In 1994, a pneumonic plague outbreak hit the Indian city of Surat. Over 6,300 suspected cases in a city of 4.4 million people. More than 50 deaths. A million residents fled. The economic hit: $1.8 billion. Tetracycline stopped it. UNICEF sent more than 11 million tetracycline capsules to India. The government stockpiled another 5 tons. The outbreak was contained. But here’s the strange part: humans had been consuming tetracycline for over a thousand years before anyone knew it existed. They were getting it from bread and beer brewed by ancient Nubians, who had no idea they were dosing themselves with antibiotics. How tetracycline ended up in 1,600-year-old bones In 1962,…