As the great debate over nurture versus nature continues, a team of geneticists have identified 40 new genes that have a direct influence over human intelligence. Writing in the journal Nature Genetics, the team conclude that there are now at least 52 genes that have a direct influence on a person’s IQ.
Analyzing the genomes of 60,000 adults and 20,000 children, the team – led by the Free University of Amsterdam – found that these 40 new genes guide the construction of healthy neurons, as well as the synapse connections that branch between them.
It’s likely that there are hundreds of additional genes that have an influence over IQ, so although this study represents the biggest haul yet in this regard, there’s still a long way to go before the cartography of our cognitive abilities is complete.
The team note that these 40 new genes, when all other factors are ruled out, explain just 4.8 percent of the variation in human intelligence seen over their subjects. If 50 percent of a person’s IQ can be explained genetically, then this means that there is a huge chasm of knowledge that geneticists have yet to fill.
“These findings provide starting points for understanding the molecular neurobiological mechanisms underlying intelligence, one of the most investigated traits in humans,” the authors write in their study.
Just to clarify straight off the bat – these genes have an influence on intelligence, but environmental factors, including lifestyle, healthcare, socio-economic background, education, and so on also have a huge effect.
Furthermore, IQ tests two types of cognitive facets known as crystallized intelligence and fluid intelligence.
The former is the ability of a person to solve puzzles or answer questions when the parameters of the problem have already been understood or conveyed clearly – mathematics is a good example of this. Fluid intelligence is the ability to solve brand new and more abstract problems, like navigating a maze, spotting hidden patterns, or even weaving through a conversation with a complete stranger.
There are plenty of other types of intelligence, including emotional intelligence – the ability to empathize, to regulate one’s own emotions, and to handle interpersonal relationships well. IQ does not take this into account, and neither do these 52 genes.
This study also only looked at the genomes of those with European descent. Other research groups will have to peer into the genetic makeup of those from other geographical settings to see if the same genes are present all over the world.
In any case, this is a remarkable study that represents a giant leap forward in our understanding of what has been referred to as the “architecture of intelligence”. It’s a tall mountain to climb, but another ledge has just been scaled by this research team.