This article explains human altruistic behavior primarily through the Tit for Tat Hypothesis, while also pointing out its limitations using examples such as the young man who lost his life trying to save a stranger on the subway.
According to evolutionary theory, organisms act in ways that benefit themselves. However, observing our surroundings, we often see people exhibiting altruistic behavior—helping others even at their own expense. To find the cause of such behavior, which cannot be explained by general evolutionary theory, much research has been conducted. As a result, several hypotheses have been proposed as possible explanations. These include the kin selection hypothesis, which posits that altruistic behavior is directed toward blood relatives for species preservation; the reciprocal altruism hypothesis, which explains altruistic exchanges between repeatedly encountered individuals; and the signaling hypothesis, which suggests altruistic acts serve to demonstrate one’s capabilities. Among these, we will focus on the reciprocal altruism hypothesis.
You’ve likely heard sayings like “What goes around comes around” or “You reap what you sow.” Literally, it means “I’ll do for you exactly what you do for me.” This idea forms the basis of the reciprocal altruism hypothesis—one explanation for why humans exhibit altruistic behavior. It suggests that altruistic behavior doesn’t just happen; it stems from the idea that if you help me, I’ll help you, and if you don’t help me, I won’t help you either. In a way, it might seem really simple. Yet, we can observe altruistic behavior around us stemming from this simple principle.
Some might believe true friendship means giving and receiving unconditionally between friends. Yet, when giving a friend a birthday gift, one might secretly expect a gift in return on their own birthday. Or, when it’s one’s turn to clean and circumstances prevent it, they might swap turns with a friend by promising to cover their next turn. These actions can all be seen as exchanges of altruistic behavior.
Here, one crucial condition must be considered: the continuity of the relationship. Take the cleaning example above: between a request from a classmate you’ll see every day and one from a friend likely transferring to a nearby school, whose request are you more likely to fulfill? Since you’re less likely to receive help from the transferring friend, you’re more likely to prioritize the request from the classmate you’ll see daily. Similarly, shopkeepers tend to give regular customers a bit more profit, even if it means a slight loss for themselves, rather than occasional customers. They know the regular will return to buy again, so it’s more profitable overall to give a little extra than to risk losing the customer by trying to squeeze out a small gain. In other words, the key condition for altruistic behavior is how long the relationship is likely to last.
Here, we see why it’s called the Reciprocity Hypothesis. When altruistic behavior occurs, the degree of reciprocity—helping those who help you and not helping those who don’t—varies depending on how often the relationship or transaction with the behaving individual is repeated. That’s why it’s called the Reciprocity Hypothesis. Thus, the Reciprocity Hypothesis explains many altruistic behaviors observed in people beyond the examples given. In relationships with individuals likely to be encountered repeatedly, altruistic actions occur because, while the moment itself may seem disadvantageous, it is advantageous when considering the overall future relationship.
However, actions like a young man losing his life trying to save someone who fell onto the tracks at a subway station, or giving up one’s seat on a bus or subway to the elderly or infirm, are not based on the expectation that the relationship will continue and that one will receive compensation. In other words, there are altruistic behaviors that this hypothesis cannot explain. Because of this, the Reciprocity Hypothesis is not accepted as the sole theory explaining altruistic behavior.
Beyond the tit-for-tat hypothesis, other theories of altruistic behavior exist, and none can fully explain the complex patterns of human behavior. While various hypotheses are proposed to understand altruistic behavior, it is interesting that no single theory can account for all situations. Considering the diversity and complexity of human behavior, it is important to comprehensively understand the aspects explained by each hypothesis. Ultimately, altruistic behavior can be seen as the result of multiple factors acting in combination.
Thus, understanding altruistic behavior is not limited to a single theory or hypothesis; it is an important subject that must be analyzed and researched from diverse perspectives. Research in this area will continue, and through it, we will gain a deeper understanding of the essence of human behavior.
