SEX DIFFERENCES: ABSOLUTE, SEX-SHARED/THRESHOLD-DIMORPHIC, AND ARBITRARY
There are absolute sex differences, but they pertain to reproduction. Females menstruate, gestate, and lactate. Males impregnate. Other behavior which is hormonally primed prenatally is shared by both sexes. The difference lies in the threshold for its elicitation. This is sex-shared/threshold-dimorphic behavior. There is also sex-different behavior of a purely arbitrary type. Some of the arbitrary differences may be traced historically to an association with the absolute sex differences. For example, it is not too difficult to recognize that breast feeding of infants historically came to include the preparation of food for all members of the family, except on special or ceremonial occasions when the men might prepare a feast. Today, many sex differences, such as those pertaining to work, play, and cosmetics, are purely arbitrary and are a product of cultural and historical caprice. Sex difference in legal status is equally arbitrary. These arbitrary differences are built into the individual, developmentally, according to the principles of identification and complementation.
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