shift occurs every hundred million years or so.. shift caused by increases/decreases in CO2 levels..
pardon me for the insertion of a wild theory here... but it sounds very much like life on earth keeps on evolving into humans who burn up all the fossil fuels of earlier life and then get killed off by the climate change that occurs as a result... earth stays warm for a while.. then cools off and the process starts all over again
Either way, sounds like a completely natural process to me. The fact that so many people stand to make so much money from it makes me go "meh".
As for your theory, I lol'd. Maybe instead of Humans, it was super evolved walking, talking, Dinosaurs like in that old TV sitcom.