The cause of the Flynn Effect isn’t fully understood, but it affects primarily those with lower scores, who may not have received adequate nutrition, education, or stimulation. Iodine deficiency is a factor in some countries. As people become better nourished and better educated, they perform better on intelligence tests. Thus it’s no surprise that a particularly large Flynn Effect has been detected in developing countries such as Brazil and Kenya. The IQ of rural Kenyan children rose eleven points in just fourteen years, a pace greater than any Flynn Effect reported in the West.
