It's about time. Take a gander at what the world looks like right now. Every year, farmers raise and slaughter some 77 billion animals for food. That's 10 animals per person. With a billion or two more of us on the planet by 2050, and with rising incomes allowing a greater appetite for meat, that number could expand. Perhaps even to 200 billion, if China and other populous nations start eating as much meat as Americans do. And on our small, fragile planet — with 70% of its surface covered by water and lots of the remaining landmass covered by rock and ice — we just cannot go there and expect to preserve our water, soil, forests and grains.