A few weeks ago, I was invited write a commentary for a Social Evolution Forum article by D.S. Wilson called “Human Cultures are Primarily Adaptive at the Group Level.” My commentary,”Should the Consensus be Essentialist and Adaptationist?” was just posted.
While I agreed with what I felt was the spirit of Wilson’s article, I had two caveats:
1) It is problematic to call human groups “cultures” in terms of multi-level selection models. The reason is that there is important variation in cultural traits within groups, and thinking of them as monolithic cultures encourages researchers to ignore this variation and instead focus on traits that are commonly held. For those of us interested in testing models of cultural evolution, this is a big problem with most ethnographic data because ethnographers (anthropologists who study culture) have tended to ignore within-group variation and, instead, describe traits that generally define their particular study group. In my commentary, I refer to this thinking as a type of essentialism.
2) I am not ready to focus on adaptation. In evolutionary biology, adaptations are traits that appear to be designed for some purpose, but that exist because of the processes of natural selection. Some evolutionists focus on adaptations and some see explaining adaptations as the primary goal of evolutionary biology. Others, including me, are less interested in adaptation itself and more interested in explaining the distribution of traits in a population which may have resulted from different evolutionary mechanisms, including drift, mutation, migration, selection at different levels of analysis, and frequency-dependent selection. In terms of cultural inheritance, there are also different learning biases (more on these in a future post) that have to be taken into account. Focusing on adaptations may encourage researchers to ignore mechanisms other than selection and non-adaptive traits. This type of thinking is called adaptationsim.
In short, when looking at the fitness landscape, adaptationists tend to focus on the peaks, but I am more interested in explaining how traits are actually distributed across the whole landscape.
“Adaptationsim” is a term used by critics. There aren’t really any self-proclaimed adaptationsts – or anyone who ever believed what the critics attacked. There are people who think that adaptations are important, and represent a useful default hypothesis for features of organisms. However, those ideas are quite reasonable and defensible.
Peter Godfrey-Smith identifies three types of adaptationism (http://www.petergodfreysmith.com/PGS-Adapt3.pdf).
When you write that adaptations “represent a useful default hypothesis for features of organisms” this is methodological adaptationism. This may be reasonable, but my preference is to consider a wider range of reasonable models than pick a default one. And I definitely think it is too early to say that group-level adaptations represent a useful default hypothesis for features of human groups.
There clearly are also advocates of other types of adaptationism. For example, explanatory adaptationism posits that the most important question in evolutionary biology is explaining adaptations. An example of prominent people who believe this are West and co-authors who write “The cardinal problem for evolutionary biology is to explain adaptation.” (http://www.zoo.ox.ac.uk/group/west/pdf/WestElMoudenGardner_11.pdf)
This is a statement of opinion and hard to argue with. However, I would rather this be phrased “the problem in evolutionary biology that most interests us is explaining adaptation” since it seems presumptuous to speak for an entire subfield. In any case, this is not a question that interests particularly interests me, so my preference would be that the study of cultural evolution not get too focused on adaptations.