In the 1990s, a South African nurse walked into a hospital with an unusual problem: Her sweat was red. The hue of her perspiration confounded medical professionals — until they delved into her diet and figured out that she was a prodigious snacker. More specifically, she had a habit of downing huge quantities of Spicy Tomato NikNaks, a South African corn chip that’s dyed red. The pigments from the NikNaks had leaked out of her body through her sweat.

Journalist and Carleton University professor Sarah Everts was intrigued when she heard about this medical mystery. As a lifelong over-sweater, she decided to delve deeper into this much-maligned, little-understood bodily process. And thus was born “The Joy of Sweat: The Strange Science of Perspiration,” a chatty, informative romp through the science and history of perspiration. This beach read is both an ode to sweat and a call to arms to celebrate, rather than spurn, this miraculous process.

And it is, indeed, a miraculous process. The first section of “The Joy of Sweat” explains the basic underlying principle: If your skin becomes wet and moisture evaporates off of it, you will cool down. Other animals take advantage of this mechanism too, but through far more questionable means. The lucky ones lick themselves or pant, while others pee, poop, or vomit on themselves, which truly puts into perspective the social embarrassment of over-sweating. Our way of sweating also works better, too. With vast amounts of bare skin, we can cool ourselves off much more efficiently than, say, a vulture pooping on itself or a dog panting. Some evolutionary biologists even believe that humanity’s unique ability to cool off through sweat helped humans dominate our predators and prey, shaping the course of our species’ history.

Now, long after we lost our fur, sweat and stink are still inextricably bound up in our social fabric. In the middle section of her book, Everts travels around Europe to a variety of kooky events and intriguing labs to research sweat and stink. In Moscow, she attends a sweat dating event, where participants pat off their sweat, put it into bottles, and then match with each other based on who’s attracted to whose scent — basically an olfactory Tinder. In the Netherlands, she stops in for some sauna theater, which has all the kitsch and panache of Eurovision but involves performance in front of a naked audience, in the 185-degree-Fahrenheit temperatures of a traditional Finnish sweat room. She visits a museum in Versailles where diligent curators chronicle historical perfumes and a textile expert in Canada in charge of restoring sweat-stained historic garments.

Lest you think Everts’ sweat tour is all fun and games, she also dives into some of the more serious and darker implications of new research about this bodily function. As Everts reminds us throughout the book, the human body is leaky, and there is much to be learned from our sweat even if it’s not bright red. In Sheffield, England, she meets with a forensic researcher who’s able to detect Everts’ caffeine addiction through analyzing the moisture on her fingertips. Other scientists are probing how much you can discern about someone’s drug use, diet, health, and other virtues and vices from their sweat. Still other researchers are getting closer to isolating the molecules that contribute to the literal smell of fear in our perspiration. Once these nascent technologies develop further, says Everts, they could become an integral tool for law enforcement. With some wearables already claiming to use sweat to detect stress and other metrics, it’s only a matter of time before detailed sweat analysis becomes part of the classic fitness tracker package for the average self-monitoring-obsessed American. Everts imagines an uncomfortable near future in which data from our sweat falls under the purview of our corporations and government, and in which, say, the Transportation Security Administration could question passengers simply because they smell fearful — outcomes that would certainly raise some hackles among those with concerns about privacy.

Although Everts finds more than enough research to report on for her book, she also points out that compared to other biological functions, sweat has not been studied extensively. In addition, misconceptions about sweat abound. One of the joys of this book is Everts’ eager myth-busting. Do humans sense pheromones? (The answer: It’s complicated). Do hairy armpits increase your smelliness? (Yes — hair creates more surface area for smelly molecules to diffuse from). Is the aluminum commonly found in antiperspirant bad for you? (Probably not, but this needs to be further studied). Does a good sweat constitute a “detox”? (No — that’s what your kidneys are for).

Everts also mounts a rousing defense for why we should love and appreciate not just our sweat, but also our stink. The sweat that comes off most of our body is salty and odorless, but the stinky stuff wafts out through the apocrine glands in our crotches and armpits, helped along by a unique set of microbes. (In one of the most interesting interviews in the book, Everts talks with a researcher with naturally mild body odor whose work is inspired by how a romantic partner’s stinky microbes colonized his armpits and changed his aroma.) Why should we hide our natural odors from our family members and friends, who probably know everything else about us?

Everts probes these questions in her last section, which is all about the war on sweat. Of course, in some cases, this anti-sweat action is understandable. The Sweate, the medieval sickness that ripped through Europe, comes up as an example, as does “extreme sweating,” or hyperhidrosis, an affliction that sometimes leads sufferers to seek a risky surgery to sever the nerve connections to the sweat glands.

But is the rest of the war necessary? In the early 1900s, “armpit entrepreneurs” desperate to offload their products had to convince the American public that sweat and stink were shameful.

Advertisements in the 1910s and 1920s cautioned women to tamp down their stink if they wanted to keep their man, while ads in the 1930s proclaimed that if men wanted to win back the jobs they’d lost in the Depression, they’d better smell good. Like many companies, these entrepreneurs invented a problem and then marketed a solution.

For all its beach-read charm, there’s a slight air of subversion to this cheerful, unabashed deep dive into the dank world of sweat and stink. During her tour of sweat and society, Everts talks with a Berlin-based scent artist who reproduced the smells of nearly two dozen men and made the resulting odors into an installation, which toured art museums around the world. The artist tells Everts, “Companies control everything with smell and taste in the entire planet. They all deodorize, camouflage. They try to cover up reality. I want to show reality.” For Everts, part of showing reality is raising a glass to sweat (without fearing that your apocrine glands are wafting musk from your armpit) and finding “serenity instead of shame” in this natural process. Just in time for the hottest days of summer.

Emily Cataneo is a writer and journalist from New England whose work has appeared in Slate, NPR, the Baffler, and Atlas Obscura, among other publications.

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