[sim1collins]

We're not sure either (I wrote this with the primary author), but we agree there's something interesting going on. The research is brought up in the deep dive more as an interesting reference point and less as any sort of primary argument.

[ckrapu]

To play along more with the ideas you guys are raising, I think that strong spatial heterogeneity driven by falling birth rates in sink-type effects are having an outsized effect on how we think about nations even if the sink is due to density. Societies and cultures which are pre- or post-sink might look at clusters of pathological behaviors as signs of cultural or genetic inferiority, causing some degree of conflict and bias.