For me nothing is more interesting than evolution by natural selection.

Why Evolution is True by Jerry Coyne.

"The evolution of whales from land animals was remarkably fast: most of the action took place within only 10 million years. That's not much longer than the time it took us to diverge from our common ancestors with chimpanzees, a transition that involved far less modification of the body. Still, adapting to life at sea did not require the evolution of any brand-new features--only modifications of old ones."