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>I don't think they "were under positive selection", I think they still ARE. So many people like to think that humans evolved to our present state and then act

>I don't think they "were under positive selection", I think they still ARE. So many people like to think that humans evolved to our present state and then act like the process has stopped. The wording here echos that a bit. Nobody thinks the process has stopped. The argument instead is that the environment has changed over time, and some traits that once increased the organism's odds of reproduction relative to peers no longer have that effect. Whether those with "certain ASD risk alleles" tend to have more or fewer children than those without is an empirical question, but I certainly wouldn't be shocked to find that the fitness benefits to "neurogenesis and cognitive ability" have declined.

wycs 9y ago
>Whether those with "certain ASD risk alleles" tend to have more or fewer children than those without is an empirical question, but I certainly wouldn't be shocked to find that the fitness benefits to "neurogenesis and cognitive ability" have declined. Getting very near indisputable now:https://www.gwern.net/docs/genetics/selection/2017-kong.pdf https://www.gwern.net/docs/genetics/selection/2017-kong.pdf The decline is actually quicker than you would think, TBH. Cognitive ability decreases reproductive fitness in this environment in women but not in men, so I imagine the decline will halt once we reach some sort of equilibrium, assuming dimorphism isn't possible quickly. I imagine selecting for dimorphism in this trait, though it would happen eventually, would take too long to matter. Not too worried as "unnatural selection" will overwhelm this small effect shortly.
- hnaccy 9y ago
  So Idiocracy was right?
  - 52-6F-62 9y ago
    Come now, Mike Judge was a physicist and a programmer—not a biologist!
  - ergothus 9y ago
    Idiocracy did a fantastic job of summarizing one aspect. Unfortunately we don't have an equally memorable option to cover the other aspects. Idiocracy assumes not just more education = fewer kids = more wealth, but also more kids = increased odds of reproduction and that these traits are reliable across generations. We've proven more education -> fewer kids, and more wealth -> more education. So far as I know, we've not proven or disproven fewer kids -> more education, more education -> more wealth, and more kids -> increased net reproduction, at least not across enough generations. Certainly these SEEM reasonable conclusions, and some have only been proven in the short-term. It might be that more kids -> less wealth -> less education -> net loss of reproduction. e.g. having 12 kids does give you more chances to push your genes to later generations, but the odds for each kid to get to reproduce are not the same as if there were fewer kids. If that difference is big enough then too many kids is a losing strategy. (in agrarian economies children are a resource, but if children can't work, the odds of the entire families' genes passing on are reduced for every new child past a certain point) Idiocracy also assumes that intelligence is highly hereditable and highly correlated to wealth - In reality that connection is far fuzzier (likely technically true, but at such a low degree that environmental factors can easily matter more) Still though - it was an amazingly effective communication of a complex topic. And I'll admit that there are news stories I read that stir my hindbrain into hear the little "bloop" noises of adding to the family tree from that scene.
    - danieltillett 9y ago
      Intelligence (g) is highly hereditable on the right hand side of the bell curve. Where non-shared environment (there is no measurable shared environmental component to g) is on the left hand side where people can end up with a g below their genetic potential. Basically it is relatively easy for the environment to push an individual below their potential, but near impossible to pull them above once a basic minimum is met.
    - losteric 9y ago
      Social stratification factor also needs to be factored into that equation. Intelligence might correlate with wealth in societies with free markets... but lower classes in a stratified society won't have access to resources that translate intelligence into success.
  - deleted 9y ago
    [deleted]

wycs 9y ago

>Whether those with "certain ASD risk alleles" tend to have more or fewer children than those without is an empirical question, but I certainly wouldn't be shocked to find that the fitness benefits to "neurogenesis and cognitive ability" have declined. Getting very near indisputable now:https://www.gwern.net/docs/genetics/selection/2017-kong.pdf https://www.gwern.net/docs/genetics/selection/2017-kong.pdf The decline is actually quicker than you would think, TBH. Cognitive ability decreases reproductive fitness in this environment in women but not in men, so I imagine the decline will halt once we reach some sort of equilibrium, assuming dimorphism isn't possible quickly. I imagine selecting for dimorphism in this trait, though it would happen eventually, would take too long to matter. Not too worried as "unnatural selection" will overwhelm this small effect shortly.

hnaccy 9y ago
So Idiocracy was right?
- 52-6F-62 9y ago
  Come now, Mike Judge was a physicist and a programmer—not a biologist!
- ergothus 9y ago
  Idiocracy did a fantastic job of summarizing one aspect. Unfortunately we don't have an equally memorable option to cover the other aspects. Idiocracy assumes not just more education = fewer kids = more wealth, but also more kids = increased odds of reproduction and that these traits are reliable across generations. We've proven more education -> fewer kids, and more wealth -> more education. So far as I know, we've not proven or disproven fewer kids -> more education, more education -> more wealth, and more kids -> increased net reproduction, at least not across enough generations. Certainly these SEEM reasonable conclusions, and some have only been proven in the short-term. It might be that more kids -> less wealth -> less education -> net loss of reproduction. e.g. having 12 kids does give you more chances to push your genes to later generations, but the odds for each kid to get to reproduce are not the same as if there were fewer kids. If that difference is big enough then too many kids is a losing strategy. (in agrarian economies children are a resource, but if children can't work, the odds of the entire families' genes passing on are reduced for every new child past a certain point) Idiocracy also assumes that intelligence is highly hereditable and highly correlated to wealth - In reality that connection is far fuzzier (likely technically true, but at such a low degree that environmental factors can easily matter more) Still though - it was an amazingly effective communication of a complex topic. And I'll admit that there are news stories I read that stir my hindbrain into hear the little "bloop" noises of adding to the family tree from that scene.
  - danieltillett 9y ago
    Intelligence (g) is highly hereditable on the right hand side of the bell curve. Where non-shared environment (there is no measurable shared environmental component to g) is on the left hand side where people can end up with a g below their genetic potential. Basically it is relatively easy for the environment to push an individual below their potential, but near impossible to pull them above once a basic minimum is met.
  - losteric 9y ago
    Social stratification factor also needs to be factored into that equation. Intelligence might correlate with wealth in societies with free markets... but lower classes in a stratified society won't have access to resources that translate intelligence into success.
- deleted 9y ago
  [deleted]