This is an interesting article in a scholarly journal that confirms what everyone with basic common sense already knew: that allowing large numbers of brown-skinned immigrants into your country is going to have ruinous effects on it.
The authors note that the average IQ in France has fallen by around 4 points per decade. They say this is due to biological causes, specifically the dysgenic effect of more intelligent people having fewer children and "replacement migration".
Dutton and Lynn report secular declines in Fullscale IQ evaluated using WAIS of four points a decade in France between the years 1999 and 2008–9. It is posited that the trend may have a partially biological cause, stemming from dysgenic fertility and, to a lesser extent, replacement migration. Given that these, and other biological phenomena are associated with the Jensen effect, it is expected that if they are the principal causes of the IQ decline then the secular change should also be associated with the Jensen effect. Furthermore if it can be demonstrated that the vectors of secular IQ decline, g loadings and the vectors of other biological indicators share variance, then the case for biological causation will be strengthened. Using the method of correlated vectors and error disattenuation, the secular IQ declines are shown to be associated with a high-magnitude Jensen effect (ρ = .833). A multi-vector common factor comprised of the vector of g loadings along with the vectors of three biological variables (subtest heritabilities, dysgenic fertilities and simple visual reaction times) was found to load substantially on the secular IQ decline vector (λ = .723). These findings indicate that the French secular IQ loss likely has a primarily biological cause.Source Source