The cause of the IQ decline is due to environmental factors, and not genetics, said Ole Rogeburg, a senior research fellow at Ragnar Frisch Centre and co-author of the study on IQ scores , published in the Proceedings of the National Academy of Sciences journal. Environmental factors include differences in the way young people are educated, increases in time spent online, changes in nutrition and less reading overall.
The downward trend is a reversal of the Flynn effect, a term that describes the vast improvement of IQ scores in many parts of the world throughout the 20th century. According to the study, the Flynn effect peaked in the mids and has declined in the decades since. Write to Mahita Gajanan at mahita. Fluoride exposure in utero linked to lower IQ in kids, study says. Read More. It's something to do with the environment, because we're seeing the same differences within families," he said.
These environmental factors could include changes in the education system and media environment, nutrition, reading less and being online more, Rogeberg said. The earlier rise in IQ scores follows the "Flynn effect," a term for the long-term increase in intelligence levels that occurred during the 20th century, arguably the result of better access to education, according to Stuart Ritchie, a postdoctoral fellow in cognitive ageing at the University of Edinburgh whose research explores IQ scores and intelligence and who was not involved in the new study.
An intelligence or IQ test. Researchers have long preferred to use genes to explain variations in intelligence over environmental factors. However, the new study turns this thinking on its head. Intelligence is heritable, and for a long time, researchers assumed that people with high IQ scores would have kids who also scored above average.
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. 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.
One potential explanation was quasi-eugenic. Alternatively, widening immigration might be bringing less-intelligent newcomers to societies with otherwise higher IQs. However, a study of Norway has punctured these theories by showing that IQs are dropping not just across societies but within families. In other words, the issue is not that educated Norwegians are increasingly outnumbered by lower-IQ immigrants or the children of less-educated citizens.
Even children born to high-IQ parents are slipping down the IQ ladder. Some environmental factor — or collection of factors — is causing a drop in the IQ scores of parents and their own children, and older kids and their younger siblings. One leading explanation is that the rise of lower-skill service jobs has made work less intellectually demanding , leaving IQs to atrophy as people flex their brains less. One leading explanation is that the rise of lower-skill service jobs has made work less intellectually demanding, leaving IQs to atrophy as people flex their brains less.
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