Few scientific ideas have taken a more unexpected path to legitimacy than this one: breathing through the butt. The technique, known as enteral ventilation, could one day serve as a backup method for getting oxygen into the bloodstream when lungs fail or airways are blocked. Instead of inhaling air, patients would receive an oxygen-rich liquid through the rectum, allowing oxygen to diffuse through intestinal tissue much like certain fish and turtles that supplement breathing through their guts.⁠ ⁠ In Japan, researchers have now completed the first human safety trial of this approach. Twenty-seven healthy men were asked to hold varying volumes of perfluorodecalin, a liquid capable of dissolving extraordinary amounts of oxygen, for one hour. The experiment ranged from 25 milliliters to a full 1,500, and while several participants reported bloating and mild discomfort at higher volumes, none experienced serious side effects. Vital signs and blood chemistry remained stable, and twenty part...