Cultural Invention is any innovation developed by people that is not of a physical construct. Cultural inventions include sets of behaviour adopted by groups of people. They are perpetuated by being passed on to others within the group or outside it. They are also passed on to future groups and generations. Sources of cultural invention can either come from outside a specific group or from within that group. Allan Hanson, a postmodern anthropologist, believed that the analytical purpose of studying cultural inventions was not to uncover which portions of a culture's belief systems are invented, but rather to study how cultural inventions become accepted as authentic within groups. This notion has been met with criticism from within the anthropological community as well as from outside sour