I have been particularly fascinated, for example, by the work of a remarkable man called Allan Savory, in Zimbabwe and other semi arid areas, who has argued for years against the prevailing expert view that is the simple numbers of cattle that drive overgrazing and cause fertile land to become desert. On the contrary, as he has since shown so graphically, the land needs the presence of feeding animals and their droppings for the cycle to be complete, so that soils and grassland areas stay productive. Such that, if you take grazers off the land and lock them away in vast feedlots, the land dies.