(Phys.org) —Human intelligence is thought to improve with each generation and a unique study of people born and raised in Aberdeen has proved that those in north-east Scotland are getting smarter.
The research by scientists at the University of Aberdeen and NHS Grampian has been published in the academic journal Intelligence.
Previous studies conducted around the world have shown an IQ increase by 3-4 points per decade. This phenomenon has come to be known as the 'Flynn effect', name after Professor James R Flynn who described it. The reason for this is unclear but better nutrition, health, higher living standards, and more socio-economic opportunities are thought to contribute.
The University of Aberdeen team examined two groups of people raised in Aberdeen, one born in 1921 and one born in 1936. These people are known as the Aberdeen Birth Cohort and were tested when they were aged 11 and when they were adults after the age of 62. The study consisted of 751 people all tested aged 11 and who were retested between 1998 and 2011 on up to five occasions.
Researchers compared the two groups at age 11 found an increase in IQ of 3.7 points which was marginally below what was expected but within the range seen in other studies. However, comparison in late life found an increase in IQ of 16.5 points which is over three times what was expected.
Dr Roger Staff, who led the study, describes the size of the intelligences gains as 'surprisingly large'. He said: "When you consider the life experiences of the two groups, those born in 1921 experienced the depression as teenagers and then World War Two.
"Those born in 1936 were children during the war and experienced food rationing. Although rationing meant that the food was not particularly appetising it was nutritious and probably superior to the older group. In addition, post war political changes such as the introduction of the welfare state and a greater emphasis on education probably ensured better health and greater opportunities.
"Finally, in their thirties and forties the 1936 group experienced the oil boom which brought them and the city prosperity. Taken together, good nutrition, education and occupational opportunities have resulted in this life long improvement in their intelligence. Aberdeen has been good for their IQ!
"These IQ gains are probably not unique to Aberdeen with similar with similar environmental changes being experienced across the UK."
Dr Staff and his collaborators now hope to expand their work to include a group of Aberdonians who were born in the 1950s known as the Aberdeen children of the fifties. Dr Staff expects the average Aberdonian IQ to increase further.
He added: "Those born in the fifties were raised in a boom time for Britain, the then prime minister Mr McMillian said at the time that 'we have never had it so good'. In addition, this group coincided with the expansion of higher education and have always lived and worked in an oil rich city."
The research findings were reviewed by Professor Flynn who first observed the phenomenon of generational intelligence increases. He commented that the study was 'very interesting' and that the results, 'should raise our estimates of British adult gains', in intelligence.
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Volume 47, November–December 2014, Pages 194–201. DOI: 10.1016/j.intell.2014.09.013