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This wikipedia article on fertility and intelligence (citation missing from wiki article needed for proving this claim) indicates that intelligent people are less fertile. Is this correlated to the number of children as well?

Thus, could one infer that intelligent people, whom are quantitatively defined by IQ, generally have fewer offspring?

Flimzy
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chrisjlee
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    It's well known that people with higher IQ have on average fewer children. But it's usually assumed that this is because they're too busy employing that IQ to raise children. E.g. a manager working 100 hour weeks isn't going to spend as much time between the sheets with her husband as does a file clerk working part time :) – jwenting Aug 22 '11 at 06:10
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    @jwenting Wasn't Einstein a file clerk? – James Aug 22 '11 at 20:32
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    Einstein has as his first job after graduating university a job as file clerk in the US Patent Office. He was of course while so employed also employing his brain with further study, rather than thinking up new and ingenious ways to attract women into his bedroom... – jwenting Aug 23 '11 at 06:09
  • `[...] while so employed also employing his brain with further study, rather than thinking up new and ingenious ways to attract women [...]` actually it seems like [Einstein had time](http://www.google.com#sclient=psy&hl=de&site=&source=hp&q=einstein+promiscuous&pbx=1&oq=einstein+promiscuous&aq=f&aqi=&aql=&gs_sm=e&gs_upl=745l745l0l1271l1l1l0l0l0l0l0l0ll0l0&bav=on.2,or.r_gc.r_pw.&fp=8f21853c6bf7807d&biw=1265&bih=829&safe=on) [for both](http://www.msnbc.msn.com/id/13804030/ns/technology_and_science-science/t/new-letters-shed-light-einsteins-love-life/#.TlOf9Gs6zJk) of these things ;) – cularis Aug 23 '11 at 12:39
  • Closely related is this Gapminder graph of [Children per women vs. Literacy rate](http://www.bit.ly/lj2gLW) – going Sep 21 '11 at 03:27
  • Let's not forget probably the biggest confounding factor: religion ([Monty Python anyone?](http://www.youtube.com/watch?v=ifgHHhw_6g8) - moderately not safe for work). – nico Sep 21 '11 at 06:41
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    @jwenting Richard Feynman was a notorious womaniser, bongo-player and part-time theoretical physicist ;) – John Lyon Sep 21 '11 at 06:47
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    @jwenting: generally men who try to "attract women into their bedroom" are not the ones who contribute most to number of children... There is a much stronger correlation between poverty and number of children then IQ and number of children. Of course there also is a correlation between IQ and poverty so... – nico Sep 21 '11 at 06:59
  • This question feels familiar. Wasn't there a similar one trying to equate fertility with evolutionary maturity several months ago? – oosterwal Sep 21 '11 at 13:33
  • @jwenting Don't forget that a lot of people in unskilled labour have to work two jobs to make ends meet, and have almost no free time. – puppybeard Sep 21 '11 at 16:10
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    Answers will need to distinguish the concept of innate fertility (how many children *could* you have if you wanted them and how *quickly* -speed of conception is a metric for fertility) and the actual number of children (which depends on conscious *choice* not just fecundity). Some people **can't** have children; others **don't** have children. – matt_black Oct 02 '11 at 20:46
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    @jwenting: I didn't know they had **US** Patent Office in Switzerland ;-) – vartec Oct 21 '11 at 09:07

1 Answers1

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You would not need to "infer" that people with high IQ generally have less offspring; this concept has long been known to be true, statistically. Just note that "fertility" as defined in this manner is simply a measure of the total number of offspring, not how capable one is of conceiving.

I found these sources in 15m of searching. I'm sure you can find many more with concentrated effort. Open up any article and refer to their references for a start.

