August 13, 2008

Brains: Bigger Is Better, Sort Of

Scientific American has an article, "High Aptitude Minds," by Christian Hoppe and Jelena Stojanovic on the relationship between brain size and IQ:

Most studies show that smarter brains are typically bigger—at least in certain locations. Part of Einstein’s parietal lobe (at the top of the head, behind the ears) was 15 percent wider than the same region was in 35 men of normal cognitive ability, according to a 1999 study by researchers at McMaster University in Ontario. This area is thought to be critical for visual and mathematical thinking. It is also within the constellation of brain regions fingered as important for superior cognition. These neural territories include parts of the parietal and frontal lobes as well as a structure called the anterior cingulate.

But the functional consequences of such enlargement are controversial. In 1883 English anthropologist and polymath Sir Francis Galton dubbed intelligence an inherited feature of an efficiently functioning central nervous system. Since then, neuroscientists have garnered support for this efficiency hypothesis using modern neuroimaging techniques. They found that the brains of brighter people use less energy to solve certain prob­lems than those of people with lower aptitudes do.

In other cases, scientists have observed higher neuronal power consumption in individuals with superior mental capacities. Musical prodigies may also sport an unusually energetic brain [see box on page 67]. That flurry of activity may occur when a task is unusually challenging, some researchers speculate, whereas a gifted mind might be more efficient only when it is pondering a relatively painless puzzle.

Despite the quest to unravel the roots of high IQ, researchers say that people often overestimate the significance of intellectual ability [see “Coaching the Gifted Child,” by Christian Fischer]. Studies show that practice and perseverance contribute more to accomplishment than being smart does.

Size Matters
In humans, brain size correlates, albeit somewhat weakly, with intelligence, at least when researchers control for a person’s sex (male brains are bigger) and age (older brains are smaller). Many modern studies have linked a larger brain, as measured by magnetic resonance imaging, to higher intellect, with total brain volume accounting for about 16 percent of the variance in IQ. But, as Einstein’s brain illustrates, the size of some brain areas may matter for intelligence much more than that of others does.

So, I guess Stephen Jay Gould didn't know what he was talking about. Imagine that!

The article makes a point that I've long noticed with myself. Thinking hard makes my head hot. When I give up thinking about something as too hard, it's usually because of an unpleasant warm sensation in my head.

Starting in the late 1980s, Haier and his colleagues have gathered data that buttress this so-called efficiency hypothesis. The researchers used positron-emission tomography, which measures glucose metabolism of cells, to scan the brains of eight young men while they performed a nonverbal abstract reasoning task for half an hour. They found that the better an individual’s performance on the task, the lower the metabolic rate in widespread areas of the brain, supporting the notion that efficient neural processing may underlie brilliance. And in the 1990s the same group observed the flip side of this phenomenon: higher glucose metabolism in the brains of a small group of subjects who had below-average IQs, suggesting that slower minds operate less economically.

In 2004 I bought a laptop with the new CPU chip that goes to sleep when it's not being used. I chose it specifically to generate less heat because when I was working hard thinking about something, I didn't want my computer working hard too, because the combination of both my brain and my computer's brain going full steam was causing my small office to overheat.

The CPU designers at Intel and AMD are always trying to figure out ways to have their chips think more efficiently in order to avoid generating so much heat. Several years ago, Intel gave up its efforts to crank clock speed up past 4 gigahertz because chips were melting.

A bigger brain would have a harder time shedding heat, simply because there is more brain to generate heat and there's more distance from the center of the brain to the outside. So, that's one reason (among many) why humans don't look like super-intelligent alien invaders from sci-fi movies.

My published articles are archived at -- Steve Sailer


Anonymous said...

Does this mean people in colder climes can have bigger brains? Or those from warmer climes have better cooling systems for their brains?

Oh, and those huge-headed aliens. They are not aliens. They are from the future. How else would you explain their anthropomorphic body structure? Not from other planets, but from our evolutionary future.

Anonymous said...

Googling results in the info that Inuits have same brain size as East Asians (slightly bigger than Euros), but Inuits only have an IQ of 91. Without wanting to sound disparaging, there is perhaps less intellectual and cultural in Thule than in Beijing, which might explain the difference.

Brett said...

On the bright side, evolution is a hill climbing algorithm, and as such we may reasonable hope that we're stuck on a local maximum, and will suitable application of intelligent engineering, find our way to higher ground.

Gatt said...

> A bigger brain would have a harder
> time shedding heat, simply because
> there is more brain to generate heat
> and there's more distance from the
> center of the brain to the outside.

You lizard-people have it rough.

AG said...

Well, rich blood circulation is more important for heat control which is like radiator of car. So size-heat issue is more important for insect.

Anonymous said...

In one of my kids' elementary drawing books, among techniques to make faces look young, fat, etc... it is explained that to make a person look smarter, draw the facial features further down the face, thus giving them a high brow - by shifting the same features higher up the face you can make them look "tough or dumb".

I like the bit in the original post about Einstein. Everyone knows he was the quintessential genius!

Anonymous said...

I know that there's a modest positive correlation between height and IQ: does brain size also correlate with height? Enough to explain the height/IQ correlation?

Anonymous said...

"So, I guess Stephen Jay Gould didn't know what he was talking about. Imagine that!"

I think I utter that phrase verbatim every time I read anything written on the subject of biological anthropology, written in the last twenty years.

Oh hey, did you hear? Psychometrics doesn't work because a guy who measures bones for a living once noted that psychometrics was preceded by people measuring skulls.

Vache Folle said...

You think your head gets hot when you think too hard? Didn't the article suggest that smarter brains were more efficient than the brains of dolts, in which case a hot head would be nothing to brag about.

Anonymous said...

I've seen an interview with Christopher Langan, who has been described in Esquire and on 20/20 as having the highest IQ in America - somewhere around 195. Make of that what you will, but there's no denying this guy has an enormous frickin' noggin. I wonder if there's a stronger correlation once you get past, say, four standard deviations in IQ.

Steve Sailer said...

"in which case a hot head would be nothing to brag about."

That was my point. When I get stumped by something I'm not smart enough to figure out, I can feel my brain overheating.

Truth said...

The smartest guy in America is a bouncer, great, he spent his Friday nights alternatively working on string theory and asking other guys, "hey, what the fuck are youze lookin' at?"

Anonymous said...

Hey Steve, somewhat off-topic but as you may know Charles Murray has been reading your blog. He wrote this great article:

Anonymous said...

Scott (off thread)
Murray had me until he cited the CPA exam as a model certification exam. As a practicing accountant, who has passed the CPA exam, I can tell you that there are thousands of perfectly competent practicing accountants who have never taken the CPA exam and never will. Although the AICPA has modified the exam, there is still quite a bit of rote memorization that must be done to achieve a passing score. A person's score on the test is much less a reflection of their ability to handle "fuzzy" problems (i.e. their analytical ability) than either their score on the SAT or GRE. Trust me - I know several high IQ individuals, who hate the idea of memorizing rote facts, who have struggled to pass the exam.

Anonymous said...

Another reason humans don't have to look like super-intelligent aliens from outer space to possess superhuman intelligence is that we've found a way to increase our thinking power ("brain power") with the use of thinking-machines, ie, computers.

Anonymous said...

Baas...Dont think so much. It make you go KA-BOOM!

Anonymous said...

michael t: "we've found a way to increase our thinking power (brain power) with the use of thinking-machines"
no we haven't. calculators have taken our calculating skills. the internet has taken our memory and our attention spans. tvs have made us stupid. spell checkers have wrecked our spelling. domesticated chickens have smaller brains than wild ones. we are self-domesticated.