Encyclopedia of Personality and Individual Differences

Living Edition
| Editors: Virgil Zeigler-Hill, Todd K. Shackelford

Vasey, Paul

  • Paul VaseyEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-28099-8_1511-1

Early Life and Educational Background

Paul L. Vasey was born in Toronto, Canada, on January 30, 1966. He received his B.A. (honors) from the University of Alberta in Edmonton (1989), his M.A. from Simon Fraser University in Burnaby, British Columbia (1991), and his Ph.D. from the Université de Montréal in Québec (1997). He conducted postdoctoral research at the Université de Montréal and Concordia University in Montréal and at York University in Toronto.

Research Interests

Japanese Macaque Research

For over two decades, Paul L. Vasey has carried out long-term research on the development and evolution of female homosexual behavior in captive and free-ranging Japanese macaques (Macaca fuscata). His Japanese macaque field sites included Arashiyama (near Kyoto) and Minoo (near Osaka). Vasey’s work demonstrated that female homosexual behavior in Japanese macaques is not used to facilitate adaptive social goals (reviewed in Vasey 2006). This evidence-based claim was a significant departure from most of the animal behavior literature, which typically framed same-sex mounting as a sociosexual adaptation. Instead, Vasey claimed that in some species, same-sex sexual behavior was a neutral, evolutionary by-product. He showed that during most same-sex mounts, female Japanese macaques stimulate their genitalia, thereby obtaining immediate sexual reward (reviewed in Vasey and VanderLaan 2012). His research group demonstrated that females sometimes choose same-sex sexual partners because they prefer them over the available male alternatives and in doing so debunked the notion that females engage in this behavior simply because they are unable to obtain a male (Leca et al. 2015a). Vasey also showed that females will compete with males for exclusive access to female sexual partners, demonstrating that mate competition can extend into an intersexual context (Vasey 1998). Research by Vasey’s group revealed that homosexual behavior develops more rapidly in female Japanese macaques than heterosexual behavior, probably because the former involves less risky interactions than the latter (Leca et al. 2015b). His group also showed that female Japanese macaques adopt arbitrary mount postures during same-sex mounts, and these vary across populations (Leca et al. 2014). This suggests that the expression of female homosexual mounting in Japanese macaques is influenced, in part, by cultural factors (i.e., group-specific social processes).

Cross-Cultural Research

Paul L. Vasey has also conducted long-term cross-cultural research on the development and evolution of male androphilia (i.e., sexual attraction to adult males) in humans at field sites in Samoa, Japan, Mexico, and Canada. Male androphilia has been widely characterized as one of the outstanding paradoxes of evolutionary psychology. Vasey’s research group has contributed in a number of significant ways toward resolving this paradox.

First, Vasey’s research group has demonstrated that culturally different forms of male androphilia (i.e., cisgender or transgender forms) share numerous psychobiological correlates including having greater numbers of older biological brothers, larger family sizes, more androphilic male relatives, similar population prevalence rates, little or no offspring production, increased gender-atypical behavior and cross-sex wishes in childhood, elevated traits of childhood separation anxiety, and gender-atypical occupational preferences in adulthood (reviewed in Vasey and VanderLaan 2014; Semenyna and Vasey 2016). Taken together, this research suggests that cisgender and transgender male androphilia are cultural variants of the same trait and share a common biological etiology.

Second, in an award-winning paper, Vasey’s research group demonstrated that transgendered form of male androphilia is likely ancestral to the cisgendered form because the former is associated with more ancestral sociocultural conditions than the latter (VanderLaan et al. 2013). As such, transgendered male androphilia is likely the best model for testing evolutionary hypotheses given that more derived forms of this trait may reflect recent cultural/historical influences that might obscure the outcome of evolutionary processes.

Third, Vasey’s group has repeatedly shown that Samoan transgendered androphilic males (known locally as fa’afafine) exhibit elevated avuncular (uncle-like) tendencies compared to Samoan women and gynephilic men although there is no social expectation that they will do so (reviewed in Vasey and VanderLaan 2014). In childhood, fa’afafine’s altruistic tendencies (and those of cisgender male androphiles) appear to manifest as heightened anxiety about the well-being of kin (reviewed in VanderLaan et al. 2016). Work by Vasey’s group also indicates that fa’afafine’s avuncular tendencies are expressed in an adaptive manner that could potentially increase fa’afafine’s indirect fitness (reviewed in Vasey and VanderLaan 2014). This work furnishes support for the kin selection hypothesis which holds that genes for male androphilia could be maintained in a population if enhancing one’s indirect fitness offsets the cost of not reproducing directly. Theoretically speaking, androphilic males could increase their indirect fitness by behaving altruistically toward kin, which, in principle, would allow those kin to increase their reproductive output.

Fourth, in contrast to their Samoan findings, Vasey’s research group has shown that there is virtually no support for the kin selection hypothesis in populations of Canadian or Japanese cisgendered androphilic males (reviewed in Vasey and VanderLaan 2014). This suggests that if kin selection contributes to the maintenance of genes associated with male androphilia, then this process may be influenced by the manner in which male androphilia is publically expressed.

Fifth, Vasey’s research group has repeatedly shown that the mothers and maternal grandmothers of fa’afafine produce significantly more offspring than those of gynephilic males (reviewed in Semenyna et al. 2016). This work is significant because it furnishes some support for the sexually antagonistic gene hypothesis, which holds that genes for androphilia produce fitness costs in males, but fitness benefits in the female kin of male androphiles. Elevated reproductive output by androphilic males’ aunts would provide the most definitive support for the sexually antagonistic gene hypothesis because androphilic males share genes with their aunts, but not their aunts’ male reproductive partners. To date, Vasey’s group has found no such evidence.

