In 1968, A.P. Vayda and Roy Rappaport articulated a new approach for the study of human-environment interaction, representing a marked departure from previous anthropological approaches. Vayda and Rappapor’s formulation advocated the adoption of “ecosystem” and component “populations” as conceptual analytical units in place of earlier conceptual units, namely “culture” and “environment.” The advantages of their approach were immediately apparent to those who had become dissatisfied with the vague and ambiguous notion of culture when used to explicate human-environment interaction and who were impressed by the achievements of the emerging fields of systems theory, ethology, and ecology. This formulation was particularly attractive in that its treatment of humans as one population among many enabled anthropologists to use theoretical models developed in other fields. Among the ecosystemic models which were soon directed to questions of human behavior were those using optimal foraging strategy, population regulation and carrying capacity, and bioenergetics.