This article is about the repetition-reciprocity hypothesis, which explains altruistic behavior in human and animal societies. The hypothesis states that altruistic behavior is driven by conditional cooperation strategies, and while it can explain altruism in non-kinship contexts, it has limitations in explaining altruistic behavior in non-repetitive interactions and interactions between multiple participants.
People refer to heroes, such as Superman and Batman, as beings who fight villains for the good of humanity. They are usually armed with expensive equipment and have superhuman strength. However, there are people who are called heroes in our society even if they don’t have superhuman powers like Superman. These are people who sacrifice themselves for the sake of others – people who perform selfless acts. Selfless acts are common in our daily lives, and they can be performed not only by people close to us, but also by complete strangers. For example, people who lend a helping hand to a stranger in a time of need, or who are willing to share their resources for the benefit of others despite the odds against them, are worthy heroes in the modern world. Their actions are unique because they put the interests of others first, as opposed to the usual self-interested behavior.
Altruism is a difficult survival strategy from an evolutionary perspective, as it involves acting solely to promote the well-being of others without expecting a reward. Nevertheless, altruistic behavior in animal societies has persisted, and researchers have tried to explain it with the kin selection hypothesis, the reciprocal reciprocity hypothesis, the eusociality hypothesis, and the communication hypothesis. The reciprocal reciprocity hypothesis is interesting because it’s based on the strategy of an eye for an eye.
To better understand the repetition-reciprocity hypothesis, let’s look at a game called the Prisoner’s Dilemma. The Prisoner’s Dilemma is a phenomenon in which two prisoners choose the first strategy of betrayal, which leads to the worst outcome, even though it is in their best interest to cooperate and hide their crimes. The game of the Prisoner’s Dilemma is a single game, not a repeated game, and the outcome of the game cannot be reversed. However, if we think of human relationships as games between members of society, the difference between games between members of society and the Prisoner’s Dilemma is a bit different. Unlike the Prisoner’s Dilemma, which is a single-player game, most relationships are long-term relationships, such as coworkers, friends, and family. Therefore, relationships can be thought of as iterations of the Prisoner’s Dilemma game, which is the starting point for the repetition-reciprocity hypothesis.
If relationships are iterations of the Prisoner’s Dilemma game, and people in society act on economic incentives, experiments have shown that game participants should choose the “eye for an eye, tooth for a tooth” (TFT) strategy in order to earn high payoffs. The TFT strategy explains that as the game is repeated, people will behave altruistically, even if they are conditionally cooperating with the other party rather than unconditionally. Conditional cooperation means that you decide your actions based on the actions of your opponent, such that if he cooperates with you, you will cooperate with him in the future, and if he betrays you, you will betray him in the future. In other words, people learn through repetition that it is economically beneficial for them to act altruistically, and therefore they will act altruistically. Unlike the previous kin selection hypothesis, the repetition-reciprocity hypothesis has the advantage of being able to explain altruistic behavior among non-kin members of society. In fact, we can see that the “eye for an eye, tooth for a tooth” model applies to both human and animal societies, regardless of kinship. Examples include studies showing that chimpanzees are more likely to share food with a fellow chimpanzee who trims their fur than with another chimpanzee, and the phenomenon that hunter-gatherer tribes always share the day’s harvest equally among their members. If chimpanzee societies and hunter-gatherer tribes did not have the certainty that the relationships between members would last, that is, that the game would repeat itself, we would not find altruistic behavior in these societies. As in the Prisoner’s Dilemma game above, it is in the individual’s best interest to either free ride or betray.
However, in a situation where there is a certainty that the relationship will continue, members of the society will act altruistically toward others because betrayal may be beneficial to the individual in the short term, but is detrimental in the long term. Of course, the iteration-reciprocity hypothesis does not fully explain altruistic behavior in modern society. First, the repetition-reciprocity hypothesis does not explain the altruism found in non-repetitive games. If the game is not repeated, betraying each other becomes the preferred strategy due to the Prisoner’s Dilemma game, and altruistic behavior is not expected in this situation. However, in the real world, many people do good deeds to people they don’t expect to see again, which is difficult to explain with the repetition-reciprocity hypothesis. Furthermore, retaliation for conditional cooperation is much harder to achieve when a large number of people are involved in the game, so the game must be repeated for conditional cooperation to occur. However, these assumptions are almost impossible to realize in practice. This remains a limitation of the iteration-reciprocity hypothesis.
As such, the reciprocity hypothesis, based on the principle of an eye for an eye and a tooth for a tooth, provides an adequate explanation for altruistic behavior in human and animal societies. In particular, it is important because it explains altruistic behavior among non-kin, which was previously unexplained by the kin selection hypothesis. However, the repetition-reciprocity hypothesis does not explain altruistic behavior in non-repeating interactions (games), and the fact that retaliation by conditional cooperation becomes difficult when many people participate in a game, as it is in modern societies, suggests that the repetition-reciprocity hypothesis is not a complete hypothesis. We believe that the weakness of the iteration-reciprocity hypothesis stems from the fallacy of assuming that there are only economic humans in society who respond to economic incentives, and that a more rigorous explanation of altruistic behavior observed in modern societies may require a more diverse approach, such as the eusocial species hypothesis or the costly signaling hypothesis. The bottom line is that human altruism is the result of a complex combination of psychological and social factors that go beyond simple economic calculations. This is why we live as social beings and why we cooperate with each other and act altruistically to create a better society.
