Partible Paternity and Anthropological Theory discusses the conception "partible paternity" within Amazonian Indian communities. "Partible paternity" is the idea that several sexual acts are necessary to produce a fetus and that the mother may have these with several men, who in turn have several sexual partners as well. Victorian anthropologists viewed this situation as "group marriage," a hypothetical state in which individual marriage and the family did not exist and which, presumably, once characterized Western society. The notion of "group marriage" was demolished by 1920, when it was shown that individual marriage and the family exist nearly everywhere. More recently, however, the idea has been resurrected by Stephen Beckerman and Paul Valentine in their book Cultures of Multiple Fathers. This book argues that Beckerman and Valentine are completely wrong—in Amazonia, the family exists everywhere, and the occasional trysts which result in shared paternity are subject to male sexual jealousy.