[HiTech RedNeck]

What is the cause and what is the effect?

Could it be that unwise use of brains dampens down so called “intelligence”?

It strikes me as very unwise to reduce intelligence to a one number quantity. If even psychological sciences were done justice, intelligence might be a ten value vector. And none of it would state what wisdom is.

[FredZarguna]

Intelligence has a definition in social science. It is nothing more nor less than what IQ tests measure. It is one number. That is not to say that the colloquial use of "intelligence" and the term-of-art used by psychometry is the same. But I am not talking about a vague word. I am saying the mean value of ONE NUMBER that constitutes intelligence in social science is statistically a whole standard deviation lower for a certain cohort. And, that ONE NUMBER strongly correlates [statistically] to a very large number of outcomes.

Sowell has argued, in very many places, that there is a feedback mechanism between certain outcomes and intelligence based on the anomalous intergenerational [historical] test results of Eastern Europeans in the early 20th century. That is as may be; but the Eastern European immigrants understood intuitively that whatever the problem was, it was their problem to solve, and not the rest of society's.