Glowacki's fascinating and informative article contends that intergroup peace is a historical achievement that is largely unmatched among other species. While some intergroup cooperation is found now and then in a few other species, it is extremely rare, and even observations of the few species that occasionally exhibit it (such as bonobos) generally reveal more intergroup violence than intergroup cooperation. Violence, from petty raids to ongoing warfare, has been common throughout human prehistory and history, but peace has also been achieved, enabling positive-sum intergroup cooperation (such as trade) by which both groups benefit. Progressively stronger and more complex social structures increased both war and peace. The two developments may not have been independent, because the greater lethality of war made peace all the more desirable.
All this resonates with our own thinking. We have sought to understand the human mind as tailored by nature and evolution to facilitate culture, as a highly potent strategy to improve survival and reproduction, which we call cultural animal theory (Baumeister, Reference Baumeister2005; Baumeister & Bushman, Reference Baumeister and Bushman2021). Elaborating on why culture is such a successful strategy for improving survival and reproduction has become an important focus for us (see Baumeister & Bushman, Reference Baumeister and Bushman2023). As Glowacki says, both war and peace can benefit individuals in terms of reproductive success. War can protect and even acquire resources, especially among agricultural societies, whereas peace can spare lives.
Glowacki focuses on hunters and gatherers, which made up most of human history and prehistory. Among those, he says, war was not broadly beneficial for groups – but peace remained elusive because of individual acts of aggression and retaliation. He points out that many seemingly peaceful groups were merely “warless,” either because their isolated territory lacked neighbors to fight, or because they had powerful neighbors whom it would have been futile and self-destructive to provoke. In other groups, however, endless small-scale raiding, in retaliatory cycles, with a steady stream of injuries and deaths, was the norm.
Glowacki says that peace requires advanced psychological capabilities to interact with other groups in a tolerant, nonaggressive fashion. Crucially, he adds, most social species lack this capability. This fits our cultural animal theory: Evolution gradually installed in the human mind traits that would make possible cultural advances that are impossible for other animals, even social animals. We speculate that the capacity for such mutually beneficial interactions with out-groups was not directly evolved but rather emerged from the traits that made cultural life in general possible. Members of a group could agree, and especially leaders might see, that intergroup cooperation would be preferable to endless retaliatory warfare.
True peace is thus an invention and an achievement. That it is a group cultural achievement is also likely, given Glowacki's evidence that individuals can initiate raids and warfare, and indeed that usually in simple societies conflict is initiated by individuals. Most individuals and the group as a whole would benefit from peace, but individual men benefit from war, if only to redeem respect after being mocked by their group's female members for lacking courage and initiative.
Crucially, therefore, peace must be achieved by collective agreement. That includes pressuring or punishing individuals who might take it on themselves to initiate violent intergroup contact.
Warfare benefits from social organization and hierarchy, so we had assumed that the egalitarian ethos of hunter–gatherer groups would minimize war – or at least that temporary command hierarchies would emerge to prepare for battle. Glowacki provides compelling evidence that our assumption was wrong: Much aggression at that level is initiated by individuals (often persuading a couple buddies to join in a fairly safe raid on another group). Hence, he says, the emergence of hierarchy not only makes for more effective warfare but it also helps make peace possible. Authority figures can prohibit young warriors from making trouble, something that would have been impossible among the egalitarian hunter–gatherers.
Another factor promoting peace is third-party mediators. The basic structure of social interaction is dyadic, and indeed many interactions are defined by complementary pairs of roles (e.g., teacher–student, physician–patient, buyer–seller). Among cultural animals, however, there is often a third role in many interactions – someone such as a referee who represents the overarching cultural perspective. Animals play and compete but only humans have referees. The game is played between two teams, but the referee enforces the abstract rules from the culture. Animals fight and steal but only humans have police, judges, and other impartial overseers who act as referees. In intergroup conflict, a third-party mediator can help move things along toward peace.
Thus, the desirable state of intergroup peace is dependent on cultural advances, such as hierarchical leadership and third-party mediation.
We also appreciate his point that incentives for peace go beyond ending the destructive impact of war on people and property. In surveying the research on evil and violence, Baumeister (Reference Baumeister1996) observed that it is typically negative-sum, insofar as the perpetrator gains less than the victim loses. Ent, Sjåstad, Baumeister, and von Hippel (Reference Ent, Sjåstad, Baumeister and von Hippel2020) extended this to show that prosocial acts of helping are typically positive-sum, in that the recipient benefits more than the cost to the helper. The idea that intergroup trade is better than war (rediscovered in the modern world after World War II) provides a potentially powerful incentive to support peace. Trade is a form of cooperation. Both parties wish to make the trade – because they are better off having done so. Works on economic history frequently confirm the benefits of trade (Acemoglu & Robinson, Reference Acemoglu and Robinson2012; Bernstein, Reference Bernstein2004), as well as the costliness of even successful war.
Technological advances and increasing populations have made modern warfare ever more lethal, which is a sad commentary on the march of human history. To think that the progress of civilization has also enabled ever greater peace is a reassuring counterpoint.
