Nonhuman primates represent the most significant extant species for com- parative studies of cognition, including such complex phenomena as numer- ical competence, among others. Studies of numerical skills in monkeys and apes have a long, though somewhat sparse history, although questions for current empirical studies remain of great interest to several fields, including comparative, developmental, and cognitive psychology; anthropology; ethol- ogy; and philosophy, to name a few. In addition to demonstrated similarities in complex information processing, empirical studies of a variety of potential cognitive limitations or constraints have provided insights into similarities and differences across the primate order, and continue to offer theoretical and pragmatic directions for future research. An historical overview of pri- mate numerical studies is presented, as well as a summary of the 17-year research history, including recent findings, of the Comparative Cognition Project at The Ohio State University Chimpanzee Center. Overall, the archi- val literature on number-related skills and counting in nonhuman primates offers important implications for revising our thinking about comparative neuroanatomy, cross-species (human/ape) cognitive similarities and differ- ences, and the evolution of cognition represented by the primate continuum.
Boysen, S. (2000). Primate numerical competence: contributions toward understanding nonhuman cognition. Cognitive Science, 24(3), 423–443. https://doi.org/10.1016/s0364-0213(00)00025-2