This is not a perfect book, but it is unique, and if you skim the first 400 or so pages, the last 300 (of some 700) are a pretty good attempt to apply what's known about behavior to social changes in violence and manners over time. The basic topic is: how does our genetics control and limit social change? Surprisingly he fails to describe the nature of kin selection (inclusive fitness) which explains much of animal and human social life. He also (like nearly everyone) lacks a clear framework for describing the logical structure of rationality (LSR—John Searle’s preferred term) which I prefer to call the Descriptive Psychology of Higher Order Thought (DPHOT). He should have said something about the many other ways of abusing and exploiting people and the planet, since these are now so much more severe as to render other forms of violence nearly irrelevant. Extending the concept of violence to include the global long-term consequences of replication of someone’s genes, and having a grasp of the nature of how evolution works (i.e., kin selection) will provide a very different perspective on history, current events, and how things are likely to go in the next few hundred years. One might start by noting that the decrease in physical violence over history has been matched (and made possible) by the constantly increasing merciless rape of the planet (i.e., by people's destruction of their own descendant’s future). Pinker (like most people most of the time) is often distracted by the superficialities of culture when it’s biology that matters. See my recent reviews of Wilson’s ‘The Social Conquest of Earth’ and Nowak and Highfield’s ‘SuperCooperators’ here and on the net for a brief summary of the vacuity of ‘true altruism’ (group selection), and the operation of kin selection and the uselessness and superficiality of describing behavior in cultural terms.
This is the classic nature/nurture issue and nature trumps nurture --infinitely. What really matters is the violence done to the earth by the relentless increase in population and resource destruction (due to medicine and technology and conflict suppression by police and military). About 200,000 more people a day (another Las Vegas every 10 days, another Los Angeles every month), the 6 tons or so of topsoil going into the sea/person/year –about 1% of the world’s total disappearing yearly, etc. mean that unless some miracle happens the biosphere and civilization will largely collapse during next two centuries, and there will be starvation, misery and violence of every kind on a staggering scale. People's manners, opinions and tendencies to commit violent acts are of no relevance unless they can do something to avoid this catastrophe, and I don't see how that is going to happen. There is no space for arguments, and no point either (yes I'm a fatalist), so I'll just make a few comments as though they were facts. Don't imagine I have a personal stake in promoting one group at the expense of others. I am 78, have no descendants and no close relatives and do not identify with any political, national or religious group and regard the ones I belong to by default as just as repulsive as all the rest.
Parents are the worst Enemies of Life on Earth and, taking the broad view of things, women are as violent as men when one considers the fact that women's violence (like most of that done by men) is largely done in slow motion, at a distance in time and space and mostly carried out by proxy -by their descendants and by men. Increasingly, women bear children regardless of whether they have a mate and the effect of stopping one woman from breeding is on average much greater than stopping one man, since they are the reproductive bottleneck. One can take the view that people and their offspring richly deserve whatever misery comes their way and (with rare exceptions) the rich and famous are the worst offenders. Meryl Streep or Bill Gates or J.K Rowling and each of their kids may destroy 50 tons of topsoil each per year for generations into the future, while an Indian farmer and his may destroy 1 ton. If someone denies it that's fine, and to their descendants I say "Welcome to Hell on Earth"(WTHOE).
The emphasis nowadays is always on Human Rights, but it is clear that if civilization is to stand a chance, Human Responsibilities must replace Human Rights. Nobody gets rights without being a responsible citizen and the first thing this means is minimal environmental destruction. The most basic responsibility is no children unless your society asks you to produce them. A society or a world that lets people breed at random will always be exploited by selfish genes until it collapses (or reaches a point where life is so horrific it's not worth living). If society continues to maintain Human Rights as primary, to their descendants one can say with confidence "WTHOE".
Those wishing a comprehensive up to date framework for human behavior from the modern two systems view may consult my book ‘The Logical Structure of Philosophy, Psychology, Mind and Language in Ludwig Wittgenstein and John Searle’ 2nd ed (2019). Those interested in more of my writings may see ‘Talking Monkeys--Philosophy, Psychology, Science, Religion and Politics on a Doomed Planet--Articles and Reviews 2006-2019 3rd ed (2019), The Logical Structure of Human Behavior (2019), and Suicidal Utopian Delusions in the 21st Century 4th ed (2019)