Chimpanzees, Warfare, and the Invention of Peace

Wilson, Michael L.

doi:10.1093/acprof:oso/9780199858996.003.0018

Cited by 128 publications

(19 citation statements)

References 113 publications

(213 reference statements)

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“…Encounters with neighbours (‘intergroup encounters’ hereafter) occur most often in boundary areas (Wilson et al 2012) and may include lethal aggression, which can account for a substantial proportion of total mortality (e.g. 9.3% at Gombe, 3.8% at Mahale Mountains National Park, Tanzania; Wilson 2013). Similar to hunting red colobus monkeys, the outcome of an intergroup encounter depends on the number of participants; parties with more males are more likely to call in response to vocalizations from simulated (Wilson et al 2001) and real (Wilson et al 2012) intruders.…”

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confidence: 99%

Ecology rather than psychology explains co-occurrence of predation and border patrols in male chimpanzees

2013

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The intense arousal and excitement shown by adult male chimpanzees, Pan troglodytes, during territorial attacks on other chimpanzees and predation upon monkeys suggest that similar psychological mechanisms may be involved. Specifically, it has been proposed that hunting behaviour in chimpanzees evolved from intraspecies aggression. Over 32 years, chimpanzees at Gombe National Park, Tanzania were significantly more likely to engage in a territorial border patrol on days when they hunted red colobus monkeys (Procolobus spp.), and vice versa, even after statistically controlling for male chimpanzee party size. We test the hypothesis that this correlation arises because hunting and patrolling are components of a specieslevel aggressive behavioural syndrome; specifically that predation arose as a by-product of territorial aggression in this species. However, hunting was equally likely to occur after a patrol and/or an intergroup interaction as it was before, and the occurrence of an intergroup interaction in which the chimpanzees approached strangers did not increase subsequent hunting probability. We also reject the hypothesis that hunting and patrolling reflect an individual-level behavioural syndrome. We identified two ‘impact hunters’ whose presence increased hunting probability. Similarly, there were also three ‘impact patrollers’, who increased the likelihood that a visit to the periphery of the community range resulted in a patrol. While this discovery has important implications for our understanding of the proximate causes of cooperation, it does not explain the temporal correlation between patrolling and hunting, since no males had such an impact in both contexts. Instead, the data suggest that the correlation arose because patrols typically involved males travelling long distances, which increased the probability of encountering prey. Additionally, parties that travelled to the periphery were more likely to encounter colobus in woodland, where hunts are more likely to occur and to succeed. Therefore, we conclude that ecological, rather than psychological, factors promote the co-occurrence of hunting and territorial aggression in this species.

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confidence: 99%

Ecology rather than psychology explains co-occurrence of predation and border patrols in male chimpanzees

2013

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“…If the attacks on neighboring communities lead to their extinction, as can happen (Goodall, ; Wilson, ), or is suspected (Nishida et al, ) the latter's females may eventually join the attacking community (Williams et al, ; Emery Thompson et al, ; Wilson, ). In that case, the higher‐ranking males may still show reduced tolerance toward these females, but are in due course forced to accept the new status quo.…”

Section: Discussionmentioning

confidence: 99%

“…Chimpanzees engage in lethal raiding, in which a party of patrolling males occasionally invades a territory and together attack and sometimes kill vulnerable members of neighboring communities (Wrangham,1999). However, attackers do not merely target the adult males of the neighboring community, but also their infants, juveniles and adult females (Goodall, ; Wrangham, ; Watts and Mitani, ; Watts et al, ; Williams et al, ; Wilson, ) of the neighboring community. Even though females with sexual swellings tend to receive less aggression (Wolf and Schulman ; Williams et al, ; Wilson, ), the fact remains that females that are not sexually attractive can be the target of serious male aggression.…”

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confidence: 99%

Why do chimpanzee males attack the females of neighboring communities?

Pradhan

Pandit

Schaik

2014

American J Phys Anthropol

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Our closest nonhuman primate relatives, chimpanzees, engage in potentially lethal between-group conflict; this collective aggressive behavior shows parallels with human warfare. In some communities, chimpanzee males also severely attack and even kill females of the neighboring groups. This is surprising given their system of resource defense polygyny, where males are expected to acquire potential mates. We develop a simple mathematical model based on reproductive skew among primate males to solve this puzzle. The model predicts that it is advantageous for high-ranking males but not for low-ranking males to attack females. It also predicts that more males gain a benefit from attacking females as the community's reproductive skew decreases, i.e., as mating success is more evenly distributed. Thus, fatal attacks on females should be concentrated in communities with low reproductive skew. These attacks should also concur with between-community infanticide. A review of the chimpanzee literature provides enough preliminary support for this prediction to warrant more detailed testing.

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“…This is also true of our closest cousins, the chimpanzees, among which intragroup killing, as well as in intergroup fighting and killing to the point of group extermination have been documented . Recent studies of several communities of chimpanzees have found their violent mortality rates to be: in one community, 20% generally, 24% among males; in another one 36% (generally); and in a third one 16% (generally). Another comprehensive study of six chimpanzee populations has set the median number of violent deaths among them at 271 per 100,000 individuals per year, as compared with 164 per 100,000 per year, which the authors calculated as the average among human hunter‐gatherers .…”

Section: Classical Rousseauism and Extended Rousseauism: Their Rise Amentioning

confidence: 92%

Proving communal warfare among hunter‐gatherers: The quasi‐rousseauan error

Gat

2015

Evolutionary Anthropology

101

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Was human fighting always there, as old as our species? Or is it a late cultural invention, emerging after the transition to agriculture and the rise of the state, which began, respectively, only around ten thousand and five thousand years ago? Viewed against the life span of our species, Homo sapiens, stretching back 150,000–200,000 years, let alone the roughly two million years of our genus Homo, this is the tip of the iceberg. We now have a temporal frame and plenty of empirical evidence for the “state of nature” that Thomas Hobbes and Jean‐Jacque Rousseau discussed in the abstract and described in diametrically opposed terms. All human populations during the Pleistocene, until about 12,000 years ago, were hunter‐gatherers, or foragers, of the simple, mobile sort that lacked accumulated resources. Studying such human populations that survived until recently or still survive in remote corners of the world, anthropology should have been uniquely positioned to answer the question of aboriginal human fighting or lack thereof. Yet access to, and the interpretation of, that information has been intrinsically problematic. The main problem has been the “contact paradox.” Prestate societies have no written records of their own. Therefore, documenting them requires contact with literate state societies that necessarily affects the former and potentially changes their behavior, including fighting.

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Chimpanzees, Warfare, and the Invention of Peace

Cited by 128 publications

References 113 publications

Ecology rather than psychology explains co-occurrence of predation and border patrols in male chimpanzees

Ecology rather than psychology explains co-occurrence of predation and border patrols in male chimpanzees

Why do chimpanzee males attack the females of neighboring communities?

Proving communal warfare among hunter‐gatherers: The quasi‐rousseauan error

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