Explanation of the transition from hunter-gatherer to agrarian societies

This is a pretty concise treatment of the environmental and social problems that are engendered by agriculture.  The article discusses how horticulture is an intermediate stage that may be inherently sustainable as opposed to agriculture's inherent unsustainability.  The one thing I would change about the article, and about anthropology's general classification of societies into these different types, is that the New World has had many societies that don't exactly fit into a neat category.  For instance, the Inca were a massive empire that was clearly agrarian and centralized, but the Incaic culture and its modern-day descendants have an animistic philosophy and a way of farming that seems not to be inherently damaging to the environment.  Call it large-scale agricultural with a horticultural mindset.  On the other hand, the hunter-gatherers that initially populated the Americas managed to wipe out a lot of animal species, despite the supposed trait of hunter-gatherer societies' being more in tune with the natural balance.