Once again, Barack Obama, the world’s most powerful military leader, has propagated an erroneous claim about the origins of war.

Speaking in Hiroshima on May 27, the President says: “Artifacts tell us that violent conflict appeared with the very first man.” World War II, he adds, “grew out of the same base instinct for domination or conquest that had caused conflicts among the simplest tribes.” [Italics added.] When accepting the Nobel Peace Prize in 2009, the President made similar claims. “War,” he said, “in one form or another, appeared with the first man.”

Obama has embraced the popular idea that war—not just aggression, or interpersonal violence, but lethal group conflict--is deeply rooted in our evolution and nature. This thesis has been propagated by such prominent scientists as Jared Diamond, Richard Wrangham, Edward Wilson and, most notably, psychologist Steven Pinker.

As evidence, deep-rooters cite the group violence of chimpanzees, our genetic cousins, and of “primitive” tribal people such as the Yanomamo, hunters who dwell in the rain forests of Amazonia.

“Chimpicide,” Pinker writes in his 2002 bestseller The Blank Slate, “raises the possibility that the forces of evolution, not just the idiosyncrasies of a particular culture, prepared us for violence." In his 2011 work The Better Angels of Our Nature, Pinker asserts that "chronic raiding and feuding characterize life in a state of nature."

In Angels, Pinker contends that civilization, especially as embodied by western, post-Enlightenment states, is helping us overcome our savage nature. This Hobbesian worldview leads Pinker to overstate the violence of pre-historic, tribal humans and to downplay the violence of modern states, notably the U.S.

The preponderance of evidence shows that war, far from being an ancient, innate behavior, was a cultural innovation—an “invention,” as anthropologist Margaret Mead put it--that emerged relatively recently in our prehistory, toward the end of the Paleolithic era.

The oldest clear-cut relic of group violence is a mass grave in the Jebel Sahaba region of Sudan. The grave contains 59 skeletons, 24 of which bear marks of violence, such as embedded projectile points. The skeletons are estimated to be 13,000 years old.

Other signs of violence of any kind dating back more than 10,000 years are rare. In 2013, anthropologists Jonathan Haas and Matthew Piscitelli carried out a review of hominid remains over 10,000 years old, including more than 2,900 skeletons from over 400 different sites. Haas and Piscitelli found only four skeletons bearing signs of violence

Counting Jebel Sahaba, that comes to a violent-death rate of less than one percent. Pinker, in Better Angels, estimates the rate of violent death among prehistoric people at 15 percent, which is much higher than global rates of violence even during the bloody 20th century.

Pinker’s estimate is also contradicted by a recent study carried out in Japan. Six scholars led by Hisashi Nakao examined the remains of 2,582 hunter-gatherers who lived 12,000 to 2,800 years ago, during Japan’s so-called Jomon Period. The researchers found bashed-in skulls and other marks consistent with violent death on 23 skeletons, a mortality rate of less than one percent.

Even this estimate might be high, the researchers note, because some injuries might have been caused by large animals or accidents. Remarkably, the team found no signs of violence on skeletons from the so-called Initial Jomon Period, which lasted from 12,000 to 7,000 years ago.

“We argue that warfare was probably not common among hunter–gatherers of the Jomon period,” Nakao and his colleagues state. Their study, they add, contradicts the claim “that warfare is inherent in human nature.”

Even after humans abandoned their nomadic ways in Japan and elsewhere, war emerged slowly and sporadically, according to anthropologist Brian Ferguson. Hunter-gatherers began settling down in the Southern Levant 15,000 years ago, and populations surged after the emergence of agriculture there 11,000 years ago.

But there is no significant evidence of warfare in the Southern Levant until about 5,500 years ago, Ferguson notes. This pattern, again, contradicts the claim that war was pervasive among early humans.

So does a study of simple hunter-gatherer societies that have persisted into the modern era. Incidents that could be described as group violence (with “group” defined as two or more people) occurred in only six out of 21 societies, according to anthropologists Douglas Fry and Patrik Soderberg. These findings "contradict recent assertions that [hunter-gatherers] regularly engage in coalitionary war against other groups."

