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Movers And Shakers

Sarah Everts’s new book takes a look at the chemistry of sweat

Everts explains her fascination with perspiration

by Megha Satyanarayana
July 14, 2021 | A version of this story appeared in Volume 99, Issue 26


Sarah Everts.
Credit: Jeorg Emes

When in Rome, the saying goes, do as the Romans do. Swap out Rome for Berlin, and you have the inspiration for Sarah Everts’s newly released book, The Joy of Sweat: The Strange Science of Perspiration.

The cover of The Joy of Sweat: The Strange Science of Perspiration, by Sarah Everts.
Credit: Jeorg Emes
Sarah Everts's new book looks at the chemistry of sweat and the history of our fascination and repulsion.

Doing as the Berliners do meant a lot of going to the sauna, says Everts, who was C&EN’s European correspondent from 2007 to 2018 and is now a journalism professor at Carleton University. Those heated hours helped solidify her fascination with perspiration.

“It was kind of amazing to be in a place where everybody’s sweating collectively,” she says, recalling that in the beginning she was a little skeptical of this source of sweat. But after indulging, she says, “there’s like this huge catharsis. You just feel so glorious.”

Everts’s book delves into the science of sweat: the biochemistry of how and why we sweat, the analytical chemistry of what exactly is in sweat, and the organic and inorganic chemistry of our deodorant, perfume, and sweat-soaked fabric. She even explores a little social chemistry, doing some myth busting involving boar pheromones and sports drinks and going to an evening of matchmaking via sweat compatibility.

Sweat is vital, Everts says. And yet it’s a source of human shame dating back as far as those same Romans who inspire our adventurous assimilation. So we asked Everts, a chemist turned journalist turned journalism professor, to enlighten us about our human glow. This interview has been edited for length and clarity.


Age: 45

Home: Ottawa, Ontario

Book release date: July 13

Sweaty addiction: “Russian banyas are amazing.” These saunas feature people using fir branches to massage the bather and to whisk the air around.

Research fail: After reading a case study of a woman who sweated red because of a dye in her snack chips, “I called the company and tried to order a bunch of Nik Naks spicy tomato, but they were obsolete.”

Sweaty sweetheart: Everts went to a sweat dating event, where people give sweat samples that are labeled with a number and then smell all the samples to pick the ones they like. At the end of the event, participants find out if their sweat made a match. Sarah liked the smell of sample 15. But did the creator of sample 15 like hers? Read the book to find out.


A book about sweat? Where did this idea come from?

One, I was kind of worried that I might sweat more than average. I was the first person in any workout­—during the warm-up—to reach for my towel.

Then, in 2007, I moved to Berlin, and in Germany, everybody goes to the sauna. I was like, “Why on earth would I go to a place to sweat for fun when I already think I sweat too much?” But it was kind of amazing to be in a place where everybody’s sweating collectively and there is no shame.

And last but not least, as a science journalist you get a million emails in your inbox each day, and one day, I got an email with the subject line with something like, “A new artificial perspiration product,” and I’m like, wait. What? There’s a market for synthetic sweat?

So these three things were all kind of percolating together to inspire the book, plus questionable claims about the health benefits of saunas.

Why are we so embarrassed about sweating? Does the shame come from the actual sweating or the fear of smelling bad?

I think it’s both. Humanity has, for a very long time, been worried about our body odor. There’s this great quote from the ancient Roman poet Catullus that kind of speaks to the shame of sweat. I would love to read it to you because it’s so . . . delicious.

“You are being hurt by an ugly rumor which asserts that beneath your armpits dwells a ferocious goat. . . . It’s a right rank beast that no pretty girl will go to bed with. So either get rid of this painful affront to the nostrils or cease to wonder why the ladies flee.”

So, 2,000 years ago, people are like, “Buddy, let’s talk.” But I think the taboo is linked to the fact that sweat is completely out of our conscious control. When you think about the other, kind of grosser things that human bodies do, you can hold those things back and remove yourself socially to deal with it. Sweating? We have millions of sweat pores that suddenly can open and immediately and olfactorily reveal things about ourselves. Like, that we’re nervous, or hot.

