I'm leaning against (but not convinced against) "intelligence genes" existing, at least to the point where some people have them and some don't, because evolution would likely have spread them to everyone.
Why? What survivability/reproduction benefits does intelligence provide beyond a certain level, particularly in pre-modern society? If you were the daughter of serfs a thousand years ago, what good would a 150 IQ do you? Especially if there's some tradeoff involved, such as a correspondingly lower ability to socialize with your peers.
Especially if there's some tradeoff involved, such as a correspondingly lower ability to socialize with your peers
If there's any reason for an "intelligence gene" not being completely wide-spread, it would be this. Intelligence would have to have some very significant drawbacks. Some people have theorized that autism is when you get "overloaded" on those intelligence genes. It strikes me as unlikely this would really provide significant pushback against the intelligence genes completely dominating the gene pool, but I agree it's possible.
But why? Even if there's no tradeoff, what advantage would Albert Einstein have had over an average intelligence competitor for mates had he lived even a mere 200 years ago? Slim, I'd think. And who's to say he would have used that narrow advantage to win a mate of above average intelligence, vs. some other desirable characteristic?
Exceptional intelligence as a strong determinant of economic and social success (and thus presumably reproductive success) seems to be a relatively recent phenomenon in the human species.
Also, we need to take a larger view of what "intelligence" is. Take the longer view of human history, and we all are probably geniuses. Those intelligence genes have indeed spread across the gene pool. It's just new ones (or new combinations of existing genes) are now showing themselves and need time to prove their fitness.
The downvotes are unfortunate, because you're absolutely right. Intelligence has an associated cost. Natural selection will only spread "intelligence genes" if the benefit outweighs the cost. In pre-modern societies, this was likely not the case. "Social intelligence" was likely much more useful than abstract reasoning ability.
Even today, the Einsteins and Teslas don't do better in the mating game than the Brad Pitts and Kobe Bryants (likely much worse).
Edit: it would be interesting if HN handles were attached to downvotes. People would likely think twice before knee-jerk downvoting if they couldn't do it anonymously.
Why? What survivability/reproduction benefits does intelligence provide beyond a certain level, particularly in pre-modern society? If you were the daughter of serfs a thousand years ago, what good would a 150 IQ do you? Especially if there's some tradeoff involved, such as a correspondingly lower ability to socialize with your peers.