Suppose, if ignoring other effects, intelligence would be under some selection pressure _s_ and disease resistance under a similar selection pressure _s_. If the two selective vectors are ~ orthogonal, the realized selection pressure would be ~s/sqrt(2).
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Replying to @arguablywrong @gcochran99 and
Note that this generalizes to _n_ equal and orthogonal selective pressures _s_: the realized selective pressure is ~s/sqrt(n). If you've got 16 different things pulling in different ways, it still only drops the realized selection on any one by a factor of 4.
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Replying to @arguablywrong @gcochran99 and
It is kind of entertaining seeing someone pretend 25% is approximately 0, though.
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Replying to @arguablywrong @gcochran99 and
Seems to me the selection pressures aren't equal at all - once you've got language and culture, selection pressure on cognition may be rather small; but selection pressures on disease/parasite resistance, climate, nutrition etc have clearly been proved very strong.
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Replying to @RCownie @arguablywrong and

the invention of language *reduced* the selective pressure for intelligence - sure.3 replies 0 retweets 12 likes -
Replying to @CovfefeAnon @arguablywrong and
Once you've got language to efficiently transmit the accumulated knowledge of a culture, new humans don't have to figure everything out from scratch.
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Replying to @RCownie @arguablywrong and
Yes, and all increases in complexity and demands on cognition stop at exactly that point rather than ... increasing.
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Replying to @CovfefeAnon @arguablywrong and
Once you've got effective transmission of culture and hence the highly directed and very rapid mechanisms of cultural evolution, then it reduces a whole lot of other selection pressures, yes.
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Replying to @RCownie @CovfefeAnon and
Vikings didn't need to evolve fur b/c they could wear woolen clothes, they didn't need to evolve flippers b/c they could build boats, and they didn't need to grow sharp claws b/c they had iron swords and axes. Culture is a BFD.
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Replying to @RCownie @CovfefeAnon and
Meanwhile, you haven't had an original thought in your whole life, yet here you are, probably well-fed and with access to a computer system. That's what cultural evolution gets you.
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So there was selective pressure for boat building skill that was novel, selective pressure for iron smelting and forging skill that was novel, selective pressure for wool weaving that was novel. All of those things are done better by more intelligent people.
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