The second, updated edition of this book is a well-written and at times funny argument for the idea that we humans are a thoroughly political animal. Politics is inherent in our form of sociality, and political differences are not aberrations but simply a fact of how we are wired. We have inborn predispositions as to where on the political scale each one of us is located. This scale, the authors contend, is one that goes from the radical stance (pro-change, novelty seeking, interested in others) to the conservative position (pro-tradition, defense of the current state, wary of others). Interestingly, the authors consider the dimension of distributive justice (pro-equality vs pro-meritocratic distribution) to be of lesser importance.
Many different studies are brought to bear on the idea that the differences in political outlook correlate with numerous other traits, ranging from food preferences, attitudes towards strangers, moral foundations, visual attention reactions, and so on. The correlations are in general not particularly strong, but neither are they negligible.
The authors discuss the current political environment of polarisation between the radical and the conservative sides. What they do not adequately account for, in my opinion, is the shift in Western societies from a focus on issues of wealth and distribution towards the so-called culture wars. A scientific analysis that cannot explain the dynamics of the political scene is lacking something. The authors' wish to drive home the innateness of political differences has led to a certain blindness to the fact that cultural and institutional dynamics must also play a strong role. If politics changes, and our genes do no, then something else must account for that change.
But all in all, this is a good read, with many interesting points and useful leads to the current literature.