Your IQ Depends on a Single Gene

Illustration for article titled Your IQ Depends on a Single Gene

If you thank your parents for your intelligence or blame them for your stupidity, you might be right—but not because of the way they raised you. In fact, a new study provides the most compelling evidence yet that intelligence is affected by a single gene.

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The research, carried out at UCLA and published in Nature Genetics, studied fMRI brain scans and DNA samples of over 20,000 people. Thanks to the massive pool of volunteers, the researchers were able to identify a single gene that has a significant, measurable—but admittedly small—impact upon intelligence.

They found that variations on a gene called HMGA2 can alter IQ by 1.29 points. The variation in the gene is just a single different molecule in its string of DNA. Despite the small difference, it's an amazing discovery to establish that such a small chemical variation can have an effect on human intelligence.

In fact, as well as raising IQ score by 1.29 points, the same gene variation also increases the overall volume of the brain by 0.58 per cent of average brain size—that's equivalent to about two extra teaspoons of brain power.

It's worth noting that the effect is small, and required a huge population of participants to identify. That means that it doesn't have a huge impact on the way we judge each other's intelligence—but it does for the first time demonstrate that single genetic differences have a role to play in determining our cognitive abilities. [Nature Genetics via New Scientist]

Image by Lasse Kristensen/Shutterstock

DISCUSSION

I worked for many years at a research place that employs a high percentage of people with advanced degrees; 50% had a Masters and 25% a PhD. I've known some very, very smart people and I have an observation to make. I think there is an optimal range of intelligence for getting along in the world and being useful. Obviously unfortunates with low intelligence have difficulty, but some of the smartest people I've met have almost as much trouble with working or social relationships, and in communicating the relevance of their work. A good friend at this R&D place has an IQ of 185; he could just barely communicate with his colleagues. For a while I was assigned as his "interpreter", as I was sometimes able to divine his meaning and communicate it to others of somewhat less lofty intelligence.

Interesting factoids from Wiki:

Average adult combined IQs associated with real-life accomplishments by various tests:

MDs, JDs, or PhDs 125+ (WAIS-R, 1987)

College graduates 112 (KAIT, 2000; K-BIT, 1992), 115 (WAIS-R)

1–3 years of college 104 (KAIT, K-BIT), 105-110 (WAIS-R)

Clerical and sales workers 100-105

High school graduates, skilled workers (e.g., electricians, cabinetmakers) 100 (KAIT, WAIS-R), 97 (K-BIT)

1–3 years of high school (completed 9–11 years of school) 94 (KAIT), 90 (K-BIT), 95 (WAIS-R)

Semi-skilled workers (e.g., truck drivers, factory workers) 90-95

Elementary school graduates (completed eighth grade) 90

Elementary school dropouts (completed 0–7 years of school) 80-85

Have 50/50 chance of reaching high school 75