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.