The causality of sexual orientation is likely to be complex and influenced by multiple factors. We advocate incorporating a broader cultural vision into evolutionary and genetic studies to account for differences in how sexual orientation is experienced, expressed and understood in both humans and non-human animals.
The data currently available to scientists studying sexual orientation is impressive in its breadth, complexity and specificity. In humans, for example, sequenced genomes and surveys of hundreds of thousands of individuals are available, as are decades of observations from brain scans, eye tracking, genital arousal recordings and daily digital diaries. If there were a single, simple explanation for differences in sexual orientation, it would probably have been discovered by now. The fact that this has not been the case suggests that basic assumptions about what causes variation in sexual orientation (e.g. occurrence, function, representation, genetic basis, stability and gender) need to be re-examined. It is likely that sexual orientation is shaped by a complex interplay of various factors. In this context, we will focus on the causes that contribute to variations in phenotype. In addition, a relatively unexplored area of research concerns the reasons for and consequences of aversion to homosexual sexuality, at both individual and societal levels. Here, we discuss these historical assumptions, the research that has overcome them, and possible directions for the future.
Human evolutionary biology, by shaking up the traditional (but arbitrary) barriers between...More