The story of “The Thorn in the Side of the Road,” which we all remember as children, depicts a father sacrificing his own eye for his sick son. Altruistic behavior like this can be explained through the theory of kin selection. This is because behaviors that help the survival of individuals who share genes with you will eventually have an advantage in spreading your own genes. Examples like thornbills and bees show how this altruistic behavior has been able to evolve and persist. However, this theory doesn’t explain why humans are altruistic to others who are not related to them.
One of the books that made me cry as a child was Kashiogi. The book depicts a devoted father who sacrificed his own eye for his sick son from the perspective of his cheerful young son. The reason the book is titled Thornbill is because the male Thornbill is also a devoted father who risks his life to spy on his eggs, just like the father of the young son in the book. How did such tear-jerkingly selfless behavior, even to the point of sacrificing one’s own life, emerge and persist? How can we explain them scientifically?
The expression of altruistic behavior can be explained through the concept of altruistic genes. This is the idea that people and animals are altruistic because the genes that cause them to be altruistic have been passed down. In order to pass on genes, one must survive, even if selfishly, so scientists have considered survival and reproduction to be the most important factor in passing on genes. From this perspective, the idea of altruistic genes being passed on is quite puzzling and has important implications. The altruistic gene causes us to sacrifice our own interests in favor of others. How did this altruistic gene, which gives to the benefit of others even at the expense of one’s own, survive and be passed on to offspring? Why do individuals who should be prioritizing their own survival, such as spiny lobsters and fathers, sacrifice for others, even at the risk of their own survival?
A biologist named William Hamilton introduced the concept of kin selection to explain this altruistic behavior. Kin selection refers to the behavior of helping more individuals with your genes survive and reproduce. By doing so, individuals increase the likelihood that their genes will be passed on to their descendants. This can explain why a male in a thornbill will defend his eggs with his life, or why a father in a book will sacrifice himself for his son. These behaviors are all part of a strategy to pass on their genes to the next generation.
In The Emergence of Altruism, a biologist named William Hamilton explains altruistic behavior among kin, such as family members and relatives, through a theory called kin selection instead of warm paternalism. If I am born to a father and a mother, I will, on average, receive half my father’s genes and half my mother’s genes. This is easy to understand if you consider that children have an equal amount of their father’s genes and their mother’s genes. In other words, I have half of my father’s genes. From a genetic point of view, I am not my father, but I am half of him. The important thing is not to survive yourself, but to spread your genes. However, the existence of other people with similar genetic factors to my father gives him the opportunity to spread his genes without having to survive himself.
This theory is also observed in the animal world. For example, when African bison encounter a predator, the weakest members of the herd will gather on the outside and the stronger members will gather on the inside to defend themselves. This increases their chances of survival while also increasing their chances of passing on their genes to the next generation. This behavior is not just an instinctive response, but a genetically programmed survival strategy.
To better understand kin selection, let’s use the example of bees in nature, rather than humans. Bees perform altruistic behaviors such as protecting the queen’s eggs and sacrificing themselves for her safety. These behaviors can also be explained by kin selection. The queen is actually a sibling to the worker bees. Siblings share many of the same genes as parents and children. We all know this on a basic level from how much we resemble our younger siblings, and in the case of bees, worker bees can’t reproduce, so they protect the eggs of their closest relatives, the queen and her nieces and nephews, even at the risk of their own lives, so that they can spread their genes far and wide. The worker bees are not making a blind sacrifice to the queen, but are ultimately trying to spread their genes for their own benefit. Since they can’t actually spread their own genes through reproduction, they’re helping individuals that look like them survive.
In this way, kin selection has answered many questions about altruistic behavior. The reason why altruistic genes, which sacrifice their own self-interest for the benefit of others, survive and are passed on is because they provide some benefit to themselves. This is especially true in the context of kinship, where helping the survival of parents, brothers, and sisters who share many of the same genes as you may end up being as beneficial as spreading your own genes. We’ve seen this in nature with the example of bees.
However, there are still a couple of questions that remain unanswered. The first is that all animals don’t necessarily live in social groups, even if they are related. The second is that, like humans, they can perform altruistic acts, even for people they’ve never met before. We often see examples of people jumping into subway tracks to save a stranger. This kind of altruism, which involves sacrificing one’s life for someone who is not even related to them, is not explained by this hypothesis. Therefore, kin selection is limited to explaining altruistic behavior in specific cases. A more holistic and complete explanation is needed to explain altruistic behavior among organisms. However, within kinship groups, kin selection is a good enough explanation for altruistic behavior. Blood is thicker than water. Very thick.
