Brain size and intelligence
Quote:
> Doesn't this presuppose that there is still some benefit to having a
larger
> brain? I personally am not aware that differences in brain size in
humans
> have any effects on intelligence ...
The published studies on IQ vs. human brain size have been reviewed
recently by Rushton and Ankney (Psychometric Bulletin and Review,
3, p21-36; 1996).
Using Magnetic Resonance Imaging (MRI) scans
to measure brain size in 8 new separate studies with a total of 381
{*filter*}s a correlation of r = 0.44 was found with IQ. MRI seems the
best way to accurately measure brain size, but even the least accurate
way (by external measurement of head size) shows a trend (studies
done this way of 45,056 humans yielded a correlation with IQ of r = 0.21).
Jensen has published studies showing head size/IQ correlation
occurs both within and among families (Intelligence, 18, p309-33; 1994).
The correlation would undoubtedly be higher if
the size of the specific parts of the brain most
involved with intelligence could be accurately
measured and if IQ tests could better measure
intelligence, but non-size related complexity,
such as of the cerebral cortex, probably
also plays a role in intelligence.
Dr. Efram E. Goldstein
