Do you really need citation for something that is so blatantly obvious?
It continues to amaze me that you think you're a skeptic. A skeptic isn't something who refuses to believe stuff. It's someone who will deeply investigate things rather than taking anyone's word for it before forming an opinion. Therefore, a skeptic would never say anything is obvious or doesn't need evidence.
Everything needs evidence, and nothing is ever really obvious. Even 2+2=4 needed formal proof.
What's more, generally speaking, the more complex the science, the more likely that things that seem "obvious" are completely wrong.