In this blog post, we will examine how altruistic behavior, which seems disadvantageous to individuals, survived in human evolution and became established as a survival strategy for groups.
“Just a bite.” It’s not easy to refuse a friend’s request to share a little ramen, even when you’re hungry. Also, if you see a friend being beaten up on the street, you feel compelled to rush over and help, even at risk to yourself. We call these acts of helping others at our own expense ”altruistic behavior.” Altruistic behavior is deeply rooted in our lives, but it is not easy to explain how it has been passed down and preserved throughout the long process of human evolution. As a simple example, imagine a world in the distant past where altruistic humans and selfish humans lived together. Altruistic humans always try to help selfish humans, while selfish humans only take advantage of their help. In other words, when food is scarce or danger arises, altruistic humans who do not receive help are more likely to die early and become evolutionarily disadvantaged. So how can we explain the persistence of altruistic behavior even after 2.3 million years of evolution?
One answer can be found in competition between altruistic and selfish groups, rather than competition between altruistic and selfish individuals. Let’s take a closer look at this. In the example above, we assumed that a person’s chances of survival were determined by competition between altruistic and selfish individuals. However, sometimes factors such as war and climate change play an important role in the survival or death of groups, which is called group selection. In the case of individual selection arising from competition between individuals, we explained in the previous example that selfish tendencies are more advantageous than altruistic tendencies. Then, what about group selection?
First, let’s consider a case where a war breaks out between two groups. If a colleague is in danger after being hit by an enemy, an altruistic person will give up their own safety and rush to help their colleague. On the other hand, a selfish person will sacrifice their colleague’s life for their own safety. In the case of selfish people, each individual makes the best choice for their own survival at that moment, but as a result, the death of their comrades weakens the military force, increasing the likelihood that the entire group will be defeated and wiped out. In addition, in various situations during war, altruistic people are prepared to devote themselves to their team, so teams with many altruistic people are more likely to win the war. In other words, at the group level, altruistic people have a higher survival rate than selfish people. In fact, ancient primitive tribes often fought wars between tribes, and the defeated tribes were often wiped out, which supports the group selection hypothesis.
Second, humans have lived as hunter-gatherers for hundreds of thousands of years. In a hunter-gatherer society, altruistic cooperation plays an important role. Let’s return to the example of “just one bite” mentioned at the beginning of this article. An altruistic tribe will not refuse a request for just one bite when there is no food, and this becomes the driving force that allows the entire tribe to survive without starving. However, if a selfish tribe repeatedly fails to hunt, they will inevitably starve to death. Furthermore, since obtaining food is not easy, it is beneficial for the entire tribe if several people cooperate to obtain it. This is because if each person hunts independently, they will only be able to catch small animals, but if they work together, they will be able to hunt large animals. Therefore, the hunting and gathering lifestyle increases the chances of survival for altruistic tribes.
Traces of this concept of group selection can also be found in modern society. For example, in crisis situations such as natural disasters and pandemics, we have witnessed how altruistic behavior promotes the survival and well-being of groups. Many people have risked their own lives to provide medical assistance or help their neighbors in need. Such behavior can be seen as simply a moral choice made by individuals, but from a broader perspective, it can be said to be part of a collective survival strategy that humanity has developed through a long process of evolution.
Although we have presented two situations that support the possibility of the group selection hypothesis, this does not mean that the hypothesis has no limitations. For group selection to work effectively, the rate at which altruistic individuals increase through group selection must be greater than the rate at which they decrease through individual selection. If individuals who are refused a “bite” before even trying to wage war against other tribes all starve to death, wouldn’t only selfish people remain in each tribe? In fact, many scholars point out the unrealistic nature of the group selection hypothesis due to this problem, and there are explanations that attempt to overcome this limitation by utilizing the characteristic of human “institutions.” Just as there are distribution systems to reduce income inequality in modern times, ancient primitive tribes had customs of sharing food. These systems became a driving force for the survival of individuals who could not obtain food. In other words, the system reduced the gap between individuals and the speed of individual selection, thereby increasing the influence of group selection.
We have looked at one hypothesis about how human altruism, which at first glance seems evolutionarily disadvantageous, has been preserved. The group selection hypothesis states that altruistic groups have a survival advantage over non-altruistic groups, and therefore altruism has been preserved at the group level. We explained the evolution of altruism, which could not be explained by competition between individuals, through two situations: war and hunting and gathering. We also briefly examined the limitations of the hypothesis and ways to overcome them. As there is still much debate and many aspects that need to be explained, it remains to be seen whether the group selection hypothesis can be established as a candidate to explain much of altruism. The evolution of altruism has more significance than a simple theory and provides important clues for understanding cooperation and interaction in human society.
