Large quantities of hair is often the result of a high level of
testosterone, a
hormone associated with
male qualities. One of these qualities is the
sex drive. An individual who has a large
sex drive but is unable to excercise it could indeed resort to
masturbation. Therefore, the quality of hair palms could possibly
cause the
masturbation rather than vice versa.
One caveat: I have never seen a hairy palm in my life. Not even an ape and i've seen them whacking off at the zoo.