I thought it would be obvious that I'm referring to the fact that prior to overpopulation of people, there developed a sustainable balance between wolves, elk,

I thought it would be obvious that I'm referring to the fact that prior to overpopulation of people, there developed a sustainable balance between wolves, elk, etc. We eliminated the wolves, and that is what led to the overpopulation of deer etc. So, the point is that we either fill the role of the wolves we eliminated or we bring back the wolves. The overpopulation of deer doesn't work.