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By Joshua Dietz
For decades, scientists have struggled to identify the relationship between genetics and intelligence. With the help of a team of researchers led by Dr. Danielle Posthuma, at the Center for Neurogenomics and Cognitive Research in Amsterdam, the intellectual burden is now a little lighter. Yahoo News has reported that scientists at the Center in Amsterdam have discovered 52 genes linked to intelligence, including 40 never before identified genes. The startling finding may have implications for our understanding of the etiology of autism. Published in the journal Nature Genetics, Dr. Posthuma’s team reports that this new grouping of genes may account for twenty percent of the discrepancies in IQ testing among the population observed for the study.
Attempts to scientifically understand intelligence have spanned centuries. The concept of IQ, or intelligence quotient, originated in the 19th century in part thanks to the work of English statistician Francis Galton. In 1905, Alfred Binet, a French psychologist developed an early form of intelligence testing in order to identify children with learning disabilities. German psychologist William Stern first coined the phrase ‘intelligence quotient’ in his 1912 book The Psychological Methods of Testing Intelligence. Debate as to what actually constituted intelligence continued throughout the 20th century, reaching a fiery pitch with the publication of Dr. Charles Murray’s book The Bell Curve in 1994. In his book, Dr. Murray discussed the differences in IQ between ethnic groups, citing data from the biological and psychological sciences – disciplines which accept the notion of a biological basis to intelligence.
While the practice of science requires cautious optimism, Dr. Posthuma’s work should serve as a strong refutation to the notions of social constructivism and scientific racism – belief systems that reject any claim of biological influence on factors like intelligence. Researchers at the Center for Neurogenomics and Cognitive Research have identified astounding links between genetics and intellectual ability.
Dr. Posthuma’s team (an international crew consisting of thirty scientists), reviewed thirteen previous studies on genetic profiles and intelligence evaluations of 78,000 people of European heritage. In their research, the scientists at the Center for Neurogenomics and Cognitive Research found that “[many] of the newly discovered gene variants linked to elevated IQ play a role in regulating cell development in the brain, especially neuron differentiation and the formation of synapses.”
Many of the genetic variations linked with high IQ also correlated with other attributes:
- More years spent in school
- Bigger head size in infancy
- Success in kicking the tobacco habit
“Gene variants associated with high IQ are also associated with higher risk of autism spectrum disorder,” she said in an interview. Of particular note, gene SHANK3, “is a very good candidate for explaining that,” she added. Dr. Posthuma’s team successfully checked the 13 databases they drew from (each used slightly different IQ tests) against the 52 gene variants to see if the combined match-up between intelligence and genetic profile was consistent. Their findings held true even after scanning a very large database that had not used for their study.
It is not yet possible for scientists to identify all the genes associated with intelligence. Dr. Posthuma observes that scientist would have to scan millions of genomes to find them all. “For intelligence, there are thousands of genes,” she said. “We have detected the 52 most important ones, but there will be a lot more.”
While Dr. Posthuma’s research is promising, new discoveries are made and overturned with astounding regularity. Just last year, researchers claimed intelligence was matrilineal. Weeks later, that claim was speedily retracted. Enthusiasm for new and exciting data ought to be tempered by the consideration for as of yet undiscovered knowledge.