December 05, 2008

Brain volume and IQ in children

Intelligence doi:10.1016/j.intell.2008.10.005

A genetic analysis of brain volumes and IQ in children

Marieke van Leeuwen et al.


In a population-based sample of 112 nine-year old twin pairs, we investigated the association among total brain volume, gray matter and white matter volume, intelligence as assessed by the Raven IQ test, verbal comprehension, perceptual organization and perceptual speed as assessed by the Wechsler Intelligence Scale for Children-III. Phenotypic correlations between the brain volumes and intelligence traits ranged between .20 and .33. Processing speed and brain volume did not correlate. The relation between brain volume and intelligence was entirely explained by a common set of genes influencing both sets of phenotypes.



terryt said...

So Neanderthals, with brain volume larger than the average modern human, were more intelligent than us?

Kosmo said...


Their big brains, big bones, and heavy muscles were also much more expensive.

I think the economy version of man won out. :)

Anonymous said...

NO because their neo cortex was not as dense, not as complex; they had more of the regions of brain that we call 'old cortex', ie limbic etc. The inside of their skulls shows far fewer folds in the cortex. So they had bigger regions of the brain that were more primitve as well. Its more about how bug the frontal cortical regions are than brain volume per se. A huge cerebellum and amygdala wont make you smart.

Anonymous said...

how big the frontal cortex is, not how 'bug' lol

Grognard said...

Neanderthals had smaller limbic areas in proportion to their neocortex. Neocortex is the last part of the brain to develop and the most complex, and is now shown to be where general intelligence takes place.

Biggest difference between humans and chimps is the difference in neocortex, and this is where neanderthals overtake average humans today.

Modern human brains "reorganize" to be smaller and more blobular than neanderthals though they start the same size and shape at birth. Since the prefrontal area is bigger on neanderthals and prefrontal size and conscientiousness have been linked in many studies, I would want to see real proof before I believed this was an advance and not something lost.