Richerson and Boyd reject the simplistic model of gene-like "memes," but they are rather vague, as they must be, on how to recognize culture or its structure. They are aware that one aspect of culture will change in reaction to and in concert with other aspects of culture, that there is a complex network of causal dependency among parts of culture. Changes in technology, occupation, education, political attitudes, division of household labor and parental responsibility, leisure activities, and styles of speech and dress are connected as both causes and effects within and between generations.
The most important question is why we should use a Darwinian model at all for history and culture.
That a theoretical formulation is desirable because it makes it easier and more efficient to write more articles and books giving simple explanations for phenomena that are complex and diverse seems a strange justification for work that claims to be scientific. It confuses "understanding" in the weak sense of making coherent and comprehensible statements about the real world with "understanding" that means making correct statements about nature. It makes the investigation of material nature into an intellectual game, disarming us in our struggle to maintain science against mysticism.