Ideology as the usable consensus of extreme personality types – see my “Let’s Kill Hitler” book idea. Basically the ideology evolves not as the continuation of first principles, but as a series of compromises on the part of part of the extreme personalities involved – basically the ideology is whatever allows a certain collection of extreme personalities to work together. Cooperation is the important thing – not the consequences. An extreme ideology will be composed of extreme members and so forth. See the the alt-right and modern wokeness. This seems graphable.
Historical changes and atmospheric pollutants – this idea needs more research, but ideological and religious extremism tracks quite nicely with leaded gas and high tobacco usage. A doubtful relationship – but seemingly possible.