Technology may be getting smarter, but humans are getting dumber, scientists have warned.
Evidence suggests that the IQs of people in the UK, Denmark and Australia have declined in the last decade.
Opinion is divided as to whether the trend is long-term, but some researchers believe that humans have already reached intellectual peak.
An IQ test used to determine whether Danish men are fit to serve in the military has revealed scores have fallen by 1.5 points since 1998.
And standard tests issued in the UK and Australia echo the results, according to journalist Bob Holmes, writing in New Scientist.
The most pessimistic explanation as to why humans seem to be becoming less intelligent is that we have effectively reached our intellectual peak.
Between the 1930s and 1980s, the average IQ score in the US rose by three points and in post-war Japan and Denmark, test scores also increased significantly–a trend known as the ‘Flynn effect’.
This increase in intelligence was due to improved nutrition and living conditions–as well as better education–says James Flynn of the University of Otago, after whom the effect is named.
Now some experts believe we are starting to see the end of the Flynn effect in developed countries–and that IQ scores are not just levelling out, but declining.
Scientists including Dr Flynn think better education can reverse the trend and point out the perceived decline could just be a blip. However, other scientists are not so optimistic.
Some believe the Flynn effect has masked a decline in the genetic basis for intelligence, so that while more people have been reaching their full potential, that potential itself has been declining.
Some have even contentiously said this could be because educated people are deciding to have fewer children, so that subsequent generations are largely made up of less intelligent people.
Richard Lynn, a psychologist at the University of Ulster, calculated the decline in humans’ genetic potential.
He used data on average IQs around the world in 1950 and 2000 to discover that our collective intelligence has dropped by one IQ point.
Dr Lynn predicts that if this trend continues, we could lose another 1.3 IQ points by 2050.
Michael Woodley, of the Free University of Brussels, Belgium, claims people’s reactions are slower than in Victorian times, and has linked it to a decline in our genetic potential.
It has previously been claimed that quick-witted people have fast reactions and Dr Woodley’s study showed people’s reaction times have slowed over the century–the equivalent to one IQ point per decade.
Jan te Nijenhuis, a psychology professor at the University of Amsterdam, says Westerners have lost an average of 14 IQ points since the Victoria Era.
He believes this is due to more intelligent women have fewer children than those who are less clever, The Huffington Post reported.
Dr Woodley and others think humans will gradually become less and less intelligent.
But Dr Flynn says if the decline in IQ scores is the end of the Flynn effect, scores should stabilise.
He thinks that even if humans do become more stupid, better healthcare and technology will mean that all people will have fewer children and the ‘problem’ will regulate itself.