Paul L Vasey

Paul L Vasey
University of Lethbridge · Department of Psychology

Ph.D.

About

177
Publications
143,158
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Introduction
Paul Vasey is a Professor and Board of Governors Research Chair in the Department of Psychology at the University of Lethbridge. He conducts cross-species research on Japanese macaques and cross-cultural research in Canada, Japan, Mexico, and Samoa to answer the question: If reproduction is the engine that drives evolution, why engage in non-conceptive sex?

Publications

Publications (177)
Article
We analysed heterosexual consortships in a free-ranging group of Japanese macaques in which adult females routinely perform female-to-male mounting (FMM). We tested whether FMM is more efficient (i.e., a ‘supernormal courtship’ behavioural pattern) than species-typical female-to-male sexual solicitations (FMSS) at prompting subsequent male-to-femal...
Article
Previous research on Japanese macaques has shown that female-to-male mounting (FMM) is performed by some females as an exaggerated form of sexual solicitation that may occur in the context of high female competition for male mates. This supernormal courtship behavior functions to prompt subsequent male-to-female mounting. In this report, we focused...
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Previous research has demonstrated that women can correctly distinguish between gay and heterosexual men’s faces significantly better than chance. This ability appears to be heightened during the most fertile portion of their ovulatory cycle. Here, we sought to replicate and extend these findings in a large sample of undergraduate women (N = 1960)....
Article
Recent reports on tool use in nonforaging contexts have led researchers to reconsider the proximate drivers of instrumental object manipulation. In this study, we explore the physiological and behavioral correlates of two stone‐directed and seemingly playful actions, the repetitive tapping and rubbing of stones onto the genital and inguinal area, r...
Article
Feminine trans individuals (i.e., individuals who were assigned male at birth but who have a feminine gender presentation and identity) are present in many cultures. In some cultures, these individuals identify as (trans) women. Many of these individuals undergo medical treatments to feminize their bodies (e.g., breast augmentation), but most do no...
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The present study examined women’s mate competition tactics in response to female and feminine-male rivals in two cultures in which competition against both occurs. In Samoa and the Istmo Zapotec (Southern Mexico), women not only compete with other women (intrasexually) but also compete with rival feminine males (intersexually) in order to access/r...
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Male androphilia (i.e., sexual attraction and arousal to adult males) is considered an evolutionary puzzle because it reduces direct reproduction, but is influenced by genetic factors, reliably occurs across cultures, and has persisted over evolutionary time. The kin selection hypothesis states that genes for male androphilia can be maintained in a...
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Representative samples, and especially population samples, are coveted sources of high-quality data in psychological science. In their recent article, Ablaza et al. (2021) used a population sample of marriages and registered partnerships in the Netherlands to examine the relationships between sibling characteristics and sexual orientation. We discu...
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Research has found that both cisgender and transgender androphilic males (i.e., males sexually attracted to and aroused by other adult males) have female-typical occupational preferences when compared with gynephilic males (i.e., males sexually attracted to and aroused by adult females). Moreover, whereas cisgender androphilic males’ occupational p...
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Heterosexual women trust mating-relevant advice received from gay men more than that received from heterosexual women. This trust is predicated on women's perception that gay men lack ulterior sexual motives and romantically pursue other gay men. However, this trust may not hold in all cultures. For example, in both Samoa and the Istmo Zapotec of S...
Article
Research shows that the female relatives of androphilic (i.e., sexually attracted to adult males) males have more children than the female relatives of gynephilic (i.e., sexually attracted to adult females) males. The mechanisms by which this occurs are unclear. The hypergyny hypothesis suggests that the female relatives of androphilic males have e...
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Previous research indicates that Euro-American women are more upset by imagining their male partners committing homosexual infidelities than heterosexual ones. The present studies sought to replicate these findings and extend them to two non-Western cultures wherein masculine men frequently engage in sexual interactions with feminine third-gender m...
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This study investigated the relations between numbers of older brothers, numbers of older sisters, and the odds of homosexuality in later-born males, including males who are most attracted sexually to prepubescent or early pubescent children (pedohebephiles) and males who are most attracted sexually to adults (teleiophiles). The authors meta-analyz...
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In many different cultures, some men express sexual interest in male-to-feminine (MtF) transgender individuals, but others do not. We examined whether, in Samoa, men who are sexually interested in fa’afafine (Samoan MtF transgender individuals) (MSF; N = 40) differed from men who were exclusively sexually interested in women (MSW; N = 41) in terms...
