War is not an inevitable feature of society, according to two scientists who analyzed acts of aggression in 21 hunter-gatherer societies.
Among people who live today most like our ancestors did long ago, most acts of murder occur as a result of individual conflicts rather than as part of major battle-style events, the researchers report in the journal Science. That would suggests that war is an artifice of society, and not an intrinsic feature of human nature.
It’s a hopeful message, but one that has met with strong criticisms from a community of anthropologists who have long debated whether warfare has an extensive evolutionary history with roots embedded in the structure of our brains, or whether war is a response to more recent developments in how societies are structured.
“Our study questions the popular picture of ‘Man the Warrior,’ where groups of prehistoric humans are seen as participating in a constant struggle against each other, and where war is something that is almost in our genes,” said co-author Patrik Söderberg of Åbo Akademi University in Vasa, Finland.
“By showing that war is the exception rather than the norm in societies with a lifestyle resembling our ancestral past, the study supports a more optimistic view on the human potential for peace.”
Other experts disagree, pointing out the complexities of defining what “war” is and the ambiguity of interpreting what archaeological discoveries say about how ancient people died, among other problems.
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"The evidence doesn't really support the claim they're making," said Michael Wilson, an anthropologist at the University of Minnesota. "It's a hard question to study. If you look at the archaeological record, there's evidence of violence going back pretty far. But if you find a spearhead or arrowhead in someone's bones, which is common, is that war or an interpersonal dispute? You just don’t know."
21 modern-day groups In an attempt to settle the debate about how built-in war really is, Söderberg and colleague Douglas Fry picked 21 groups of foragers that they felt best represented the way people lived before complex societies developed. In an attempt to be as authentic as possible, they excluded groups that rode horses, lived in large settlements, had access to stable sources of food like fisheries, or developed complex societies with social classes and hierarchies.
For each population included in the study, the researchers looked at high-quality ethnographies for examples of lethal aggression. They turned up nearly 150 cases of aggressive death.
Among the Tiwi people of Australia, the researchers found an unmatched 69 examples of lethal acts. Among the other 20 groups, there were an average of just 3.5 deadly events documented, ranging from zero to a maximum of 15.
For more than half of the non-Tiwi murders, just one person killed another single person. About a quarter of examples involved more than one killer and a single victim. And just over 20 percent involved one killer murdering more than one victim.
In two-thirds of the cases, killers and victims belonged to the same group. Aggressive deaths were often a result of men fighting over women or other personal disputes.
Together, Söderberg and Fry interpret their findings to suggest that warfare is rare among foraging groups, a result of modern circumstances and not an inherent feature of human nature.
"In general," Söderberg said, "these societies present a lifestyle in which lethal aggression is not so much about organized conflicts between different groups as it is about individual quarrels stemming from personal motives, such as two men competing over a woman or a family revenging a murder by targeting the killer."
Objections raised But there are numerous problems with those conclusions, according to other experts. Excluding sedentary foragers from the study sample, for example, probably skewed the results because hunter-gatherers have lived in settlements for tens of thousands of years, said Sam Bowles, director of the behavioral sciences program at the Santa Fe Institute. And in many cases, there are high levels of violence between these sedentary groups.
All the groups that were included in the study, Bowles added, live in places with governments that have worked hard to reduce violence among hunter-gatherer populations, and those efforts were already well-established when the ethnographies used in the new paper were conducted.
What’s more, Wilson said, the researchers looked only at numbers of aggressive murders documented in the ethnographies they reviewed, but rates over time would have been far more revealing.
Along with other criticisms, the new paper fails to refute the argument that war has always been part of human life, Wilson said. But that doesn’t mean that all hope is lost
“I think that people like Douglas Fry who are making a big effort trying to say that warfare does not have a deep evolutionary history think the answer needs to be that warfare is not a part of human nature, and therefore we don’t have to have warfare,” Wilson said, adding that the new paper falls in line with arguments that Fry has made in the past.
“I think that’s misguided. It’s clear that warfare occurs very commonly wherever there are people, but it doesn’t always occur. If we can find why people are less likely to go to war in some instances, then we’ll be doing something useful. I think it’s a very optimistic way of going forward.”