From glancing at that chart, there also appear to be correlations with religion and distance from the equator (i.e. regions having more or less daily sunlight).
True, but it is still an interesting link. I wonder if it is because of the isolation and the breaking of family ties in a developing world, which is is linked to the level of mobility and also with culture.
From glancing at that chart, there also appear to be correlations with religion and distance from the equator (i.e. regions having more or less daily sunlight).