The reasons for altruistic behaviour in organisms like humans are related to a long evolutionary process. In particular, the kin selection hypothesis explains altruistic behaviour among kin, but not among non-kin. As a result, various theories have emerged to explain the evolution of altruism.
Can we survive on our own at birth without any help from those around us? The chances of survival would be slim, not to mention the fact that we would be exposed to various external dangers. Humans, as well as almost all other creatures, are born in the safe nest of their parents and grow up to be able to live independently. Without parental care, many lives would be lost as soon as they were born. For example, baby turtles run full speed towards the ocean as soon as they emerge from their eggs, but most of them are eaten by predators and only a few survive to grow up. This is a great example of how difficult it is for individuals born without parental care to survive in the wild.
In addition, as we know from the daily headlines about the ‘hero who saved a child from falling on the subway tracks’ and the ‘faceless angel who donates to help the less fortunate,’ all living things receive help from many sources other than their parents during their lives. There’s no doubt that altruistic motivations are common in our society. For example, during the COVID-19 pandemic that swept the world in 2020, countless healthcare workers and volunteers stepped up to help others, risking their lives to do so. They worked in dangerous situations, despite not directly benefiting themselves. These acts of selflessness happen every day, reminding us that humans are not just about personal gain.
However, given that it is in our personal best interest to benefit from the help of others, it is puzzling that such altruistic human co-operation, which emerged so long ago, is still present today. Why are we so altruistic, even to the point of sacrifice? And ultimately, how did altruistic co-operation survive and evolve in our society in the face of competition from selfish humans? In this article, we’ll explore the concepts and limitations of the kin selection hypothesis, one of the many hypotheses that explain the causes of altruistic behaviour, to help us better understand the motivations for altruistic behaviour in humans that often defy common sense.
The kin selection hypothesis was formalised by biologist William Hamilton in 1963, and there’s no better way to describe it than to say that ‘blood is thicker than water’ – that is, it’s natural for us to help those with whom we share blood. To understand this better, it’s important to know what we mean by ‘blood’. When we say that we ‘share blood’ with our family, siblings, and relatives, we don’t mean that we actually share the same blood with them through blood donation, but rather that we ‘share the same genes’. So what exactly is a gene? Genes are called genes because they are the determinants of traits, which are shapes or properties that an organism has, such as ‘tall’ or ‘fair’ skin, and are passed from parent to child. When you hear someone say, ‘You look just like your mum!’, it’s because the child has inherited the genes that the parent has, so the genes that the child has only come from the parent, so parents, children, and siblings share the same genes.
So, let’s get back to the point and talk about the hypothesis of kin selection. **The idea, which comes from the book The Descent of Man by Richard Dawkins, is that if we look at the behaviour of living things from the point of view of the genes instead of the organisms, the genes have the goal of spreading themselves as much as possible in the world. To do this, it needs to have as many offspring as possible who are likely to share its genes with each other, so an altruistic act performed on a being that ‘shares blood’ with you will help it survive and, in turn, increase its chances of spreading its shared genes. In other words, the ‘kin selection hypothesis’ starts from the premise that what seems altruistic to us may actually be ironically not altruistic at all. This hypothesis can explain altruistic behaviour in the world of bees. All worker bees in a honeybee colony are sisters, and the queen is the ‘chosen one’ of these sisters, so all eggs laid by the queen become her nieces and nephews. In this case, the worker bees are more likely to pass on their own genes to their offspring if they work their entire lives to nurture and feed their sisters, rather than reproduce themselves. Therefore, the extreme altruism shown by worker bees who spend their entire lives working would not be considered a sacrifice from a genetic point of view under the kin selection hypothesis.
But is this hypothesis really true? If it were true, we would live a cold, barren life where we would no longer need to feel warmth and gratitude for all our future altruistic acts. Fortunately, this hypothesis has major holes in its explanation of altruism. First and foremost, it cannot explain altruistic behaviour by beings who do not share a drop of blood. Just as mixing paint with water dilutes and thins the paint, so if I marry a partner who does not share my genes and have children, who then have new children, and so on, the proportion of genes shared between me and my offspring will decrease. From a genetic point of view, helping individuals with a higher proportion of genes shared with you is ultimately more beneficial for the spread of your genes, so according to the ‘kin selection hypothesis’, you should help the more closely related you are to yourself, and for the same reason, you should not help those who are not related to you. However, in reality, as we see in the newspapers, there are many instances of people helping people they don’t know at all, and according to Tim Clutton-Brock of the University of Cambridge, unrelated meerkats take turns standing guard and making loud alarm signals when an intruder appears, at the risk of giving away their location. These and other examples show that the blood-selection hypothesis is limited in its ability to explain altruistic behaviour among unrelated beings.
By looking at altruistic behaviour from the perspective of the gene rather than the individual, the blood-selection hypothesis provides a new perspective on the selfish motivations of genes. However, the hypothesis has a fatal limitation: it cannot explain good deeds that occur between unrelated beings. However, it is clear that kin selection is a very powerful explanation for the altruistic behaviour of individuals, especially in highly organised bee colonies and termite colonies. It is also clear that for a very long time in human history, our ancestors lived in kin-based groups, so kin selection must have played a role in the maintenance and evolution of our altruistic traits. Considering this, the kin selection hypothesis is significant because it was the first to provide an important key to explaining the motivation for altruistic behaviour, something that everyone has been wondering about. When combined with the hypothesis that explains altruistic behaviour between unrelated individuals, it provides a complete explanation for why altruistic cooperation, a long-studied and controversial phenomenon, could be evolutionarily competitive.