We have millions of sweat pores that suddenly can open and immediately and olfactorily reveal things about ourselves.

What are some of the things about sweat that interested you as someone with a chemistry background?

It was the realization that the chemical composition of sweat is so much more interesting than just salt and water and maybe some stink molecules.

Like everybody else, I’ve accidentally tasted my own sweat, and it’s salt water. But what was an utter revelation was where sweat was actually sourced. We’re wet—our organs are covered in this interstitial fluid, and when we need to cool down, our sweat glands release that interstitial fluid and anything that’s percolating in our blood that’s a small molecule—or a reasonably small molecule.

That exploded my head because so many secrets about our vices or even just our health are literally pouring out of our bodies all day or onto our yoga mats or left behind in a fingerprint. And that’s exciting and terrifying, that all of this information is readily detectable in a fingerprint.

What are some of the most interesting recent findings about sweat?

We’ve known for a while that bacteria are responsible for body odor, but what we are learning about the microbiome and its impact on body odor—what species are doing what and where and who are the bigger players—that’s what’s sharpened into focus in the last decade.

Then there’s the way we are able to chemically analyze a fingerprint—that level of sensitivity and accuracy comes from mass spectrometry innovations that have come out in the last decade.

Finally, there’s what we are learning about the evolution of sweat and sweat glands and why humans lost their hair and developed this mechanism to cool down. I think that’s where the next 10 years is really going to go—genetically tracing the evolution of sweat.

So what is the future of sweat?

Personal measurement—it’s not just forensic scientists who are interested in what comes out in our sweat, but athletes, coaches, and the general public. There’s going to be a lot of cool stuff to be discovered in sweat, and you know, smart-watch add-ons and other things that look at, say, lactate levels so we can adjust our workouts.

This book feels like it was a lot of fun to research. What were some favorite moments?

A really great part of doing this book was trying different sweat ceremonies. I went to Korean jimjilbangs—including one in New Jersey. I went to banyas (Russian saunas). I went to hammams in the Middle East. And then, ultimately, the Aufguss World Championship, where people are doing acrobatic towel dancing to music in costume in an extremely hot Finnish sauna. That was kind of amazing.

Obviously you can’t put everything in a book. What got left on the cutting-room floor?

One thing I couldn’t include was the way my sweat glands are counted. You’re born with a whole bunch of eccrine sweat glands, but they only become fully active when you are a toddler. A lot of estimates are taken from cadavers, but obviously you get only the total number—you don’t know if they were active or not.

To count the glands, Andrew Best at the University of Massachusetts Amherst uses a drug called pilocarpine, put into a gel and pushed into the skin with an electrical current. It activates the floodgates, and all the active sweat glands go haywire. And then you put this puttylike polymer over that spot, and as the sweat comes pouring out, it makes little impressions like stars in the night sky. Then you use a digital camera to do the count. You do this over different parts of the body and calculate an overall count.

And your count?

Three million.

Is that normal?

Yes, we have between 2 million and 5 million, so it’s pretty standard. He was like, “Sorry to tell you this, but you are pretty average.”

Anything else you wish you could have included?

There are a lot of questionable online entrepreneurs that sell pheromone cologne, which is of course ridiculous because no chemist has found a human pheromone—a sex pheromone—yet, extracted it, and put it back into a bottle. So I became a little obsessed with what’s in these colognes. Some advertise having androstenol and androstenone, which is a legit wild-boar pheromone. So I suddenly came up with the idea of buying one of these pheromone colognes on the internet and testing it by seeing if it would attract a wild boar. I bought a very large stuffed anteater that I used as my proxy boar. I spritzed it with pheromone cologne and hung it in a tree in the forest outside of Berlin. Then I got video cameras used by evolutionary biologists—boars are nocturnal—and I set it up to see what animals in the forest would be attracted to it.


I did manage to attract some wild boars. But they didn’t try to mount the thing—they were just like, “What is this?”


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