You have
Access
Glowacki's fascinating and informative article contends that intergroup peace is a historical achievement that is largely unmatched among other species. While some intergroup cooperation is found now and then in a few other species, it is extremely rare, and even observations of the few species that occasionally exhibit it (such as bonobos) generally reveal more intergroup violence than intergroup cooperation. Violence, from petty raids to ongoing warfare, has been common throughout human prehistory and history, but peace has also been achieved, enabling positive-sum intergroup cooperation (such as trade) by which both groups benefit. Progressively stronger and more complex social structures increased both war and peace. The two developments may not have been independent, because the greater lethality of war made peace all the more desirable.
All this resonates with our own thinking. We have sought to understand the human mind as tailored by nature and evolution to facilitate culture, as a highly potent strategy to improve survival and reproduction, which we call cultural animal theory (Baumeister, Reference Baumeister2005; Baumeister & Bushman, Reference Baumeister and Bushman2021). Elaborating on why culture is such a successful strategy for improving survival and reproduction has become an important focus for us (see Baumeister & Bushman, Reference Baumeister and Bushman2023). As Glowacki says, both war and peace can benefit individuals in terms of reproductive success. War can protect and even acquire resources, especially among agricultural societies, whereas peace can spare lives.
Glowacki focuses on hunters and gatherers, which made up most of human history and prehistory. Among those, he says, war was not broadly beneficial for groups – but peace remained elusive because of individual acts of aggression and retaliation. He points out that many seemingly peaceful groups were merely “warless,” either because their isolated territory lacked neighbors to fight, or because they had powerful neighbors whom it would have been futile and self-destructive to provoke. In other groups, however, endless small-scale raiding, in retaliatory cycles, with a steady stream of injuries and deaths, was the norm.
Glowacki says that peace requires advanced psychological capabilities to interact with other groups in a tolerant, nonaggressive fashion. Crucially, he adds, most social species lack this capability. This fits our cultural animal theory: Evolution gradually installed in the human mind traits that would make possible cultural advances that are impossible for other animals, even social animals. We speculate that the capacity for such mutually beneficial interactions with out-groups was not directly evolved but rather emerged from the traits that made cultural life in general possible. Members of a group could agree, and especially leaders might see, that intergroup cooperation would be preferable to endless retaliatory warfare.
True peace is thus an invention and an achievement. That it is a group cultural achievement is also likely, given Glowacki's evidence that individuals can initiate raids and warfare, and indeed that usually in simple societies conflict is initiated by individuals. Most individuals and the group as a whole would benefit from peace, but individual men benefit from war, if only to redeem respect after being mocked by their group's female members for lacking courage and initiative.
Crucially, therefore, peace must be achieved by collective agreement. That includes pressuring or punishing individuals who might take it on themselves to initiate violent intergroup contact.
Warfare benefits from social organization and hierarchy, so we had assumed that the egalitarian ethos of hunter–gatherer groups would minimize war – or at least that temporary command hierarchies would emerge to prepare for battle. Glowacki provides compelling evidence that our assumption was wrong: Much aggression at that level is initiated by individuals (often persuading a couple buddies to join in a fairly safe raid on another group). Hence, he says, the emergence of hierarchy not only makes for more effective warfare but it also helps make peace possible. Authority figures can prohibit young warriors from making trouble, something that would have been impossible among the egalitarian hunter–gatherers.
Another factor promoting peace is third-party mediators. The basic structure of social interaction is dyadic, and indeed many interactions are defined by complementary pairs of roles (e.g., teacher–student, physician–patient, buyer–seller). Among cultural animals, however, there is often a third role in many interactions – someone such as a referee who represents the overarching cultural perspective. Animals play and compete but only humans have referees. The game is played between two teams, but the referee enforces the abstract rules from the culture. Animals fight and steal but only humans have police, judges, and other impartial overseers who act as referees. In intergroup conflict, a third-party mediator can help move things along toward peace.
Thus, the desirable state of intergroup peace is dependent on cultural advances, such as hierarchical leadership and third-party mediation.
We also appreciate his point that incentives for peace go beyond ending the destructive impact of war on people and property. In surveying the research on evil and violence, Baumeister (Reference Baumeister1996) observed that it is typically negative-sum, insofar as the perpetrator gains less than the victim loses. Ent, Sjåstad, Baumeister, and von Hippel (Reference Ent, Sjåstad, Baumeister and von Hippel2020) extended this to show that prosocial acts of helping are typically positive-sum, in that the recipient benefits more than the cost to the helper. The idea that intergroup trade is better than war (rediscovered in the modern world after World War II) provides a potentially powerful incentive to support peace. Trade is a form of cooperation. Both parties wish to make the trade – because they are better off having done so. Works on economic history frequently confirm the benefits of trade (Acemoglu & Robinson, Reference Acemoglu and Robinson2012; Bernstein, Reference Bernstein2004), as well as the costliness of even successful war.
Technological advances and increasing populations have made modern warfare ever more lethal, which is a sad commentary on the march of human history. To think that the progress of civilization has also enabled ever greater peace is a reassuring counterpoint.
Competing interest
None.