In this blog post, we’ll examine why humans engage in altruistic behavior from an evolutionary perspective through the lens of the Repeated Reciprocity Hypothesis.
Do you remember watching the animated series “Black Rubber Shoes” when you were a child? In one of the episodes of “Black Rubber Shoes,” the main character, Ki-young, helps an elderly man who has collapsed on the side of the road. It turns out that the man is the chairman of a ramen company, and Ki-young gets to eat as much ramen as he wants—a rare treat at the time. What’s more, Ki-young shares all that ramen with his neighbors and throws a feast. What message does this story convey to us? Simply put, it is “Let’s help others.”
While many people, including South Koreans, do help others, they don’t always receive great luck or positive outcomes like Ki-young did. So why do we help others? At first glance, acting selfishly might seem more advantageous for human survival. However, the perspective known as “the emergence of the altruistic human” directly refutes this idea. From here on, we’ll examine this issue from an evolutionary perspective and discuss the “Repeated Reciprocity Hypothesis.”
The Repeated Reciprocity Hypothesis is a theory that suggests humans engage in altruistic behavior as a better long-term choice for maintaining lasting relationships with others. Simply put, it can be described as the “Tit for Tat” (TFT) strategy. It means that if the other person helps you, you help them in return; if the other person does not help you, you do not help them either. A classic example illustrating the effectiveness of this TFT strategy is the “Prisoner’s Dilemma” game. In the Prisoner’s Dilemma, two suspects are interrogated while isolated in separate rooms. Each suspect has two choices: to confess or to deny the crime. If both deny the crime, they each receive a one-year prison sentence; if only one confesses, the confessor is released immediately, and the denier receives a seven-year prison sentence. Conversely, if both confess, they each receive a five-year prison sentence. So, which choice is most advantageous?
Robert Axelrod, a professor of political science at the University of Michigan, held a global contest to find the strategy that would yield the highest payoff in the Prisoner’s Dilemma game, and the winning strategy was the TFT (Tit-for-Tat) strategy. This strategy involves cooperating in the first round and then mirroring the opponent’s behavior from the previous round in subsequent rounds. If the opponent cooperates, you cooperate again; if the opponent defies, you respond by defying in return. Although it is a very simple strategy, it demonstrated the best performance in repeated interactions.
Ultimately, we act altruistically based on the expectation that if we help others, they will help us in return—in other words, that we will benefit in the future. Therefore, if the other party does not help us, we refrain from helping them as a form of “retaliation.” Ultimately, this behavior can be viewed as a kind of “insurance” for future benefits.
We can find the reason why humans act altruistically in repeated and sustained relationships in the concept of “reciprocity.” By maintaining reciprocal relationships, we build better bonds and help others in the present to secure more favorable outcomes in the future. The repeated reciprocity hypothesis is one of several hypotheses explaining the emergence of altruistic behavior in humans. It has the advantage of explaining acts of helping complete strangers—something the “kin selection hypothesis,” which posits that humans act altruistically because they consider not only their own interests but also those of their relatives, cannot account for.
However, there are phenomena that even the repeated reciprocity hypothesis cannot explain. If the repeated reciprocity hypothesis were the fundamental cause of human altruistic behavior, we would only cooperate with others conditionally within repeated and sustained relationships. Yet in reality, not all of our altruistic behavior occurs solely within such relationships. Consider, for example, tipping at a restaurant. If it’s a restaurant we plan to visit again, we might leave a tip in the hope of receiving better service. However, many people also leave tips at restaurants they’re unlikely to visit again. This phenomenon is difficult to fully explain using the repeated reciprocity hypothesis alone.
Most phenomena observed in repeated and reciprocal relationships can be explained by the repeated reciprocity hypothesis. However, this hypothesis alone is insufficient to account for all the various other situations. Consequently, various theories have been proposed to supplement it. Representative examples include the “costly signaling hypothesis,” the “group selection hypothesis,” and the “birds of a feather flock together hypothesis,” which explain behaviors such as tipping and donating. These various hypotheses support the possibility that altruistic individuals had a survival advantage and were preserved through natural selection. Ultimately, altruistic behavior is, in some respects, a selfish choice. But whatever the reason, we must continue to live altruistic lives in the future.
