In this Ted talk about reversing desertification by Allan Savory he speaks about how modern societies have created a process where the land is turning into desert. This process mostly comes about by the removal of herds of wild animals from grazing land. In his well-thought-out hypothesis he proposes we substitute herds of domestic cattle to bring back the nutrients that are needed for greenery to grow, thereby protecting the minerals in the soil from erosion. Another reason to eat grass-fed beef!