Researchers have discovered 40 new genes tied to intelligence.
They clarified, however, that their results showed that intelligence is potentially more complex than previously thought, with no clear genetic pattern and easy explanation behind it. Many of the discovered genes, though, have other prominent roles even though most play a part in brain development.
“These findings provide new insight into the genetic architecture of intelligence,” wrote the team, led by Danielle Posthuma from Vrije Universiteit, on the journal Nature Genetics.
The team studied databases comprising a sample of nearly 80,000 adults and children, all of which were of European descent. One database covers outstandingly intelligent people as well as some twin studies.
They used two types of genetic analysis to point out the genes linked to intelligence, focusing at all the genes in the DNA map of humans.
What they discovered: more than 52 genes, including 40 that had never been associated with intelligence before. The identified genes are mostly expressed in brain tissue, and there were discovered genes that also regulate cell development.
One gene, known as SHANK3, is part of the formation of synapses, or connections in between brain cells. Mutations in this given gene can result in autism spectrum disorder.
The FOXO3 gene has different versions tied to brain cell death as well as longevity, while other genes have ties with conditions such as Alzheimer’s disease and obesity.
Posthuma told Newsweek that she did not expect finding as many genes as their team did.
“I’ve run a lot of genome studies and a lot of the time you don’t find a lot of genes, even though the traits you are investigating are highly heritable,” she said. “And it’s only if you have a really large sample size that you start to find things.”
Intelligence: A Complicated Matter
However, while 52 genes sounds like a lot, Posthuma added that there are hundreds more needed in order to have a solid picture of intelligence’s genetic influence. Current results, for instance, were estimated to account for up to 4.8 percent of the variance in intelligence.
Genes also appeared to account for about 70 percent of the variation in educational attainment among the studied individuals.
The bad news for those who want to produce smart children is that the genes cannot be used for genetically engineering more brilliant creatures. IQ’s heritability, explained Posthuma, is 80 percent, making it quite a journey to find all the necessary genes. Even with their identification too, environmental factors as well as gene interactions may still be at play.
In other studies, it appeared that up to half of a person’s intelligence is inherited, leaving the other half to a mix of other factors.
Further, it can be a messy affair: intelligence could be accompanied by “so many small effects” influencing not only IQ but other traits as well. Play around and you might end up with an intelligent animal – but with a variety of other problems, Posthuma warned.
In 2015, a group of British researchers found clusters of so-called intelligence genes, which may unlock ways to boost mental ability.