NEW ORLEANS, LOUISIANA—Last week, earwax was all over the news after the American Academy of Otolaryngology-Head and Neck Surgery advised against do-it-yourself ear cleaning. (Nothing “smaller than your elbow in your ear,” they said.) The very next day, mechanical engineers here explained one reason why: Ears are self-cleaning, thanks to fluid properties in the wax. Getting enough pure wax to test was quite a challenge, though. The team collected it from recently dead pigs, dogs, rabbits, and sheep, picking those species because they represented a range of body size, ear canal type, and lifestyle. They then used tests typically reserved for understanding the fluid properties of humanmade materials to measure how well wax sticks to itself and "flows" under pressure. Wax from all the mammals was similar, acting a lot like ketchup, which sticks at first and then finally comes out of the bottle when shaken, they reported last week at the annual meeting of the Society for Integrative and Comparative Biology. When the researchers added dust to the wax, it gradually dried out and crumbled, much like dough with too much flour in it. When they recreated ear wax in the lab, coating the inside of an artificial ear with a flour-water paste, they discovered that the paste stuck firm until they blew air through the ear (similar to air that normally enters the ear). Then it dried out; when the artificial ear was lightly deformed, it fell out, demonstrating what likely happens to dirty wax in the ear when jaws move, they suggest. So throw out those Q-tips! Not only does the work support the notion that most people don't need to clean their ears, but it also points to possible new technologies for air filtration.