Easterly is an economist at NYU (who published one of the earliest papers on the subject), I'm not sure about the others. However the discussion is a good representation of some of the debate that's gone on regarding interpreting correlations between regular-ness of borders and GDP (i.e. is it that having artificial borders was disruptive, or was it that borders were drawn artificially in areas that had fundamental characteristics which have caused them to have lower GDP today).