Halloween merchandise is worth around $10 billion per annum in America alone. Ghosts, witches, and zombies are obviously products of a uniquely human imagination – but why? Harvey Whitehouse , Professor of Social Anthropology in the Institute of Social and Cultural Anthropology , University of Oxford, writes that the answer lies in the way the human brain develops. The reason why ghosts, witches, and zombies are so appealing to us is because they violate our early developing expectations about