Science Sez Ageing Populations Are Making Us Stupider

We’re getting stupider, if you hadn’t noticed.

Granted, given the recent political ups and downs of the world, and the proliferation of our fellow citizens graduating from the School of Hard Knocks, this may not be news to you.

Since around 1975, average IQ scores around the world have fallen.

While once this falling rate of brain power was attributed to society’s smartening women tending to have fewer children, new evidence suggests the change could, in fact, be due to people living longer than ever.

As we enter advanced ages, certain types of intelligence begin to falter.

New Scientist reports that for nearly a century, the average IQ scores of wealthy nations continued to rise steadily and predictably, gaining around three points every decade.

This is attributed to improvements in social conditions, such as public health, nutrition, and education.

This trend, otherwise known as the “Flynn effect” has been seen in many countries since its first discovery in the 1940s, from the Netherlands through to Japan.

Come 2004, however, researchers began to notice what appears to be a reversal in this once uber-predictable trend. Average IQ scores began to decline.

Michael Woodley of the Free University of Brussels, in Belgium, says the drop is “around 7 to 10 IQ points per century.”

The Flynn effect has been heavily supported by evidence, and news of its sudden reversal still courts controversy.

This controversy, however, pales in comparison to the firestorms that occur when theories explaining the decline are put forward.

Woodley subscribes to the fertility hypothesis: the idea that the most educated people in Western countries have been having fewer children than their less gifted peers, thus bringing intelligence down generation by generation.

But such a theory is difficult to test – owing to a lack of data.

“A lot of this is piecing together patchy datasets from the past,” argues the University of Edinburgh’s Stuart Ritchie.

“We’re in the dark with historical trends .”

Adding further hypothetical confusion to an already hypothetically confused hypothesis is the changing of IQ tests over time.

At least, that used to be the case.

Robin Morris, from London’s Kings College, and his band of researching rascals, have begun breaking down historical IQ test into different component categories that are more easily comparable.

Looking through more than 1,750 different types of IQ tests from 1972 onwards, Morris’s team separated the content into two kinds of sub-test: one measuring short-term memory, one assessing a person’s working memory.

This working memory is the ability we have to hold information for processing, reasoning, and decision making.

Unlike its short-term counterpart, this memory is a space in which information can be manipulated, rather than just retained and repeated.

Observing the test performance of people throughout time, the team saw a clear pattern: while short-term memory scores have continued to rise in line with the Flynn effect, working memory has been moving in the opposite direction.

This suggests that any reversal in IQ improvements may be due to this lowering of working memory ability.

Morris was reluctant to speculate on why this change had occurred, but did comment that remembering something in the short term is easier than keeping things in working memory – a process that requires more complex brain power.

What he was more happy to discuss, however, was another trend he noticed among the historical IQ tests: the increased proportion of people sitting the tests who were in their sixties or older.

Working memory is known to decline as we age, while short-term memory is usually preserved.

Morris’s team writes that the over sixties groups may be partly responsible for the decline in working memory scores in more economically developed nations.

“The idea that population ageing may be responsible is interesting and may serve as an alternative to the oft-proposed – but empirically little-supported – selective fertility patterns,” explains Jakob Pietschnig of Austria’s University of Vienna.

“It is a novel hypothesis that seems plausible and makes sense.”

Both Pietschnig and Ritchie insist that they would like to see stronger and more specific tests of this idea, however, which looks at elements of intelligence which are well-established to decline with age – such as processing time and reaction speed.

Until this time, Ritchie cautions that the hypothesis of reversing IQs should be treated with scepticism, meaning that – at least for now – our grey matter shortcomings are not something we can excuse

“This is speculative stuff, and it’s only a handful of papers. Anyone drawing conclusions is jumping the gun.”