For a while, rising IQ scores seemed like clear evidence of social progress, palpable proof that humanity was getting steadily smarter — and might even be able to boost brainpower indefinitely. Scholars called it the “Flynn effect,” in homage to J.R. Flynn, the researcher who recognized its full sweep and import.
These days, however, Flynn himself concedes that “the IQ gains of the 20th century have faltered.” A range of studies using a variety of well-established IQ tests and metrics have found declining scores across Scandinavia, Britain, Germany, France and Australia.
Details vary from study to study and from place to place given the available data. IQ shortfalls in Norway and Denmark appear in longstanding tests of military conscripts, whereas information about France is based on a smaller sample and a different test. But the broad pattern has become clearer: Beginning around the turn of the 21st century, many of the most economically advanced nations began experiencing some kind of decline in IQ.