Bret Stetka in Scientific American:
In his 2011 book The Better Angels of Our Nature: Why Violence Has Declined, Harvard University psychologist and famed intellect Steven Pinker argues humans are now living in the most peaceful era in the history of our species. At the time the U.S. was mired in two wars in the Middle East and Central Asia, the conflict in Darfur had just come to a close and terrorist insurgent group Boko Haram was setting off bombs across northern Nigeria. Such examples still abound years later. Last week violent incidents in New York City and Sutherland Springs, Texas, left many dead and injured. “The claim that we are living in an unusually peaceful time may strike you as somewhere between hallucinatory and obscene,” Pinker wrote. “I know from conversations and survey data that most people refuse to believe it.” Yet there is plenty of evidence supporting Pinker’s claim. Most scholars agree the percentage of people who die violent war-related deaths has plummeted through history; and that proportionally violent deaths decline as populations become increasingly large and organized, or move from “nonstate” status—such as hunter–gatherer societies—to fully fledged “states.” Still, there are many ways to look at the data—and quantifying the definition of a violent society. A study in Current Anthropology published online October 13 acknowledges the percentage of a population suffering violent war-related deaths—fatalities due to intentional conflict between differing communities—does decrease as a population grows. At the same time, though, the absolute numbers increase more than would be expected from just population growth. In fact, it appears, the data suggest, the overall battle-death toll in modern organized societies is exponentially higher than in hunter–gatherer societies surveyed during the past 200 years.
The study—led by anthropologists Dean Falk at The Florida State University and Charles Hildebolt at Washington University in Saint Louis—cut across cultures and species and compared annual war deaths for 11 chimpanzee communities, 24 hunter–gatherer or other nonstate groups and 19 and 22 countries that fought in World Wars I and II, respectively. Overall, the authors’ analysis shows the larger the population of a group of chimps, the lower their rate of annual deaths due to conflict. This, according to the authors, was not the case in human populations. People, their data show, have evolved to be more violent than chimps. And, despite high rates of violent death in comparison with population size, nonstate groups are on average no more or less violent than those living in organized societies. Falk and Hildebolt point out Pinker’s claims are based on data looking at violent death rates per 100,000 people. They contend such ratios don’t take into account how overall population size alters war death tallies—in other words how those ratios change as a population grows, which their findings do. There is a strong trend for larger societies to lose smaller percentages of their members to war, Falk says, but the actual number of war deaths increases with growing population sizes. “This is not what one would predict if larger societies were less violent than smaller ones,” she says. Falk adds that small communities are not necessarily more violent than larger populations—they are simply more vulnerable to losing a significant portion of their population due to outsider attacks. “If I walk down a dark alley at night, I am potentially more vulnerable to being killed than I am when I attend a football game,” Falk says. She admits citing a population of one in an alley is an extreme example. But she adds that smaller populations suffering a higher percentage of casualties at the hands of another population are not necessarily more innately violent than large modern societies are—they might instead just be the victims.