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
20 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