Original ArticleBody counts in lowland South American violence
Introduction
Amazonian anthropology has long been central to understanding the nature of warfare in pre-state human societies. The classic raiding experience in Amazonia (glossed loosely here as tribal warfare) was for a group of men to attack an enemy village at dawn, kill several enemies, and quickly retreat into the forest to avoid a counter-attack (Chagnon, 1968, Larrick et al., 1979, Ross, 1988, Conklin, 1989, Verswijver, 1992, Fausto, 2001, Beckerman and Yost, 2007, Beckerman and Valentine, 2008). The “Great Protein Debate” crystallized an argument between those that saw tribal warfare among the Yanomamo and other Amazonian societies as population control in response to low-density protein availability (Harris, 1974, Gross, 1975) versus those that argued for plentiful protein availability (Beckerman, 1979) with warfare as a strategy for status striving and capturing wives (Chagnon & Hames, 1979). Yet another argument saw warfare as more novel, driven primarily by competition for European goods like machetes and shotguns (Ferguson, 1995). The perspective taken here is that warfare was traditionally a persistent feature of many tribal societies in lowland South America well before 1500 AD and even more paramount in chiefdoms that collapsed during the early stages of European colonization (Carneiro, 1981, Hemming, 1978, Redmond, 1994, Balée, 2007).
Comparative ethnographic information on actual death events may help shed light on the proximate and ultimate causes of violence. By “death event” we refer to activity that led to violent death(s) as recorded ethnographically such as a particular duel, homicide, or warfare raid. Event-level analyses may provide some information for evaluating two recent evolutionary models of intergroup aggression. One of these, the “chimpanzee model” (Wrangham, 1999, Wrangham and Glowacki, 2012), derives from repeated observations of coalitions of wild chimpanzee males killing members of neighboring communities when there is a local imbalance of power so that the killing(s) can be carried out relatively safely for the aggressors. The resultant fitness benefits may take the form of increased access to more land, food, and females and even the eventual replacement of the neighboring group (Wilson, Wallauer, & Pusey, 2004). There are several resemblances between chimpanzee and tribal warfare, including male coalitions, group territoriality, low cost but lethal intergroup killings, and similar fitness benefits, making the chimpanzee model potentially applicable to warfare in small-scale human societies (Manson and Wrangham, 1991, Wrangham and Peterson, 1996). Wrangham and Glowacki (2012) have found these chimpanzee–human similarities to hold for human hunter–gatherers and we extend this analysis here to lowland South American societies.
Another model, “parochial altruism” (Bowles, 2006, Bowles, 2009, Choi and Bowles, 2007), sees widespread cooperation in human societies as the result of genetic group (multi-level) selection where within-group cooperation allows some altruistic groups to better displace or otherwise out-compete other more self-serving groups of individuals (Darwin, 1871, Alexander, 1974, Hamilton, 1975, Wilson and Dugatkin, 1997). Parochial altruism resembles the chimpanzee model in that aggressive male behaviors have been selectively favored through the success of more dominant groups. However, it further suggests selection for uniquely human psychological traits adapted for within-group cooperation and between-group warfare not seen in chimpanzees (Wrangham & Glowacki, 2012), potentially including self-sacrificing behaviors (Bowles & Gintis, 2011), strong reciprocity (Gintis, 2000), treachery (Wadley, 2003), cultures of honor (Nisbett & Cohen, 1996), and revenge-seeking (Beckerman and Valentine, 2008, Boehm, 2011). Here we evaluate evidence for these derived psychological mechanisms in lowland South American warfare. In general, the most salient levels of selection and the proximate and ultimate motivations of warfare are underexplored, and that is why we focus here on quantifying the intensity of competition at multiple scales of social organization within and between lowland South American societies.
Section snippets
Methods
Ethnographic literature for lowland South America was searched for event-level information of individual homicides, duels, and raids by looking through ethnographies for relevant index entries of “violence”, “war”, “killing”, “raids”, and “homicide”. Of these ethnographic works, 11 include data on the total number of deaths attributed to violence (1281, not including infanticide but including violent deaths by non-indigenous perpetrators) as a fraction of total recorded deaths (4215 deaths,
Violent deaths
Cause-of-death data focusing on violent deaths in pre-contact or more traditional time periods are available for 11 lowland South American societies (Table 1). Violent deaths include both indigenous and non-indigenous conflict in the form of duels, homicides, and raids, but not infanticide. The percent of deaths arising from violence varies considerably from the Tsimane at 6%, the only group in the sample with no active warfare, to the pre-contact Waorani with incessant revenge raids at 56%.
Discussion
The compilation of 11 anthropological studies reporting cause of death in traditional lowland South American societies shows that violence led to about 30% of all deaths of which about 70% were males. These results are similar to mean values found in global surveys of farmer-foragers (Keeley, 1996, Bowles, 2009, Pinker, 2011). Cause-of-death studies are mixed in terms of the seriousness of internal versus external warfare. Event-level analyses suggest that external warfare events have higher
Acknowledgments
This paper benefited from conversations with Karthik Panchanathan, Martin Daly, Ray Hames, Mark Flinn, and Kim Hill. Financial support was provided by Research Board and Arts & Science Alumni Organization Faculty Incentive Grants (University of Missouri) to RW.
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