Human intelligence increases by three IQ points a decade

Human intelligence is increasing by about three IQ points each decade due to improved health, education and nutrition, a new UK study has found.
"You'll probably be smarter than your parents and almost definitely be smarter than your grandparents," said Roger Staff, who led the study at the University of Aberdeen.
The study found that people born in 1936 scored considerably better on intelligence tests than those born in 1921 and that the improvements extended into old age.
Scientists believe that IQ is still on an upward trend, meaning that, on average, children born today are likely to surpass their parents in intellectual abilities, 'The Times' reported.

In the study, scientists compared two groups of people raised in Aberdeen, one set born in 1921 and the other in 1936. Both groups - 751 people in total - were given IQ tests at the age of 11 and then again at the age of 60.
At the age of 11, the 1936 group were 3.7 IQ points ahead, and the gap had widened to 16.5 points by the time the participants were pensioners - more than three times the size of increase seen in previous studies.

The inter-generational increase in IQ - known as the 'Flynn effect' - has previously prompted debate about whether it reflects a genuine improvement in cognitive skills or is simply down to people getting better at tests.

Staff argued that the changes are likely to be genuine, as they are seen across a wide variety of countries, which have had very different testing regimes in schools over the past century.
Staff said the differences may be due to changes in nutrition, education and healthcare.
"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's," Staff said.
The 1936 group were also young enough to benefit from the Aberdeen oil boom, which meant that they were, on average, wealthier later in life and therefore more able to eat well and spend money on intellectually stimulating activities.

This could explain why the IQ gap widened significantly as the two groups got older, researchers said.