This volume brings together information about recent discoveries and current theories concerning the origin and early evolution of anthropoid primates monkeys, apes, and humans. Although Anthropoidea is one of the most dis tinctive groups of living primates, and the origin of the group is a frequent topic of discussion in the anthropological and paleontological literature, the topic of anthropoid origins has rarely been the foeus of direct discussion in primate evolution. Rather, diseussion of anthropoid origins appears as a ma jor side issue in volumes dealing with the origin of platyrrhines (Ciochon and Chiarelli, 1980), in discussions about the phylogenetic position of Tarsius, in descriptions of early anthropoid fossils, and in descriptions and revisions of various fossil prosimians. As a result, the literature on anthropoid origins has a long history of argument by advocacy, in which scholars with different views have expounded individual theories based on a small bit of evidence at hand, often with little consideration of alternative views and other types of evidence that have been used in their support. This type of scholarship struck us as a relatively unproductive approach to a critical issue in primate evolution.