ABSTRACT
In strictly biological terms, sexual behavior is commonly related to reproduction, which favors evolution (Ågmo 1999). This concept, however, is questionable, as evolution favors the persistence of the most convenient characteristics at a certain moment and in a particular context. Undoubtedly in species with sexual reproduction, evolution is not possible without sexual behavior, but the notion that the ultimate purpose of this behavior is to achieve fertilization is a teleological rather than biological perspective, because there is no linear relationship between sexual behavior and fertilization (Møller and Birkhead 1991; Manson, Perry, and Parish 1997; Ågmo 1999). Thus, reproduction is one of the consequences of mating, so mating cannot be considered exclusively a reproductive behavior (Ågmo 1999; Meisel and Mullins 2006; Ågmo 2007a). An additional explanation is that
8.1 Why Copulate?.............................................................................................. 131 8.1.1 Hormonal Influence .......................................................................... 132 8.1.2 Wanting Sexual Activity ................................................................... 133
8.2 How Reward is Measured ............................................................................. 134 8.2.1 Liking Sexual Behavior ..................................................................... 134
8.3 Factors Altering Sexual Reward and Partner Selection ............................... 135 8.3.1 Sexual Behavior in Males and Females under Sexual Satiety
and the “Coolidge Effect”................................................................. 136 8.4 Biological Basis of Sexual Reward ............................................................... 138 8.5 Concluding Remarks .................................................................................... 139 Epilogue ................................................................................................................. 139 References .............................................................................................................. 140
animals mate because it is rewarding, which in turn assures that the animal will seek its repetition, as occurs with other behaviors such as feeding or social behavior (Berridge and Robinson 1998). Furthermore, sexual intercourse has other implications, depending on the species; for example, it was recently proposed that copulation in rats may prevent other males from impregnating the female (Lucio, Fernández-Guasti, and Larsson, see Chapter 5). In primates, including bonobos and chimpanzees, sexual behavior has different nonreproductive connotations (Wrangham 1993; Hrdy 1995), that is, (1) paternity confusion, in which the female copulates with different males, which may inhibit later potential harm toward her offspring; (2) practice interactions, where adolescent females or males interact sexually, gaining experience for their future sexual performance; (3) sex in exchange for food, when provisions are scarce, or for protection from a male, which provides an opportunity for mating; and (4) sex communication: in this case, sexual behavior helps to develop social relationships (e.g., homosexual interactions between a recent immigrant female with an older local one, thereby gaining social integration and protection), that prevents aggressions or repairs social relationships after an aggressive outburst (Wrangham 1993; Hrdy 1995; Manson, Perry, and Parish 1997). In humans, the reasons to have sex also go beyond fecundation, and are even more complex, and there are many interpretations to account for sexual encounters (for a discussion, see Pfaus et al. 2012).