Article
Many heterosexual women perceive gay men to be especially trustworthy friends because both groups are sexually attracted to men, but their romantic/sexual partners tend to be different types of men (i.e., heterosexual vs. gay). This reduces the possibility of sabotage in romantic/sexual competition and ulterior motives in friendship. We sought to r...
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Some heterosexual men express sexual interest in feminine trans individuals with penises. It is possible that this interest arises from a tendency for heterosexual men to be sexually responsive to gender in addition to sex. We compared the self-reported sexual attraction and visual attention patterns of Canadian undergraduate heterosexual men ( N =...
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Darwinian sexual selection theory holds that mate selection occurs inter-sexually, and mate competition occurs intra-sexually for opposite-sex partners. We demonstrate that inter-sexual mate competition can also occur among humans at appreciable rates that vary by culture. In Canada, inter-sexual mate competition was both rare and inconsequential....
Article
Research on male androphilia (i.e., sexual attraction towards adult males) consistently finds that androphilic males tend to have more older biological brothers than males who are gynephilic (i.e., sexually attracted to adult females). This fraternal birth order effect (FBOE) has been well replicated among androphilic males who present publically i...
Article
In certain populations of Japanese macaques, adult females mount adult males in the context of heterosexual consortships (i.e., temporary but exclusive sexual associations between a male and a female). Previous research suggested that, in this primate species, female-male mounting (FMM) may be a behavioral adaptation. This functional hypothesis hol...
Article
Inferring functional components of behavioral sequences is a crucial but challenging task. A systematic comparison of their temporal structure is a good starting point, based on the postulate that more functional traits are less structurally variable. We studied stone handling behavior (SH) in Balinese long-tailed macaques, a versatile form of ston...
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The fraternal birth order effect (FBOE) is the finding that older brothers increase the probability of homosexuality in later-born males, and the female fecundity effect (FFE) is the finding that the mothers of homosexual males produce more offspring than the mothers of heterosexual males. In a recent paper, Khovanova proposed a novel method for co...
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Previous research has consistently demonstrated that both transgender and cisgender androphilic males (i.e., males attracted to adult males) display and recall higher levels of childhood female-typical behavior (CFTB) and lower levels of childhood male-typical behavior (CMTB) compared to gynephilic males (i.e., males attracted to adult females). In...
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The prevalence of women’s and men’s heterosexuality, bisexuality, and homosexuality was assessed in 28 nations using data from 191,088 participants from a 2005 BBC Internet survey. Sexual orientation was measured in terms of both self-reported sexual identity and self-reported degree of same-sex attraction. Multilevel modeling analyses revealed tha...
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Male androphilia (i.e., sexual attraction toward adult males) is influenced by biological factors, reliably occurs across diverse cultures, and has persisted over evolutionary time despite the fact that it reduces reproduction. One possible solution to this evolutionary paradox is the sexually antagonistic gene hypothesis (SAGH), which states that...
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In Samoa, feminine natal males who possess male-typical genitalia are known locally as fa’afafine. Some Samoan men express sexual interest in fa’afafine, whereas others do not. To assess the sexual orientation of men who are sexually interested in fa’afafine, we collected sexual attraction ratings and viewing times of Samoan men’s and women’s faces...
Article
The Dark Triad (DT) personality traits of Machiavellianism, sub-clinical narcissism, and sub-clinical psychopathy overlap with variation in women's interest in casual sex (sociosexuality), and heightened use of mate-competition tactics. The present study sought to replicate links between DT traits and female-typical mate competition tactics, such a...
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Across cultures, androphilic males (natal males who are predominantly sexually attracted to adult men, not women) tend to present in one of two forms: cisgender or transgender. Previous research has shown that, although their gender presentation and identities are distinct, the two forms are similar in many other ways. The present study examined wh...
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In numerous non-Western cultures around the world, a small but meaningful proportion of individuals occupy alternative gender categories beyond the man/woman binary. A substantial body of past research has shown that feminine, same-sex attracted males in Samoa––a nonbinary gender known as fa’afafine––are more altruistic toward their nieces and neph...
Article
We assessed the effect of a progestin-based contraceptive treatment (chlormadinone acetate) on female heterosexual and homosexual behaviors in a free-ranging group of Japanese macaques (Macaca fuscata) living at Arashiyama-Kyoto, Central Japan. The data included estimated intensity of fertility cues, sexual solicitations and mounting behaviors coll...
Article
We assessed the effect of a progestin-based contraceptive treatment (chlormadinone acetate) on female heterosexual and homosexual behaviors in a free-ranging group of Japanese macaques (Macaca fuscata) living at Arashiyama-Kyoto, Central Japan. The data included estimated intensity of fertility cues, sexual solicitations and mounting behaviors coll...
