In this blog post, we explore the evolutionary reasons and social mechanisms that have allowed altruistic behavior to survive and thrive in society, despite being disadvantageous to the individual.
In human society, we often see people engaging in cooperative behavior. Moreover, altruistic behavior is observed in various animals, including ants, bees, meerkats, vampire bats, and chimpanzees. Altruistic behavior refers to actions in which one sacrifices oneself to help another. In other words, altruistic behavior results in personal loss—so would anyone rationally choose to deliberately create a situation that causes them harm?
Intuitively, it is easy to see why altruistic behavior is difficult to sustain. One logical model that explains this is the “Prisoner’s Dilemma” game. Two people have been arrested as suspects in a case, and the police can only solve the case if they confess. The police take the two to separate interrogation rooms and present them with the terms of a confession deal. If both confess, they will each receive a five-year sentence; if both deny the charges until the end, they will each receive a one-year sentence. However, if one confesses and the other denies the charges until the end, the confessor is released, while the denier receives a seven-year sentence. From the perspective of the two individuals, confessing seems to be the best strategy, but in reality, the best outcome would have been for neither to confess (resulting in a one-year sentence each). This is why the scenario is called the “Prisoner’s Dilemma.” In other words, altruistic or cooperative behavior is never a good strategy for the individual. This naturally raises the question of how altruistic behavior can exist in society.
Let’s explain this problem through the “phenomenon of like-minded people grouping together.” If we create a new game where altruistic and selfish behaviors interact, when two altruistic people meet, each receives a payoff of 1. We define this as cooperation. On the other hand, suppose that when an altruistic person meets a selfish person, the altruistic person receives a payoff of -1, and the selfish person receives a payoff of -2. We define this as “defection” (a result caused by the selfish person’s defection). Furthermore, if we design a trading game where the payoff is set to 0 when two selfish people meet, we can see that, just like in the Prisoner’s Dilemma, altruistic behavior can never be a good strategy, and defection becomes the best strategy.
Based on this game, let’s examine how altruistic behavior can exist. If players use cooperation or defection as strategies, the player who chooses defection will ultimately gain more than the player who chooses cooperation. Therefore, players who choose cooperation find themselves in a situation where survival is difficult. However, when players who choose cooperation interact with one another, they can receive higher payoffs than when players who choose defection interact with one another. Since the defection strategy yields high returns only when the opponent cooperates, an environment favorable to altruistic individuals will be created if altruistic people gather and interact with one another. If altruistic people gather in this way, it explains how altruistic behavior becomes widespread in society.
According to research by sociologists and biologists, Jared Diamond has revealed that people tend to choose partners who share similar religious or political views. He states that we consider religious or political views to be important factors when selecting a partner or making friends. Whether a person is altruistic or selfish is a cultural and behavioral trait, and Diamond’s research suggests that the phenomenon of like-minded people clustering together is entirely plausible. People who have grown up in the same cultural background can gauge each other’s dispositions to some extent through speech patterns, facial expressions, and behavior. If we can determine whether a counterpart is altruistic or selfish before engaging in a transaction, altruistic people will ultimately seek out and transact with other altruistic individuals like themselves, making it highly likely that people will cluster together. Thus, it is reasonable to conclude that altruistic people may gather together to survive, and there is a strong possibility that such groups will emerge in society.
However, the “phenomenon of like-minded people clustering together” is often described using the negative expression “birds of a feather flock together” and is sometimes interpreted with a critical undertone. While an increase in the frequency of this phenomenon may lead to more altruistic people and have a positive impact on society, it could also reduce the benefits derived from diversity. Of course, the heterogeneity stemming from selfish tendencies is unlikely to bring about positive diversity, but imagining a village composed entirely of kind-hearted people makes it easier to understand the negative aspects of this phenomenon. For example, the idea of inventing machines to make work easier might never arise.
We have explained how altruistic behavior has persisted despite being considered evolutionarily unstable, through the “clique formation” phenomenon among altruistic individuals. In the game described above, altruistic behavior is not the best strategy for an individual when trading with a selfish player; however, when trading with similar individuals, altruistic behavior acts as a sufficiently advantageous strategy and becomes one that can thrive. The reason altruistic people have thrived in society is precisely because this phenomenon of like-minded individuals clustering together can occur sufficiently. While the phenomenon of altruistic people clustering together may have drawbacks for societal prosperity, since society is vast and altruistic individuals themselves possess diverse characteristics, this phenomenon is unlikely to cause major problems. Furthermore, if the number of altruistic people increases due to this clustering phenomenon and everyone helps one another, it could create a situation where transactions based on cooperative strategies—as described in the game above—benefit everyone.
