If you're like me and believe that the smartest dude on earth is mr. wikipedia then you can simply believe that "in humans, defecation may occur (depending on the individual and the circumstances) from once every two or three days to several times a day."
Since we all know (well...at least wikipedia does...) there are about 6.7 billion people living and therefore shitting on this planet.
Now, if you think about it...
THAT'S A WHOLE LOT OF CRAP!!!
Dude, I mean where the hell is it all going to go??
It's not like it just disappears after you flush.
Just think, maybe in a couple of hundred years aliens will drive by, and on their spaceshi