The evolution of social behaviour in animals, is one of the major unsolved problems in evolutionary biology. This is because, in many social animals only one or a small number of individuals reproduce while the remaining forgo reproduction and work for the welfare of the rest of the group. Why such altruistic workers are not eliminated by natural selection, which is expected to promote the ‘survival of the fittest’, is hard to explain. The theory of Inclusive Fitness (also known as Kin Selection), which argues that altruism can evolve by natural selection if it is directed toward close genetic relatives, was proposed in the mid 20 th century. In this talk I will describe some of our research in this field, discuss the recent bitter controversy about the theory, venture my own response to the controversy and focus attention on the process of science.