100 year LIFE cycle ?
The rise of first the Radical (Liberal) parties, then the Socialist parties and finally the Green parties in 100 year increments may just be a coincidence ---- or it might tie into a theory that historians of science have long had.
Historians of science have long noted the very long time period powerful personalities in science can have to be dominant in their field.
They make their major discovery in their twenties which quickly leads to powerful positions on department hiring committees, on scientific society boards, as editors of big science journals, as advisors to government and industry.
Nominally they retire at 65, but actually remain professors emeritus, still writing journal articles and books. Their lifestyle and income often ensures they remain healthy and productive into their late nineties.
Their power only wanes years after their deaths, as textbooks gradually get updated to include newer ideas.
So it is truly said " older science opinions don't get changed by new evidence, only by the deaths of their original proponents."
Ideologies like Science Theories ?
This idea from the world of science neatly ties in with the rise, apogee and fall of political ideologies : each gets one long, long, human lifetime to flourish.
I believe that the revolution of 1989 did see the fall of one (outdated) global divide (Left vs Right) and the rise of a new global divide I call - metaphorically - Skygods vs Earthlings.
It might be gone by 2089, I certainly will be - and so might our current human civilization unless we all wake up and start healing this Earth, not killing it ....