How Does IQ Impact Social Mobility?

  • Thread starter Niels Bohr
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In summary, Charles Murray's book, The Bell Curve, which argues that differences in IQ are primarily responsible for differences in socioeconomic success, has been thoroughly debunked. A number of books have been written on the topic since then, most of which criticize the book.
  • #36
although the lower IQ people have more children per individual, fewer of them tend to have children at all, which keeps the position in rough balance
I wish.

While it's true that fertility tends to be somewhat worse in the very lowest IQs than among the generally low IQ, this is a slight difference which doesn't balance anything out. In his book Dysgenics, Richard Lynn reports that there is an inverse correlation of .3 between IQ and fertility which includes all IQ levels.

To give you a better idea of what's going on, I'll give you a table from Jensen's book, The g Factor:



Fertility of American Whites
IQ... Fertility
<71... 1.59
71-85... 1.68
86-100... 1.76
101-115.. 1.44
116-130.. 1.15
>131... 0.92


So while the <71 and 71-85 groups are slightly lower than the 86-100 group, they are both still higher than any group above 100 and far above the >131 group. Every group with an IQ below 100 has better fertility than any every group above 100 IQ, and the inevitable result is a dysgenic decline to IQ. (The situation is even more stark for blacks.)

Moreover, estimates of the rate of dysgenics using such methods understate the problem because they only look at differential fertility. The Bell Curve states that "the IQ of people born abroad is .4 standard deviation lower than the mean of those born in the United States;" in other words, the average IQ of immigrants is six points below the national average. Since our own fertility rates are low, immigrants represent an important and growing demographic, and their assimilation into America results in a decrease to America's average IQ which only exacerbates the dysgenic threat.

--Mark
 
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  • #37
in the middle of the 20th century,Higgins,Reed,and Reed (1962)demonstrated a slightly positive fitness effect for IQ —just the opposite of “dysgenesis.”

Ah, yes - it is well known that during the middle of the 20th century the trends were briefly reversed. This is because the intelligent are more responsive to economic trends; when the economy is good, high IQ individuals have more children, and when the economy is bad, they have fewer. But the above circumstance is the exception to a well established long term trend.

--Mark
 

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