Did nutrition cause the Flynn effect on IQ?

What has caused the Flynn effect? Secular increases in the Development Quotients of infants

Richard Lynn

aUniversity of Ulster, Coleraine, Northern Ireland, BT52 1SA, UK

Received 23 March 2008;  revised 17 July 2008;  accepted 17 July 2008.  Available online 21 September 2008.
Results of five studies show that during the second half of the twentieth century there were increases in the Development Quotients (DQs) of infants in the first two years of life. These gains were obtained for the Bayley Scales in the United States and Australia, and for the Griffiths Test in Britain. The average of 19 data points is a DQ gain of approximately 3.7 DQ points per decade. Similar gains of approximately 3.9 IQ points per decade have been present among pre-school children aged 4–6 years. These gains are about the same as the IQ gains of school age students and adults on the Wechsler and Binet tests. This suggests that the same factor has been responsible for all these secular gains. This rules out improvements in education, greater test sophistication, etc. and most of the other factors that have been proposed to explain the Flynn effect. It is proposed that the most probable factor has been improvements in pre-natal and early post-natal nutrition

More from professor Lynn; a bit of an ass at times, but not stupid. This suggests that most of the IQ gains made through the 20th century a mainly attributable to better nutrition (we are about 30 points smarter than we used to be in the Victorian era).

This would also be another kick in the teeth for the ‘environment only’ supporters who believe we are all born the same, but our IQ’s vary solely from environmental factors. Generally malnutrition isn’t common even among the poorest groups in the West, so this makes most IQ differences you see between individuals due to genetics. The current estimate of heritability is 70% ish, with most of the 30% being nutrition and infantile stimulation. I’d like to see a study of vegetarian/vegan children to see if they compare well to omnivores.

5 responses to “Did nutrition cause the Flynn effect on IQ?

  1. Isn’t Lynn shooting himself at the feet? He was the one who built the controversial hypothesis that there are “racial” differences re. IQ. If most of these differences are due to nutrition (wow, he must have got hs neurones working really hard to reach to such an obvious conclussion!) all his theory is down.

    Sure he’s not talking of “racial” differences here but changes through time but a simple coparison between any developement/wealth/literacy maps with his alleged “racial” differences is very revealing.

  2. The racial difference in IQ goes back way before Lynn, Eynsenk I think noticed it first.

    As far as I know, the average height and weight of black and white Americans is the same, suggesting inadequate nutrition isn’t the issue. However, it’s not fair to compare poorer nations IQ with Europe or America. You need to pick two countries with the same kind of living conditions as a fair comparison, and African nations still performs appallingly compared to poor east Asian nations with a similar GDP and living standards.

    The most common view among psychology phd’s (they were polled a while ago) is that IQ variation between races is at least partly genetic. The ‘all environment’ is a real minority viewpoint, it’s really the media that push that idea as the paradigm.

    This item is really just to explain the IQ increase in developed countries in the last 100 years. On average we are 30 points smarter, and 4 inches taller than the Victorians. Both increases are mostly due to nutrition, it seems.

    The IQ increases were mostly seen in evidence at the lower end of the range, so it seems our social care sytems have improved our IQ by making sure poor kids don’t go hungry.

    I’m curious, why would he put jews then east asians down as the smartest if he came to this conclusion via a racist ideology?

  3. I’m not sure I buy this “all environment is almost just media” thing, unless it’s some really strawmanesque concept. Not that this example can be taken as the overall pattern, but about “the bell curve”, wikipedia mentions, “The initial positive reception of The Bell Curve in media such as newspapers and television talk shows was troubling to critics such as economist Edward S. Herman and evolutionary biologist Joseph L. Graves […] The second wave of reviews, […] was composed of expert opinion in the relevant fields. It provided a belated substitute for the peer-review process to which Murray and Herrnstein did not originally submit their work.”

    I don’t think that necessarily someone holding any view on genetic differences between races or groups is “racist”, but at the same time I don’t think that the fact that the newest ranks put some asians and jews at the top completely disproves racism by itself either. Racism/discrimination is a quite complicated process, and I think that most of the time more influenced by social class than race per se (most caste systems are within races), even though they’re often accompanied by a “racialization” of a group.

    I also don’t discard the possibility of a genetic difference between groups (“big races” or smaller ones), as a continuity of genetic differences between individuals, but I think that often it just gets ridiculously simplified, and I hate to use that word, “reductionist”.

  4. Melissa (Dorsey) McDowell

    Have you read “Guns, Germs and Steel,” by Jared Diamond? He touches on the subject by outright saying that hunter-gatherer peoples have to pay a lot of attention to their environments and are forever actively seeking new resources. He says he found these people to be more intelligent than people who grew up watching TV or otherwise being passively entertained.

    macrobiotic diet children…

    • Yeah, Don’t get me started on GGaS. It got me so irritated I started throwing things and swearing. Much more accurate is the book ‘the ten thousand year explosion’.

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