Color blindness affects a significant number of people, although
exact proportions vary among groups. In Australia, for example, it
occurs in about 8 percent of males and only about 0.4 percent of
females.[17]
Isolated communities with a restricted gene pool sometimes produce
high proportions of color blindness, including the less usual
types. Examples include rural Finland, Hungary, and some of the Scottish islands. In the United
States, about 7 percent of the male population – or about 10.5
million men – and 0.4 percent of the female population either
cannot distinguish red from green, or see red and green differently
(Howard Hughes Medical Institute, 2006). It has been found that
more than 95 percent of all variations in human color vision
involve the red and green receptors in male eyes. It is very rare
for males or females to be "blind" to the blue end of the
spectrum.
