The WSJ has published an essay by Steven Pinker on the decline of violence, which is adapted from his upcoming book The Better Angels of Our Nature: Why Violence Has Declined. Pinker points out six major declines in violence in human history, starting with the shift from the hunter-gatherer life:
The first was a process of pacification: the transition from the anarchy of the hunting, gathering and horticultural societies in which our species spent most of its evolutionary history to the first agricultural civilizations, with cities and governments, starting about 5,000 years ago.
For centuries, social theorists like Hobbes and Rousseau speculated from their armchairs about what life was like in a “state of nature.” Nowadays we can do better. Forensic archeology—a kind of “CSI: Paleolithic”—can estimate rates of violence from the proportion of skeletons in ancient sites with bashed-in skulls, decapitations or arrowheads embedded in bones. And ethnographers can tally the causes of death in tribal peoples that have recently lived outside of state control.
These investigations show that, on average, about 15% of people in prestate eras died violently, compared to about 3% of the citizens of the earliest states. Tribal violence commonly subsides when a state or empire imposes control over a territory, leading to the various “paxes” (Romana, Islamica, Brittanica and so on) that are familiar to readers of history.
This was followed by the “civilising” process in Europe, a humanitarian revolution around the time of the Enlightenment, the respite from major war since World War II, the decline of war worldwide and the rights revolutions which involves a “growing revulsion against aggression on smaller scales”.
The facts speak for themselves, so Pinker’s explanations for what lies behind these declines is more interesting. His three major explanatory factors are the pacifying influences of the state, of commerce and of cosmopolitanism. A change in inherent human nature is ruled out:
Is it because violence has literally been bred out of us, leaving us more peaceful by nature?
This seems unlikely. Evolution has a speed limit measured in generations, and many of these declines have unfolded over decades or even years. Toddlers continue to kick, bite and hit; little boys continue to play-fight; people of all ages continue to snipe and bicker, and most of them continue to harbor violent fantasies and to enjoy violent entertainment.
It’s more likely that human nature has always comprised inclinations toward violence and inclinations that counteract them—such as self-control, empathy, fairness and reason—what Abraham Lincoln called “the better angels of our nature.” Violence has declined because historical circumstances have increasingly favored our better angels.
I look forward to reading Pinker’s reasoning in more detail. While many of the changes in violence occur over the very short-term, the longer term trend has occurred over thousands of years, with ample potential for evolutionary change. Further, the hypothesis of Donohue and Levitt on the legalisation of abortion and crime suggests that changing the population composition can can have large effects in short periods, although it is not clear whether the cohort eliminated in the wake of the Roe v Wade decision would have been criminals due to upbringing or inherent traits.