Genetic Canalization

“Canalization is the reduced sensitivity of a phenotype to changes or perturbations in the underlying genetic and nongenetic factors that determine its expression. ”

as long as environmental ( or genetic) perturbations aren’t too large, they have little effect.

Makes sense: developmental sloppiness  would generally reduce fitness.

This varies with particular traits: under various kinds of stress, you would expect natural selection to particularly favor canalization of traits that are important to fitness.  Maybe intelligence is more important to fitness than height?

Shared environment generally has little effect on adult intelligence.  Canalization? Or consider Stuart Ritchie’s work suggesting that extra years of school increases intelligence: considering canalization, I doubt it.

Educational experts naturally consider canalization when considering new educational interventions. That’s a joke, son.


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16 Responses to Genetic Canalization

  1. TheBalkan says:

    Is there a tradeoff between robustness to genetic vs. non-genetic perturbations?

  2. JayMan says:

    Ritchie’s claims are based on non-genetically informative studies (i.e., apples-to-oranges comparisons) or on positive results from twin control studies (which aren’t as meaningful as negative results, thanks to developmental noise). So no, I wouldn’t buy it.

  3. Smithie says:

    There is Ron Unz’s idea that East Asians are somehow more canalized on intelligence than other groups. It’s a fun idea, but probably crazy.

  4. Peter Connor says:

    But East Asians are probably highly canalized on social conformity, because that was ruthlessly enforced…

    • kn83 says:

      Tendencies towards conformity itself is highly heritable.

    • ccscientist says:

      One can argue that rice farming leads to selection for social conformity more than other types of farming.

    • ThinkingCat says:

      Right. Conformism is a serious disease common among peoples with intensive agriculture, especially the more peaceful ones. The hydraulic empire has obviously made it much worse.

      I wonder whether Mongols and Central Asians are very conformist though. This selection is definitely fairly modern and below the level of race.

  5. Space Ghost says:

    Maybe intelligence is more important to fitness than height?

    I know some guys on the Internet who would disagree with you.

  6. dearieme says:

    “extra years of school increases intelligence”: suppose that the way to develop your intelligence is to use it. Then schooling might have that effect (or, given current fashions, perhaps I should say that schooling might once have had that effect).

    But wouldn’t there be other ways of spending time – e.g. various kinds of employment or even hobbies – that would also be capable of increasing intelligence? Perhaps some of these other ways would be a better bet for some people that extra schooling.

    Then again, maybe my hypothesis is wrong anyway.

    • Toddy Cat says:

      It’s really hard to tell. Stuart Ritchie might be right about schooling, but he is so utterly averse to the idea of group differences, or anything that might tangentially suggest this, that he ignores many useful lines of inquiry. O’Brian would be pleased – his Crimestop is almost perfect.

  7. JRM says:

    Would this be an example of genetic canalization?

  8. JP Irwin says:

    This is further proof of the wisdom of Soviet weapons design. Make your design robust to poor manufacturing precision, robust to the worst events. Make your rifle design so idiot proof, the thing still works even if Arabs build it!

  9. Spangel says:

    But why would we have seen the Flynn effect if it intelligence were that stable? And why would the iq difference be definitively greater in identical twins than within the same person taking the test twice if minute genetic and development differences couldn’t drive real phenotypic changes in intelligence?

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