Eusociality, where some individuals reduce their own reproductive potential to raise others' offspring, is what underpins the most advanced form of social organization and the dominance of social insects and humans. One of the key ideas to explain this has been kin selection theory or inclusive fitness, which argues that individuals cooperate according to how they are related. I have had doubts about it for quite a while. Standard natural selection is simpler and superior. Humans originated by multilevel selection—individual selection interacting with group selection, or tribe competing against tribe. We need to understand a great deal more about that.