They have been a part of us ever since we have been. The current incarnation in the US is based on religious fundamentalism/evangelicism but religion is merely the vehicle through which they rampage through society. They sometimes serve society in the form of a posse, but can also turn, to the detriment of society, into a lynch mob.
Russian pogroms, Nazis and Facsists, the Chinese cultural revolution, the Moral Majority all have common roots in our collective psyches. In trying to understand this phenomenon we tend to focus on the Hitlers, the Stalins, the Idi Amins, the Dick Cheneys, the James Dobsons. While these people are part of the problem for every one of them there is a class of people ready to saddle up and bash heads for the cause.
Who are these people?
I used to think it couldn't happen here, now I think it can happen anywhere.
While there are some people out there who seem to believe that you can disprove the theory of evolution by not evolving mentally, there are also people out there studying this type of right wing fundamentalist behavior. This is much more than just a disagreement on issues, it is a disagreement on how people see the world. It's not my religion versus your religion, or my policies versus your policies. It is Critical Thinking versus Unyielding Belief.
A friend of mine recently turned me on to Bob Altemeyer, a professor at the University of Manitoba and his work regarding Right Wing Authoritarianism.
Professor Altemeyer (notice how I am appealing to the Authoritarian inside of you by calling him 'Professor') is publishing his new book, The Authoritarians on the web one chapter a week (he is up to chapter7 now). Take a look, you won't be disappointed.