On the useful site, Evolutionary Theories in the Social Sciences, a working paper by Richard Nelson on evolutionary theories of cultural change.
[T]here are at least four intertwined “details” about the evolution of human culture that differentiate that process from biological evolution in important ways. They are, first, the often major role of human purpose, intelligence, and intellectual interaction, both in the generation of variety, and in the selection process. Second, selection criteria and mechanisms seldom involve directly issues of human survival or reproduction. The well being of certain kinds of organizations may be at stake, but often not. Third, the entity that is evolving − an aspect of human culture − is a phenomenon that cannot simply be characterized as the aggregation of the population of traits possessed by individuals, but has a collective property. These aspects of the evolution of human culture all are involved in a fourth important difference; the way human individuals and groups are involved with culture and its evolution is different in many ways from the manner in which genes and living entities are related in the evolution of species.