Over the last century, humans have become much, much cleverer. In fact, new research by the University of Vienna shows how across the world, the average IQ has risen by 30 points during that time.
Why this has happened is not entirely clear, but the researchers say it's a combination of better food quality and availability, improved medical services and education for a bigger chunk of the population.
The trend has never been completely steady – there have been times of rapid improvement and times of little improvement at all, such as in World War II when nutrition was poor and stress level was high.
But what's happening now is surprising – the findings, published in the journal Perspectives on Psychological Science, suggest improvement has been slowing by a considerable degree recently, for no obvious reason.
“This may indicate that beneficial effects of factors improving our test scores have peaked,” the researchers suggest, adding that the consequence would be an end to increases in IQ.
More needs to be done to determine what exactly is going on in our brains, but if it turns out to be more than a blip in IQ gains, the researchers believe it's possible our intelligence could actually go in reverse for the first time in recorded history.
Future research will show whether these observed decelerations of the IQ gains will lead to an end or ultimately a reversal.