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Over a ten year period in France, from 1999 to 2008-9, IQ has declined in France by almost 4 points. What is the cause? Immigration? Dysgenics? A reversal of the Flynn Effect? No doubt that numerous people would attribute the decline in intelligence in France due to MENA and SSA immigration. But is this true?

Lynn and Dutton (2015) show how differing studies show both positive and negative gains in IQ. To prevent further evidence of these negative Flynn gains, they looked to the IQ of France from 1999-2009.

The WAIS-III was standardized in France in 1999 while the WAIS-IV was standardized in 2009. This was a great opportunity to see if the intelligence of the French dropped using the new WAIS-IV. The sample was of 79 people who were of a different sample than that of the broader WAIS-IV French standardization. The average age of the sample was 45, ranging between 30 and 63 years of age. Half of this sample took the WAIS-IV first while the other half took the WAIS-III first to control for practice effects. They used a separate sample to compare the norms of generated by the two standardizes samples.

The above table from the paper, table 3, shows the comparison between the two WAIS tests. Positive ds indicate lower scaled scores on the III in comparison to the IV and thusly higher scores. What these data show is that the IV is harder than the III and IQ declined because the test got ‘tougher’ (because full-scale intelligence declined). As noted above, this phenomenon of decreasing IQ scores has been noticed for about 20 years now. The symbol search showed the smallest decline while there was no change in digit span. The biggest gain was in vocabulary.

This is pretty shocking. In ten years, verbal comp decreased by 4 points, perceptual reasoning index by 3.1 points, no change in working memory index, processing speed index decreased by .7 points, perceptual organization index decreased by 3.9 and the whole full-scale IQ decreased by 3.8 points. Lynn and Dutton discuss the results:

In addition, the Full Scale IQ on the WAIS IV sample of 79 subjects was calculated based on a comparison with the WAIS IV sample of 876 subjects, which was representative of the French population on key variables such as education and region. The scores of this sample of 876 subjects were set at 100 and a comparison made with the sample of 79 subjects. As can be seen in Table 4, on this basis the IQ of the sample of 79 subjects was 101.1 with an SD of 14.7, where the French norm would be 100 and the SD 15. As such, the smaller sample can be regarded as representative of the French population in terms of intelligence.

So this small sample can be regarded as representative of the French population. Lynn and Dutton say that the digit span showing no increase corroborates findings from another researcher that showed that there was no change in forward or backward digit span in 85 years. They then say:

. . .improvements in the quality of nutrition during the twentieth century made a major contribution to increasing IQs. But it seems improbable that the quality of nutrition declined in recent years in France and in the other economically developed countries in which declining IQs have been reported.

So one possible cause is that nutrition has declined in France. From Dubuisson et al, 2010:

These repeated surveys highlighted the fact that trends in French food habits have moved towards an average European diet at the crossroads between Mediterranean and Northern diets, and that food consumption changes impacted, to a lesser extent, nutritional intake.

It shows that the French diet is in between Med and Nord diets. Really, as Lynn and Dutton asserted, there was no decline in nutritional quality for the French.

Another possible cause is a decrease in quality of schools. Flynn says a part of the reason for the rise in IQ was due to the advent of scientific thinking. However, this is not a good explanation either since school quality seems to not have been affected.

Flynn also talks about the media and its role. Lynn and Dutton say:

However, this would not explain declines in other forms of intelligence and, moreover, it might be argued that the desire and ability to read such literature would be underpinned by general intelligence and so a decline in the consumption of such literature would partly reflect a decline in general intelligence, as vocabulary is a measure of intelligence.

It is also worth noting that, apparently, reading may actually increase general intelligence (post coming on that soon).

Now, finally, the theory we’ve all been waiting for: Is it increased immigration?

Lynn and Dutton state:

This increase has occurred throughout western Europe and a number of studies have shown that immigrants from North Africa and south-west Asia typically have an average IQ of around 85 to 90 (Lynn, 2006, Lynn, 2008, Lynn and Vanhanen, 2012 and Rindermann and Thompson, 2014; for a large meta-analysis see te Nijenhuis, de Jong, Evers, & van der Flier, 2004). This conclusion has been confirmed by Kirkegaard (2013) who has shown that in Denmark the number of non-European immigrants increased from approximately 50,000 in 1980 to 400,000 in 2012 and the IQ of non-European immigrants in 18–19 year old military conscripts was 86.3, relative to 100 for indigenous Danes. These immigrants are likely to have had some impact on reducing the average IQ of the populations, but it is doubtful whether the increase in the number of immigrants with lower IQs has been sufficiently great to have had a major effect.

