Life history theory attempts to explain between- and within-species variation in maturational and reproductive patterns, whereas sexual selection attempts to explain between- and within-sex differences in intersexual mate choice and intrasexual competition for members of the opposite sex. These two expansive evolutionary theories have been used by developmental scientists and social/personality psychologists to explain the variation observed in human reproduction, including the timing of reproductive events and individual differences in orientation toward mating and parenting. In Part I of the following paper, I review research related to life history theory and sexual selection in humans. I then show how integrating the principles of sexual selection with life history models of human reproductive strategies can address existing limitations. In Part II, I empirically examine many of the unique propositions that emerge from theoretical integration using a longitudinal dataset on adolescent development. Under investigation is an expanded model of sociosexual development that incorporates key principles from Belsky, Steinberg, and Draper's (BSD) psychosocial theory and sexual selection theory. I specifically examine the role of early rearing conditions within the home, as specified by BSD, and self-perceived mate value, as highlighted by a sexual selection perspective, on timing of sexual debut and sexual risk taking. The current study combines variable-centered and person-centered methods to assess specialized developmental trajectories. In total, the study provides novel support for BSD theory, while also highlighting needed revisions to account for the role of self-perceived mate value on adolescent sexual behavior.

Doctor of Philosophy / Department of Psychological Sciences / Gary L. Brase / Operational Sex Ratio (OSR: the ratio of reproductively viable males to females in a given population) has been theorized and studied as a construct that may influence behaviors. The encoding of sex ratio was examined in order to determine whether the cognitive process underlying it is automatic or effortful. Further, the current work examines whether OSR or Adult Sex Ratio (ASR: the ratio of adult males to females) is encoded. The current work involved four experiments; two using frequency tracking methodology and two using summary statistic methodology. Experiment 1 found a strong correlation between OSR of conditions and estimates of sex ratio. Participants in Experiment 1 were uninformed on the purpose of the experiment, thus the strong correlations between actual and estimated sex ratio suggest a level of automaticity. Experiment 2 found a strong correlation between the ASR of conditions and estimates, suggesting that individuals do not encode OSR over ASR. Experiments 3.a. and 3.b. demonstrated automaticity in estimates of sex ratio from briefly presented sets of faces, for two different durations: 1000ms and 330ms, the later of which is widely accepted as the length of a single eye fixation. Overall this work demonstrated a human ability to recall proportion of sexes from arrays of serially presented individuals (Experiments 1 and 2), and that ASR is encoded when participants are presented with conditions including older adults. This work found the encoding of sex ratio to be highly automatic, particularly stemming from the results of Experiments 3.a. and 3.b. Conclusions from this work help to verify previous research on sex ratio’s effect on mating strategies through evidence supporting the automatic nature of encoding sex ratio. Further, the current work is a foundation for future research regarding sex ratio, and leads to several proposals for future endeavors.

This thesis expands our understanding of the role of several different mating behaviours in the process of forming and maintaining human mating pair-bonds. Chapter 2 investigated within-sex mating strategies and found that their distribution reflects the presence of two phenotypes, one favouring the pursuit of short-term mating and one the establishment of mating pair-bonds, each driven by prenatal testosterone exposure. Chapter 3 investigated the possible functional role of kissing in mating relationships, and found that it was utilised divergently by individuals pursuing different mating strategies, with those interested in short-term mating utilising it to assess the suitability of potential mates at initial relationship stages, and those interested in long-term mating using it to mediate pair-bond attachments. Chapter 4 examined female attitudes towards kissing across the menstrual cycle and found that attitudes varied with cycle phase, mediated by fluctuations in the hormone progesterone. This chapter also investigated the effects of kissing-related information on mate assessment and found that such information influenced mate desirability, even in the presence of typically dominant visual cues. Lastly, Chapter 5 investigated the cognitive effects of established pair-bonds, finding that individuals ‘in love’ with a mating partner show improved empathising abilities, particularly males when it comes to assessing negative emotional states in others. Using an evolutionary framework, each chapter of this thesis contributes novel insights to our understanding of these diverse behaviours. These results suggest that that future research must take into account within-sex phenotypic differences in order to truly understand human mating strategy decisions, and that different mating strategy phenotypes might adaptively utilise the same courtship behaviours in divergent ways. Furthermore, these results also suggest that pair-bonding in humans may be a relatively recent phenomenon, and that the formation of such pair-bonds can have adaptive cognitive effects for males within such bonded relationships.

