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Natural selection to increase intelligence on a group level is impossible unless there's variance in the group for natural selection to operate on. https://en.

Natural selection to increase intelligence on a group level is impossible unless there's variance in the group for natural selection to operate on. https://en.wikipedia.org/wiki/Fisher%27s_fundamental_theorem_of_natural_selection https://en.wikipedia.org/wiki/Fisher%27s_fundamental_theorem... "The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time."

skybrian 9y ago
The genetic variation that got us here isn't necessarily the same as the variation that remains, though. Perhaps there used to be more variation? (There is the Flynn effect, but that's too quick to be genetic. Whatever its cause is apparently more important than genetics?)
- rlanday 9y ago
  That's a good point, the amount of variation changes over time. I'd be extremely surprised if the current amount somehow fell all the way to zero though. There's apparently some speculation (according to the Wikipedia article on the Flynn effect at least) that the Flynn effect is due to non-genetic factors, in which case the underlying genetic trends are being obscured. There's a claim that genotypic IQ could be decreasing but we're not seeing that reflected effect in phenotypes due to environment improvements (which probably won't continue forever).