By 2050, the U.N. predicts, our planet will be inhabited by 2 billion more humans. If income and body mass continue their current upward trends, those billions will be richer and fatter than we are. That means they’ll want meat, not grain. They’ll also want seconds. But will 2050’s concentrated agricultural feeding operations—much less its free-range heritage pig farms—be able to produce enough livestock to meet the demand? A growing number of optimistic soothsayers say yes, reports Greg Beato. But only if we expand our definition of livestock to include such underutilized food sources as mealworms, grasshoppers, and Sago grubs.