The minimum group paradigm is a methodology in social psychology most commonly used to investigate the minimum conditions required for discrimination between groups. The most trivial distinction, such as eye colour, reveal the propensity in humans to form an in-group bias. The tendency to favour one’s group, even a group formed over something as arbitrary as shirt colour, will be taken to self-harm. Studies in which groups are created and offered money show a zero-sum mentality to maximise the difference between groups rather than the amount their group receives. Sam Bowles used mathematical models to show that conflict between groups for scarce resources was a necessary ingredient in our evolution for the emergence of altruism within groups. The only similarly divisive species are chimpanzees, giving weight to the idea that kindness and hatred are intertwined. Models show that the past conditions were ripe for both altruism and ethnocentrism, but only when both were present.