Today, most people hearing the word "rust" start running for a tetanus shot. But for most of human history, the real menace was stem rust. The agricultural blight has been causing famines for thousands of years, turning promising green leaves into inedible silvered chuff. That's why the Romans had a special day dedicated to appeasing the rust god, Robigus. Each year, in April, the Robigalia festival directors would sacrifice tawny-colored animals (i.e. ruddy-furred pups and not-so-sly foxes), cutting their entrails out of their bodies, while also dancing and singing. Today, agricultural scientists are just as worried about rust, but instead of a bloody bacchanal, they're, you know, genetically-modifying crops.