Pick-up lines are a "ritual that tries to turn strangers into lovers" (Murray, 1985, p.17). By studying how pick-up lines are perceived by the population, we might learn how the phenomenon of short- or long-term mating is initiated. By taking into account mating strategies, mate value, attractiveness, and flirting strategies, a pattern of behaviors and reactions may be observed. This study examines perceived pick-up line appropriateness and effectiveness when the attractiveness of the man delivering them varies. To test the effectiveness of 2 different types of pick-up lines, an online survey featuring 1 of 4 videos was administered. Results indicated that a humorous pick-up line was perceived as more effective and favorable than a slightly insulting one. An attractive man was perceived to be more communicatively competent than an unattractive man. Men, regardless of attractiveness, were perceived as more socially attractive when using a humorous pick-up line.

abstract: The present study tested the hypothesis that women dress modestly to signal to other women that they pose no mate poaching threat and are sexually restricted, and that this is especially true for religious women. Participants were 392 Muslim women living in the United States. They read two passages describing fictional situations in which they met with a potential female friend and then indicated what kind of outfit they would wear in both situations. In one situation, the participant obtained a reputation for promiscuity; in the other situation, reputation was not mentioned. I predicted that participants would choose more modest outfits for the promiscuous reputation passage, because if women dress modestly to signal sexual restrictedness, then they should dress more modestly around women with whom they have a reputation for promiscuity—to counteract such a reputation, women may wish to send a strong signal that they are not promiscuous. The hypothesis was partially supported: Less religious women chose more modest outfits for the promiscuous reputation situation than they did for the no reputation situation. This suggests that some women dress modestly to signal sexual restrictedness to other women, but that this is especially true for women who are less religious, not more. More religious women dress more modestly than less religious women, but they may not dress modestly to signal sexual restrictedness. Two important goals for this area of research are to determine the proximate reasons that more religious women dress modestly and to investigate modest dress among non-Muslim religious women. / Dissertation/Thesis / Doctoral Dissertation Psychology 2020

