The book "Human Animals" by Frank Hamel explores the ancient belief that humans can change into animals and vice versa, which has been present in various cultures around the world. The belief originated from the theory that all things are created from one substance, mind, or spirit, and transformation from one form to another becomes a feasible idea. Transformation was believed to be accomplished in various ways, including self-transformation or by the agency of a sorcerer, witch, or the devil himself. The book examines different motives for transformation, including greed, cruelty, cannibalism, and the desire for personal power. Additionally, involuntary change into animal shape was thought to occur as a punishment for crime and was regarded as a judgment of the gods. Hamel also discusses the connection between this belief and the science of breaking up matter into electrons.
This is an older book about shapeshifting humans. It is a rather dry read but is well-researched and gives many examples from the beginning of documented history.