It's not so much 'superior genes' as an absence of deleterious mutations. The brain requires the cooperation of the greatest number of genes (compared with othe

It's not so much 'superior genes' as an absence of deleterious mutations. The brain requires the cooperation of the greatest number of genes (compared with other organs) in order in the develop in embryo. Since the industrial revolution infant death has thankfully dropped but it seems likely this improvement has had the side-effect of increasing the number of deleterious mutations and therefore also of decreasing the average IQ in Western populations.