World Kindness Day is a global 24-hour celebration dedicated to paying-it-forward and focusing on the good. We are encouraged to perform acts of kindness such as giving blood, cleaning a communal microwave at work, or volunteering at a nursing home.
Of course, even without the encouragement of an international awareness day, kindness and selflessness are widespread among both humans and animals. Many people donate to charity and feel significantly happier as a direct result of doing so. In the animal kingdom, many species show kindness by refraining from violence when settling conflicts. Instead they may use comparatively harmless fighting conventions. Typical examples include male fiddler crabs fighting over a burrow but never crushing each other’s bodies with their huge pincers, rattlesnakes wrestling without ever biting each other or Bonobos helping strangers even without being asked.
The benefits gained from receiving kindness are intuitively obvious. But the motivations for engaging in kindness are much less so. In fact, the very existence of kindness and altruism seems to contradict Darwin’s theory of evolution, based as it is on a competitive process of natural selection in which only the fittest survive. For example, the selfless behaviour of sterile ants, who protect their colonies from dangerous predators, poses a problem that Darwin himself at first considered “insuperable, and actually fatal to my whole theory”.
So how could kind behaviour have evolved – and why was it not eliminated by natural selection? Many theorists have grappled with this problem over the years. We review the most prominent ideas below.
Early approaches, from the time of Darwin up to the 1960s, tried to explain the evolution of kindness by hypothesising that individuals behave cooperatively for the good of their group or species, irrespective of personal costs. This theory – “group selection theory” – was the only explanation for many decades, but it is now regarded with scepticism. How could cooperative populations, which allegedly survived better than competitive populations, have evolved in the first place?
Part of the answer is provided by the more recent selfish gene theory, widely known through Richard Dawkins’s bestselling book, or “inclusive fitness”, according to which natural selection favours kindness to our close relatives, who look similar to us and share our genes. Helping a relative is a way of passing on copies of our own genes, and it benefits the helper in proportion to how related he or she is to the recipient.