IN THE LATE 1960s, a Pennsylvania man named Alan Litman fretted that his wife wouldn’t be safe coming home late on the mean streets of Pittsburgh. So he did what any doting husband would do—he figured out a way to fill a portable, easily deployed spray can with tear gas. Then he started marketing the product to law enforcement. Today his invention is known as Mace, a brand now synonymous with private citizens packing a ton of heat. The company’s triple-action variety is a one-two punch of painful riot-control agents—pepper spray and tear gas, which have been used for decades to subdue and incapacitate people without killing them—plus UV dye to make targets readily identifiable post-melee.
Your gut is something of an immunological mystery.
Unlike the rest of the body, which tends to treat foreign invaders with a singular purpose—seek and destroy—the stomach cannot afford to be so indiscriminate. It exists to help fuel the body, and that means routinely welcoming foreign bodies in the form food.