Pinker emphasizes—most recently in a blast at me and other critics of the deep-roots theory--that just because war is innate does not mean it is inevitable. In his Hiroshima speech, Obama also seems, superficially, to repudiate genetic determinism. “We’re not bound by genetic code to repeat the mistakes of the past,” he says. “We can learn. We can choose.”

But read Obama’s speech carefully. He holds out hope not for the eradication of war but only of nuclear weapons, and probably not “in my lifetime.” He does not mention his own plan to revamp the U.S. nuclear arsenal.

In spite of all his uplifting rhetoric, Obama is basically reiterating what he said in 2009: “We must begin by acknowledging the hard truth: We will not eradicate violent conflict in our lifetimes. There will be times when nations--acting individually or in concert--will find the use of force not only necessary but morally justified.”

This is why the deep-roots theory is so insidious. Not only does it lack empirical support. It also makes people pessimistic about peace. Since 2003, I have asked thousands of people whether war will ever end, and almost everyone says no. Pessimists often defend their outlook with some version of the deep-roots claim.

Consider these quotes from high-ranking U.S. military officials. Former Secretary of Defense Donald Rumsfeld says in the 2013 Errol Morris documentary The Unknown Known: "Human nature being what it is, I'm afraid we'll have to continue to ask young men and women to come serve our country."

Marine General James Mattis, former head of the U.S. Central Command, said at a meeting I attended in 2010: “The nature of man has not changed, unfortunately. And it's not going to change anytime soon, I don't think. So we are going to have to be ready to fight, across the range of military operations, whatever the enemy chooses to do."

In a recent interview with Jeffrey Goldberg in The Atlantic, Obama displays the intelligence, thoughtfulness and decency that led me and many other voters to have high hopes for his presidency. But he also demonstrates a troubling tendency, like Pinker, to blame war on “tribalism” and to overlook the role of U.S. militarism.

Obama can still become a great peace leader. As a first step, he should consider alternatives to the deep-roots theory of war. He might check out A History of Warfare by John Keegan, arguably the greatest modern historian of war. Keegan argues that the primary cause of war is not “human nature” or competition for resources but “the institution of war itself.”

Like his predecessor Jimmy Carter, Obama could also ponder the possibility that U.S. militarism is doing more harm than good. He could even propose ways in which the U.S. could reverse that trend, perhaps by slashing its bloated military budget, ceasing drone assassinations and halting research on and sales of arms.

Most importantly, like John F. Kennedy, Obama should declare that peace is possible--not in the distant future but soon. The first step toward ending war is to believe we can do it.

Postscript: I haven’t seen any hard evidence that Obama has been influenced by Pinker. But historian/hawk Niall Ferguson recently wrote in The Atlantic (in a piece castigating Obama for being reluctant to use force in Syria and elsewhere—I know, the irony) that Obama “believes (following my Harvard colleague Steve Pinker) ‘that overall, humanity has become less violent, more tolerant, healthier, better fed, more empathetic, more able to manage difference.’” (That’s an Obama quote, which does indeed sound Pinker-esque, from the aforementioned interview by Jeffrey Goldberg.) Perhaps the Pinker fan is Ben Rhodes, Obama’s “foreign-policy guru.” Rhodes, who worked on Obama's 2009 Nobel and Hiroshima speeches, could have inserted references to the deep-roots theory into them. But again, that's just a hunch.

Post-Postscript: Our probable next President Hillary Clinton—who according to a recent New York Times Magazine profile is more hawkish than Obama and even Donald Trump--may also be a long-time believer in the deep roots theory of war. In 1998 New York Times columnist Maureen Dowd wrote: “Last year Hillary Clinton raved about a book she was reading called Demonic Males, about how naughtiness is wired into males of all species.” Written by aforementioned anthropologist Richard Wrangham and a journalist, Demonic Males is one of the most extreme defenses of the deep-roots theory of war. "Chimpanzee-like violence," Wrangham writes, "preceded and paved the way for human war, making modern humans the dazed survivors of a continuous, five-million-year habit of lethal aggression." This dramatic claim is contradicted by abundant archeaological and anthropological studies, including those cited above and others included in Further Reading.

Further Reading:

Meta-Post: Horgan Posts on War and Peace