Well this is interesting

Maybe Friedrich Engels's Conditions of the Working-Class in England in 1844 would have had a different outlook on urban life if only everyone composted their poop instead of throwing it out the window. But then who would have been Karl's partner in crime? And gosh what the heck would have all those swine eaten?

http://www.treehugger.com/files/2010/09/recycling-poop-sustainable-farming.php