The author of this book begins the proceedings by observing that “You and I have probably never met, but you might be shocked to learn how well we know one another and how intimately our lives are connected” (p. vii). What is one to make of a book with such an inscrutable beginning? Is this a “self-help” book that will alter the life of the reader in no uncertain terms? Or is it a tome about the powerful nexuses that exist between a reader and his or her many---but hitherto unknown---relatives?

Interestingly, this book turns out to be neither a self-help book nor a book about the potent connections between a reader and his or her seemingly unknown relatives. Instead, this book is an informative and colorful rendition of the many advances that modern evolutionary psychology has made in comprehending and credibly explaining many facets of human behavior.

For instance, consider the following question: Can Playboy magazine be bad for one’s mental mechanisms? The author sheds light on this question by first pointing to some key differences in the ways in which men and women perceive each other. Specifically, we are told that beautiful women capture both male and female attention and they “monopolize downstream cognitive processes” (p. 14). In contrast, although handsome men do grab women’s eyes, they “quickly get washed out of the stream of mental processing” (p. 14). An implication of this difference is that relative to men, women are more selective and less interested in casual affairs with strangers. What looking at Playboy centerfolds does for men is that it changes their adaptation level for what they consider beautiful. The insalubrious implication is that real women do not look as attractive once one’s mind has been calibrated to suppose that centerfolds represent normal women. Further, for men in relationships, “exposure to beautiful photos undermines their feelings about the real flesh-and-blood women with whom their lives are actually intertwined” (p. 17).

A key finding discussed by the author is that the human brain typically does not use the same set of rules to make decisions about different people in one’s life. Given this state of affairs, the author proposes to use of what he calls a “domain-specific theory.” In this view of the human brain, there is no single self in one’s head. Instead, “there is a confederation of modular subselves, each one specialized to do one thing well” (p. 81). The author helpfully illustrates this point by noting that the “team player,” the “night watchman,” the “good spouse,” and the “parent” are all examples of the separate characters that a person can have running inside his or her head.

A central motif running throughout this tome is that different kinds of behavior can be explained when studied using the lens of reproductive success. The author repeatedly contends that although men can afford to have a sexual relationship with an attractive stranger with little or no cost, a woman needs “to make an informed decision...” (p.120) in large part because she will have to devote significant amounts of both time and energy to take care of any offspring. Although this contention is not apocryphal, it is also true that in large parts of the developed world, the easy availability of both contraceptives and abortion has made it a lot less necessary for women to make “informed decisions.” Therefore, it would have been interesting to report the results of experimental studies that are designed to determine whether the availability of contraceptives and abortion has changed women’s attitudes towards casual relationships in particular and mating strategies in general. Unfortunately, the author says very little about this germane topic.

The discussion of why men apparently go out of their way to avoid purchasing Consumer Reports “best buys” is of uneven quality. Here are two examples of quixotic thinking on the author’s part. First, he contends that if we “calculate the value of [a Toyota and a Lexus] from the perspective of Consumer Reports, it is clearly less rational to buy the Lexus” (p. 128). The author does not define “rational” and hence this quoted sentence is not obviously true. In this regard, suppose that consistent with standard practice in modern economics, we define rational behavior to mean goal-oriented behavior. Then, if a person’s goal is to buy a luxury car and we observe this person buying a Lexus when he could have bought a Toyota, then his behavior is not “less rational.” Second, the author claims that “[e]conomists define utility as expected future satisfaction” (p. 129). At the very least, this claim is misleading. What is true is that economists think of utility as the happiness or satisfaction that an individual derives by undertaking a particular action. The word “expected” means “average” and this would be pertinent only if utility were being talked about in a stochastic setting. In addition, in the usual case, utility refers to the current happiness or satisfaction from a current action and not the future happiness or satisfaction from a current action.

In sum, as noted above, this book makes a few errors of both commission and omission. In addition, its discussion of relevant concepts from economics is rudimentary and occasionally misleading. Finally, there is a “truth in advertising” issue because the book has very little to say about the meaning of life. These caveats notwithstanding, it should be noted that this is a lucid book written in a very chatty and easily readable style and filled with interesting anecdotes from the author’s life. This book is recommended to all readers who wish to learn about the many ways in which evolutionary psychology can shed valuable light on topics as varied as homicidal tendencies and sexual fantasies.