This book is largely a reiteration of what's been said by many others on the evolutionary underpinnings of human behavior, but the author places this information loosely within a cost-benefit framework. He says that we play "games" with each other not for fun, but for seeking benefits for ourselves. Whether we aggress or retreat depends on the situation we find ourselves relative to others and our conscious or non-conscious assessment of benefit.
What's not clear is the degree to which inner attributes have a role in all of this. The same situation can and does generate different actions and responses because of who we are. The author acknowledges that "individuals' physiological and psychological characteristics" have a role and that, for example, "some may be predisposed to act dominant and others to act subordinate," but this is not his emphasis. In stressing his argument that situational dynamics are key, the author quotes the proverb, "opportunity turns man into a thief." That perspective suggests we all have a common tendency to engage in self-interest cost-benefit calculations. That approach does not recognize that there's considerable variability among individuals on particular traits and dispositions that make "rational models of behavior" that apply universally problematic at best. Inner, inborn, and variable dispositions might have a far more determining role in what we do in any particular situation than what the author articulates.
In making his rational model work, the author too narrowly categorizes relationships in terms of competition (self at the expense of other) and cooperation as self-other cooperation for mutual benefit. In addition to the utilitarian cost-benefit relationships he emphasizes, another prong to cooperation might be those social tendencies that promote group bonding without cost-benefit assessments. Rather than self standing apart from the other and the group, the self and other are merged as one so that there is little assessment of relative benefit. Of course, this organic relationship has a self-interested benefit as the self's welfare is tied to his or her union with the group, but this is far removed from what the author seems to be saying.
Despite these comments, this is an interesting book with a good point of view. The author observes that many remark about how much primates are "like us." He says that's another example where we see ourselves as the center of the world. He counters by saying "how much we are like them." That is a more accurate way to describe us and our primate heritage. This ties us to the same life force we share with all beings and that's a healthy, and even uplifting, perspective.