Was Civilization the Cure for Primordial Human Violence?

Hobbes is hot. The 17^th-century British philosopher argued that before civilization, our ancestors were mired in a “war of all against all.” Only the emergence of powerful governments, “Leviathans,” Hobbes called them, curbed our violent tendencies.

Many influential modern scholars, notably Harvard psychologist Steven Pinker, espouse versions of this Hobbesian view. In his 2011 bestseller The Better Angels of Our Nature, Pinker asserts that even the most war-torn modern states are “far less violent than traditional bands and tribes.” “Hobbes got it right,” Pinker declared in a 2007 essay.

The Hobbesian view overlaps with what I call the deep-roots theory of war, which holds that lethal group violence is innate, bred into us by natural selection. These claims have consequences. Many people believe that if war is innate, it is inevitable, and hence efforts to eradicate it are futile.

A new study in Nature, “The phylogenetic roots of human lethal violence,” adds fuel to the debate over the origins of violence. The study, carried out by Jose Maria Gomez of the University of Granada and three other researchers, asserts that “lethal violence is deeply rooted in the primate lineage” and that humans “inherited their propensity for violence.”

In a commentary in Nature, biologist Mark Pagel claims that the Gomez study represents a “serious blow” in favor of the Hobbesian viewpoint. Actually, the study contradicts Hobbesian/deep-roots models, which depict lethal violence as a genetic disease that civilization has helped to cure.

Gomez and his colleagues compiled estimates of rates of lethal violence observed within more than 1,000 mammalian species, including our own. The group found similar rates of intra-species violence among closely related species. Rates tended to be higher among social, territorial species, notably primates.

The group calculates that Homo sapiens, based on its genetic proximity to chimpanzees and other species, should have a mortality rate from intra-species violence of about two percent. That means violence causes two out of every hundred deaths.

Empirical data on violent deaths among Paleolithic humans—before the advent of agriculture and permanent settlements—also indicate that two percent died violently, according to Gomez et al. This estimate is almost an order of magnitude lower than that of Pinker, who claims that the average rate of violent death among prehistoric people was 15 percent.

Gomez’s group also shows lethal violence surging rather than declining for thousands of years after humans settled down and formed chiefdoms, states and empires. According to their data, lethal violence started declining worldwide about 500 years ago and fell below Paleolithic levels during the last 100 years.

Unlike Pagel in his commentary on their study, Gomez and his colleagues are cautious in drawing conclusions, and they emphasize the uncertainties in estimates of rates of ancient bloodshed. But they strike a Hobbesian note when commenting on the recent decline in global violence. “It is widely acknowledged,” they write, “that monopolization of the legitimate use of violence by the state significantly decreases violence in state societies.”

States, at their best, do indeed promote peace both within and beyond their borders. But during the last 100 years states have also been responsible for horrific warfare and genocide—and the invention of weapons that can destroy civilization. States represent the solution to violence, but they are also part of the problem.

John Horgan directs the Center for Science Writings, which is part of the College of Arts & Letters. This column is adapted from one originally published on his ScientificAmerican.com blog, “Cross-check.”