Within Canada, young adults have been identified as being at high risk for sexually transmitted infections (STI). One major contributing factor is inconsistent condom use, particularly within monogamous relationships (Civic, 2000; Critelli & Suire, 1998; Misovich, Fisher & Fisher, 1997; Winfield & Whaley, 2005). This research used qualitative methods to investigate the process by which young women rationalize inconsistent condom use and the relational influences that aid in this transition. A sample of fifteen women (between 18-24 years of age) were surveyed and interviewed. Using grounded theory analysis, the results indicated that the process of discontinuing condoms is multifaceted. Within relationships, unprotected sex comes to signify developmental milestones for the couple. It is associated with desirable relationship characteristics of commitment, trust, intimacy and fidelity. The results suggest that health promotion interventions should emphasize the high risk for STI posed by using condoms inconsistently within the monogamous relationships of young adults.

Within Canada, young adults have been identified as being at high risk for sexually transmitted infections (STI). One major contributing factor is inconsistent condom use, particularly within monogamous relationships (Civic, 2000; Critelli & Suire, 1998; Misovich, Fisher & Fisher, 1997; Winfield & Whaley, 2005). This research used qualitative methods to investigate the process by which young women rationalize inconsistent condom use and the relational influences that aid in this transition. A sample of fifteen women (between 18-24 years of age) were surveyed and interviewed. Using grounded theory analysis, the results indicated that the process of discontinuing condoms is multifaceted. Within relationships, unprotected sex comes to signify developmental milestones for the couple. It is associated with desirable relationship characteristics of commitment, trust, intimacy and fidelity. The results suggest that health promotion interventions should emphasize the high risk for STI posed by using condoms inconsistently within the monogamous relationships of young adults.

Menopause, the cessation of reproductive capabilities before death, is a detrimental trait for female fitness, yet persists in all human populations. Numerous hypotheses have been published to describe how menopause has been maintained but failed to explain the origin and genetic basis of this trait. In 2013, Morton et al. proposed an influence of the mate choice behaviour, specifically a bias in mating ages that could allow for a trait, seemingly detrimental to fitness, to become neutrally fixed in a population. The goal of our research, presented herein, is to understand the role of the mating system, the sexual behaviour of a group, and especially mate choice, on the origin and evolution of menopause under a serial monogamy scenario. Analysis was conducted using an agent-based computational model that simulated populations. The populations were generated according to specified demographic parameters and reproduced according to a serial monogamy mating system. With the model, parameters were investigated including population lifespan, fecundity, pairing eligibility, age of loss of fecundity, and timing of decay in fecundity. Simulations revealed that, under certain restrictions, menopause can neutrally evolve. When mate choice was restricted to a particular age preference bias, menopause can appear with no diminishment of fitness. This novel mode for the origin of menopause is inferred to result from the accumulation of deleterious mutations in the female genome. By combining this ability of fertility-diminishing mutations to accumulate with research into the genetic basis of menopause, we provide a system for the evolution of menopause in a population of serial monogamy. / Thesis / Master of Science (MSc) / Despite decades of research into menopause, there remains no clear understanding of how this deleterious trait came to persist in the human population. It has been proposed that a bias in mate choice such that only younger females are chosen to mate can result in the accumulation of deleterious mutations, ultimately leading to menopause. We analyzed the evolution of menopause under a mating system of serial monogamy by a computational simulation. We came to three main conclusions. Firstly, under modern demographic parameters, menopause cannot evolve under serial monogamy. Secondly, in a population of shortened longevity, similar to chimpanzee, menopause neutrally appears at an age presently experienced by women. Finally, when mate choice is restricted such that only young females are eligible to mate within a system of serial monogamy, menopause can evolve. This means with the current mate choice shift towards older women, menopause can be postponed or even eliminated.

Introduction: Sexually Transmitted Diseases, including HIV/AIDS, continue to be a major burden in the United States. Sexual partnering behaviors contribute to the spread of STDs. Sexual concurrency has been shown to exponentially increase STD prevalence in populations. Serial monogamy with short periods between sexual partners also introduces risk. Methods: We identified sexually active men and women from the 2006-2010 National Survey of Family Growth (NSFG) and used sub sets for each particular study. Sexual partnering was defined as being concurrent, serially monogamous or monogamous in the previous year. Polytomous logistic regression models were developed to evaluate the associations between age of sexual debut among adult men, age of menarche and discordant heterosexual identity and behavior among all women and sexual partnering patterns. Descriptive, mediation, subpopulation and stratified analyses were also conducted. Results: Sexual debut < 15 and 15-17 years was associated with concurrency (adjusted odds ratio (aOR)<15: 2.19; 95% Confidence Interval (CI): 1.36-3.55; aOR 15-17: 1.69; 95% CI: 1.04-2.75). This association was mediated by lifetime number of partners (further adjusted for lifetime partners: OR<15: 1.26; 95% CI: 0.74-2.22; OR15-17: 1.13; 95% CI: 0.67-1.92). Age of menarche was not associated with subsequent concurrent sexual partnering (adjusted odds ratio (aOR)early: 1.09; 95% Confidence Interval (CI): 0.57-2.09; aORaverage: 1.13; 95% CI: 0.64-1.99) or serial monogamy (aORearly: 0.75; 95% CI: 0.41-1.38; aORaverage: 0.71; 95% CI: 0.39-1.29). A subanalysis among currently unmarried women did not alter this relationship. Heterosexually discordant women who had both male and female partners in the previous year were 5.5 times as likely to report having a concurrent relationship (95% CI: 2.77-11.09) and 2.43 times as likely to report engaging in serially monogamous relationships (95% CI: 1.19-4.97) with their male partners than concordant women. Conclusions: Sexual partnering behaviors are potentially modifiable and reducing risky partnerships will contribute to a decrease in STD acquisition and transmission. Our findings have important implications. Clinically, they support the provision of comprehensive services, regardless of sexual identity. For policy, they confirm the need for early, inclusive and thorough sexual and reproductive health programming for our youth, in particular focusing on the benefits of lifetime partner reduction.