: change the frame of ‘solving problems’

Referring to strategies and adaptations as solutions to “ancestral problems” is standard in the literature.

However, the phrase is not always logically precise.
You only solve a problem when you’re facing a specific, well-defined challenge.

But evolutionary changes often arise not from solving discrete problems, but from seizing novel opportunities.

Take for example this quote:

“Physical aggression solves several adaptive problems.”

Besides sounding morally off with the ‘solving problem’ frame, it would be more correct to say that physical aggression created opportunities for those who could use it with lower costs relative to the benefits.

But I’m aware of being on the anal retentive side on this :).

REVIEW

The Cambridge Handbook on Sexual Psychology Volume 2: Male Sexual Adaptations is a comprehensive, high-quality resource for understanding evolutionary logic in mating, particularly when it comes to male sexual psychology and adaptations.

If I were to offer some suggestions, it’s that a few chapters lean a bit too heavily on more speculative theories. Flagging those more clearly—or trimming them—would help.
Also, while some comparisons with female adaptations are useful, I’d encourage the editors to focus more tightly (if not entirely) on male-specific dynamics. That would make the four-volume series even tighter and on-topic, also helping with future information retrieval (e.g.: do I need to revisit a male adaptation? I’m sure it’s going to be on volume 2, and not anywhere else).

On the plus side? Pretty much everything else.
I especially appreciated the editors’ decision to avoid over-focusing on individual studies. That approach gives us readers the broad literature overview we’re really after—and the one that’s most useful. (That said, it might help to briefly note the statistical power of key studies and, more importantly, the overall strength of empirical support for the different theories).

Overall, this book gave me several new insights and directly helped me improve multiple articles on this website—which is the highest compliment I can give any handbook.

Big thanks to the editors and all contributors. I’m grateful for the work you’ve done and look forward to what’s next.

Check:

• First volume, overview; volume 2, female adaptations
• Best evolutionary psychology books
• Get this book on Amazon