One way of interpreting this body of research is as follows: Sexually antagonistic selection for genes that promote female reproductive output results in an evolutionary by-product, namely, male androphilia. Where the ancestral form of male androphilia – the transgendered form – predominates, elevated avuncularity by male androphiles may further facilitate elevated reproductive output by their female kin. This, in turn, would have serendipitous effects on the sexually antagonistic genes in question even though androphilic males’ avuncularity was not originally built by selection to do so. Markedly elevated avuncularity might result in distinct fitness advantages that could form a unique basis on which kin selection might act. If so, then the cognitive underpinnings mediating avuncularity in male androphiles may have subsequently undergone secondary adaptive modification. This suggestion is consistent with the findings reported by Vasey’s research group that fa’afafine’s avuncular cognition exhibits adaptive design features (reviewed in Vasey and VanderLaan 2014). Empirically documented characteristics of the ancestral human sociocultural environment, such as maximally inclusive kinship systems and social tolerance of male-male sexuality, may have facilitated this process (VanderLaan et al. 2013).

Transgender androphilic males, such as fa’afafine, typically engage in sexual activity with masculine males who self-identify as men. Using both subjective (self-report) and objective (viewing-time) measures, Vasey’s group has shown that these men exhibit bisexual patterns of sexual attraction that are distinct from those of strictly gynephilic men and from those of fa’afafine themselves (Petterson et al. 2015; Petterson et al. 2016).


  1. Leca, J.-B., Gunst, N., Ottenheimer-Carrier, L., & Vasey, P. L. (2014). Intergroup variation in non-conceptive mounting behavior in Japanese macaques: could it be cultural? Animal Behavior and Cognition, 1, 381–405.CrossRefGoogle Scholar
  2. Leca, J.-B., Gunst, N., Huffman, M. J., & Vasey, P. L. (2015a). Effect of female-biased sex ratios on female homosexual behavior in Japanese macaques: evidence for the “bisexual preference hypothesis”. Archives of Sexual Behavior, 44, 2125–2138.CrossRefPubMedGoogle Scholar
  3. Leca, J.-B., Gunst, N., & Vasey, P. L. (2015b). Comparative development of heterosexual and homosexual behaviors in free-ranging female Japanese macaques. Archives of Sexual Behavior, 44, 1215–1231.CrossRefPubMedGoogle Scholar
  4. Petterson, L. J., Dixson, B. J., Little, A. C., & Vasey, P. L. (2015). Viewing time measures of sexual orientation in Samoan cisgender men who engage in sexual interactions with fa’afafine. PLoS ONE, 10(2), e0116529.CrossRefPubMedPubMedCentralGoogle Scholar
  5. Petterson, L. J., Dixson, B. J., Little, A. C., & Vasey, P. L. (2016). Reconsidering male bisexuality: sexual activity role and sexual attraction in Samoan men who engage in sexual interactions with fa’afafine. Psychology of Sexual Orientation and Gender Diversity, 3, 11–26.CrossRefGoogle Scholar
  6. Semenyna, S., & Vasey, P. L. (2016). Sex and male sexual orientation differences in occupational preferences in Samoa. Human Nature, 27, 283.CrossRefPubMedGoogle Scholar
  7. Semenyna, S., Petterson, L. J., VanderLaan, D. P., & Vasey, P. L. (2016). Reproductive output by the relatives of Samoan men and fa’afafine: a replication study. Archives of Sexual Behavior, 31, 51–62.Google Scholar
  8. VanderLaan, D. P., Ren, Z., & Vasey, P. L. (2013). Male androphilia in the ancestral environment: an ethnological analysis. Human Nature, 24, 375–401.CrossRefPubMedGoogle Scholar
  9. VanderLaan, D. P., Petterson, L. J., & Vasey, P. L. (2016). Femininity and kin-directed altruism in homosexual men: a test of an evolutionary developmental model. Archives of Sexual Behavior, 45, 619–633.CrossRefPubMedGoogle Scholar
  10. Vasey, P.L. (1998). Female choice and inter-sexual competition for female sexual partners in Japanese macaques. Behaviour, 135: 579–597.Google Scholar
  11. Vasey, P. L. (2006). The pursuit of pleasure: homosexual behaviour, sexual reward and evolutionary history in Japanese macaques. In V. Sommer & P. L. Vasey (Eds.), Homosexual behaviour in animals: an evolutionary perspective (pp. 191–219). Cambridge: Cambridge University Press.Google Scholar
  12. Vasey, P. L., & VanderLaan, D. P. (2012). Is female homosexual behaviour in Japanese macaque truly sexual? In J. B. Leca, M. J. Huffman, & P. L. Vasey (Eds.), The monkeys of stormy mountain: over half a century of research on the Arashiyama Macaques (pp. 153–172). Cambridge: Cambridge University Press.Google Scholar
  13. Vasey, P. L., & VanderLaan, D. P. (2014). Evolving research on the evolution of male androphilia. Canadian Journal of Human Sexuality, 23, 137–147.CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG 2016

Authors and Affiliations

  1. 1.University of LethbridgeLethbridgeCanada

Section editors and affiliations

  • Ilan Dar-Nimrod
    • 1
  1. 1.University of SydneySydneyAustralia