Monday, 25 February 2013

Relationship between intelligence and life history speed: population and individual levels

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The relationship between population and speed of life history is probably somewhat complex; but (as far as I understand the matter) I think it could be summarized by saying that:

1. At the population level, there is usually a correlation between higher intelligence and slower life history speed.

(This is presumably due to natural selection, historically, in situations where both higher intelligence and slower life history are, on average, adaptive.).

But:

2. At the individual level, within a population, intelligence and life history speed are uncorrelated.

Or, more accurately, intelligence and life history speed are dissociated at the individual level; such that a highly intelligent person may have either slower or faster life history; and the same applies to low intelligence persons.

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The dissociation can be seen in two stereotypical male high intelligence types: the sexually aggressive business executive or politician (fast life history - urgency of reproductive effort leading to early sex, multiple partners, more children with lower/ zero investment per offspring); versus the nerdy professor (slow life history - delayed reproductive effort, late marriage to single partner, few children with high investment per offspring).

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The dissociation is, presumably, caused because while intelligence and personality are inherited, life history is triggered by the environment, by some experience (probably) early in life.

Or, an individual's specific life history trajectory is selected-from a certain range of possible life history speeds.

The range of possible life history speeds is innate and inherited, but the specific life history speed which is embarked upon is a consequence of environmental cues, triggers or stimuli.

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This implies that fast life history parents often have slow life history children and vice versa.

And this means that life history is different from intelligence and personality, because childrens' intelligence and personality is, on average, similar to their parents'.

(Yet, at the same time, some populations will have different average life history speeds from others; and a different average range of life history speeds.)

5 comments:

  1. 2. At the individual level, within a population, intelligence and life history speed are uncorrelated.
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    Surprising, if true. How do we know it is true?

    The reason I say "surprising" is that now in the multicultural West we are looking at actual "populations" formed by the forced association of radically different natural populations.

    In, say, medieval England, the non-association of intelligence and life history speed would be less surprising, though the claim that there was no association would still call for evidence.

    But imagine a population now. Half its members are of genetic type W, with an average IQ of 100, a slow life history speed, and an inherited temperament that includes a tendency to create culture congenial for that sort of person. Half the members of this population of forced association are of genetic type B, a full standard deviation less intelligent, and built for speed in temperament, in the sort of culture that they make, and in physical rates of maturation. They are a year to two years faster to puberty and so on.

    The two sub-groups of this population are different kinds of animals stalled together, with different genes, bones and brains, and consequently different typical cultures, polities, economies and so on.

    Why would you expect that in this artificial population of forced association there would be zero correlation between intelligence and life history speed?

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  2. I now have data:
    http://jaymans.wordpress.com/2012/06/01/liberalism-hbd-population-and-solutions-for-the-future/#evidence
    Scroll down a bit.

    Intelligence and reproduction are inversely correlated only amoung liberals and moderates.

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  3. @Thu - the way I have expressed it is that above replacement fertility is *chosen* (only) among those of orthodoxly traditional religiousness.

    And I regard this as one of the strongest of arguments against atheism (and 'liberal' religions).

    To be self-identified in 'liberal' (etc) is not precisely *incompatible* with holding the kind of religious convictions (leading the kind of religious life) that correspond with chosen above-replacement fertility - but it is unusual (and based on inconsistency of conviction when it is reported - but of course many religious conservatives *vote* for extreme liberal government because Leftism bribes them with privileges and subsidies - certainly not because they approve of the Leftist agenda as such)

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  4. "At the individual level, within a population, intelligence and life history speed are uncorrelated.

    Or, more accurately, intelligence and life history speed are dissociated at the individual level; such that a highly intelligent person may have either slower or faster life history; and the same applies to low intelligence persons."


    Dissociated is more accurate, but even at the individual level there is certainly a negative correlation between intelligence and life history speed, as seen by the relationship between IQ and sex drive.

    Interestingly, it's not clear that the conservative advantage in fertility at high IQ levels is due to faster life history per se. There is some evidence that suggest that (with a very important caveat that I will soon note) liberals have higher sex drives, as seen by Satoshi Kanazawa's finding that liberals are more likely to be unfaithful and my own finding that the men with the most children have report the fewest number of sex partners.

    The caveat of course is that both data sets are based on self-report and are likely be wrong because the respondents were lying (conservatives may be less willing to admit to having sexual affairs or to admit the true number of sexual partners they've had).

    In any case, if this is accurate, greater conservative reproduction, at the high-IQ levels especially, may not be clearly related to life history speed.

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