Brain imaging evidence for the genetic basis of IQ and behavioral restraint

A UCLA study points to very high heritability of IQ and behavioral restraint–probably the two most important traits in the modern world. It also points to the brain mechanisms responsible for differences in these traits. Paul Thompson and his colleagues

used a new type of brain-imaging scanner to show that intelligence is strongly influenced by the quality of the brain’s axons, or wiring that sends signals throughout the brain. The faster the signaling, the faster the brain processes information. And since the integrity of the brain’s wiring is influenced by genes, the genes we inherit play a far greater role in intelligence than was previously thought.

Genes appear to influence intelligence by determining how well nerve axons are encased in myelin — the fatty sheath of “insulation” that coats our axons and allows for fast signaling bursts in our brains. The thicker the myelin, the faster the nerve impulses.

For example, the connections in the parietal lobe associated with math and logic are 85% heritable, while the connections in the frontal lobe responsible for working memory and  for inhibiting impulsive behavior are 65% heritable. Behavioral restraint not really IQ  but relate to behavioral control–things like being able to inhibit immediate gratification and plan for the future . These are traits that show important race differences associated with criminality, especially impulsive criminality (as opposed, say, to most white collar crime).

The difficulty for the left will be to convincingly argue that the sorts of interventions they have been championing will really change brain myelination. As noted in my previous blog, they seem to be running out of ideas on how to improve educability of low-IQ populations, and Head Start doesn’t work either. They may take comfort in the possibility that genetic engineering could actually do the trick:

And could this someday lead to a therapy that could make us smarter, enhancing our intelligence?

“It’s a long way off but within the realm of the possible,” Thompson said.