Genetically altering IQ is more or less about flipping a sufficient number of IQ-decreasing variants to their IQ-increasing counterparts. This sounds overly simplified, but it’s surprisingly accurate; most of the variance in the genome is linear in nature, by which I mean the effect of a gene doesn’t usually depend on which other genes are present.
So modeling a continuous trait like intelligence is actually extremely straightforward: you simply add the effects of the IQ-increasing alleles to to those of the IQ-decreasing alleles and then normalize the score relative to some reference group.
(I’m particularly thinking of model editing approaches which assume linearity, like activation additions or patching via probes. Are human traits encoded “linearly” in the genome, or are we picking up on some more general property of complex systems which only appears to be linear for small changes such as these. Of course, to a first approximation everything is linear.)
My impression is that the effects of genes which vary between individuals are essentially independent, and small effects are almost always locally linear. With the amount of measurement noise and number of variables, I just don’t think we could pick out nonlinearities or interaction effects of any plausible strength if we tried!
This seems probably false? The search term is Epistasis. Its not that well researched, because of the reasons you mentioned. In my brief search, it seems to play a role in some immunodeficiency disorders, but I’d guess also more things which don’t seem clearly linked to genes yet.
I don’t understand why you’d expect only linear genes to vary in a species. Is this just because most species have relatively little genetic variation, so such variation is by nature linear? This feels like a bastardization of the concept to me, but maybe not.
Edit: Perhaps you can also make the claim that linear variation allows for more accurate estimation of the goodness or badness of gene combos via recombination. So we should expect the more successful species to have more linear variation.
Interesting to compare model editing approaches to Gene Smith’s idea to enhance intelligence via gene editing:
(I’m particularly thinking of model editing approaches which assume linearity, like activation additions or patching via probes. Are human traits encoded “linearly” in the genome, or are we picking up on some more general property of complex systems which only appears to be linear for small changes such as these. Of course, to a first approximation everything is linear.)
My impression is that the effects of genes which vary between individuals are essentially independent, and small effects are almost always locally linear. With the amount of measurement noise and number of variables, I just don’t think we could pick out nonlinearities or interaction effects of any plausible strength if we tried!
This seems probably false? The search term is Epistasis. Its not that well researched, because of the reasons you mentioned. In my brief search, it seems to play a role in some immunodeficiency disorders, but I’d guess also more things which don’t seem clearly linked to genes yet.
I don’t understand why you’d expect only linear genes to vary in a species. Is this just because most species have relatively little genetic variation, so such variation is by nature linear? This feels like a bastardization of the concept to me, but maybe not.
Edit: Perhaps you can also make the claim that linear variation allows for more accurate estimation of the goodness or badness of gene combos via recombination. So we should expect the more successful species to have more linear variation.