Dehumanisation overturns our social instincts and conceives our fellow humans as unnatural beings. Combined with a perceived physical threat, this metaphysical transgression leads to atrocity writes David Livingstone-Smith

I have been studying dehumanization for the last fifteen years, and over that period my understanding of it has changed and deepened. Like most other researchers, I started out believing that when people dehumanize others, they think of them as subhuman animals—as rats, or cockroaches, or bloodthirsty predators. But I eventually came to recognize that this account isn’t quite right. Dehumanizers don’t think of their victims as nothing but animals. In the most dangerous kind of dehumanization—the kind that leads to the worst abuses and atrocities—dehumanizers conceive of their victims as monstrous, unnatural beings.