When we think of glue, we think of applying it to hold things together. The problem with social glue, however, is that it binds one sub-population at the expense of a rift in the larger population. That is, neither type of social glue necessarily generates new, additional cohesion. Rather, human social cohesion seems to act in more of a thermodynamic way, extracting cohesion from one source and accumulating it in another. It seems better to me to approach application from a more fundamental level, when we ask the question, “what factors can retard the processes of social segregation or ethnogenesis?” or “which mechanisms add to total cohesion across social groups?” Two such mechanisms may be migration (Richerson & Boyd, 2008) and economic equality (Baland, Bardhan, & Bowles, 2007; Wilkinson & Pickett, 2009).

I just published a commentary on Whitehouse’s piece on social glue on Social Evolution Forum.