In this blog post, we’ll examine how human cooperation and altruism are formed and maintained, focusing on the reciprocity hypothesis.
A man with an unfamiliar name gave cola to some of the participants and then asked all of them to buy him a lottery ticket. As a result, a significant number of those who purchased lottery tickets were the participants who had received cola from him. This experiment, conducted by Dennis Regan, is a prime example of the phenomenon “you get what you give” and can be explained by the reciprocity hypothesis. The reciprocity hypothesis states that when people receive a favor from someone, they feel indebted and a sense of obligation to repay it. In addition to Dennis Regan’s experiment, various studies have shown that the reciprocity hypothesis exerts a significant influence on human relationships. Now, let’s take it a step further and consider, through the lens of the reciprocity hypothesis, “How did altruistic humans survive in competition with selfish humans?”
The 2010 MBC documentary ‘Tears of the Amazon’ features the Zoé, an indigenous tribe of the Amazon, and presents an unvarnished view of their way of life. Rather than simply dividing the meat among themselves—which skilled male hunters bring back from the forest—they carefully distribute it collectively for over two hours in full view of the entire tribe. Hunting is highly likely to fail due to various variables, and for the Zoé, who do not practice agriculture, a failed hunt directly leads to a crisis of survival. Therefore, even for their own sake, they need a kind of social safety net to prepare for the possibility of a failed hunt. When I share my catch with those who were unsuccessful, they feel an implicit sense of obligation to repay that favor in the future. As a result, when I fail to hunt, I can receive help from them, and in this way, all members of the Zoé tribe can ensure their stable survival.
However, if there is a free-rider within the Zoé tribe who only takes without giving back, this social insurance system—which has been implicitly established among the people—will be undermined. If the free-rider is someone who will soon leave the Zoé tribe, they may benefit from just a few instances of free-riding without suffering any consequences. However, since most members of the Zoe tribe live in the same community from birth until death, those who consistently act as free-riders are highly likely to become alienated from the community. Being alienated from the community significantly reduces one’s chances of obtaining food, which can lead to difficulties in survival or, even before that, result in expulsion from the community.
Therefore, for the reciprocity hypothesis to function properly and deter free-riding, it is necessary that relationships among actors be sustained over time; the concept that explains this is the repeated reciprocity hypothesis. One might wonder whether the repeated reciprocity hypothesis is important only for primitive tribes living by hunting in the wild and is no longer relevant to people living in modern society. However, even today, the repeated reciprocity hypothesis remains applicable within various social relationships.
South Korea’s wedding culture serves as a prime example. A typical practice involves giving a wedding gift to an acquaintance’s wedding and later receiving a gift in return when one gets married. The reason people give wedding gifts to acquaintances is partly to reduce the financial burden of their own wedding through the gifts they will receive in the future, and partly to maintain social relationships and bonds. Although there has been no shortage of criticism of this wedding gift culture recently, the reason it does not easily disappear is that it is difficult to resolve at once the kind of creditor-debtor relationship that has been formed over a long period of time. Thus, in modern society, even if the Reciprocity Hypothesis is not directly linked to survival, it plays an important role in maintaining social relationships, and sociality occupies a very important place in human life.
Of course, the reciprocity hypothesis has its limitations, and various alternative hypotheses have been proposed to supplement or replace it. Nevertheless, reciprocity is still regarded as one of the key concepts explaining human cooperation and social trust today. This principle of reciprocity has enabled altruistic individuals to survive even in competition with selfish ones, and it has served as a vital driving force for societal development based on trust and cooperation, a legacy that continues to this day.
