Evolution is a wonderful thing. So wonderful, in fact, that Ludum Dare #24 is about it. Now, as for evolution itself, you must understand it visually. And to do that, use the most important way of viewing: the video game. Precisely, the video game: Micro2Mega.
In Micro2Mega, you have been de-evolved from a human all the way to a single-cell micro-organism. You must play through the levels to evolve back into a human. In each level, you will collect the DNA (but watch out for the evil DNA!). Once you have enough DNA, the game will tell you to enter The Evolver. The Evolver is a sort of time portal, which will teleport you to the next stage of the life. Play through, and don’t lose too many strands of your precious DNA!