summarize,cite and speculate on some research which contributes to the discussion of the (possible) evolutionary function of heterosexual nonproductive sexual behavior.

summarize,cite and speculate on some research which contributes to the discussion of the (possible) evolutionary function of heterosexual nonproductive sexual behavior. Please use some nonhuman primate data in addition to human data. In addition, please be as efficient as possible and avoid introductory discussions (filler) about evolution and sexual behavior. Restrict paper to heterosexual nonreproductive sexual behavior only. Minimize or avoid any discussion on masturbation.