After 85 years, antibiotics are growing impotent. So what will medicine, agriculture and everyday life look like if we lose these drugs entirely? A few years ago, I started looking online to fill in chapters of my family history that no one had ever spoken of. I registered on Ancestry.com, plugged in the little I knew, and soon was found by a cousin whom I had not known existed, the granddaughter of my grandfather’s older sister. We started exchanging documents. After a few months, she sent me something disturbing. It was a black-and-white scan of an article clipped from the...