Now, however, "there is good evidence to support the notion that schooling does make you 'smarter' in some general relevant way as measured by IQ tests," said study author Taryn Galloway, a researcher at Statistics Norway in Oslo.
Findings from the large-scale study appear in this week's online edition of the Proceedings of the National Academy of Sciences.
IQ, or intelligence quotient, is a widely accepted measure of intelligence. The IQ score comes from several combined, standardized tests.