The methods I investigated essentially are some of the currently best approaches for implementing tests to determining which of several transmission pathways most govern the spread of a trait. This type of question is core to cultural evolutionary analysis, and in my view core to the original mandate of anthropology. A good example of a running anthropological discussion on this matter would be the analysis of Welsch et al. 1992 and the critiques, counter critiques, and reanalyses that followed. In my view, this entire exchange is some of the best of anthropology.
Of course, post-Boas cultural anthropology tends not to view articles like Welsch et al. 1992 as of foundational interest. That’s because much of American cultural anthropology left behind methods that systematically compared across different sites or cultures in favor of particularist accounts conducted though increasingly humanistic modes of research. Nothing wrong with the latter by the way – I regard it as a completely valid intellectual activity. It’s just not the entirety of what anthropology was founded to do, and the result has left a significant portion of scientific research on culture without a disciplinary home.
Most biologically inclined anthropologists, meanwhile, in recent memory had vigorously adopted the behavioral ecology paradigm (Grafen’s phenotypic gambit) – which is essentially utility maximization theory from microeconomics with reproductive success or its proxies in replacement of money. Studying cultural evolution is difficult to fit into this framework because classical behavioral ecology is intentionally heuristically teleological rather than explicit and mechanical. Behavioral ecologists don’t necessarily think people are intentionally trying to maximize fitness outcomes, although some might, but they think at least that the mechanical operations of the mind result in a being that behaves as if it is maximizing fitness. In the classic approach no attempt is made to understand the causal mechanisms. That’s all fine, it just only gets you so far. Wouldn’t you rather actually know about the mechanisms themselves?
The perhaps unexpected irony is that folks interested in cultural evolutionary models, by articulating proximate mechanisms, arguably are the ones being more reductionist than those sticking within the classical behavioral ecology paradigm. It’s ironic because cultural research has so often been assumed to have something to do with non-reductionist notions. Thornhill and Palmer in their controversial book at one point say people prefer cultural explanations because culture is consistent with the idea of free will – but cultural explanations offered by cultural evolutionists are just as causal as explanations offered by behavioral ecologists. Both explain individuals’ behavior as a mechanistic result of prior events. In fact, I’d argue cultural evolutionists are being more causal in that they usually seek to specify causal mechanisms start to finish, ultimately and proximately, while behavioral ecology in its classical approach leaves proximate mechanisms unspecified. Fincher and Thornhill’s well-known articles on infectious disease stress and cultural traits are good examples – we are left at the end of the papers with only a functional relationship (heuristic teleology) and don’t know if that is mediated by cultural inheritance, individual learning, an innate reaction norm, or genetic variation.
The second irony is that “behavioral economics,” that moves beyond utility maximization and into proximate causes, has become mainstream or nearly so in microeconomics, and microeconomics essentially is where behavioral ecology first coopted its theory.
Which brings me back to social network analysis applied to cultural diffusion. Cultural diffusion as a theorized process really sits between proximate and ultimate causation in the traditional sense because it is 1) a proximate factor in individual’s personal development, 2) has an epidemiological and phylogenetic character to its own as cultural history, and 3) ultimately can’t fully escape biological selection because, at least among any longstanding cultural variants, natural selection will favor directly cultural variants that promote fitness or genes that bias people to prefer such variants. The other thing I like about studying cultural diffusion, inheritance, and related processes is the hypotheses are eminently refutable. I think culture often is important, but whether it is important or not to a particular case is an empirical matter. Folks like me doing this, I think, often find cases in which culture is not the most important process involved. In some of my own research, I’ve proposed that genetic variation accounts for some cross-society differences in personality traits that are usually interpreted as entirely socially learned (Matthews and Butler 2011). My recent paper tries to advance the empiricist and refutable tradition of cultural research by determining which of the currently available methods perform best at discerning cultural diffusion processes.