Brainpower: It's The Development Stupid!

by Edward Hugh

Organ size seems to be a keynote topic with many people, and the brain is, of course, no exception. It has long been thought by some that bigger brains mean more cubic capacity and hence more intelligence. Would that things were ever so easy! Well today comes news of a piece of brain research which seems nicely nuanced, when it comes to brain size what matters most is not what you have but how you got it:

When it comes to brains, big is the way to go. Many studies have found a correlation--albeit only a modest one--between the size of a person's brain and various measures of mental ability. Now, a study adds a new wrinkle, suggesting that how the brain develops may be even more important to one's intellect than the organ's final dimensions.

The top scoring children had a delayed but extended cortical growth spurt, the researchers report in the 30 March Nature. In these children, who scored above 120 on the IQ tests, the cortex started out relatively thin. Then it grew rapidly, peaking in thickness around age 11 before falling off. In children with average IQ scores (around 100) cortical thickness peaked between 7 and 8 years of age.

Now anyone who knows even a smattering of Life History Theory is going to be fascinated by this. John Gabrieli, a cognitive neuroscientist at MIT is quoted as saying: "The exciting thing they suggest is that prolonged maturation is a good thing for intellectual development".

And of course:

"Whether that extended process in the highest-scoring kids is determined by genetics or is susceptible to environmental influences--parenting or teaching styles, for example--is an open question, says Richard Passingham, a cognitive neuroscientist at Oxford University, U.K."

Or indeed whether the two - the expression of the genetic and the environmental - are not in some way interconnected, indeed aren't we offering a far too limited definition of 'environment' if we restrict it here to things like "parenting or teaching styles". At this point I could go on to write an essay length post, so I think I'd better stop.

You can find the original reports on the research in this issue of Nature.