There is a myth that more cruel and aggressive people should be more successful in reproduction, as this is an advantageous behavioral strategy. An example can be drawn from the research of anthropologist Napoleon Chagnon, according to which greater reproductive success compared to tribesmen of their own age is found among those men of the Yanomami indigenous people living in Brazil and Venezuela who commit murders. It is claimed that they have 2.5 times more wives and 3 times more children.
As Chagnon and some other researchers believe, the success of aggressive men in reproduction is the rule for primitive societies. According to their evolutionary logic, killers push their neighbors out of reproduction and have more offspring, meaning murder becomes a hereditary trait. Therefore, humans became born killers in the course of evolution. But if this conclusion is examined in more detail, it turns out that 6 arguments can be put forward against it:
- Computer simulations of evolutionary processes have shown that neither a warlike strategy (hawk), consisting of carrying out attacks, nor a timid strategy (dove), consisting of retreating during attacks, are as evolutionarily stable strategies as the “retaliator strategy,” where individuals behave non-aggressively but will still fight back in the event of an attack. Timid individuals cannot compete with aggressive individuals, but at the same time, aggressive individuals risk sustaining injuries in battles. Therefore, the mixed retaliator strategy is the most optimal.
- Data from animal behavior research shows that most intra-species aggression is non-lethal. Of course, in some situations, killing conspecifics can be beneficial, but in most cases, this is not the case. Accordingly, in the course of biological evolution, inhibitors of intra-species aggression are developed, preventing harm in battles.
- Military research has shown that the average healthy individual has strong internal resistance to committing murder. Only 1-2% of soldiers with sociopathic tendencies do not experience this in battle. There are also a number of evolutionary factors as to why such resistance is inherent in humans. As with animals, killing conspecifics is rarely a strategy encouraged by natural selection for humans.
- Humans possess the potential for competition, aggression, and even committing murder, and wars occur in many societies. However, examples of absolutely non-violent societies, such as the Semai and Paliyar peoples, show that humans are capable of living peacefully. This raises questions regarding the claim that murder is a natural trait of humans.
- Research on the Yanomami people has methodological problems. Firstly, anthropologist Brian Ferguson questioned the claim that killers and non-killers were of comparable age. Accordingly, the difference in the number of children may be explained by the difference in age of the studied individuals. Chagnon ignored this criticism. Secondly, examining Chagnon’s data, Ferguson concluded that even if killers had a reproductive advantage, it was nowhere near as large as 3 times. The criticism of Chagnon’s research does not end there; there are many other reasons why they may be methodologically unsound.
- Other studies demonstrate opposite results. For instance, a study of the Waorani people of Ecuador showed that zealous warriors who carry out raids on fellow tribesmen have lower reproductive success. They did not have more wives or children; moreover, their children were less likely to survive to reproductive age. As a result, warlike men proved to be not as individually fit as less aggressive men.
As we can see, a large amount of theoretical and empirical data shows that in various social circumstances, killers should have fewer children than non-killers. And the idea of murder as an evolutionarily advantageous strategy for humans faces many obstacles.
