This article explains why altruistic behavior has been able to persist and evolve in human societies despite the laws of natural selection favoring selfish behavior, through the hypothesis of group selection. It discusses how human societies maintain altruistic behavior through cooperation and institutions, and how altruistic groups have an advantage in the competition for survival.
We see many altruistic behaviors in our society, such as donating blood or cleaning up alleys. It’s not just a coincidence; it plays an important role in the maintenance and development of our society. Altruistic behaviors promote trust between individuals and communities, strengthen social bonds, and ultimately help everyone live in a better environment. But altruistic behavior is a conundrum from the perspective of natural selection.
Natural selection is the theory that explains how traits that are favorable for survival and reproduction are passed on to the next generation. If altruistic people help others even at their own expense, while selfish people can get help without having to put in any effort, then altruistic people are bound to be eliminated in the competition for survival between the two groups. According to natural selection, members of a society will choose selfish strategies that favor their survival, and eventually selfishness will prevail in our society. However, contrary to natural selection’s prediction, there are many examples of altruistic behavior in our society. Where does the ability to suppress selfishness and act altruistically come from, despite the fact that it is possible to maximize profit through free riding?
One of the keys to unlocking this mystery is the group selection hypothesis. Simply put, group selection is the hypothesis that the characteristics of a group affect the survival of the group, just as the characteristics of an individual affect the survival of the individual. In other words, natural selection acts on groups rather than individuals. Interestingly, altruistic behavior, which would be a weakness under individual selection, becomes a strength under group selection, giving the group an advantage in the competition for survival.
To better understand this, we need to emphasize once again the importance of social cooperation. Human societies have fundamentally relied on mutual cooperation to develop. Cooperation was essential because it was difficult for individuals to obtain all the resources they needed to survive and reproduce on their own. For example, prehistoric humans realized the value of cooperation through large-scale hunting and resource distribution. More than just a survival tool, these cooperative behaviors played an important role in shaping and maintaining culture and norms.
Consider the zerglings being consumed by defilers in StarCraft: if there were a lot of selfish zerglings, no one would be willing to die, and it would be difficult to win a battle between races. On the other hand, if there were many altruistic zerglings, they would be willing to sacrifice themselves and help their species win.
If we look at human history, there seems to be a lot of room for group selection to come into play. In primitive tribal societies, tribal wars were common and highly lethal. Groups with more altruistic individuals would have been more likely to win intergroup conflicts. In pre-farming hunter-gatherer societies, success in hunting and gathering depended on how selflessly members cooperated. Selfless acts of cooperation, such as finding safe shelter and protecting people from raids, were essential to surviving tens of thousands of years in harsh environments. The more altruistic a group was, the more likely it was to survive in harsh environments.
However, there are still questions to be answered. In individual selection, altruistic individuals cannot be as successful as selfish individuals and are at risk of extinction, but in group selection, groups with more altruistic individuals are more successful or have an advantage in the survival competition than those without. Because individual selection and collective selection work in opposite directions, for the collective selection theory to be convincing, it must be shown that the rate of collective selection has overwhelmed the rate of individual selection.
Humans have slowed down individual selection and amplified the effects of collective selection through “institutions”-rules, customs, laws, etc.-that affect interactions among members of society. One of these institutions is equal income distribution. The food-sharing practices of ancient hunter-gatherer tribes acted as a mechanism for equalizing income distribution, making it less likely that altruistic and selfish individuals would differ from each other, thus increasing the likelihood that group selection would occur.
Conformist cultural transmission also strongly favors group selection. Conforming cultural transmission means that if more than half of the people in a group are altruistic, more people will learn altruistic strategies, leading to more altruistic people, and if more than half of the people are selfish, more selfish people will learn selfish strategies, leading to more selfish people. The reason why conformist culture transfer is important is that even small differences within a group can make a big difference between groups. Imagine a group of 55% altruistic people and a group of 45% altruistic people. The difference between the two groups is only 10%, but if conformist culture transfer occurs within the groups, the first group will become more altruistic and the second group will become less altruistic. Conformist cultural transmission would create a large gap between the groups, increasing the effectiveness of group selection.
So far, we have solved the mystery of how altruistic humans have survived by using the theory of group selection. Group selection is the hypothesis that natural selection occurs in groups and that group characteristics affect the survival of the group, and humans have greatly increased the effect of group selection through institutions and conformist cultural transmission, creating an environment in which altruistic humans can survive. Although group selection has limitations in that it is not evolutionarily stable, it is a compelling hypothesis that explains how altruistic behavior has evolved in human societies.
