And I have proof!  One of the pieces of evidence that UFO enthusiasts use to prove that aliens have visited Earth is the fact that so many people who have claimed to be abducted all describe aliens that look similar.  Small and very bony, with a big head, and large eyes... the classic "gray alien".  But if you think about it... that description doesn't make any sense.

Look at our own civilization.  As man has become more advanced, and has needed to perform less and less manual labor, our weight has increased.  In fact, according to many, we're facing an obesity epidemic.  So how is it that a civilization even more advanced, which one would suspect doesn't need to perform any manual labor, could remain so slender?  If the aliens were all insanely obese, then I might believe you.  But anorexic aliens?

I don't think so.