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Previous studies examining the associations between women’s sexual orientation and mental health have obtained inconsistent results. Whereas some studies have suggested that status as a lesbian or bisexual woman may be associated with greater mental health risk, others have suggested that bisexual women may be specifically vulnerable to mental heal...
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This is the first quantitative study of heterospecific sexual behavior between a non-human primate and a non-primate species. We observed multiple occurrences of free-ranging adolescent female Japanese macaques (Macaca fuscata) performing mounts and sexual solicitations toward sika deer (Cervus nippon) at Minoo, central Japan. Our comparative descr...
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Two studies examined the connection between women's sexual orientation, their sociosexuality (i.e. willingness , attitudes, and desires associated with uncommitted sexual behaviour), and Dark Triad traits (Machiavellianism, nar-cissism, and psychopathy). Both studies found that moderately bisexual women reported less-restricted sociosexuality, as w...
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Male androphilia (i.e., male sexual attraction to other adult males) is known to cluster within families. Some studies demonstrate that male androphilia clusters in both the paternal and maternal familial lines, whereas other studies demonstrated that it clusters only in the latter. Most of these studies were conducted in Euro-American populations...
Data
Question about your father’s and mother’s side of the family (Spanish Version). (DOCX)
Data
Question about your father’s and mother’s side of the family (English Version). (DOCX)
Presentation
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Because tool use behaviour is more functionally constrained than object-directed play, the former should be more temporally structured (i.e., more predictable in its sequence) than the latter. Stone play (SP), defined as the non-functional and culturally transmitted manipulation of stones in several macaque species, is an ideal candidate behaviour...
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Homosexuality is an evolutionary puzzle. Many theories attempt to explain how a trait undermining individual reproduction can be maintained, but experimental testing of their predictions remains scarce. The kin selection hypothesis (KSH) is an important theoretical framework to account for the evolution of human homosexuality, postulating that its...
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Bullying is characterized by the repeated attempts of a group or individual to gain social advantage by the use of relational, verbal, or physical aggression against a target, especially when there is a perceived or actual power imbalance (Espelage & Swearer, 2003). One consistent finding is that gay (i.e., androphilic) males report higher rates of...
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The current study evaluated the possibility that greater negative mental health outcomes reported among gay, lesbian, and gender-atypical individuals, compared to gender-typical individuals, are present in childhood and persist into adulthood. Sex and sexual orientation differences in self-reported adulthood and recalled childhood indicators of dep...
Chapter
Homosexual behavior, involving genital contact between same-sex individuals, has been observed in more than 50 primate species, including prosimians, monkeys, and apes. The frequency with which such behavior is expressed varies greatly both between and within species. In some primate species, this behavior facilitates adaptive social goals such as...
Article
Full-text available
Having a greater than average number of older biological brothers is a robust correlate of male androphilia (i.e., sexual attraction and arousal to adult males). Previous investigations have sought to understand whether this fraternal birth order (FBO) effect is also systematically related to recalled indicators of childhood gender nonconformity (C...
Article
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The current study tested the hypothesis that men who are androphilic (sexually attracted to adult men) in a non-Western, developed country—Japan—would recall engaging in more female-typical behavior, and less male-typical behavior, in childhood, compared to men who are gynephilic (sexually attracted to adult women). Androphilic men, androphilic wom...
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Read-only version of article available at: http://rdcu.be/l2wf ABSTRACT: The sexually antagonistic gene hypothesis (SAGH) for male androphilia posits that genes associated with androphilia (i.e., sexual attraction to adult males) will result in lowered reproduction when present in males, but increased reproduction when present in females. Findings...
Article
Full-text available
Androphilia refers to sexual attraction toward adult males, whereas gynephilia refers to sexual attraction toward adult females. The kin selection hypothesis posits that androphilic males help kin increase their reproductive output via kin-directed altruism, thus offsetting their own lowered reproduction and contributing to the fitness of genes und...
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The Istmo Zapotec are a pre-Columbian cultural group indigenous to the Istmo region of Oaxaca, Mexico. Istmo Zapotec recognize three genders: men, women, and muxes. Like Istmo Zapotec men, muxes are biological males. However, unlike Istmo Zapotec men, most muxes are exclusively androphilic (i.e., sexually attracted to adult males), relatively femin...
Article
Full-text available
Previous research established that male androphilia (i.e., sexual arousal and attraction to adult males) clusters in families. Some studies find that male androphilia clusters in both the paternal and maternal lines, while others find that it clusters only in the latter. Most of the research investigating the familial nature of male androphilia has...