Sources:

  • Campbell, C., & Preston, S. (1993). Differential fertility and the distribution of traits: the case of IQ. The American Journal of Sociology, 98(5), 997+.
  • Gelade, G. A. (2008). The geography of IQ. Intelligence, 36, 495-501.
  • Harvey, J., & Lynn, R. (2008). The decline of the world's IQ. Intelligence, 36(2), 112+.
  • Hondroyiannis, G., & Papapetrou, E. (2005). Fertility and output in Europe: new evidence from panel cointegration analysis. Journal of Policy Modeling, 27, 143-156.
  • Loehlin, J. C. (1997). Dysgenesis and IQ: What Evidence Is Relevant?. American Psychologist, 52(11), 1236-1239.
  • Lynn, R., & Jarvey, J. (2008). The decline of the world's IQ. Intelligence, 36, 112-120.
  • Lynn, R., & Van Court, M. (2004). New evidence of dysgenic fertility for intelligence in the United States. Intelligence, 32, 193-201.
  • Meisenberg, G. (in press). National IQ and economic outcomes. Personality and Individual Differences.
  • Meisenberg, G. (2010). The reproduction of intelligence. Intelligence, 38(2), 220+.
  • Preston, S. H., & Campbell, C. (1993). Differential fertility and the distribution of traits: the case of IQ. American Journal of Sociology, 98(5), 997-1019.
  • Redwood, A. L. (1983). An economic-demographic approach to forecasting national and subnational birth rates. Socio-Economic Planning Sciences, 17(5-6), 355-363.
  • Reeve, C. L. (2009). Expanding the g-nexus: Further evidence regarding the relations among national IQ, religiosity and national health outcomes. Intelligence, 37(5), 495-505.
  • Retherford, R. D., & Sewell, W. H. (1989). How intelligence affects fertility. Intelligence, 13(2), 169-185.
  • Retherford, R. D., & Sewell, W. H. (1988). Intelligence and family size reconsidered. Biodemography and Social Biology, 35(1-2), 1-40.
  • Shatz, S. M. (2008). IQ and fertility: A cross-national study. Intelligence, 36(2), 109.
  • Van Court, M., & Bean, F. D. (1985). Intelligence and fertility in the United States: 1912–1982. Intelligence, 9(1), 23-32.
  • Vining, D. R., Bygren, L., Hattori, K., Nystrom, S., & Tamura, S. (1988). IQ/fertility relationships in Japan and Sweden. Personality and Individual Differences, 9(5), 931-932.
  • Vining, D. R. (1982). On the possibility of the reemergence of a dysgenic trend with respect to intelligence in American fertility differentials. Intelligence, 6(3), 241-264.
Oddthinking
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stoicfury
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    Welcome to Skeptics! We [expect answers to provide references for all significant claims they make](http://meta.skeptics.stackexchange.com/questions/5/must-answers-be-referenced). I'm curious about that statistic you mention as I suspect it would be extremely hard to correct for confounding factors. – Mad Scientist Aug 21 '11 at 07:20
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    +1 Roger that Fabian. I didn't realize this was a "significant" claim, as you put it. Is there a definition of "significant" somewhere? For example: I think the center of the Sun is not made of ice cream. Would I have to cite that? I think Evolution by natural selection is a valid theory in explaining the diversity of life on Earth. Would I have to cite that? Both appear to be "obvious", in some regard, but vary drastically in the amount of evidence for each. Just trying to wrap my head around what is required to cite and what is not. Thanks! :) – stoicfury Aug 21 '11 at 17:00
  • If you don't measure fertility as the ability to have descendants, but as the empirical number, a person which has 3 children with 30 but none with 20 would loose some IQ meanwhile? – user unknown Aug 21 '11 at 20:28
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    Please add quotes from some of your relevant sources. Good answers here will quote the relevant material so we don't have to take your word for it! I also agree with Fabian that it would be good to see that the studies have at least attempted to correct for some of the confounding factors. – John Lyon Aug 22 '11 at 01:27
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    @stoicfury, the [rule-of-thumb](http://meta.skeptics.stackexchange.com/questions/5/must-all-answers-be-referenced) is whether it would be known by high school science student. Obviously, that still leaves a lot of grey area. – Oddthinking Aug 22 '11 at 02:39
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    @user unknown, I couldn't understand your objection. Could you please explain it again for someone like me who has lost some IQ? :-) Are you arguing the question should really say "[fecundity](http://en.wikipedia.org/wiki/Fecundity)" rather than "fertility"? – Oddthinking Aug 22 '11 at 02:44
  • @Oddthinking: Yes. – user unknown Aug 22 '11 at 06:22
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    @stoicfury Providing a list of references is not enough. You should also quote relevant parts here so that anyone can check quickly and easily what the sources say about the subject. I know it is tough, and it is unusual, but this is how it works here. Visit meta if you want to check why or to discuss the policies. – Suma Sep 21 '11 at 05:54