I’m glad you put this here. It got deleted while I was working on an answer on your IQ neutering question.

Ok, so everyone has established that the concept is evil.

Now that that’s settled, let’s hypothesize.

I looked up the percentile chart for IQ, and it’s probably not completely accurate, but it gives us somewhere to start.

So, you’ve made it so 97.7% of the current population cannot reproduce. That leaves 181.4 million potential parents.

The WHO estimates that one in 6 people experience infertility. That leaves us with 149.6 million potential parents. Roughly the population of Russia.

Of those who are naturally able to reproduce and passed your IQ test, only 30% of them are between the ages of 20-39. At any given time you’d have 45 million people who are at the age to have a child. Sure, you could go a little younger, or older, but we’re talking about a society of geniuses. They will be less likely to get knocked up in high school, or risk the potential effects of a geriatric pregnancy.

These people will be spread out across the whole world. So, let’s just assume they will be scattered equally throughout the 6 habitable continents. Australia would probably not have as many fertile geniuses as the entirety of Europe or Asia, they only have 26M total people as it is, so let’s just loop them in with nearby Asia and divide by 5.

Each continent now has about 9 million potential parents.

Let’s zoom in on North America, because that’s where I live, and the numbers work out well. North America is 9.5 million square miles. That works out to a little less than one fertile person per square mile.

You haven’t completely eliminated the less intelligent people, so our fertile geniuses will still be interacting with the “dummies”, and whether you like it or not, they will fall in love and not have children.

And I just realized we didn’t even count the 5-10% of people who are gay. They probably won’t be procreating much.

So, if you were lucky enough to pass the test, and wanted to start a family, you’d have to find one of the 1.5 million straight Members of the opposite sex scattered across the continent. And then one of you will have to uproot and move cross country just to be together, and it would probably help if you had some things in common or found each other attractive.

We’d never see the third generation. Humankind would die out before that happened.