Wednesday, November 12, 2014

The Evolution of War among Humans and Chimpanzees

I have written many posts about the debate between the Hobbesian and Rousseauean social scientists over the evolution of war.  In recent weeks, there have been new contributions to that debate.  On the Hobbesian side, Napoleon Chagnon and his colleagues have just published an article in the Proceedings of the National Academy of Sciences on warfare among the Yanomamo.  On the Rousseauean side, Douglas Fry has just published an article in the Journal of Aggression, Conflict, and Peace Research criticizing the myths about war among nomadic foragers.

The Yanomamo are an indigenous tribal population of foraging horticulturalists who live in the Amazon rainforest along the border region of southern Venezuela and northern Brazil.  Chagnon is one of the most famous anthropologists who has studied them.  He has provoked intense controversy with his depiction of the Yanomamo as the "fierce people" and with his claim that those men who engage successfully in lethal coalitionary warfare tend to have more wives and offspring and thus greater reproductive fitness than other men, which suggests that warfare is an evolutionary adaptation.  Moreover, Chagnon also accepts Richard Wrangham's "chimpanzee model" for explaining the evolution of warfare--the idea that the common ancestor of chimpanzees and humans engaged in the sort of male coalitionary raiding that can be observed in chimpanzees.

The social organization of lethal coalitionary aggression differs, however, between chimpanzees and humans.  Among chimpanzees, the raiding parties are genetically related males from the same natal community.  Among human foragers, the raiders are largely related by marriage rather than genetic kinship.  Rather than a "band of brothers," Chagnon and his colleagues indicate, human raiding parties are a "band of brothers-in-law."  The evolutionary advantage for men who form alliances for raiding is that this gives them access to their friends' female relatives as potential wives.

The underlying assumption here--that warfare was an evolutionary adaptation for human foraging bands--is challenged by Fry.  He argues against what he identifies as four myths:  that nomadic foragers are warlike, that there was a high rate of warfare in the Pleistocene, that the data support Wrangham's "chimpanzee model" for the evolution of war, and that the establishment of formal state bureaucracy brought an inevitable decrease in the aggression in forager societies.

In a previous post last year, I have summarized the five objections from Wrangham and his colleagues to Fry's arguments.  In this new article, Fry responds to one of those objections.  Wrangham and Glowacki have argued that in surveying the data on foraging societies, the only appropriate cases for assessing their chimpanzee model are nomadic foraging societies living next to different nomadic foraging societies, because most of the nomadic foragers studied by anthropologists have been constrained by neighboring farming societies that could dominate them politically and militarily.  If one looks at hunter-gatherer societies with neighboring societies of hunter-gatherers, Wrangham and Glowacki argue, one sees a universal pattern of warfare.

In response to this, Fry accuses Wrangham and Glowacki of cherry-picking their cases and thus relying on a biased sample of cases.  According to Fry, this ignores the many cases that work against their argument: "For instance, ethnographic cases of forager communities living in proximity to one another but that lack raiding, ambushes, feuding, or 'shoot-on-sight' practices include the nomadic foragers of central peninsular Malaysia such as the Batek, Chewong, and Jahai (Endicott and Endicott, 2008, 2014; Endicott, 2013; Howell, 1989; Sluys, 2000), the Montagnais, Naskapi, and East Main Cree bands of Labrador, Canada (Lips, 1947), and the neighboring South Indian forager societies described by Gardner (2013)" (262).

From my examination of these cases, however, I don't see how they support Fry's characterization.  For example, Lips reports that the Montagnais-Naskapi bands of the Labrador peninsula of Canada were bound together by the same language and a common culture and that they had never fought a war with one another.  But he also reports that they had fought wars against the Eskimo and the Iroquois (399).  Moreover, Lips indicates that these bands were constrained by the authority of the Canadian government and by their economic and social dependence on the Hudson's Bay Company.

Similarly, Kirk Endicott reports that the Batek of peninsular Malaysia lived under the authority of the Malaysian state of Kelantan acting through the Department of Aboriginal Affairs and the Department of Wildlife and National Parks.  He also reports: "Probably the original reason the Batek prohibited fighting with outsiders was the fear that they would be killed or enslaved.  Like other Orang Asli, they were victims of slave raiding by Malays during the nineteenth and early twentieth centuries" (2013, 248).

Sluys reports the same situation for the Jahai of northern peninsular Malaysia.  First, they were enslaved by Malays, and then they were put under strict control by the Malaysian government.

Gardner reports that the South Indian foragers have been constrained first by the British and then by the Indian government.  "In most instances, most have been isolated from one another for centuries, if not millennia, by farming peoples on the intervening plains" (Gardner 2013, 311).

So none of these cases fulfill the conditions specified by Wrangham and Glowacki.  None of these cases can serve as proxies for the nomadic foragers of the Pleistocene.

Douglas P. Fry and Patrik Soderberg, "Myths About Hunter-Gatherers Redux: Nomadic Forager War and Peace," Journal of Aggression, Conflict, and Peace Research 6 (2014): 255-66.

Shane J. Macfarlan, Robert S. Walker, Mark V. Flinn, and Napoleon A. Chagnon, "Lethal Coalitionary Aggression and Long-Term Alliance Formation among Yanomamo Men," Proceedings of the National Academy of Sciences, early edition (2014).

Some of my previous posts on the debate over the evolution of war can be found here, here, here, here, here, here, here, here, and here.

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