Toy model for the adaptive origins of the sexual orientation continuum

Same-sex sexual behavior is ubiquitous in the animal kingdom, but its adaptive origins remain a prominent puzzle. Here I suggest the possibility that same-sex sexual behavior arises as a consequence of the competition between an evolutionary drive for a wide diversity in traits, which improves the adaptability of a species, and a drive for sexual dichotomization of traits, which promotes opposite-sex attraction and increases the rate of reproduction. A simple analytical “toy model” is proposed for describing this tradeoff. The model exhibits a number of interesting features, and suggests a simple mathematical form for describing the sexual orientation continuum.