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Previous research has found that sex differences in occupational preferences are both substantial and cross-culturally universal. Androphilic males tend to display “gender-shifted” occupational preferences, with relatively female-typical interests. Past research has overwhelmingly relied on Western samples; this article offers new insights from a n...
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Ongoing political controversies around the world exemplify a long-standing and widespread preoccupation with the acceptability of homosexuality. Nonheterosexual people have seen dramatic surges both in their rights and in positive public opinion in many Western countries. In contrast, in much of Africa, the Middle East, the Caribbean, Oceania, and...
Article
A growing body of literature has revealed sex/gender differences in the acoustics of the sibilant fricative /s/. It has been suggested that some of this sex/gender-related variation might be socially motivated and acquired. However, the necessary developmental research to corroborate this proposal is absent from the literature. To address this, we...
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Androphilia refers to sexual attraction and arousal toward males whereas gynephilia refers to sexual attraction and arousal toward females. This study tested the adaptive feminine phenotype model of the evolution of male androphilia via kin selection, which posits that the development of an evolved disposition toward elevated kin-directed altruism...
Article
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In many non Western cultures, same-sex attracted males are markedly feminine in terms of their gender role presentation and are recognized as members of a “third” gender. These third gender males engage in sexual activity with masculine males who are recognized as men. The sexual orientation of these masculine men remains an open question. Using a...
Article
Same-sex genital interactions (SSGIs) occur across the order Primates, yet explaining their maintenance in evolutionary terms appears problematic; as such interactions seem to counteract reproductive goals. We hypothesised that in more promiscuous species, where sexual motivation, mating effort, and non-conceptive heterosexual behaviour are greater...
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Cultural primatology (i.e., the study of behavioral traditions in nonhuman primates as a window into the evolution of human cultural capacities) was founded in Japan by Kinji Imanishi in the early 1950s. This relatively new research area straddles different disciplines and now benefits from collaborations between Japanese and Western primatologists...
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Mona monkeys (Cercopithecus mona) were introduced from West-Central Africa to the Caribbean island of Grenada about 250 years ago. Little is known, however, about the recent trends in size and conservation status of this non-native primate population. We estimated the population density and abundance of mona monkeys in and around the forested areas...
Article
Camperio Ciani et al. argued that the Urak-Lawoi people of Ko Lipe island live in a "traditional," "subsistence primitive society" reminiscent of the "ancestral" human past and that their socio-cultural situation is "remarkably similar" to Samoa. On this basis, they asserted that the Ko Lipe Urak-Lawoi are an appropriate population for determining...
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In recent years, bullying has come into focus as a critically important social issue that demands empirical understanding to inform best practice regarding both intervention and prevention. In Western cultures, low physical aggression in boys, but high physical aggression in girls, predicts elevated victimization due to bullying, and we predicted t...
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We aimed to explain the frequent and prevalent female homosexual behavior in the context of female-biased operational sex ratios (OSR) and qualified sex ratios (Q) in a free-ranging group of Japanese macaques (Macaca fuscata) living at Arashiyama-Kyoto, Japan. Our data included the average availability of sexually mature males during females' putat...
Article
This study presents data bearing on an evolutionary developmental model of male homosexuality. This model hypothesizes that a predisposition toward elevated kin-directed altruism among homosexual males is expressed in childhood as elevated concern for close attachment figures (e.g., parents) and proximally influenced by the concomitant behavioral e...
Article
Full-text available
Androphilia refers to attraction to adult males, whereas gynephilia refers to attraction to adult females. The current study employed self-report and viewing time (response time latency) measures of sexual attraction to determine the sexual orientation of Samoan cisgender men (i.e., males whose gender presentation and identity is concordant with th...
Article
We explored the role that sexual and social partners play in the expression of female homosexual behavior among adolescent female Japanese macaques at Arashiyama, Japan. Our data fully or partially supported all the predictions related to four non-mutually exclusive hypotheses, namely the “adult male disinterest in adolescent females” hypothesis, t...
Article
Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The manner in which male androphilia is expressed varies cross-culturally. Sex-gender congruent male androphiles occupy the gender role typical of their sex, behave in a relatively masculine manner, and id...
Article
We used cross-sectional focal data collected in adolescent and adult females to elucidate the comparative development of heterosexual and homosexual behaviors in female Japanese macaques (Macaca fuscata) living at Arashiyama, Japan, in a group where adult females routinely exhibit sexual interactions with both males and females. Our data fully or p...