Cultural transmission, copying errors, and the generation of variation in material culture and the archaeological record

Archaeologists are adept at analyzing variation in artifacts. The discipline has well established and tested methods to track change through time and to evaluate the function of artifacts that depend upon measures of variation in the archaeological record. Although a critical concept, the means by which variation in material culture is generated is not well understood. This paper explores one source of variation, copying errors, and systematically examines how cultural transmission processes act to amplify, reduce, or maintain such variation. Using simple models, we generate expected distributions for the amount of variation that occurs through time under varying circumstances. This variation is caused by small errors that are transmitted from one person to another in the propagation and replication of cultural traits. These baseline values provide useful null models for explaining variation in prehistoric assemblages of artifacts. We use measurements of projectile points from Owens Valley and Woodland ceramics from Illinois to demonstrate the value of this approach.