Few Clues to High IQs

Christopher Wanjek

Date: 11 April 2006 Time: 04:49 AM ET

Kids with high IQs have a distinct pattern of brain development, according to a 20-year study of more than 300 young minds published in the March 30 issue of the journal Nature.

And for the next big brain study, scientists will get these smart kids to figure out what this Nature study really means.

Like all brain and intelligence studies, this one is loaded with implications. If smart brains are biologically different from dumb brains, does that mean that genetics and therefore race determine intelligence?

Yes and no. That is, yes to the former to some degree (if you can define intelligence), and no to the latter. Regardless, dim-witted eugenicists will use the study to advance their cause of breeding super-intelligent humans.

The study, led by Dr. Philip Shaw of the National Institutes of Mental Health, found surprisingly that the brains of smarter kids developed more slowly than the brains of children with average to lower intelligence, based on standard IQ tests.

The scientists conducted a series of MRI scans of these children's prefrontal cortex every couple of years as they grew up. The prefrontal cortex is the seat of memory, language and abstract reasoning. For those with lower measured intelligence, the prefrontal cortex grew thicker with neuron-rich gray matter more quickly and reached a peak thickness at age 8. For the smartest kids, the cortex was thinner early on and didn't reach peak thickness until age 11.

Why the "smart" brains developed differently is an open question. This could have something to do with genes. But this could easily be from intellectual stimuli early in life that guided the brain's development.

At best the study shows that people deemed smart by virtue of a test that some argue is culturally and gender biased have brains that develop differently from people who don't do as well on that test. It's a good study, but that's all it really says about intelligence.

For myth-busters like myself, though, the study rules out the notion that smarter people have bigger brains. Brain sizes in the Nature report had nothing to do with IQ test performance.

Yet simple logic renders the "big brain equals big smarts" argument silly. Women have smaller brains than men, on average. And smaller people, particularly dwarfs, often have smaller brains. Unless you are prepared to defend the stance that women and short people are dumber, case closed.

There have been geniuses with tiny brains and idiots with huge ones. The average brain size is about three pounds, or 1,400 grams. The brain of the French writer Anatole France was only 2.24 pounds, well below average. Lord Byron's brain was nearly twice this amount, over four pounds.

Our heads are swelled if we think humans have the biggest brains.

Whales and elephants have bigger ones. We don't even top the list when comparing brain size and body mass. With our 1:44 ratio, yes, we beat out monkeys with a 1:70 ratio. But we don't come close to mice and rats, at around 1:20, and small birds, at 1:15. An obese human likely has the same brain-to-body ratio as a monkey without suffering from a lack of intelligence. But maybe rats really are smart. They can navigate the New York City subway system far better than I can.

Logic also rules out the genetic argument. Australia was once a penal colony. Today it has one of the lowest crime rates in the world. America was created from the forsaken, hapless classes from Europe and beyond. Today America is a technological leader.

Think of all the cultures that once ruled a good chunk of the known world. Mongolia, Babylonia, Egypt, Greece ... What happened to those genes that gave rise to such intellectual superiority?

Shaw and his colleagues from the National Institutes of Health and McGill University sidestepped the question of genetics in their Nature report. That was pretty smart. As for IQ, I did rather well on an Internet-based test while the two eggs I was boiling for lunch exploded after the water evaporated. What an idiot.

Christopher Wanjek is the author of the books “Bad Medicine” and “Food At Work.” Got a question about Bad Medicine? Email Wanjek. If it’s really bad, he just might answer it in a future column. Bad Medicine appears each Tuesday on LIveScience.