Jealousy exists, like love and sex, to help propagate an individual's genes. It is a mechanism of the species to help insure for males paternity, and for females that their offspring receive the benefit of male protection, support and guidance. Jealousy is not "necessary" (as the subtitle disinformationally suggests) in the same sense that sex per se is necessary; nor is it an emotion, like love, that we might want to retain, had we our druthers. Jealousy is the emotional downside of the sexual/reproductive strategies employed by humans. It is "necessary" in the same sense (although not to the same degree) that pain is necessary. Furthermore, in the environment we now find ourselves, as opposed to the prehistoric savannahs in which the mechanism of jealousy proved adaptive, it is unnecessary, and something we might want to understand and come to grips with in an attempt to lessen its hold on us.
But what this book is really about is infidelity, how and why it occurs, and what can be done to forestall it. In this context, jealousy (not envy which is directed at somebody who has something we want) is seen as an adaptive mechanism to protect the individual against a straying partner, either through heightened awareness or through inducing threats of reprisal, or through actual punishment of the infidel. Buss, a psychologist and author of the college text, Evolutionary Psychology: The New Science of the Mind, uses case histories from our culture and others and the results of personality inventories laced with humor to illustrate how the experience of jealousy leads to "mate guarding" and "mate retention tactics" that help the individual secure his or her position in the "mating market." As such jealousy is seen as a "signal" to both one's self (awakening one to the imminent danger of infidelity) and to one's partner (as a warning that one is on to the other's tricks). Consequently, Buss defines jealousy (p. 196) as "an adaptive signal of an impending threat to a primary love relationship." Included in this view is the understanding that infidelity, painful as it is, is a normal human behavior practiced by "as many as half of all married individuals."
The style here is easy and accessible to a wide range of readers. The material is light-hearted (inasmuch as such a serious subject can be) but without any pasting-over of the dangers of jealousy. Underpinning the exposition is a thorough knowledge of human sexuality as derived from biology and evolutionary psychology. Buss not only knows what he is talking about, but imparts the information in a manner that, chapter by chapter, leads the reader to a deep and satisfying understanding of infidelity and the mechanism of jealousy.
Along the way we learn some unsettling facts. For example, marital happiness has no effect on the instance of male infidelity. "In fact, 56 percent of the men who were having affairs judged their marriage to be very happy" (p. 146). Or that women pursue a sexual strategy including a "desire to stray" that "exists today solely because that's what benefitted ancestral women" (p. 159). We also learn which type of personality is likely to stray (pp. 148-151) and that the more attractive partners ("those...higher in mate value") are more likely to cheat (p. 143). Also interesting is the semi-obvious observation that women can attract a higher-ranked male on a one-night stand than as a husband (and so might), and that men will stoop to lower-ranked females for pure sex than those they choose for wives.
Buss devotes the last two chapters to coping mechanisms. He concludes with the fine observation that "knowledge...of our dangerous passions...will, in some small measure, give us the emotional wisdom to deal with them." This observation is what evolutionary psychology is all about, and why it is the emergent psychology of the twenty-first century.
Best joke (p. 185): At a therapist's gathering with a straying husband, his wife and the other woman, the wife informs the affairee that she is still sleeping with her husband, and that he has lied to both of them. "The affairee felt betrayed and stalked out, saying...that all men betray their wives, but only a real asshole would betray his girlfriend." Buss adds, "Therapy was unsuccessful in this case."