Steve Hsu argues that deleterious alleles are the main limit on IQ and so if we can get rid of them, perhaps by embryo selection, then:
In the context of human genetics, it’s clear there’s plenty of room at the top — possibly as much as +30 SDs based on existing variance in the human population!
An increase of 30 SDs would be really enormous. In IQ an SD is 15 points, so +30 SDs would be 450 points. (Today’s mean IQ is set at 100.) Now, that would be some kind of supergenius or even hypergenius.
First, what would it be like to be a hypergenius with a 400-500 IQ? (I’d love to find out!)
Second, what kind of society would emerge that included some hypergeniuses? There’d be lots of invention, but lots more inequality between the hypergeniuses and the rest.