Comparisons of different primate species suggest that male homosexuality evolved along with male cooperation which passed through distinct stages of 1) marking territories, 2) marking submissive males via mechanisms previously used for territorial markings, 3) marking alliances via mutual gestures of dominance and submission. Among humans, exclusive male homosexuals are at the extreme submissive end of a dominant/submissive personality continuum. Individuals at the two extremes of this continuum do not reproduce — extreme dominants because they die in fights, and extreme submissives because they do not attempt reproduction. However, due to the selective advantage of individuals with genes for both dominance and submission, individuals at the extremes of the continuum continue to appear in accordance with Mendelian laws. Psychological research on the the characteristics of male homosexuals and on general attitudes toward homosexuals agrees with the predictions from this theory.

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