Regardless, current estimates that I've seen point to the population of the Earth stabilizing at around 10 billion. People always say that we can't move from industrial to more sustainable types of farming because our current population levels couldn't be sustained. Where is that cut-off point? 1 billion? Less? I think that point is what all "enlightened" nations should be aiming for in terms of policy — the point where we could all survive comfortably without having to depend on oil-based products just to feed us. (Otherwise, it'll eventually have to happen naturally, and it won't be pretty.)