Scientists have studied different forms of aggression in primates
Aggressive behavior in primates can manifest itself in different ways, from ordinary conflicts within a group to deadly attacks. The researchers decided to test how these behaviors are related to each other and whether they can be considered as manifestations of a single evolutionary mechanism. About how different forms of aggression are interconnected in primates — in the material of Izvestia.
Five forms of aggression: what the researchers compared
The work of scientists from the University of Lincoln has been published in the scientific journal Evolution Letters. The researchers analyzed data on 100 free-living primate species, including humans. The sample included only species that did not receive additional nutrition and lived in groups.
Scientists compared five forms of intraspecific aggression: mild aggression between groups and within groups, the killing of adults between groups and within groups, as well as infanticide — the killing of cubs by members of their own species. The aim was to determine how closely different behaviors are evolutionarily related.
Bonaventura Maiolo, Professor of Social Evolution at Lincoln University
Understanding the evolutionary roots of violence is important not only for biology, but also for how we think about human behavior.
Ordinary conflicts don't always involve murder.
The analysis showed that two types of moderate aggression were weakly associated with lethal behaviors. In other words, species that had more common aggressive interactions did not necessarily have a higher incidence of deadly violence.
The authors note that this calls into question the idea of aggression as a single feature that can be placed on a single scale — from less serious conflicts to murder. According to the results of the work, moderate and deadly aggression may have different evolutionary relationships.
The deadly forms of aggression turned out to be more strongly connected
In contrast to moderate aggression, the three studied forms of lethal behavior—killing adults within a group, killing adults between groups, and infanticide—showed moderate positive evolutionary relationships. The link between the killing of adults within and between groups was particularly noticeable.
At the same time, the influence of the evolutionary kinship of species on deadly aggression turned out to be generally stronger than on moderate aggression. It was most pronounced for infanticide and killing of adults within the group.
Different forms of behavior may have different prerequisites.
The results show that intraspecific aggression in primates should be considered as a set of several related but not identical features. Their frequency and severity may depend on the age and gender of the conflict participants, membership in one or different groups, and other conditions.
To understand the origin of aggression in humans, this means that it is impossible to automatically transfer the features of ordinary conflicts to deadly violence. The authors believe that when studying the evolution of aggression, it is necessary to take into account a specific type of behavior, rather than considering aggression as a single property of a species.
Bonaventure Maiolo
Our study shows that the evolution of aggression follows more complex patterns than earlier models suggested, that it is biologically inaccurate to rank species based on their general propensity to aggression, and that we need a more nuanced approach when discussing whether humans are inherently violent.
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