Studies show that the global population IQ score has been decreasing since the second half of the 1970s, about 7 percentage points every decade. On the contrary, before 1975, the IQ score grew by about 3 percentage points in one decade.
According to NBC News’, IQ scores in France, Scandinavia, Britain, Germany and even Australia are beginning to decline. This trend could soon carry over to the US as well.
A recent empirical study from Norway is based on IQ testing for compulsory military service. Researchers from Ragnar Frisch Center for Economic Research examined data from 730,000 men born between 1962 and 1991. And they found out that the IQ score increased only until 1975.
Genes (in terms of parents’ intelligence) alone can explain only about half of the IQ variability among humans. In one possible explanation, it has been suggested that the average intelligence decreases because families with more children have lower IQs. However, Ole Rogeburg, who works as a senior researcher at the Ragnar Frisch Center, disagrees with this statement. He argues that the reasons why IQ score has grown over time and now decreases are found in environmental factors, according to CNN.
Another factor is the technology that makes life easier for us, and it does so well that we don’t have to think so much – because the technical achievements will solve the problem for us. The authors also pointed out children spend less and less time reading than the previous generation and spend more time online. New generation children exchanged books for computers and smartphones.
A few years ago, a team of biochemists in Indonesia tested the validity of the information that malnutrition of young children causes permanent brain damage. Indonesian University team led by Pek Hien Liang and Tijook Tiauw Hiem measured the intelligence of 107 children aged 5-12. 46 were undernourished, 17 suffered from vitamin A deficiency, others were healthy. Children’s intelligence was measured by clinical and laboratory tests including food intake. For greater validity, the children passed intelligence tests.
The vitamin A deficient group and other signs of malnutrition had the lowest number of IQ points. One of the most interesting aspects of the study was joint monitoring by the entire team. The intellectual and physical development of children “can be predicted with great precision on the basis of their nutrition in pre-school years. The study concluded that malnourished children showed the lowest IQ, while well-fed peers had the highest IQ.
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Sources: How to Develop and Sky High by I. Q., by Stephen Langer, 2002; https://edition.cnn.com/2018/06/13/health/falling-iq-scores-study-intl/index.html, https://themindunleashed.com/2019/05/world-getting-dumber.html