The Adam Effect is defined as the moment at which something takes on enough meaning to affect an entire culture.
IE -- Someone eventaully came upon poison ivy. They probably did not realize at first that the plant gave them the irritating rash. So shamans, priests, etc... deemed these persons as unclean. It wasn't until the connection was made between encountering the plant giving the person the rash. This is an "Adam Effect". Eventually the "news" of this connection was shared, but among what people? What level of economoic status was this information shared? Did only Indians know about poison ivy and its effects? Who were the first of the "elite" to be aware of the toxic property of this plant. White man named the plant, did native Americans name the plant before the "white-man"? If so, how was it that it was figured out that poison ivy can give a person a bad rash?
Well the point is that there was a moment in TIME that a connection was made between the toxic properites of the plant and the irritating rash that occurred after encountering the plant. That connection and the sharing of that conneciton is consider to be the "Adam Effect".