Genes linked to attaining higher levels of education are declining.
Researchers have found that people with these genes tend to have fewer children and so contribute less to the gene pool. If this decline continues, they predict it could reduce the IQ of future generations.
'It isn't the case that education, or the career opportunities it provides, prevents you from having more children,' Dr Kari Stefansson, CEO of genetics firm deCODE, which ran the study, explained to the Guardian. 'If you are genetically predisposed to have a lot of education, you are also predisposed to have fewer children.'
The study – published in the Proceedings of the National Academy of Sciences – used a database of genome sequences from nearly 130,000 Icelanders born between 1910 and 1990. Researchers compared the incidence of gene variants known to predispose people to higher education with each person's level of formal education, age when beginning a family, and number of children.
They found a small decline in the frequency of the 'education genes' over 65 years, which could be interpreted as a decrease in IQ of 0.04 points per decade. Individuals with these genes also tended to have fewer children. This decline is significant on an evolutionary timescale and the researchers suggest it could significantly impact educational attainment in society.
The researchers suggest that people with these genes are predisposed to have fewer children, mainly because they begin families later in life. Yet even people who carried these 'education genes' but did not spend a long time in education still had fewer children than those without the genes. The effect was stronger in women than men.
Other experts have pointed out that social and environmental changes could override small genetic effects on educational attainment.
'There is definitely a genetic overlap between higher educational attainment, having children later and having fewer children. But whether you can say that results in changes over time, and in evolution, I'm not so sure,' Melinda Mills, professor of sociology at Oxford University, who was not involved in the study, told the Guardian. 'To have natural selection and evolution you need something to be happening in a consistent manner over many generations.'
'There are all kinds of things in the environment that may prevent this decline having all that much impact on the true education that people receive,' said Dr Stefansson. 'If we continue to improve the availability and quality of educational opportunities, we will presumably continue to improve the educational level of society as a whole. Time will tell whether the decline of the genetic propensity for education will have a notable impact on human society.'