Over the past century, violent images from World War II concentration camps, Cambodia, Rwanda, Darfur, Iraq, and many other times and places have been seared into our collective consciousness. These images have led to a common belief that technology, centralized nation-states, and modern values have brought about unprecedented violence.
Our seemingly troubled times are routinely contrasted with idyllic images of hunter-gatherer societies, which allegedly lived in a state of harmony with nature and each other. The doctrine of the noble savage—the idea that humans are peaceable by nature and corrupted by modern institutions—pops up frequently in the writing of public intellectuals like, for example, Spanish philosopher José Ortega y Gasset, who argued that “war is not an instinct but an invention.”
But now that social scientists have started to count bodies in different historical periods, they have discovered that the romantic theory gets it backward: Far from causing us to become more violent, something in modernity and its cultural institutions has made us nobler. In fact, our ancestors were far more violent than we are today. Indeed, violence has been in decline over long stretches of history, and today we are probably living in the most peaceful moment of our species’ time on earth.
A history of violence
In the decade of Darfur and Iraq, that statement might seem hallucinatory or even obscene. But if we consider the evidence, we find that the decline of violence is a fractal phenomenon: We can see the decline over millennia, centuries, decades, and years. When the archeologist Lawrence Keeley examined casualty rates among contemporary hunter-gatherers—which is the best picture we have of how people might have lived 10,000 years ago—he discovered that the likelihood that a man would die at the hands of another man ranged from a high of 60% in one tribe to 15% at the most peaceable end. In contrast, the chance that a European or American man would be killed by another man was less than 1% during the 20th century, a period of time that includes both world wars. If the death rate of tribal warfare had prevailed in the 20th century, there would have been two billion deaths rather than 100 million, horrible as that is.
Ancient texts reveal a stunning lack of regard for human life. In the Bible, the supposed source of all our moral values, the Hebrews are urged by God to slaughter every last resident of an invaded city. “Go and completely destroy those wicked people, the Amalekites,” reads a typical passage in the book of Samuel. “Make war on them until you have wiped them out.” The Bible also prescribes death by stoning as the penalty for a long list of nonviolent infractions, including idolatry, blasphemy, homosexuality, adultery, disrespecting one’s parents, and picking up sticks on the Sabbath. The Hebrews, of course, were no more murderous than other tribes; one also finds frequent boasts of torture and genocide in the early histories of the Hindus, Christians, Muslims, and Chinese.
But from the Middle Ages to modern times, we can see a steady reduction in socially sanctioned forms of violence. Many conventional histories reveal that mutilation and torture were routine forms of punishment for infractions that today would result in a fine. In Europe before the Enlightenment, crimes like shoplifting or blocking the king’s driveway with your oxcart might have resulted in your tongue being cut out, your hands being chopped off, and so on. Many of these punishments were administered publicly, and cruelty was a popular form of entertainment.
We also have very good statistics for the history of one-on-one murder, because for centuries many European municipalities have recorded causes of death. When the criminologist Manuel Eisner scoured the records of every village, city, county, and nation he could find, he discovered that homicide rates in Europe had declined from 100 killings per 100,000 people per year in the Middle Ages to less than one killing per 100,000 people in modern Europe.
And since 1945 in Europe and the Americas, we’ve seen steep declines in the number of deaths from interstate wars, ethnic riots, and military coups, even in South America. Worldwide, the number of battle deaths has fallen from 65,000 per conflict per year to less than 2,000 deaths in this decade. Since the end of the Cold War in the early 1990s, we have seen fewer civil wars, a 90% reduction in the number of deaths by genocide, and even a reversal in the 1960s-era uptick in violent crime.
Given these facts, why do so many people imagine that we live in an age of violence and killing? The first reason, I believe, is that we have better reporting. As political scientist James Payne once quipped, the Associated Press is a better chronicler of wars across the globe than were 16th-century monks. There’s also a cognitive illusion at work. Cognitive psychologists know that the easier it is to recall an event, the more likely we are to believe it will happen again. Gory war zone images from TV are burned into memory, but we never see reports of many more people dying in their beds of old age. And in the realms of opinion and advocacy, no one ever attracted supporters and donors by saying that things just seem to be getting better and better. Taken together, all these factors help create an atmosphere of dread in the contemporary mind, one that does not stand the test of reality.
