The Iroquois system reflected the radically divergent priorities that a society must have during peacetime and during war. Because modern society often fights wars far away from the civilian population, soldiers wind up being the only people who have to switch back and forth. Siegfried Sassoon, who was wounded in World War I, wrote a poem called “Sick Leave” that perfectly described the crippling alienation many soldiers feel at home: “In bitter safety I awake, unfriended,” he wrote. “And while the dawn begins with slashing rain / I think of the Battalion in the mud.”
Given the profound alienation of modern society, when combat vets say that they miss the war, they might be having an entirely healthy response to life back home. Iroquois warriors did not have to struggle with that sort of alienation because warfare and society existed in such close proximity that there was effectively no transition from one to the other. In addition, defeat meant that a catastrophic violence might be visited upon everyone they loved, and in that context, fighting to the death made complete sense from both an evolutionary and an emotional point of view. Certainly, some Iroquois warriors must have been traumatized by the warfare they were engaged in—much of it was conducted at close quarters with clubs and hatchets—but they didn’t have to contain that trauma within themselves. The entire society was undergoing wartime trauma, so it was a collective experience—and therefore an easier one.
A rapid recovery from psychological trauma must have been exceedingly important in our evolutionary past, and individuals who could climb out of their shock reaction and resume fleeing or fighting must have survived at higher rates than those who couldn’t. A 2011 study of street children in Burundi found the lowest PTSD rates among the most aggressive and violent children. Aggression seemed to buffer them from the effects of previous trauma that they had experienced. Because trauma recovery is greatly affected by social factors, and because it presumably had such high survival value in our evolutionary past, one way to evaluate the health of a society might be to look at how quickly its soldiers or warriors recover, psychologically, from the experience of combat.
Almost everyone exposed to trauma reacts by having some sort of short-term reaction to it—acute PTSD. That reaction clearly has evolved in mammals to keep them both reactive to danger and out of harm’s way until the threat has passed. Long-term PTSD, on the other hand—the kind that can last years or even a lifetime—is clearly maladaptive and relatively uncommon. Many studies have shown that in the general population, at most 20 percent of people who have been traumatized get long-term PTSD. Rather than being better prepared for extraordinary danger, these people become poorly adjusted to everyday life. Rape is one of the most psychologically devastating things that can happen to a person, for example—far more traumatizing than most military deployments—and according to a 1992 study, close to one hundred percent of rape survivors exhibited extreme trauma immediately afterward. And yet almost half of rape survivors experienced a significant decline in their trauma symptoms within weeks or months of their assault.
That is a far faster recovery rate than soldiers have exhibited in the recent wars America has fought. One of the reasons, paradoxically, is because the trauma of combat is interwoven with other, positive experiences that become difficult to separate from the harm. “Treating combat veterans is different from treating rape victims, because rape victims don’t have this idea that some aspects of their experience are worth retaining,” I was told by Dr. Rachel Yehuda, the director of traumatic stress studies at Mount Sinai Hospital in New York. Yehuda has studied PTSD in a wide range of people, including combat veterans and Holocaust survivors. “For most people in combat, their experiences range from the best of times to the worst of times. It’s the most important thing someone has ever done—especially since these people are so young when they go in—and it’s probably the first time they’ve ever been free, completely, of societal constraints. They’re going to miss being entrenched in this defining world.”