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IQ distribution curve

  1. Jan 9, 2017 #1
    What does the distribution curve of IQ in the world population look like? If the average IQ for all countries is 90 (Richard Lynn and Tatu Vanhanen “IQ and the Wealth of Nations”), with an average IQ for sub-Saharan Africans of 70, I suppose that the distribution curve is higher on the downside.

    If the environment is equalized (relevant to IQ) and gene pools merge, I suppose that the normalized bell curve becomes reality. In the absence of catastrophes, is the evolution of intelligence then limited by IQ drift (including the Flynn effect)?

    Is advanced intelligence fundamentally different from other "most relevant traits" from an evolutionary point of view? Does the complexity of the trait make a disadvantageous mutation more likely?
     
  2. jcsd
  3. Jan 9, 2017 #2

    jedishrfu

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  4. Jan 9, 2017 #3

    jim mcnamara

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    That book has taken a severe drubbing by other specialists in the fields of Psychology and Economics. I would tend to view conclusions presented there with a strong sense of skepticism. In other words, countries without a middle class have statistically low IQ scores. Many professionals view this as a cultural artifact, not a genetic one.

    Check the criticisms here:
    https://en.wikipedia.org/wiki/IQ_and_the_Wealth_of_Nations

    To answer your questions:
    No.
    No.

    @jedishrfu - those numbers came from the authors of the book, BTW.
    @Evo will probably have something to say.
     
  5. Jan 9, 2017 #4

    jedishrfu

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    Yeah, I see that now. I was addressing the OP's request for chart of IQ stats across the world. The stats for the poorer countries seemed off and I figured it has something to do with limited education in poorer countries and the inability of IQ tests to properly factor that in ie you can't score well if you can't read well.
     
  6. Jan 9, 2017 #5

    Vanadium 50

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    Those numbers simply cannot be right. Right in the sense that they cannot measure what we think they are measuring. If Equatorial Guinea has an average IQ of 59, that means that half the population is mentally unable to harvest vegetables. It means that even though 0.02% of the world's population lives there, 5% of those with IQs below 59 do.
     
  7. Jan 9, 2017 #6

    jedishrfu

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  8. Jan 9, 2017 #7

    mfb

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    By definition, the distribution should form a bell curve centered at 100. If measured values don't reflect that, the measurement is poorly calibrated.
    IQ test results are not determined by genes alone. They have a correlation with the number of children, but the pattern can be complex, including negative correlations.
     
  9. Jan 9, 2017 #8
    Thanks for the link to the criticisms. I am not particularly interested in the book and I only mentioned it as a reference, as required in this forum, so that I could use the figures of 70 for average sub-Saharan Africa and 90 for world average IQ. Do you know of another source where I could get better numbers and see a proper graph? So far I only saw a list of some country IQs which does not give me a world distribution curve, even if I made it myself.

    As I understand it, all Homo Sapien peoples have very similar brains, so the main difference affecting IQ scores would be the different environments. Am I right so far?

    So if we equalize the environments we will get a normalized bell curve instead of the current (I suppose) lop-sided one. The mean world IQ is then higher and we get more high IQ people because the high point of the curve shifts to the right. Is such a development realistic and consistent with evolution theory?
     
  10. Jan 9, 2017 #9

    jim mcnamara

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    Yes, that is a pretty good start. And I don't think IQ is useful in anything but predicting possible success in schoolwork. So I wouldn't use IQ to measure anything meaningful about population trends or evolution. For example, in Gabon - the lowest IQ score - an everyday person cannot function there without being fluent in as few as three languages. Many people speak more than 5. Multi-lingual conversations there are interesting due to the plethora of languages. As @Vanadium 50 noted, with an IQ of 58, people on average in Gabon could never do this multiway language thing - example:

    What happens is something like this: Person A wants to speak with person B, neither speaks a common language, person C speaks a language person A understands, person D comes along and speaks a language person C understands. This often grows to several people acting as intermediaries. This is an everyday experience.
     
  11. Jan 9, 2017 #10
    I assume you mean that more kids in a family reduces nutrition and other disadvantages. I called this environment. So do you agree that we only have two factors - genetic and environment, and that the genetic difference is negligible?
     
  12. Jan 9, 2017 #11

    mfb

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    No, I mean reproduction rates in large parts of the world are active choices. People in developed countries don't get as many children as they can feed, they get as many children as they want. And that depends on the education, which is correlated with results in IQ tests.
     
  13. Jan 9, 2017 #12
    I am using IQ as a proxy for general intelligence. There's no other way to do it, is there. I'm assuming that the general environment and intelligence level of African kids is on catchup, but Western intelligence levels have to increase too, don't they. So I'm wondering what evolution is likely to do about it.
     
  14. Jan 9, 2017 #13
    So what do you think is the result in the world IQ distribution curve? Could it develop into a top-left declining to bottom-right curve with a shift of the mean to the left, instead of a bell? My interest in this thread is not to speculate, but to understand how evolution works in practice using IQ as an interesting example.
     
  15. Jan 9, 2017 #14

    Vanadium 50

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    I think we have already demonstrated that the metrology is flawed. Until that is fixed, your question has no answer.
     
  16. Jan 9, 2017 #15

    Evo

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    This is a widely debunked racist publication, thread closed.
     
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