-mitch
http://www.thehub.com.au/~mitch
Brain Not Evolving Any Time Soon
NEW YORK (Reuters) -- If you've ever struggled through a physics class
or tried to master differential equations, you may be disappointed to
find out that humans won't be getting any smarter any time soon.
The brain has reached -- or is very close to -- its maximum potential
in terms of the evolution of intelligence, according to a report in
New Scientist.
"There is no incremental improvement path available to the brain,
which makes evolution difficult," stated researcher Chris Winter in
the article.
Peter Cochrane, Winter and colleagues at the Advanced Applications and
Technologies section of BT Laboratories in Ipswich, England, looked at
various brain models to determine how the organ could evolve to
process more information, or to do so more rapidly. They found that
the brain could get bigger if the heart evolved to pump more blood to
supply the additional tissue with oxygen and nutrients.
However, this rapidly turns into a 'chicken and egg' situation -- the
axons of nerves in a bigger brain would need to be wider to process
information more rapidly. Therefore, each nerve axon would need more
insulation and a greater blood supply -- leaving less room for a
greater overall number of nerves. So the bigger the nerves, the
greater the blood supply they need, the more blood vessels they
require, the less room there is for bigger nerves....
While brain size is considered a relatively poor indicator of
intelligence, the number of nerves and their connections is important.
Dolphins and whales are the only animals that even come close to the
number of nerves and nerve connections found in the human brain.
And if the brain was larger, nerve signals would also have farther to
travel from one area of the brain to another, possibly limiting its
efficiency as well as any advances in processing power, according to
the article.
Because of the delicate balance between the size and number of nerves
and the blood needed to nourish them, the brain is now at its maximum
capacity -- or at least within 20% of capacity -- in terms of
intelligence, the researchers concluded.
However, new structures may evolve in the brain or existing structures
may specialize in ways that increase intelligence, noted Dr. Robert
Barton, a lecturer in biological anthropology at the University of
Durham in the U.K.
"They assume that processing information involves the whole brain, and
that is not necessarily the case," he said in the article. SOURCE: New
Scientist (January 25, 1997)