Chalk One Up For the Hereditarians


Pretty interesting, and I have long suspected this, or actually worried about it, because I’m opposed to the hereditarian line. However, you can’t have Flynn Effects raising IQ’s by 3 points via genetics, so the Flynn Effect shows that environment can also play a strong role in, at the very least, increasing IQ scores.

For those who don’t want to click the link, the article states that UCLA researchers have found evidence that intelligence is largely inherited. That’s overstating the case of what they found, though. What they found was identical twins had very similar levels of myelin sheathing in the brain’s axons in brain regions key to intelligence, such as the corpus callosum and the parietal lobes.

Myelin is a coating on axons, which are the connections between neurons, or brain cells. The fatter the sheathing, the better the axons work, that is, the faster the axons fire messages. Myelination of the brain actually peaks in middle age, which is not really evidence that this process is intimately linked to intelligence, since fluid IQ (a measure of pure, raw brain speed) peaks around age 23 and then drops. Crystallized IQ often keeps going up into middle age and beyond.

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5 thoughts on “Chalk One Up For the Hereditarians”

  1. It’s just one piece of the puzzle. I think we’re still a ways off from the full, clear picture. Growing up impoverished does have an effect on IQ. Why else would south of the Mason-Dixie line whites score lower than Northern whites.

  2. To Tulio:

    Growing up impoverished does have an effect on IQ. Why else would south of the Mason-Dixie line whites score lower than Northern whites.

    Because they reproduce with their cousins..? Ok seriously there could be a number of factors.. but note that a high percentage of Whites below the Mason-Dixon line are Scotch-Irish or British. In the North you have Jews which tend to outperform and wider variety of people of European background. As Robert said it could be simply a matter of people with get up and go – got up and went. Smarter people from the South have traditionally migrated to New York and Boston. That seems to be abating.. I would like to see IQ comparisons among Whites high school students in the last decade between Northern and Southern schools. Southern Whites are not nearly as impoverished in general compared to their Northern peers as they were say 60 to 80 years ago.

    1. Jews are only 2% of the country, they don’t effect aggregate IQ much.

      I tend to think it’s cultural differences. Thomas Sowell has a book called “black rednecks and white liberals”. In it he talks about the Scotts Irish culture and about the pathologies that existed in that culture even before they came to America and many of these traits were some of the same things we associate with black culture. Even ebonics he says has it’s roots in the Scotts-Irish dialect.

      Now you look at the culture of New England and it’s just a more refined culture overall. I think more refined cultures lead to higher IQ, though of course that IQ obviously has genetic constraints.

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