If you have a mutation that gives you +10 IQ that doesn’t make it hard for you to relate with your fellow tribe of hunter-gatherers.
There´s a lot more inbreeding in hunter-gatherer tribes that results in mutations being distributed in the tribe than there is in modern Western society.
The key question is whether you get more IQ if you add IQ-increasing mutations from different tribes together, I don’t think that it being disadvantageous to have +30 IQ more than fellow tribe members would be a reason why IQ-increasing mutations that are additive should not exist.
If you have a mutation that gives you +10 IQ that doesn’t make it hard for you to relate with your fellow tribe of hunter-gatherers.
There´s a lot more inbreeding in hunter-gatherer tribes that results in mutations being distributed in the tribe than there is in modern Western society.
The key question is whether you get more IQ if you add IQ-increasing mutations from different tribes together, I don’t think that it being disadvantageous to have +30 IQ more than fellow tribe members would be a reason why IQ-increasing mutations that are additive should not exist.