Study Suggests Environmental Factors May Contribute to IQ Decline


The Proceedings of the National Academy of Sciences of the United States of America (PNAS) has published a study suggesting environmental factors may be playing a part in the decline of intelligence scores.

The study, plainly titled, “Flynn effect and its reversal are both environmentally caused,” analyzed IQ scores for Norwegian men born between 1962 and 1991. And while average intelligence increased by a statistically significant three percent from 1962 to 1975, the scores steadily decreased after that point.

Co-author and Senior Research Fellow at the Ragnar Frisch Center for Economic Research in Norway, Ole Rogeberg, said that similar studies done in Denmark, Britain, France, the Netherlands, Finland, and Estonia have produced very similar results. “It’s not that dumb people are having more kids than smart people, to put it crudely,” he said. “It’s something to do with the environment, because we’re seeing the same differences within families.”

University of Edinburgh Postdoctoral Fellow in Cognitive Ageing Stuart Ritchie credits the “Flynn effect” for the initial rise. The Flynn effect is a term coined to describe the long-term increase in intelligence that occurred over the course of the 20th century — largely believed to be the result of better access to education.

The results of this test turn theories on heritable intelligence on their heads. Where once experts largely believed that IQ was genetic and that less intelligent people tended to reproduce more liberally, there are strong indications that the environment in which a child is raised matters much more to the development of their intellect than previously thought.

Most importantly to this conclusion is that the study examined siblings who had been born in different years. “The main exciting finding isn’t that there was a decline in IQ,” Ritchie said. “The interesting thing about this paper is that they were able to show a difference in IQ scores within the same families.”

Kings College in London Psychology Professor Robin Morris thinks that traditional IQ tests themselves may have outlived some of their usefulness — especially in a rapidly-evolving world, in which technology has so thoroughly redefined the context. “In my view, we need to recognize that as time changes and people are exposed to different intellectual experiences, such as changes in the use of technology, for example social media, the way intelligence is expressed also changes. Educational methods need to adapt to such changes,” he said.