Theory

I have a theory.

Millions of years ago, there may have been another, intelligent civilization. One made-up of non-humanoids. When they were dying out, they took the dinosaurs with them. That could potentially explain a lot. Anyway, now our civilization may die out because of global warming, nuclear war, or worse, and we may wipe out, say, the elephant. Then, millions of years in the future, the next type of intelligent life to spring into the forefront will wonder, "What wiped out the Elephants?"

Wouldn't it be cool to survive to see what animal will become (the next?) a form of intelligent life?