Depending upon willingness to limit reproduction of the lower classes, six to te

Depending upon willingness to limit reproduction of the lower classes, six to ten generations at most. The principle problem for any polity is the reduction of the number of people below say, 90 IQ, and the raising of the aggregate IQ (neoteny, genetic load) of the population to above 95. That’s very hard for a 75 IQ population but not very hard for a 90-92 population.

I mean, you get islam as useful because you have a population with an average IQ of 84, meaning more than half of your population is incapable of participation in a modern economy.