We need to borrow from the many ingenious examples of cultures who have responded wisely to their ecological impacts, The terraces all over the Mediterranean were built to stem the tide of severe erosion from centuries of overgrazing with goats and sheep. The terraces of Turkey, Spain, and Greece are mostly a polyculture perennial food forest like we describe in permaculture as a truly sustainable agriculture. Another brilliant adaptation to limits are the terraces of the Inca and the Aymara in Peru and Bolivia.

These systems enabled food production in landscapes where you could not grow any major food crops before creating their extensive and spectacular engineering feats of terrace systems and roads throughout an extremely rugged and barren environment. One of the most productive horticultural systems in the world was employed by the Aztec around what today is Mexico City.