Bladder cancer in humans has been associated with cigarette smoking. Since dogs can also develop this deadly cancer, they can serve as model for evaluating treatment methods. In a study at the Massachusetts Institute of Technology, beagles were exposed to a carcinogenic chemical from cigarette smoke. It turned out that those dogs urinating every four hours had only one third as much carcinogen left in their bladder as the animals voiding every eight hours. Indeed some surveys on humans have also shown that in rural areas bladder cancer is less frequent than in urban areas. The suggestion has been that men relieve themselves more regularly when they do not have to search for a bathroom. So where’s the nearest tree?