Talking to Ingo Brigandt about his ethnic nepotism paper, he brought up an interesting concern about evolutionary psychology.

Evolutionary psychology postulates mental or behavioural modules based on alleged selective demands. Note that these modules are functionally defined and that the assumption is that for each important ecological and behavioural function there is a *distinct* mental module. (E.g., as jealousy has an important social effect on reproductive success, evolutionary psychologists postulated the existence of a jealousy module). Evolutionary developmental biologists talk about ‘modules’ as well. however, they have a structural-developmental understanding of module. A module is a homologue, i.e., a structure that is structurally-developmentally defined and a character that exists across species as it is inherited from a common ancestor. On this account, something is a unique module if it is a single character that may vary relatively independently from other characters. To figure out whether something is a unique character one has to study its evolution on a phylogenetic tree (or its variation within a species). In addition to this standard comparative method, evolutionary developmental biology offers insights as to whether a module is developmentally individualized so that it evolves as a real unit or character.

He goes on:

The point of this is that whether there is really a jealousy module (distinct from other postulated modules) depends on whether the *material * basis of this feature can actually vary and change in evolution without affecting other traits. But this can only occur if this module is developmentally dissociated from other modules. Mainstream evolutionary psychology does not address any of these questions, that’s why I think that this approach and relate[d] ones (Salter, etc) are scientifically not fruitful. What one has to do is to view behavioral features, emotions, and the like as modules in the sense of homologues, and study their variation in humans and homologize them with the corresponding traits in closely related organism. Once one has an idea as to how these characters have changed on the phylogenetic tree and what their developmental underpinning is, scientists are in a position to actually explain the evolution of behavior.

I’m not so sure about this last part. Investigating the underlying neurophysiology of behavioral/psychological adaptations seems like something that can be teased out independent of their actually being adaptive, in the same way one can investigate the heritability of general intelligence without necessarily trying to find high-IQ QTLs. In other words, evolutionary psychology seems to work on a different explanatory level (i.e. this behavior is or is not an adaptation) that would exist with or without modern evo-devo.

He does seem right in suggesting that it may be premature to label any of these adaptations modules, though.

Posted by God Fearing Atheist at 06:07 PM