IQ correlates with skin colour

Tropical-adaptedness appears to be all but identical with mental retardation.
I like this statement.  The threshold for mental retardation should be 85 since people with this IQ could either not pass American High School or barely pass it, and the threshold was indeed 85 originally, but was dropped to 70 to make blacks look better, which you likely know.
Tropically-adapted people generally score below 85 IQ points, on average, i.e., the majority of these people are aptly designated naturally mentally retarded; naturally in the sense that their mental retardation does not result from developmental insults/disruptions.

Ecological correlations between IQ, skin color, temperature and GDP per capita