Worker bees cannot reproduce, but they make altruistic sacrifices to protect the queen and her eggs. According to the kin selection hypothesis, this behavior is explained by an evolutionary strategy that seeks to benefit genes beyond the survival of the individual.
If worker bees could talk, it wouldn’t be hard to hear them say, “Protect the queen!” Worker bees are not capable of reproducing themselves, but they dedicate their entire lives to protecting the queen and her eggs. They care for the eggs she lays and defend the hive with their lives in the event of an invasion. They sacrifice their entire lives for individuals other than themselves. The role of the worker bee in bee society is not just about physical labor. They work as a single organism, each doing their part to ensure the survival of the colony as a whole. In particular, the role of the worker bee is crucial to maintaining order in the bee society and ensuring future generations by keeping the queen, who is responsible for reproduction, safe and secure. However, this selfless sacrifice poses a mortal threat to the survival of each individual. Why has altruistic behavior not disappeared and evolved not only in bees but also in human and biological societies? To solve this mystery, we need a convincing hypothesis, one of which is the kin selection hypothesis. This hypothesis explains how altruistic behavior evolved based on the fact that individuals related to each other share the same genes. The idea is that by considering the fact that kin share genes with each other, we can learn something about each individual’s behavior that we didn’t know before.
Genes are the information that characterizes an individual and are passed down from parent to child. Individuals with genes that are favorable for survival will survive competition, reproduce, and leave many offspring, while those with genes that are unfavorable for survival will slowly disappear. This is what many people think of as natural selection from an individual perspective. When organisms reproduce, they inherit genes from their parents’ sperm and eggs, so they share some genes with their parents, and they also share genes with siblings who inherit genes from the same parent. In particular, bees have a higher degree of gene sharing among relatives than other species because all sperm from the father have the same chromosomes. The queen and worker bees share 75% of their genes, and the queen’s eggs and worker bees share 50% of their genes. This is a very high level of gene sharing, even compared to human societies, and because of this genetic structure, bees feel an instinctive responsibility for the survival of other individuals. So, while a worker bee’s devotion to the queen and her eggs may be to the detriment of the individual, it may be to the benefit of spreading the genes they share. In this way, the kin selection hypothesis explains that altruistic behavior evolved among related individuals because they share the same genes.
What does this altruistic behavior between related individuals mean from a genetic point of view? Biologist Richard Dawkins argued that altruistic sacrifice between individuals is selfish from a genetic point of view. He believed that it is the genes, not the individuals, that compete to survive and increase their numbers, and that individuals are nothing more than survival machines controlled by these genes. In other words, genes are selfish because they act to increase the number of their own genes rather than the survival of the individual. If there is a gene A, then an individual with gene A will strive for its own survival as well as the survival of other individuals with the same gene. Looking at the world through the lens of selfish genes can help us better understand the commitment of kinship behaviors. Consider a situation in which an enemy invades a bee society and the queen and her eggs are in danger, and a single worker bee can save them if he sacrifices his own life. As mentioned above, due to the specialized reproduction process of bees, worker bees share 75% of their genes with the queen and 50% with her eggs. If a worker bee sacrifices itself to save the queen and one of her eggs, it is sacrificing 100% of its genes to save 125% (75%+50%) of its genes, which means that from a selfish gene perspective, this behavior is completely rational.
So far, we’ve seen how altruistic behaviors that could be detrimental to the individual could evolve without being culled based on the hypothesis of kin selection. But the origins of altruistic behavior are not limited to bee and insect societies. Self-sacrifice for family members and close acquaintances is also common in human societies. The kin selection hypothesis explains that altruistic behavior among kin evolved because it can be detrimental to the individual but beneficial to the genes. It is one of the most logical and compelling hypotheses that introduces the concept of genes to explain how altruistic behavior evolved. The kin selection hypothesis effectively explains what other hypotheses, such as the group selection hypothesis, fail to explain. Of course, it has limitations, such as not explaining altruistic behavior among unrelated individuals. However, this limitation can be compensated for by explanations such as individuals only returning favors to those who have returned favors to them, or altruistic individuals banding together to benefit from each other. Thus, as we continue to develop keys to unlock the mystery of altruistic sacrifice, we may be able to unlock some of the mysteries of human and other creature behavior.
