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(1)
Considerable attention has been paid to the size or relative size
of the human brain. The first point of interest is that the ratio
of brain weight to body is at a maximum at birth and decreases
with age, reaching a fairly steady level by maturity. In other
5 words, newborn babies have very large brains, relatively speaking,
weighing some 300 grams. This is roughly the size of the brain
of an adult male chimpanzee. Children and their brains continue
to grow for many years, gradually increasing their ability to learn
and remember. There have been suggestions that the growth of
10 the brains of children is not steady, but occurs suddenly, each
period of rapid growth (2) associated with a particularly
important developmental or intellectual stage. These stages could
be the ability to reason abstractly, to talk, or even to do
arithmetic. The idea of sudden brain growth is still around, but
15 has not attracted much enthusiasm.
Some research has shown differences in the relative sizes of
the brains of males and females of the same age, but so far no
great differences have been found between people of the same
age but of different ethnic groups. Obviously the brain of a
small Japanese teenager is very much smaller than that of a
giant Russian boy. But when brain size is adjusted for size or
weight of the body, there ( 3 ) great advantage for either
with respect to intelligence. Moreover, in measuring intelligence
one has, of course, to take into account the effects of education
and cultural background.
Individual brain sizes, particularly of famous people, have also
