Toilets are an interesting invention. It seems like we have an instinct to want to shit in the same place every time. Toilets are one of those old inventions that I can't imagine ever uninventing. The people who are around 500 years from now will still want to shit in the same place every day. I suppose when we were nomadic then we'd designate a corner of the cave for all of us to go shit in. Maybe the instinct has lasted so long because it's so closely related to disease. For example, our instinctual hatred for the smell of shit is highly functional at disease prevention. Perhaps the desire to shit in a designated corner, away from our usual activities, has a similar functional basis. (I don't know enough about evolution to know whether I'm, well, talking out of my ass.)
