In Humanity, English ethicist Jonathan Glover begins with the now commonplace observation that the last 100 years were perhaps the most brutal in all history. But the problem wasn't that human nature suddenly took a sharp turn for the worse: "It is a myth that barbarism is unique to the twentieth century: the whole of human history includes wars, massacres, and every kind of torture and cruelty," he writes. Technology has made a huge difference, but psychology has remained the same--and this is what Glover seeks to examine, through discussions of Nietzsche, the My Lai atrocity in Vietnam, Hiroshima, tribal genocide in Rwanda, Stalinism, Nazism, and so on.