The simpliest way it help is this. When this country was settled one of the first thing that occured was the preditors were removed. This caused the balance of nature to get out of whack. Hunting allows for the preditors to re-enter the system. Now the preditors are human but we are still doing the same job. With it being a sport it also allows for a control system that prevents over harvest. If anything there is an under harvest in many areas, but even with that we have it back in balance to the point that wildlife is not destroying its own habit though over population (over grazing/browsing). Now of course we might destroy the habitat to build another damned shopping mall but that is another story entirely.

-john