Armed conflict and its consequences concern us all. But where does war actually come from? In our new book, Sex and War: How Biology Explains War and Terrorism and Offers a Path to a Safer World, Thomas Hayden and I argue that warfare and terrorism are written in our DNA. But that doesn’t mean humanity is doomed to a future as violent as our past has been. Understanding the biological basis of our warring instincts, we argue, gives us our best hope of decreasing the frequency and brutality of warfare.
Biologically speaking, war is an unusual behavior—very few other animals intentionally set out to kill members of their own species. Along with chimpanzees, with which we share a common evolutionary ancestor, we humans have a rare and terrible behavioral predisposition: Our young males, in the prime of life, are prone to band together and attack members of neighboring groups. The conflicts currently underway in the the Democratic Republic of the Congo, Darfur, Iraq, and elsewhere all have many proximate causes—political, religious, environmental, and otherwise. But contrary to long-held beliefs about the cultural roots of war, we argue that the behavior that makes the systematic slaughter of other human beings possible in the first place is based on a suite of evolved behavioral predispositions, which we call “team aggression.”
Anyone who has been in combat will tell you he fought not for a flag, or democracy, or some other abstraction, but for his buddy in the trench, his mate in the torpedo boat, or the soldier next to him in the up-armored Humvee. Intense loyalty for one’s immediate comrades, along with loss of empathy for the members of the enemy, are at the heart of team aggression, and of warfare and terrorism. These predispositions stretch back more than seven million years to our ape ancestors’ early battles for survival. We are all descended, by definition, from the victors of innumerable conflicts over resources, territory, and the right to mate. And we bear the marks of this legacy in the behaviors and impulses that spur us on to lethal conflict to this day, even when other solutions might be available.
The big question then becomes not, “Why do wars break out?”—that is the easy part—but, “Why does peace break out?,” as we know it often does. Far from condemning us to a future of warfare, understanding war’s biological roots can point us toward policies that increase the likelihood of peace, which also has deep roots in our biology. The first step toward peace is to do everything possible to grant women greater decision-making power in society. Team aggression is primarily a male drive, and while women are certainly competitive and capable of fighting bravely and ferociously, in the vast expanse of human history there is not a single record of women banding together spontaneously to attack their neighbors. Our book argues that when women have more agency, their societies become less warlike.
There is an aphorism: “If you want peace, understand war.” In Sex and War, we argue that understanding war also means understanding our own biology and evolutionary history. If we can do that, we can find more ways to help the biology of peace win out over the biology of war.
Malcolm Potts is Bixby Professor of Population and Family Planning at the University of California, Berkeley, School of Public Health. For more media coverage of Sex and War, see Newsweek, Wired Science, andThe Scientist.