Vasey, Paul

Permanent URI for this collection

https://opus.uleth.ca/handle/10133/4749

Browse

Browsing Vasey, Paul by Title

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Do monkeys use sex toys? Evidence of stone tool-assisted masturbation in free-ranging long-tailed macaques
    (Wiley, 2022) Cenni, Camilla; Christie, Jessica B. A.; Van der Pant, Yanni; Gunst, Noëlle; Vasey, Paul L.; Wandia, Nengah; Leca, Jean-Baptiste
    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, respectively, that may have been co-opted into self-directed tool-assisted masturbation in long-tailed macaques (i.e., “Sex Toy” hypothesis). We predicted that genital and inguinal stone-tapping and rubbing would be more closely temporally associated with physiological responses (e.g., estrus in females, penile erection in males) and behavior patterns (e.g., sexual mounts and other mating interactions) that are sexually motivated than other stone-directed play. We also predicted that the stones selected to perform genital and inguinal stone-tapping and rubbing actions would be less variable in number, size, and texture than the stones typically used during other stone-directed playful actions. Overall, our data partly supported the “Sex Toy” hypothesis indicating that stone-directed tapping and rubbing onto the genital and inguinal area are sexually motivated behaviors. Our research suggests that instrumental behaviors of questionably adaptive value may be maintained over evolutionary time through pleasurable/self-rewarding mechanisms, such as those underlying playful and sexual activities.
  • Thumbnail Image
    Item
    Familial patterning and prevalence of male androphilia among Istmo Zapotec men and muxes
    (Public Library of Science, 2018) Gómez, Francisco R.; Semenyna, Scott W.; Court, Lucas; Vasey, Paul L.
    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 where fertility is low and the sexual orientation of male relatives can sometimes be difficult to ascertain. These two factors can potentially confound the results of such studies. To address these limitations, we examined the familial patterning of male androphilia among the Istmo Zapotec of Oaxaca, Mexico––a high fertility, non-Euro-American population where androphilic males are known locally as muxes, a third gender category. The Istmo Zapotec recognize two types of muxes––muxe gunaa and muxe nguiiu––who typify the transgender and cisgender forms of male androphilia, respectively. We compared the familial patterning of male androphilia between muxe gunaa and muxe nguiiu, as well as between gynephilic men and muxes (both cisgender and transgender forms combined). Istmo Zapotec muxe gunaa and muxe nguiiu exhibit similar familial patterning of male androphilia. Overall, muxes were characterized by significantly more muxe relatives than gynephilic men. This familial patterning was equivalent in both the paternal and maternal lines of muxes. The population prevalence rate of male androphilia was estimated to fall between 3.37–6.02% in the Istmo Zapotec. This is the first study that has compared cisgender and transgender androphilic males from the same high fertility population and demonstrated that the two do not differ with respect to the familial patterning of male androphilia.
  • Thumbnail Image
    Item
    Inter-group variation in non-conceptive sexual activity in female Japanese macaques: could it be cultural?
    (Sciknow Publications Ltd., 2014) Leca, Jean-Baptiste; Gunst, Noelle; Carrier, Lydia Ottenheimer; Vasey, Paul L.
    We compared two non-conceptive sexual behavioral patterns (female-male mounting – FMM – and female-female mounting – FFM) across four free-ranging groups of Japanese macaques (Macaca fuscata) living at three different field sites in Japan (Arashiyama, Minoo, and Jigokudani). We found marked inter-group differences and covariation in the frequency and form of FMM and FFM. This result supports the view that FMM and FFM in Japanese macaques are developmentally and evolutionarily linked. The customary occurrence, high prevalence, and great diversity of FMM and FFM at Arashiyama may be the result of combined favorable socio-demographic conditions, namely few resident males, most of them being old, sexually under-motivated, and less aggressive and controlling than the average male Japanese macaques. We suggest that FMM and FFM may be cultural sexual practices in the Arashiyama-E group. In most other populations, all the aforementioned favorable sociodemographic conditions are not met, and although female mounting may occasionally be expressed by several group members, it does not reach the group-level tradition status. Our cultural interpretation of female mounting in Japanese macaques is consistent with evidence of the social transmission of courtship behaviors and mating preferences in various animal taxa, including nonhuman primates and humans. Our study may have implications for the evolution of non-conceptive sexuality in humans, including sexual fluidity in women.
  • Thumbnail Image
    Item
    Offspring production among the extended relatives of Samoan men and fa'afafine
    (Public Library of Science, 2012) VanderLaan, Doug P.; Forrester, Deanna Lee; Petterson, Lanna J.; Vasey, Paul L.
