THE JOY OF SWEAT

A popular-science treatment of an overlooked area of study.

Perspiration is neither a fashionable body secretion nor of much interest to publishers, so most readers have not encountered a book on the subject, but science writer and journalism instructor Everts fills that gap admirably. She begins with a few jolts. A resting human produces as much heat as a 60-watt light bulb, which is usually more than we need. Evaporating fluid consumes heat, a process that keeps us cool. Through several million tiny sweat glands, we extract fluid from the blood and spread it over the skin. Odorless until bacteria act on it, it develops a smell, unique to every individual. Though repulsive to most Americans, in other parts of the world it is considered unobjectionable and sometimes interesting. Few readers will skip the chapter on the history of deodorants, an American invention. Outside of humans, sweating is uncommon. Horses and most monkeys and apes sweat; other animals pant, roll in mud, stay in the shade, or work at night. The sole purpose of human sweat is to cool the body; despite the common belief, it doesn’t remove waste or toxins, so excessive sweating has no health benefits. Throughout, Everts mixes facts with interviews and encounters with sweat-related activities across the world: Smell-dating is a real thing, as are sauna theaters, where several hundred naked spectators watch a performance in a 185-degree arena. Fingerprints are an impression left behind by sweat, and their chemical analysis may reveal other valuable forensic information. Everts interviewed a man who underwent surgery to treat massively excessive sweating, a fairly common medical condition. A rare genetic mutation produces children born without sweat glands; if not discovered early, they can die of heatstroke. The author’s prose is sometimes flippant and dense with amusing asides, quips on stinkiness, and embarrassing encounters, but she delivers a solid education.

Fascinating information for tolerant readers.