No peace without biology

In our new book about the biology of warfare, Sex and War: How Biology Explains Warfare and Terrorism and Offers a Path to a Safer Future, we trace the biological origins and evolution of war. The conclusion we draw is unavoidable. War, simply put, is a biological phenomenon.

When war and biology are discussed together, it is usually in relation to biological weapons, or the physiology of the battlefield, or, goodness knows, the wounds endured by warriors both in combat and long afterwards. But it turns out that there is a much more intimate connection between biology and organized violence: evolution.

War has most often been studied by social scientists -- anthropologists embedding themselves with hunter-gatherer tribes, archaeologists teasing evidence of past epochs of war and peace from the ground, and psychologists and sociologists poking and prodding the minds of warriors and others. But one question often goes unasked: Why war? Why do we humans, almost alone among the animals, band together and intentionally kill members of our own species?

That is a question only biology can answer -- and as Theodosius Dobzhansky famously said, "nothing in biology makes sense but in the light of evolution." Humans, of course, are descended from a long line of ape ancestors, including a common ancestor with chimpanzees some five to seven million years ago. As Jane Goodall, Richard Wrangham and others have shown, we also share with chimps the bizarre propensity to attack and kill others of our own species. And evolution explains why.

Chimpanzees -- and virtually every hunter-gatherer society studied -- live in male-dominated social groups, in which the males are blood relatives and females move from one group to another. The dominant males largely monopolize breeding opportunities, leaving younger males with little choice but to work their way up the in-group hierarchy, or to launch attacks on neighboring out-groups if they are to secure the resources, territory, and females they require to survive and pass on their genes.

We are all descended, in other words, from the victors in conflicts over resources, territory, and mates. The majority of those battles was instigated and fought by males, with the most skilled, ferocious and cunning surviving to pass on their genes. Human males today bear the marks of this legacy in the behaviors and impulses that still spur us on to lethal conflict -- including the widespread and devastating association between war and rape -- even when other solutions might be both available and preferable.

That war and the behaviors that make it possible are evolved characters will not seem surprising to most biologists. But it is a radical, and indeed offensive, idea to many social scientists. War must be a learned behavior, they have long concluded -- at least in part as an a priori conclusion developed in response to the horror of the 20th century's world wars. Surely the carnage and depravity of those conflicts could not be natural, they reasoned. It must have been culture gone astray that taught humans such "inhumanity." Besides, if war and warring behavior were learned, the thinking went, then they could be unlearned, and humanity could progress towards lasting peace.

Biologists know that life is never so simple. Contrary to the received wisdom of the social sciences, war is indeed rooted deeply in our DNA. But crucially, the fact that war is an evolved behavior does not in any sense condemn us to a future as bloody as our collective past. Behavioral predispositions function in response to environmental stimuli: change the environment, and you change the biological response. In Sex and War; we show that a series of relatively simple strategies, including the empowerment of women and slowing population growth, can help the biology of peace win out over the biology of war.

Dobzhansky, of course, was right about the need for evolution to make sense of biology. In Sex and War, we argue that understanding human biology through the lens of behavioral evolution is the only way to make sense of both war and peace.

Sex and War: How Biology Explains Warfare and Terrorism and Offers a Path to a Safer Future, by Malcolm Potts and Thomas Hayden, BenBella Books, Dallas, Texas, 2008. 457 pp. ISBN: 978-1-933-77157-1. $24.95 US/$27.95 CAN.

Thomas Hayden is a science journalist and a lecturer in the School of Earth Sciences at Stanford University, where he teaches science communications and environmental reporting. Malcolm Potts, an obstetrician and research biologist, is the Bixby Professor of population and family planning at the University of California, Berkeley. Dr Potts has helped develop new ways of delivering family planning in low-income settings, he has been a leader in reducing maternal deaths in developing countries and in efforts to slow the spread of HIV/AIDS.

Related stories:

Six-legged soldiers [24th October 2008]

Do Chimps Have Culture? [August 2007]

Rolling Back the Fog of War [22nd November 2004]

Ethics and war challenge biologists [25th March 2003]