In this blog post, we’ll examine why altruistic behaviors—which seem evolutionarily disadvantageous—have persisted to this day, using the costly signaling hypothesis.
Why Do Altruistic Behaviors Persist?
We often hear news stories about people who, despite an announcement that a subway train is about to arrive, jump onto the tracks without hesitation to rescue someone who has fallen. Fortunately, there have been cases where both the person who fell onto the tracks and the rescuer emerged unharmed, but there have also been cases where this was not the outcome. In one such instance, Lee Su-hyun, a student studying abroad in Japan, lost her life while trying to rescue an intoxicated Japanese man at a train station in Tokyo. While some people stand helplessly, not knowing what to do when they see someone on the tracks, the actions of those who jump in without hesitation move many people. However, it is not easy to actually carry out such actions, as they can put one’s own life at risk. Yet, considering that living organisms evolve in ways that benefit themselves, such heroic behavior appears to be evolutionarily disadvantageous. So how have these altruistic acts persisted to this day? Among the various hypotheses explaining why altruistic behavior has endured, let’s explore the “costly signaling hypothesis.”
What is the costly signaling hypothesis?
The costly signaling hypothesis explains that altruistic behavior has persisted because it allows individuals to demonstrate their capabilities. As the name suggests, this hypothesis views altruistic behavior as equivalent to sending a costly signal, since engaging in such behavior requires one to bear various costs—such as time, effort, and risk. In other words, the very fact that someone engages in altruistic behavior despite the costs involved serves as a signal demonstrating their competence and resources.
Let’s examine this hypothesis through a real-world example. According to Kristen Hawkes, among the Aché tribe in Paraguay, the same individuals tend to be successful hunters, and there is little variation in who provides the meat and who receives it. Furthermore, it is known that directly boasting about one’s abilities is subject to disciplinary action within this tribe. Therefore, while men must demonstrate their superiority to women in order to secure a good spouse, they cannot do so overtly. In this situation, consistently hunting and sharing the meat they obtain becomes a way to naturally demonstrate their abilities without facing disciplinary action. Ultimately, for the men who hunt, the benefits gained from having their abilities recognized outweigh the costs involved, such as the physical labor required for hunting.
Does altruistic behavior still hold meaning in modern society?
As seen in the previous example, not everyone is capable of altruistic behavior. Therefore, the level of altruistic behavior indirectly demonstrates an individual’s capabilities and serves to distinguish capable individuals from those who are not. From this perspective, altruistic behavior acts as a mechanism that allows evolutionarily fit individuals to secure an advantageous position for reproduction. According to the costly signaling hypothesis, the reason altruistic behavior has persisted to this day is also due to the benefits it provides.
So what are these benefits in modern society? As society has developed, living alone has become virtually impossible. People meet and form relationships with various others every day. In this environment, altruistic behavior serves as a signal that one is a trustworthy person with whom others can maintain long-term relationships. Ultimately, altruistic behavior can be viewed as a cost willingly borne to form and maintain long-term human relationships.
Significance and Limitations of the Costly Signaling Hypothesis
The costly signaling hypothesis explains why altruistic behavior has persisted from an evolutionary perspective, while also accounting for cases that are difficult to explain fully with other hypotheses alone. A prime example is the act of donating money to someone asking for help on the street.
Some hypotheses suggest that people choose to cooperate to avoid retaliation from others. However, this explanation alone cannot fully account for the act of helping a stranger encountered on the street, as the likelihood of retaliation from that person is virtually nonexistent. In contrast, the costly signaling hypothesis explains that such altruistic behavior is performed to demonstrate one’s financial means and generosity to those around them and to earn a good reputation.
However, this hypothesis also has its limitations. It fails to adequately explain altruistic behavior that occurs in situations where there is no one to whom the individual wishes to present a favorable image. Despite these limitations, the costly signaling hypothesis is significant in explaining why altruistic behavior has persisted from an evolutionary perspective and in understanding various examples of altruistic behavior.
