Homosexuality as a ritual to express rank among males

Sometimes seemingly abnormal behaviour proves on closer inspection to be adaptive after all. Consider specific cases cases of homosexuality, which we are conditioned to think of as necessarily abnormal. In the macaques pseudocopulation is a common ritual used to express rank among males, with the dominant individual mounting the subordinate. 

-E.O. Wilson, Sociobiology p. 22, 25th Anniversary Edition