That would depend on the selection pressures in Muslim societies. GP was probably talking about the US, Europe, and East Asia where smart and motivated non-reli

That would depend on the selection pressures in Muslim societies. GP was probably talking about the US, Europe, and East Asia where smart and motivated non-religious people use their increased opportunity to move to the cities. Cities decrease birthrates for the middle classes. In Muslim communities, however, I would expect number of children to correlate with wealth/income (which is correlated with IQ) and with religiosity (which is not). So the overall picture is a lot more murky.