It’s a problem that has been debated ever since Darwin: how have hundreds of species of insects and other animals evolved altruistic helpers that give up their own reproduction for the sake of others?Recently, the orthodox explanation – that they favour their own genes indirectly by helping their kin – has been fiercely challenged by Edward O Wilson, one of the most prominent evolutionary biologists of our time. But now a research team led by William Hughes, of Leeds University, UK, claims to have falsified Wilson’s predictions, showing that genetic relatedness is really the key.