Honestly, I don’t know, and I wish I had more data on this. On one hand, the thing that you described (also, the Idiocracy movie) sounds plausible. On the other hand, there seem to be a lot of smart people out there. How is that possible? Seems like there are some forces in the opposite direction, but I can only make a guess about what they are. And individual guess can be wrong, but the fact seems to be that there are enough smart people out there. So, here go the guesses:
You focus on the top of the bell curve; people with IQ 150+ having few kids. But if you look at the opposite end of the curve, people with IQ 50- have even fewer kids (often because they are sick and die young). Perhaps the long-term source of high intelligence is not geniuses breeding like rabbits, but the average people breeding like rabbits and once in a while randomly getting a genius child.
The religious groups can actually preserve the high-IQ genes. The smart atheists often end up childless, but the smart people growing up in a religious cult may channel their IQ into having many children and taking care of them. Also, successful cult leaders probably have higher than average intelligence.
Marital infidelity? Less intelligent fathers unknowingly bringing up children of more intelligent fathers? Here again, I think you make the mistake of only looking at academically successful people as examples of IQ, ignoring people who channel their high IQ into social skills.
Generally, I think it is the non-nerdy people with IQ about 125 who reproduce successfully a lot, and as a group happen to generate a few IQ 150+ children and grandchildren, who keep the intelligence elite existing. The IQ 150+ people are not a separate species; they are mere extremes on the continuum.
Honestly, I don’t know, and I wish I had more data on this. On one hand, the thing that you described (also, the Idiocracy movie) sounds plausible. On the other hand, there seem to be a lot of smart people out there. How is that possible? Seems like there are some forces in the opposite direction, but I can only make a guess about what they are. And individual guess can be wrong, but the fact seems to be that there are enough smart people out there. So, here go the guesses:
You focus on the top of the bell curve; people with IQ 150+ having few kids. But if you look at the opposite end of the curve, people with IQ 50- have even fewer kids (often because they are sick and die young). Perhaps the long-term source of high intelligence is not geniuses breeding like rabbits, but the average people breeding like rabbits and once in a while randomly getting a genius child.
The religious groups can actually preserve the high-IQ genes. The smart atheists often end up childless, but the smart people growing up in a religious cult may channel their IQ into having many children and taking care of them. Also, successful cult leaders probably have higher than average intelligence.
Marital infidelity? Less intelligent fathers unknowingly bringing up children of more intelligent fathers? Here again, I think you make the mistake of only looking at academically successful people as examples of IQ, ignoring people who channel their high IQ into social skills.
Generally, I think it is the non-nerdy people with IQ about 125 who reproduce successfully a lot, and as a group happen to generate a few IQ 150+ children and grandchildren, who keep the intelligence elite existing. The IQ 150+ people are not a separate species; they are mere extremes on the continuum.