A new study confirms what other studies have found: IQ scores around the world have been dropping since the late 20th century.
The cause isn’t genetic but environmental.
And “environmental” means things like the education system, media, nutrition, less reading and other factors.
The new study, published in the Proceedings of the National Academy of Science, focused on data from three decades of Norwegian births between 1962 and 1991.
Analyzing cognitive ability scores and other data, the researchers wanted to narrow a wide variety of proposed explanations down to the ones most likely to be responsible.
What they discovered is that IQ can vary significantly among siblings and that the decline is not a case of low IQ parents having more children than high IQ parents.
In the end, the researchers found environmental factors to be the likely culprit.