I personally don’t think that migration into Europe from MENA and SSA countries has been enough to put that big of a dent (over 1/3rd of an SD) in average IQ in France, and Europe as a whole. Since people are coming from areas closer to the equator and have higher rates of children since they are r-selected, could this be why France has seen a decrease in intelligence?

No.

Woodley of Menie and Dunkel (2015) reviewed Lynn and Dutton’s paper and said:

Replacement migration in France involving populations exhibiting lower means of IQ and higher rates of total fertility, such as Algerians, Moroccans, Tunisians and Roma (Čvorić, 2014 and Lynn and Vanhanen, 2012) may be increasing the rate of secular losses at the level of g, consistent with speculations advanced in Dutton and Lynn (2015), however the additional loss in g due to this process is anticipated to be very small. Based on a simulation, Nyborg (2012) estimates that in Denmark, replacement migration may be reducing heritable g by .28 points per decade, which would increase the overall loss in g to 1.51 points per decade ( Woodley of Menie, 2015), this still being only 37.75% of the loss observed in the French cohort.

An Environmental Explanation?

Since we still need an explanation for 62.25 percent of the 3.8 decrease in full-scale IQ other than dysgenic fertility, are there any environmental explanations? Environmental explanations can be anything from child abuse, to poor schooling, to poor nutrition, etc. Was there an increase in any of these or other variables that negatively affect IQ which would explain the 3.8 point decline in IQ?

One of the most likely candidates is nutrition. Lack of certain vitamins, especially in childhood, would prevent the brain from receiving the proper nourishment to grow.

The INCA study took record of food consumption from 2,373 people aged 4 to 92 from a 7-week period and from that they saw which nutrients they were deficient in (Touvier et al 2006). To measure if and how much they were nutrient deficient, they used the Estimated Average Requirement (EAR). The vitamins used were calcium, magnesium, iron, vitamins C, A, B6, and B12, thiamin, riboflavin, niacin, pantothenic acid, and folate. A lot of these have to do with proper brain functioning and ability to reach its full-size potential. For instance like the B vitamins and iron. Being deficient in those nutrients depresses brain size and with it IQ. For instance, being deficient in vitamin B 12 and folate leads to decreased  brain size in childhood. The negative effects of being deficient in these nutrients may partially explain some of the 3.8 point decrease in full-scale IQ.

Regarding the prevalence of the aforementioned nutrient deficiencies in these populations, the authors state:

We also calculated daily consumption of 44 food groups by age and gender. This paper shows how the combination of both data sets, i.e., inadequacy and food consumption data, allows a preliminary screening of potential food vehicles in order to optimize fortification. The prevalence of inadequacy was particularly high for the following groups: for calcium, females aged 10-19 years (73.5%) or aged 55-90 years (67.8%), and males aged 15-19 years (62.4%) or aged 65-92 years (65.4%); for magnesium, males aged 15-92 years (71.7%) and females aged 10-90 years (82.5%); for iron, females aged 15-54 years (71.1%); and for vitamin C, females aged 15-54 years (66.2%). Two examples are provided to illustrate the proposed method for the optimization of fortification.

Most vitamins and minerals have positive effects on brain functioning, some more than others, but notice the prevalence of iron defieciency in the females aged 15-54 years (71.1 percent). With the cohort cited by Lynn and Dutton (2015) and Woodley of Menie and Dunkel (2015) being aged 30 to 63 with an average age of 45, the prevalence of iron deficiencies in the INCA study, along with the other deficiencies in the cohort, may partially be responsible for the decline in IQ.

The Flynn Effect

PumpkinPerson describes it well here:

One of the biggest mysteries in psychology is the Flynn Effect; the fact that over the 20th century, people have been performing better and better on IQ tests.  Of course, the average IQ in Western countries by definition is always about 100, however because people keep scoring higher every decade, the tests routinely have to be made more difficult and the norms must be regularly updated to keep the mean IQ from rising far above 100.

However, in first-world countries, in the past 20 or so years, it has been in decline, particularly in France. It’s due to a mix of dysgenic fertility and nutrient deficiencies. Since Flynn gains are largely due to advancements in better nutrition, Flynn loses would then be attributed in part to nutrient deficiencies as well as dysgenic fertility.

The cause for the 3.8 decrease in IQ in France is low fertility rates amongst the French population as well as nutrient deficiencies. Clearly, ameliorating this decrease in IQ can be reversed by the K-selected having more children and healthier eating habits. Drops in IQ won’t be attributed to MENA and SSA populations until the future, but for now, the cause for the decrease is the French themselves.