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Facts
for thought
It is the
human brain that has got our species where it is today.  Together
with a clever hand and the ability to speak, both of which need a good
brain, it was the dramatic evolution of humanity's cerebral hemispheres
that permitted this single species to become the most accommodating, wide-ranging,
intelligent, vociferous, creative and potentially destructive species
the world has ever known.
Three million
years ago the biggest brain among our ancestors measured 450 cubic centimeters
(equivalent to that of modern chimpanzees and gorillas). Average modern brains
are closer to 1,400 cc for males and 1,250 cc for females.
But brain
function is not dictated solely by size. Some intelligent humans have
brains twice the weight of other intelligent humans. The human brain is
still a fairly diminutive part of the body, despite its massive size increase
over the course of evolution. Size (and weight) of brain tissue is less
important than the degree of convolution. Such folding, causing ridges
and grooves, leads to a greater surface area, and this is highly relevant
to the brain's ability. So too is neural organization, the interconnections
between the millions of nerve cells within the 1.4 kilograms of human
brain. These cannot be mapped in a living brain, and there is no way —
yet — of discovering even in a dead brain where its former owner would
have rated on the IQ scale.
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