I think a study in the ‘70’s indicated that babies that cried a lot developed more cerebral convolutions than the happy, smiley ones. One of the sharpest employees in the office said, “They told me I was a very good baby,” and stared thoughtfully into space....
Off to look up “Great Courses.”
Something I read recently pointed out that traditional child-rearing in Africa results in children who are secure and content, but not intellectually stimulated. It’s probably related to what you said.