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Monday, 23 July 2012
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Human societies with very high mortality during childhood an early adulthood over many generations will be (relatively) low IQ societies - because reproductive success is mostly a matter of rapid development, early sexual maturity, and high fertility (number of childbirths) hence smaller and simpler brains.
Reproductive success is mostly a matter of fertility, sheer numbers of babies, to compensate for the high chance that each will be killed before completing reproduction.
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Societies with high mortality during childhood and also during early adult life may well favour rapid increase in general intelligence over the space of relatively few generations, insofar as higher intelligence reduces mortality rates.
Fertility will be (and needs to be) significantly above two babies per woman on average, but beyond this number, fertility is almost irrelevant because reproductive success comes from lowering mortality.
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Societies (such as the whole modern world) which have low mortality rates in childhood and early adulthood (low by human historical standards) will become (relatively) low IQ societies if they are secular - due to lower fertility among those with higher IQ -
- but this will not necessarily happen if/when societies/ groups (which must be coincident) are orthodox, traditionally religious (perhaps monotheistic).
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So there is one high IQ sweet spot for sure (high mortality through into early adult life with universal above-replacement fertility) and one possible sweet spot (low mortality but fertility differentially higher in higher IQ).
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Human societies with very high mortality during childhood an early adulthood over many generations will be (relatively) low IQ societies - because reproductive success is mostly a matter of rapid development, early sexual maturity, and high fertility (number of childbirths) hence smaller and simpler brains.
Reproductive success is mostly a matter of fertility, sheer numbers of babies, to compensate for the high chance that each will be killed before completing reproduction.
*
Societies with high mortality during childhood and also during early adult life may well favour rapid increase in general intelligence over the space of relatively few generations, insofar as higher intelligence reduces mortality rates.
Fertility will be (and needs to be) significantly above two babies per woman on average, but beyond this number, fertility is almost irrelevant because reproductive success comes from lowering mortality.
*
Societies (such as the whole modern world) which have low mortality rates in childhood and early adulthood (low by human historical standards) will become (relatively) low IQ societies if they are secular - due to lower fertility among those with higher IQ -
- but this will not necessarily happen if/when societies/ groups (which must be coincident) are orthodox, traditionally religious (perhaps monotheistic).
*
So there is one high IQ sweet spot for sure (high mortality through into early adult life with universal above-replacement fertility) and one possible sweet spot (low mortality but fertility differentially higher in higher IQ).
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