Cool article from SciAm about the quest to understand the genetic differences (if there are any) that account for individual intelligence.Go read the whole article -- this is the cutting of current research into intelligence.Searching for Intelligence in Our Genes
IQ is easy to measure and reflects something real. But scientists hunting among our genes for the factors that shape intelligence are discovering they are more elusive than expected
By Carl Zimmer
Key Concepts
- Researchers have powerful new technologies to probe genes and the brain, looking for the basis of intelligence differences among individuals.
- Their work is providing a new understanding of what intelligence is, while also revealing unanticipated complexity in the interplay between genes and environment.
- The more scientists learn about the role of genes in intelligence, the more mysterious it becomes, but the quest is still worth pursuing.
In Robert Plomin’s line of work, patience is essential. Plomin, a behavioral geneticist at the Institute of Psychiatry in London, wants to understand the nature of intelligence. As part of his research, he has been watching thousands of children grow up. Plomin asks the children questions such as “What do water and milk have in common?” and “In what direction does the sun set?” At first he and his colleagues quizzed the children in person or over the telephone. Today many of those children are in their early teens, and they take their tests on the Internet.
In one sense, the research has been a rousing success. The children who take the tests are all twins, and throughout the study identical twins have tended to get scores closer to each other than those of nonidentical twins, who in turn have closer scores than unrelated children. These results—along with similar ones from other studies—make clear to the scientists that genes have an important influence on how children score on intelligence tests.
But Plomin wants to know more. He wants to find the specific genes that are doing the influencing. And now he has a tool for pinpointing genes that he could not have even dreamed of when he began quizzing children. Plomin and his colleagues have been scanning the genes of his subjects with a device called a microarray, a small chip that can recognize half a million distinctive snippets of DNA. The combination of this powerful tool with a huge number of children to study meant that he could detect genes that had only a tiny effect on the variation in scores.
Still, when Plomin and his co-workers unveiled the results of their microarray study—the biggest dragnet for intelligence-linked genes ever undertaken—they were underwhelming. The researchers found only six genetic markers that showed any sign of having an influence on the test scores. When they ran stringent statistical tests to see if the results were flukes, only one gene passed. It accounted for 0.4 percent of the variation in the scores. And to cap it all off, no one knows what the gene does in the body.
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