Original Article
Body counts in lowland South American violence

https://doi.org/10.1016/j.evolhumbehav.2012.08.003Get rights and content

Abstract

Violence was likely often a strong selective pressure in many traditional lowland South American societies. A compilation of 11 anthropological studies reporting cause of death shows that violence led to about 30% of adult deaths, of which about 70% were males. Here violent deaths are further itemized at the level of ethnographically-reported death events (particular duels, homicides, and raids) to provide more detailed insight into the causes and consequences of within- and between-group violence. Data for 238 death events (totaling 1145 deaths) from 44 lowland South American societies show that attacks are more deadly when treachery is used, when avenging a previous killing, and on external warfare raids between ethnolinguistic groups. That revenge raids kill more people on average than the original grievance, at least when conflicts are between ethnolinguistic groups, indicates a tendency towards increasingly vicious cycles of revenge killings. Motives of killings as noted in ethnographic sources, in order of importance, reportedly include revenge for previous killings and other wrong-doings like sorcery, jealousy over women, gain of captive women and children, fear or deterrence of impending attack, and occasionally the theft of material goods. Results may have implications for understanding the potential for multi-level selection by delineating the force of competition at varying scales of analysis within and between lowland South American societies.

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.

References (71)

  • S. Beckerman et al.

    Upper Amazonian warfare

  • S. Beckerman

    Life histories, blood revenge, and reproductive success among the Waorani of Ecuador

    Proceedings of the National Academy of Sciences of the United State of America

    (2009)
  • A.V. Bell et al.

    Culture rather than genes provides greater scope for the evolution of large-scale human prosociality

    Proceedings of the National Academy of Sciences of the United State of America

    (2009)
  • C. Boehm

    A natural history of retaliatory violence

    British Journal of Criminology

    (2011)
  • S. Bowles

    Group competition, reproductive leveling, and the evolution of human altruism

    Science

    (2006)
  • S. Bowles

    Did warfare among ancestral hunter–gatherers affect the evolution of human social behaviors?

    Science

    (2009)
  • S. Bowles et al.

    A cooperative species: Human reciprocity and its evolution

    (2011)
  • R. Boyd

    The puzzle of human sociality

    Science

    (2006)
  • R. Boyd et al.

    Culture and the evolutionary process

    (1985)
  • Bugos, P. E. Jr. (1985). An evolutionary ecological analysis of the social organization of the Ayoreo of the Northern...
  • S.M. Callegari-Jacques et al.

    Autosome STRs in native South America: Testing models of association with geography and language

    American Journal of Physical Anthropology

    (2011)
  • R.L. Carneiro

    The chiefdom: Precursor of the state

  • N. Chagnon

    Yanomamö: The fierce people

    (1968)
  • N. Chagnon

    Studying the Yanomamö

    (1974)
  • N. Chagnon

    Life histories, blood revenge, and warfare in a tribal population

    Science

    (1988)
  • N. Chagnon et al.

    Protein deficiency and tribal warfare in Amazonia: New data

    Science

    (1979)
  • B. Chapais

    Primeval kinship: How pair-bonding gave birth to human society

    (2008)
  • J.-K. Choi et al.

    The coevolution of parochial altruism and war

    Science

    (2007)
  • Conklin, B. A. (1989). Images of health, illness and death among the Wari' (Pakaas Novos) of Rondonia, Brazil. PhD...
  • C. Darwin

    The descent of man, and selection in relation to sex

    (1871)
  • J.D. Early et al.

    The Xilixana Yanomami of the Amazon: History, social structure, and population dynamics

    (2000)
  • C. Fausto

    Inimigos Fiéis: História, Guerra e Xamanismo na Amazônia

    (2001)
  • R.B. Ferguson

    Yanomami warfare: A political history

    (1995)
  • S.A. Frank

    Foundations of social evolution

    (1998)
  • Cited by (55)

    • Parochial reciprocity

      2023, Evolution and Human Behavior
    • Spatial ability as a distinct domain of human cognition: An evolutionary perspective

      2022, Intelligence
      Citation Excerpt :

      The devil is in the details and the details in this case can be found in the anthropological and historical records (see Geary, 2021). These indicate high-levels of male-on-male aggression and high male mortality rates and reproductive skew (i.e., some males disproportionately reproduce; Betzig, 2012; Chagnon, 1988; Walker & Bailey, 2013), as in other species with intense competition among males (Janicke et al., 2016). The competition included the use of blunt force (e.g., clubs) and projectile weapons (e.g., stones, spears) and larger travel ranges for men than women.

    • The impact of economic inequality on conspiracy beliefs

      2022, Journal of Experimental Social Psychology
    View all citing articles on Scopus
    View full text