I casually read or heard a fact about elephants that I like so much I've never tried to confirm it, because it might not be true - allegedly, by tagging elephants with GPS trackers, researchers determined that elephants will go tens or even hundreds of miles out of their way to avoid even the slightest hill. That's interesting. And apparently true, according to the BBC: http://news.bbc.co.uk/2/hi/science/nature/5222616.stm I used to work for a railway in mountainous territory. You go an awful long ways out of your way to avoid climbing hills if you're heavy. I used to play Railroad Tycoon. Does that count? Your trains go slower when going up a slope, but the game didn't take increased fuel costs into account.