High intellect may not be down to education and good genes alone, scientists have discovered a virus that may cause stupidity.
American scientists from Johns Hopkins School of Medicine and the University of Nebraska have identified a virus that impairs brain activity by attacking human DNA.
Those affected by the algae virus, known as ATCV-1, may experience difficulty with learning or memory.
The scientists made the chance discovery while analysing throat microbes for a different purpose.
The virus was detected from throat swabs of 40 out of 90 participants.
Researchers found those who did not have the virus in their system achieved higher scores in tests measuring cognitive function, including visual processing and attention span.
"This is a striking example showing that the ‘innocuous’ microorganisms we carry can affect behaviour and cognition," said Robert Yolken, a virologist who led the original study.
“Many physiological differences between person A and person B are encoded in the set of genes each inherits from parents, yet some of these differences are fuelled by the various microorganisms we harbour and the way they interact with our genes.”
The study’s findings were published in the Proceedings of the National Academy of Sciences.