Does Size Matter?
Researchers have linked sudden and disproportionate brain growth during the first year of life to autism, suggesting that excessively rapid growth prevents the child from making the connections that guide normal behavior [source: BBC].
Another study indicated that children and adolescents with attention
deficit hyperactivity disorder (ADHD) possess brains that are 3 to 4
percent smaller on average than those without ADHD [source: Goode]. Scientists have also revealed that brains shrink with age, though cognitive functions may remain unaltered [source: Britt].
But
the question everyone wants to know is, what link exists between a big
brain and a big IQ? Is bigger better? Since we're talking about the
brain, then surely an enhanced version must lead to more smarts and more
talent, right?
Well, it depends which scientist you ask.
Scientists have been divided about what they're measuring and how
they're measuring it. Anthropologists have long used a skull's interior
volume and compared it against body size for a rough estimate of
intelligence, measurements known as encephalization quotients.
As brain-imaging techniques have improved, though, scientists have
measured actual brains with greater precision. But is it size or is it
neurons that we need to measure? Is it weight or circumference? Should
encephalization quotients use total body weight or lean body mass?
Should we correct for body size at all? How do you measure intelligence?
With
so many brains tackling these questions, it's hard to reach a consensus
on what might be the most meaningful measure. That hasn't stopped
researchers from drawing conclusions, though. In 2005, psychologist
Michael McDaniel evaluated studies that used brain-imaging and standard
intelligence tests and found that unequivocally, bigger brains
correlated with smarter people [source: McDaniel].
Since
males have the bigger brains, they must have the smarts, right? In one
study, scientists converted the SAT scores of 100,000 17- and
18-year-olds to a corresponding IQ score and found that males averaged
3.63 IQ points higher than the females [source: Jackson, Rushton].
The study, did, however, use about 10,000 more females than males,
which may have affected the average, but the study's authors believe
that the greater the brain tissue, the greater the ability for cognitive
processing [source: Bryner].
Remember
those studies with twins on the last page? In one study, after the
scientists drew conclusions about the role of genetics in brain matter,
they gave the twins intelligence tests. They found a link between
intelligence and the amount of gray matter in the frontal lobes. Since
frontal lobes appeared to be controlled by genetics, the results
indicate that parents pass along the potential for genius.
But should gals just throw up their arms, curse their parents and refuse to make sense of nuclear physics?
Nope. You've got to go out and shake what your momma gave you. These
areas may just lay the groundwork for intelligence down the line or
indicate the potential for genius if a person works hard. Albert
Einstein may be a perfect example that it may not be overall size that
matters, but size of certain sections beyond just the frontal lobe. Einstein,
for example, had a perfectly normal-size brain, but certain parts of it
were larger than normal, including the inferior parietal region, which
affects mathematical thought [source: Wanjek].
It's
also worth noting that the strangest things seem to increase brain
size. Scientists have found that the brains of London's cab drivers
enlarge and change as they learn complicated routes. Cab drivers who
have been navigating the streets for years had significant structural
changes, as they exhibited a larger posterior hippocampus and a slightly
smaller front hippocampus [source: BBC].
So
until we know more about all the exact mechanisms of brain growth, you
may as well check out the stories on the next page. They just may make
you brainier.
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