  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.