Finally, there is the fact that our behavior often falls short of our rising expectations. Violence has gone down in part because people got sick of carnage and cruelty. That’s a psychological process that seems to be continuing, but it outpaces changes in behavior. So today some of us are outraged—rightly so—if a murderer is executed in Texas by lethal injection after a 15-year appeal process. We don’t consider that a couple of hundred years ago a person could be burned at the stake for criticizing the king after a trial that lasted 10 minutes. Today we should look at capital punishment as evidence of how high our standards have risen, rather than how low our behavior can sink.
Expanding the circle
Why has violence declined? Social psychologists find that at least 80% of people have fantasized about killing someone they don’t like. And modern humans still take pleasure in viewing violence, if we are to judge by the popularity of murder mysteries, Shakespearean dramas, the Saw movie franchise, Grand Theft Auto, and hockey.
What has changed, of course, is people’s willingness to act on these fantasies. The sociologist Norbert Elias suggested that European modernity accelerated a “civilizing process” marked by increases in self-control, long-term planning, and sensitivity to the thoughts and feelings of others. These are precisely the functions that today’s cognitive neuroscientists attribute to the prefrontal cortex. But this only raises the question of why humans have increasingly exercised that part of their brains. No one knows why our behavior has come under the control of the better angels of our nature, but there are four plausible suggestions.
The first is that the 17th-century philosopher Thomas Hobbes got it right. Life in a state of nature is nasty, brutish, and short—not because of a primal thirst for blood but because of the inescapable logic of anarchy. Any beings with a modicum of self-interest may be tempted to invade their neighbors and steal their resources. The resulting fear of attack will tempt the neighbors to strike first in preemptive self-defense, which will in turn tempt the first group to strike against them preemptively, and so on. This danger can be defused by a policy of deterrence—don’t strike first, retaliate if struck—but to guarantee its credibility, parties must avenge all insults and settle all scores, leading to cycles of bloody vendetta.
These tragedies can be averted by a state with a monopoly on violence. States can inflict disinterested penalties that eliminate the incentives for aggression, thereby defusing anxieties about preemptive attack and obviating the need to maintain a hair-trigger propensity for retaliation. Indeed, Manuel Eisner attributes the decline in European homicide to the transition from knightly warrior societies to the centralized governments of early modernity. And today, violence continues to fester in zones of anarchy, such as frontier regions, failed states, collapsed empires, and territories contested by mafias, gangs, and other dealers of contraband.
James Payne suggests another possibility: that the critical variable in the indulgence of violence is an overarching sense that life is cheap. When pain and early death are everyday features of one’s own life, one feels less compunction about inflicting them on others. As technology and economic efficiency lengthen and improve our lives, we place a higher value on life in general.
A third theory, championed by journalist Robert Wright, invokes the logic of non-zero-sum games: scenarios in which two agents can each come out ahead if they cooperate, such as trading goods, dividing up labor, or sharing the peace dividend that comes from laying down their arms. As people acquire know-how that they can share cheaply with others and develop technologies that allow them to spread their goods and ideas over larger territories at lower cost, their incentive to cooperate steadily increases, because other people become more valuable alive than dead.
Then there is the scenario sketched by philosopher Peter Singer. Evolution, he suggests, bequeathed people a small kernel of empathy, which by default they apply only within a narrow circle of friends and relations. Over the millennia, people’s moral circles have expanded to encompass larger and larger polities: the clan, the tribe, the nation, both sexes, other races, and even animals. The circle may have been pushed outward by expanding networks of reciprocity, à la Wright, but it might also be inflated by the inexorable logic of the Golden Rule: The more one knows and thinks about other living things, the harder it is to privilege one’s own interests over theirs. The empathy escalator may also be powered by cosmopolitanism, in which journalism, memoir, and realistic fiction make the inner lives of other people, and the precariousness of one’s own lot in life, more palpable—the feeling that “there but for fortune go I.”
Whatever its causes, the decline of violence has profound implications. It is not a license for complacency: We enjoy the peace we find today because people in past generations were appalled by the violence in their time and worked to end it, and so we should work to end the appalling violence in our time. Nor is it necessarily grounds for optimism about the immediate future, since the world has never before had national leaders who combine pre-modern sensibilities with modern weapons.
But the phenomenon does force us to rethink our understanding of violence. Man’s inhumanity to man has long been a subject for moralization. With the knowledge that something has driven it dramatically down, we can also treat it as a matter of cause and effect. Instead of asking, “Why is there war?” we might ask, “Why is there peace?” If our behavior has improved so much since the days of the Bible, we must be doing something right. And it would be nice to know what, exactly, it is.