Clyborg,
Oh, I totally understand. And I think that would be great too! I just threw in my own idea before, sort of expounding on yours, but taking a term mentioned, and running in another direction with it... or more to the point, reducing the term "evolution" to it's very basic meaning.
Of course, I thought about my own idea after the fact, and realized it would probably be rather boring playing through, without some sort of "fun" factor. How do you get fun out of Neanderthal (or whatever rung from the evolutionary ladder)? Unless maybe you take it in some comic direction, like Fred Flintstone/Barney Rubble or something. But that's old. lol!
... maybe Fred Flintstone evolving to George Jetson. lol. Ok, ok, the subject line in this topic says "Game Idea"... it didn't say it had to be a great one!
But yours definitely is!