In a scrubby pasture in deep southwest Georgia, reclaimed from growing pesticide-drenched cotton, Allan Savory—ecologist, philosopher, TED speaker—stoops to pluck a blade of grass.

“What can we do to increase productivity, make this pasture more diverse, get more species of grasses to return here?” he asks the 50 people clustered around him in paddock boots and seed-company caps. They look at him raptly, and he gives them the answer they drove hours to hear: “We can use livestock. Livestock is the most powerful tool we have.”

Savory, 80, is the originator of a compelling—and in some quarters deeply controversial—theory that argues that that everything we know about maintaining natural landscapes is wrong. Instead of fearing overgrazing, and taking livestock off land