Peter J. Richerson and Robert Boyd, whose theory is discussed in the present article, are convinced that culture is, also from the point of view of biological evolutionary theory, an adaptive system that, however, could lead also to maladaptive behavior. The authors consider the present day decrease (or, rather, downswing) of fertility to be a prominent example of maladaptive behavior. The present study discusses this theory from the point of view of historical demography and cultural history. It discusses the suitability of the criteria of maladaptation and stressed the fact that the decrease of fertility can be considered, until certain degree, an adaptive behavior (increasing the fitness)., Jan Horský., and Obsahuje bibliografii