Are intraspecific killings common in mammals?

Started by Volunto, Feb 07, 2023, 06:31 PM

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A study of 1024 mammalian species showed that only about 40% of them were observed to have lethal violence – cases of death of individuals from aggressive actions by members of their species (including infanticide, cannibalism, and intergroup aggression). Of course, this figure may be underestimated due to the lack of data, but even after adjusting for this probability, non-violent intraspecific relationships are still common and prevail over violent ones. Overall statistics show that lethal violence is the cause of death in mammals in only 0.3% of cases. Many researchers have come to the conclusion that most intraspecific aggression is non-lethal, and individuals which avoid agonistic situations involving serious possibilities of defeat or injury are evolutionarily successful.

As for the relationship of territoriality and social behavior with lethal violence, in both cases, there was an elevated level of it, which is easily explained by the increase in the number of conflicts due to more frequent social contacts and territorial fights. However, even for social territorial species, the overall level of lethal violence does not exceed 0.8%. Of course, against the background of other mammals, primates stand out with an increased level of violence. However, in their case, the overall level of lethal violence does not exceed 2.5%. And the closest human relative, the pygmy chimpanzee (or bonobo), is widely known for its non-violent nature.

As data from the study of 1024 mammalian species show, the most lethal violence is observed in lemurs and marmosets, as well as suricates, in which case its level can reach almost 20%. However, such cases are an extreme exception. Species with a level of lethal violence above 2.5% do not account for even 13% of all considered by this study. If we take species with its level above 5% (such a level is observed in the most violent hominids), then we get only 6% of those at all. We can safely assume that killing a conspecific is not the rule but rather the exception.