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The Effect of Competition on Men's Sexual Behavior

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The Effect of Competition on Men's Sexual Behavior THE EFFECT OF COMPETITION ON MEN’S SEXUAL BEHAVIOR by Gregory Gorelik A Thesis Submitted to the Faculty of The Charles E. Schmidt College of Science in Partial Fulfillment of the Requirements for the Degree of Master of Science Florida Atlantic University Boca Raton, Florida August 2014 ABSTRACT Author: Gregory Gorelik Title: The Effect of Competition on Men’s Sexual Behavior Institution: Florida Atlantic University Thesis Advisor: Dr. David F. Bjorklund Degree: Master of Science Year: 2014 Evidence in humans suggests that men are especially competitive with other men over resources and, if successful, are valued as attractive mating prospects by women. Previous studies also show that men experience an increase in testosterone following a win and a decrease in testosterone following a loss. If an increase in testosterone following a victory is an evolved physiological response aimed at readying a man for an increase in mating opportunities, then experimentally manipulating competitive outcomes should differentially affect men’s sex-drive. One-hundred thirteen men were randomly assigned to experience a win, a loss, or no competitive feedback. Participants’ sex-drive was gauged by their responses to photographs of women of differential attractiveness. Results showed that only single men exhibited a higher sex-drive in the winning condition, followed by the control and losing conditions, respectively. Limitations and practical applications to decreasing instances of rape and sexual coercion are discussed. iii THE EFFECT OF COMPETITION ON MEN’S SEXUAL BEHAVIOR List of Tables .................................................................................................................... vii List of Figures .................................................................................................................. viii The Effect of Competition on Men’s Sexual Behavior ...................................................... 1 Selection within a Biological Context ............................................................................. 1 Sexual Selection .............................................................................................................. 2 Social Status and Sexual Selection in Humans ............................................................... 7 Male Social Status, Testosterone, and Sexual Behavior ................................................. 9 The Present Study.......................................................................................................... 13 Sex-drive measures. ................................................................................................... 14 Methods ............................................................................................................................ 16 Population...................................................................................................................... 16 Materials ........................................................................................................................ 16 Procedure ....................................................................................................................... 17 Results ............................................................................................................................... 20 Factor Analysis .............................................................................................................. 20 Target Sex Drive ........................................................................................................... 21 Participant Sex Drive .................................................................................................... 23 Discussion ......................................................................................................................... 26 Future Directions ........................................................................................................... 30 iv Appendix ........................................................................................................................... 32 References ......................................................................................................................... 49 v TABLES Table 1. Target Sex Drive Questionnaire ......................................................................... 42 Table 2. Participant Sex Drive Questionnaire .................................................................. 43 Table 3. Means and Standard Deviations for Target Sex Drive ....................................... 44 Table 4. Means and Standard Deviations for Participant Sex Drive ................................ 45 Table 5. Demographics Questionnaire .............................................................................. 46 vi FIGURES Figure 1. Photographs used to gauge participants’ sex drive, separated by high attractiveness and low attractiveness ................................................................ 47 Figure 2. Mean Participant Sex Drive Ratings for Mated Participants and Single Participants, separated by target attractiveness ................................................ 48 vii The Effect of Competition on Men’s Sexual Behavior The present study aims to uncover whether and to what degree the manipulation of men’s social status affects their sexual motivation and interest. In line with previous research in humans and other primates showing a relationship between social status, testosterone level, and sexual behavior, I hypothesize that by experimentally manipulating male participants’ self-perceived social status, a concomitant change in their sexual motivation and interest will be observed. More specifically, I predict that an increase in a male participant’s self-perceived social status (resulting from a victory in a competitive task against another man) will cause an increase in his sexual motivation and interest. Likewise, I predict that a decrease in a male participant’s self-perceived social status (resulting from a loss in a competitive task against another man) will cause a decrease in his sexual motivation and interest. The rationale for these predictions stems from the evolutionary biological concepts of sexual selection, the extended phenotype, life history theory, and the challenge hypothesis, as discussed in the ensuing sections. Selection within a Biological Context Natural selection ensures that organisms are adapted to both animate and inanimate aspects of their environments. Thus, not only are biological adaptations selected to exploit geological and meteorological resources, organisms also possess adaptations that enable them to interact with other organisms, whether of the same or of a different species. Humans are no different. Our evolution includes a history of selection 1 pressures stemming from non-biological sources such as the degree of sunlight to which our ancestors were exposed (Jablonski & Chaplin, 2000), the types of landscapes they traversed (Cerling et al., 2011), and the composition of the air they breathed (Beall, 2006). In addition to the adaptations sculpted by these non-living factors in our species’ ancestral environments, humans, like all other organisms, also possess adaptations that were selected to deal with the presence of countless biological forms, from viruses and bacteria (Aidoo et al., 2002), to plants and animals (Cochran & Harpending, 2009; Holden & Mace, 1997). As social primates, ancestral humans were also subject to the selection pressures stemming from other humans with whom they interacted (Bailey & Geary, 2009; Brüne & Brüne-Cohrs, 2006). Therefore, our ancestors’ bodies and minds had to contend with the presence of the bodies and minds of their conspecifics in order to survive and reproduce, and their survival and reproduction depended on their ability to cooperate as well as compete with their conspecifics. Of course, these conspecifics were under similar selection pressures to successfully navigate their social environments as well. This dynamic interplay between the needs of our ancestors to cooperate and/or compete with one another may have been a primary factor responsible for the evolution of the enlarged human brain (Bailey & Geary, 2009). Thus, coevolutionary relationships between our ancestors and their conspecifics, whether mutualistic, commensal, predatory, or parasitic, cannot be overlooked in evolutionary examinations of human social and sexual behavior. Sexual Selection A sexually reproducing organism’s evolutionary success is not only dependent on its ability to survive but also on its ability to reproduce. For example, a male who lived 2 for 100 years but who fathered no children (nor possessed any genetic relatives who themselves reproduced), would be an evolutionary dead-end, as none of his genes would be represented in subsequent generations. In contrast, a man who lived only for 25 years but who was successful at conceiving many children (and/or helping his genetic relatives to rear theirs), would thereby propagate his genes into the next generation and pass on his reproductively successful traits to his offspring. This is an important distinction, as evolutionary success is more dependent on reproduction than it is on survival. In sexually reproducing organisms such as humans, reproductive success rests on an individual’s ability to outcompete sexual rivals and procure access to mates—a process that (Darwin, 1859/2006) termed “sexual selection.” In contrast to natural selection, which entails that
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