Among multi-male, multi-female primate groups, males engage in direct contest competition for access to mates. The priority-of-access model (PoA model) generally predicts that male reproductive success increases with male dominance rank, but the strength of this relationship is expected to decrease with increasing female reproductive synchrony, particularly in seasonally breeding primates. Genetic paternity studies support the model’s predictions, having found a positive relationship between male dominance rank and reproductive success. However, in addition to dominance status and female reproductive synchrony, a number of proximate factors also impact males’ ability to sire offspring, which have not been considered in studies of male reproductive strategies.By integrating behavioral, genetic, morphological, and hormonal analysis as more direct measures of reproductive success in individual males, this dissertation investigated the relationship between male dominance rank and reproductive success and including the proximate factors affecting this relationship in wild northern pig-tailed macaques (Macaca leonina). The main objectives of this study are: 1) to identify the relationships between male dominance rank, male mating success, and male reproductive success, and assess to what extent female synchrony affects these relationships; 2) to identify the proximate factors that may reduce the reproductive success of the top-ranking male and assess variation in male mating tactics related to dominance rank and migration status (i.e., resident males vs. extra-group males); and 3) to evaluate the function of males’ red ornaments that may be used to signal male dominance status (male-male competition) to attract females (female mate choice) or both. The study was conducted at Khao Yai National Park, northeastern Thailand. Systematic data collection on CH group occurred from September 2015-June 2017. The group composition was recorded daily as well as births, deaths, individual emigrations and immigrations, females’ parity status, and the presence of extra-group males (EGMs). Sociosexual data and male-female interactions (i.e., copulations, ejaculatory copulations, consortships, grooming, female proceptive behaviors and receptive behaviors) were recorded during females’ receptive periods. To assess male reproductive success, genetic paternity analyses were conducted on fecal DNA samples collected from 18 adult and subadult males, 22 adult females, and 25 juveniles and infants. To measure red skin coloration of males, hindquarter images were collected non-invasively for seven adult males. From those images, skin color and luminance were computationally quantified to assess variation in male anogenital reflectance. Lastly, fecal samples were collected from nine adult males to assess monthly levels of fecal testosterone by microtitreplate enzyme immunoassay. The distribution of births and matings suggested that northern pig-tailed macaques, at least in this group, are best categorized as moderate seasonal breeders. Indeed, 33-67% of births occurred within a three-month period. Copulation data revealed a positive relationship between male dominance rank and mating success, supporting the predictions of the PoA model. However, the distribution of male reproductive success indicated that: 1) high-ranking males controlled a proportion of paternity much lower than predicted by the PoA model; 2) middle-ranking males controlled a proportion of paternity higher than predicted by the model; and 3) EGMs, not considered in the PoA model, controlled a surprisingly large proportion of paternity despite a low observed mating success. When females were simultaneously receptive, lower-ranking and subadult males engaged in opportunistic and surreptitious copulation and avoided direct competition with higher-ranking males, and most females approached and mated with EGMs out of the resident adult males’ sight. However, one EGM also mated in full sight of resident adult males. This is the first study to report mating and successful paternity by EGMs in a moderately seasonally breeding species.Four male mating tactics were identified: 1) the top-ranking resident male tactic, in which the male competes for the alpha male position to control priority of access to receptive females through long consortships and copulations; 2) the lower-ranking resident male tactic, in which the male copulates opportunistically and surreptitiously out of sight of higher-ranking males mostly during the mating peak; 3) the subordinate EGM tactic, in which the male lives semi-solitarily and copulates opportunistically and surreptitiously, mostly during the mating peaks; and 4) the super-dominant EGM tactic, in which the EGM copulates irrespective of the presence of other males and in full sight of even the highest-ranking resident male. In addition, I found support for female mate choice. Darker and redder males had more mating partners, received more female proceptive behaviors, and were engaged in more consortships and grooming with receptive females. Furthermore, males became redder and darker as female reproductive synchrony increased. Together, these results suggest that male red ornaments exhibited in the male’s anogenital area is attractive to females. Furthermore, behavioral evidence of female mate choice towards EGMs was found. This dissertation provides a comprehensive picture of the complex male mating tactics of northern pig-tailed macaques. To achieve reproductive success, males engage in a diversity of mating tactics, strongly influenced by male dominance rank and the degree of female reproductive synchrony. However, mate-guarding costs, surreptitious copulations by lower-ranking males and EGMs, and female mate choice, need to be included in an extended version of the PoA model to provide stronger predictions of the distribution of male reproductive success in primates.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20218号 / 理博第4303号 / 新制||理||1618(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 古市 剛史, 教授 Fred Bruce BERCOVITCH, 教授 平井 啓久 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

The thesis is divided into three parts. The first part is focused on the main theories of human mating strategies, such as sociosexual orientation and sexual strategies theory, which emphasizes intersexual differences as a result from the asymmetry of parental investment, and strategic pluralism theory, which highlights intrasexual variation in mating behavior. The second part consists of one review article published in the Encyclopedia of Evolutionary Psychological Science and one original research article published in The Journal of Sex Research, a peer-reviewed journal. In this part we explored possible evolutionary origins and adaptive values of paraphilic interests and their prevalence in the Czech population. The third part consist of one article published in the peer-reviewed journal Personality and Individual Differences and two research studies which are currently under peer-review in two international journals. The main aim of this part was to test whether individual differences in femininity-masculinity, Big Five personality traits, and propensity to sexual excitation and inhibition are associated with individual sociosexual orientation. A further aim was to test whether attention towards sexual stimuli is affected by an individual's level of sociosexual orientation and by depressive...

付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24876号 / 理博第4986号 / 新制||理||1712(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 平田 聡, 教授 三谷 曜子, 教授 松田 一希 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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