In this paper I explored the biological basis of human sexuality including sex drive and sexual orientation in order to assist people with learning about their own sexuality, and how sexual identity and preference is linked to biological mechanisms. Studies have found that hormone levels, such as testosterone, influence our sexuality, that physical sexual arousal can affect our subjective sexuality and cause us to make sexual behavioural choices we wouldn’t make when unaroused, and that there are physical differences in the brain’s amygdala between homosexual and heterosexual brains. In my first (correlational) study, I tested the strength of these relationships by examining naturalistic daily changes in their variables longitudinally over a two-week period. I measured the level of testosterone using a period tracking app, physical arousal using a set scale, amygdala activity through the heartbeat, and the amount of sexual activity with journal entries. Data in this correlational study showed significant correlations of sexual activity with testosterone level, physical arousal, and amygdala activity. Based on the strength of correlation found between physical arousal and sexual activity, I then conducted a second (experimental) study to test for specifically a causal relationship between these two variables. Over a two-week period, on alternating days the participant was assigned to either a high physical arousal day (watching pornographic videos) condition or a low physical arousal (no pornographic videos) condition and the effect this had upon sexual activity that day was measured. The results from the experimental study failed to find a causal role of physical arousal on sexual activity. A possible practical application of the current findings are the ability to know best when to engage in sexual activity to get pregnant, though the true cause of human sexuality still remains to be discovered.
