The social insects include the bees, ants, wasps and termites. They are called social because they assemble into large colonies of sterile workers that support the excessive reproduction of a relative, usually a parent. These insects present a conundrum, because their form of sociality involves foregoing reproduction to aid the reproduction of another: what is known as reproductive altruism. Because our theories of evolution are based upon successful reproduction, this is a puzzle. You will learn how scientists think they have solved the puzzle, and you will learn a lot of fascinating stuff about these insects along the way.