ABSTRACT
Human beings usually live a long time. During their lifetime, certain attributes will follow them from birth to death. For almost everyone, gender is one of these persistent characteristics. Most of us who are born a male will die a male. Other traits may come and go. An obvious example is the developmental categories that we all put on and take off as we pass through life. Our days of infancy, childhood and adolescence are now long past, and some of us may even find ourselves walking about the earth as so-called senior citizens.