    Androphilia refers to sexual attraction to adult males, whereas gynephilia refers to sexual attraction to adult females. Male androphilia is an evolutionary paradox. Its development is at least partially influenced by genetic factors, yet male androphiles exhibit lower reproductive output, thus raising the question of how genetic factors underlying its development persist. The sexual antagonism hypothesis posits that the fitness costs associated with genetic factors underlying male androphilia are offset because these same factors lead to elevated reproduction on the part of the female relatives of androphilic males. Western samples drawn from low fertility populations have yielded inconsistent results when testing this hypothesis. Some studies documented elevated reproduction among the matrilineal female kin of androphilic males, whereas others found such effects in the paternal line. Samoa is a high-fertility population in which individuals reproduce closer to their maximum capacities. This study compared the reproductive output of the paternal and maternal line grandmothers, aunts, and uncles of 86 Samoan androphilic males, known locally as fa’afafine, and 86 Samoan gynephilic males. Reproductive output was elevated in the paternal and maternal line grandmothers, but not aunts or uncles, of fa’afafine. These findings are consistent with the sexual antagonism hypothesis and suggest that male androphilia is associated with elevated reproduction among extended relatives in both the maternal and paternal line. Discussion focuses on how this study, in conjunction with the broader literature, informs various models for the evolution of male androphilia via elevated reproduction on the part of female kin.
  • Thumbnail Image
    Item
    Sexual adaptation: is female-male mounting a supernormal courtship display in Japanese macaques?
    (Brill, 2022) Gunst, Noëlle; Leca, Jean-Baptiste; Vasey, Paul L.
    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” behavioral pattern) than species-typical female-to-male sexual solicitations (FMSS) at prompting subsequent male-to-female mounts (MFM). In a context of high femalefemale competition for male mates, we found that (1) FMM functioned to focus the male consort partner’s attention as efficiently as FMSS and prevented him from moving away, and (2) FMM was more efficient than species-typical FMSS at expediting MFM (i.e., the most fitness-enhancing sexual behavior of a mating sequence). We concluded that FMM could be considered a supernormal courtship behavioral pattern in adult female Japanese macaques. This population-specific sexual adaptation may result from a combination of favorable socio-demographic conditions. This study has implications for the evolutionary history of non-conceptive mounting patterns in Japanese macaques and non-conceptive sexuality in humans.
  • Thumbnail Image
    Item
    Viewing time measures of sexual orientation in Samoan cisgender men who engage in sexual interactions with Fa'afafine
    (Public Library of Science, 2015) Petterson, Lanna J.; Dixson, Barnaby J.; Little, Anthony C.; Vasey, Paul L.
    Androphilia refers to attraction to adultmales, 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 their biological sex) who engage in sexual interactions with transgender male androphiles (known locally as fa’afafine) compared to: (1) Samoan cisgender men who only engage in sexual interactions with women, and (2) fa’afafine. As expected, both measures indicated that cisgender men who only engaged in sexual interactions with women exhibited a gynephilic pattern of sexual attraction, whereas fa’afafine exhibited an androphilic one. In contrast, both measures indicated that cisgendermen who engaged in sexual interactions with fa’afafine demonstrated a bisexual pattern of sexual attraction. Most of the cisgender men who exhibited bisexual viewing times did not engage in sexual activity with both men and women indicating that the manner in which bisexual patterns of sexual attraction manifest behaviorally vary from one culture to the next.
  • Thumbnail Image
    Item
    When males have females on their backs: male's tolerance, solicitation, and use of female-male mounting in Japanese macaques
    (Wiley, 2022) Gunst, Noëlle; Leca, Jean-Baptiste; Vasey, Paul L.
    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 on the male consort partners’ responses to FMM. We studied a free-ranging population of Japanese macaques at Arashiyama, Japan, in which FMM is frequent and prevalent. We analyzed 240 consortships involving 31 females and 19 males. We tested three hypotheses regarding male’s tolerance, solicitation, and use of FMM. First, we found that FMM was tolerated by male mountees who were no more likely to aggress their female partners during a short time window around a FMM, than they were during the rest of the consortship period. Second, we showed that FMM could be triggered by male recipients, via explicit male-to-female sexual solicitations. Third, we found that some males may utilize FMM in a quest for their own sexual stimulation, which sometimes culminated in masturbation by the male during FMM. Our findings indicate that male partners facilitate the expression of FMM both passively (via their tolerance) and actively (via their solicitation). In addition, FMM appears to enhance the sexual arousal of male partners during consortships. We argued that, for females to have expanded their repertoire of sexual solicitations by adopting FMM, male mates must have played a role in the evolutionary origins and maintenance of this non-conceptive, but intense and powerful female mating tactic.