Miller’s point being that those thousands of genes can easily be driven to fixation by evolution within a fairly short time, yet have not, and it’s not clear from the GWASes yet if they’re even under directional selection.
Right now, between the GCTAs and the failure to find lots of important rare variants affecting intelligence such as mutation load (eg no Swedish paternal age effect, unlike many disorders), the consensus seems to be swinging towards some sort of frequency-dependent or stabilizing selection: greater intelligence comes with some sort of fitness penalty (greater energetic consumption?) or maybe greater vulnerability to developmental disruption through poor environment and so a net disadvantage which favors poorer but more robust variants (and eventually, canalization). Given the accumulation of archaic & ancient genomes and further intelligence GWASes, we may be able to get a definitive answer to the old puzzle of why intelligence is heritable at all in the next few years.
Hence my old point about nootropics: for the effective ones, the reason the evolutionary argument fails may simply be that they require more metabolic resources which would be a fitness disadvantage but that no longer applies in the modern calorie-overload environment.
Probably because of different genes, which are thousands, and different early development wiring and education. It can’t be replaced by a few drugs.
Miller’s point being that those thousands of genes can easily be driven to fixation by evolution within a fairly short time, yet have not, and it’s not clear from the GWASes yet if they’re even under directional selection.
Right now, between the GCTAs and the failure to find lots of important rare variants affecting intelligence such as mutation load (eg no Swedish paternal age effect, unlike many disorders), the consensus seems to be swinging towards some sort of frequency-dependent or stabilizing selection: greater intelligence comes with some sort of fitness penalty (greater energetic consumption?) or maybe greater vulnerability to developmental disruption through poor environment and so a net disadvantage which favors poorer but more robust variants (and eventually, canalization). Given the accumulation of archaic & ancient genomes and further intelligence GWASes, we may be able to get a definitive answer to the old puzzle of why intelligence is heritable at all in the next few years.
Hence my old point about nootropics: for the effective ones, the reason the evolutionary argument fails may simply be that they require more metabolic resources which would be a fitness disadvantage but that no longer applies in the modern calorie-overload environment.