CapelDodger
Penultimate Amazing
This is just one example of a way in which stewardship, planning, and movement of information avoids what is called the "tragedy of the Commons" in which no one has incentive to protect a common resource--so they don't. It was true of grazing sheep on common land in England two centuries ago, and it remains true today. The same is true of the human component of global warming, and of recycling, petroleum use, etc.
In medieval Britain common land was carefully managed by local communities, who were instinctively stewards and understood what was sustainable. People don't normally soil their own homes; real damage is usually done at a distance or by transient populatons.
(There's an excellent book, The Voices of Morebath, which provides a wonderful flavour of how this operated http://www.amazon.co.uk/Voices-More...=sr_1_1?ie=UTF8&s=books&qid=1223847936&sr=1-1)