What's the evolutionary advantage of

sleep?
I can understand big predators requiring sleep to conserve energy.
But why do humans need sleep? A group of humans who needed no or much less sleep could have easily outcompeted us.

>>13
That's stupid, if your species don't already have external testicles, it's hardly going to woo the ladies when your mutant self suddenly pops them out.
And if you were stuck in that situation, it'd be an evolutionary triviality to pop them back in while replacing them with useless, brightly-colored flesh bags.