One more thing from today's WSJ on the mutability of intelligence. Only about a quarter of one's intelligence is genetically predetermined:
http://online.wsj.com/article/SB10001424...72642.html
(here's the link to the article in Nature:
http://www.nature.com/nature/journal/vao...0781.html)
excerpts:
"Nearly a quarter of the changes often seen in a person's intelligence level over the course of a lifetime may be due to genes, a proportion never before estimated, new research shows.
The study suggests that genes may partly explain why some people's brains age better than others, even though environmental factors likely play a greater role over a lifetime.
. . . .
The new study, published in the journal Nature, offers one of the first estimates of how much genes and the environment contribute to fluctuations in a person's intelligence between adolescence and old age. It found that genetic differences account for 24% of the variation.
. . . .
DNA and IQ
How scientists discovered that almost one-quarter of the change in intelligence over a lifetime is due to genes:
Scientists found decades-old intelligence tests done on 1,940 11-year-olds in Scotland, and then retested the participants at age 65 and above.
DNA from blood samples was collected from all 1,940 people.
An analysis of half a million genetic markers in the participants revealed various genetic similarities.
Scientists compared these genetic similarities with the participants' intelligence levels in both youth and old age.
The study concluded 24% of the life-span changes in intelligence could be linked to genes, the rest to environmental factors.
. . . .
Scientists elsewhere have determined that a person's intelligence level as measured by an IQ test isn't fixed at birth. Instead, a person's IQ can rise or fall as the person ages. One recent brain-scanning study found that a teenager's IQ can increase or decline by as many as 20 points in just a few years.
There also has been progress in figuring out which environmental factors may affect intelligence. For example, experiments have shown that IQ scores can change after just a few weeks of cognitive training, though the increases are small and tend to fade after a few months.
Meantime, a three-decade study done at the U.S. National Institute of Mental Health found that people whose jobs involved setting up elaborate systems or dealing with tough or complex relationships tended to do better over time on cognitive tests.
Schooling also has been shown to boost IQ, while music lessons have been associated with higher IQ throughout life. And brain-imaging studies have found that circus jugglers and London cab drivers who use maps can show brain changes linked to practice. . . . ."