The “Lucifer Principle” is freelance journalist Bloom’s theory that evil-which manifests in violence, destructiveness and war-is woven into our biological fabric. A corollary is that evil is a by-product of nature’s strategy to move the world to greater heights of organization and power as national or religious groups follow ideologies that trigger lofty ideals as well as base cruelty. In an ambitious, often provocative study, Bloom applies the ideas of sociobiology, ethology and the “killer ape” school of anthropology to the broad canvas of history, with examples ranging from Oliver Cromwell’s reputed pleasure in killing and raping to Mao Tse-tung’s bloody Cultural Revolution, India’s caste system and Islamic fundamentalist expansion. Bloom says Americans suffer “perceptual shutdown” that blinds them to the United States’ downward slide in the pecking order of nations. His use of concepts like pecking order, memes (self-replicating clusters of ideas), the “neural net” or group mind of the social “superorganism” seem more like metaphors than explanatory tools.