In almost every human society some people get more and others get less. Why is inequity the rule in human societies? The Origins of Unfairness looks at cultural evolution in groups divided into social categories like gender and race to consider this question. Philosopher Cailin O'Connor explores how simple processes of interaction and learning tend to generate unfairness across a wide range of circumstances - an important lesson for social justice. Inestablishing just societies it is crucial to fight personal biases, but ultimately this may not be enough when the most basic cultural evolutionary processes lead to inequity.