Earthly Materials: Journeys Through Our Bodies' Emissions, Excretions, and Disintegrations – A Weird and Wonderful Tour of Mucus, Breath, and Tears

by Cutter Wood

Bill Bryson’s The Body meets Mary Roach’s Gulp (with a dash of What’s Your Poo Telling You?) in this rollicking and delightfully educational tour of our bodily emissions—from mucus to sweat to poop—revealing them to be as fascinating as they are embarrassing and proving how essential they are to human health. 

In biology class, we learn that the body is a fundamentally cohesive organism, a collection of organs and tissues working together to a common purpose, all overseen by the brain and wrapped up tidily in a covering of skin. But while this idea of the body isn’t false, it fails to give us a complete picture in one crucial though the system appears tidy and self-contained on the page, in reality it is far from it. Whether it is blowing its nose, mopping sweat from its brow, or excusing itself to the restroom, the human organism is essentially porous.

Our bodies continuously shed material, and while we often think of these materials as wastes, they serve far more complex functions. The exchange, elimination, and frequent disguise of our effluence has been elemental to the development of human civilization, and our lives today are still governed by a host of laws and superstitions and social mores about the materials our bodies leave behind.

In thirteen discrete chapters, Earthly Materials tells a story about one of the materials the human body sheds—from breath and urine to vomit and tears. Sometimes the questions examined are historical. What have we physically done with all the urine produced in our cities? Sometimes they approach the matter through a philosophical lens. Is it ever logical to cry? Sometimes they explore recent scientific discoveries. How does mucus undermine our understanding of natural selection? But they always offer a window into how we negotiate our place in the world and how we get along with one another.

Genres: Nonfiction, Science, Audiobook, Medical, Biology, Health

384 pages, Kindle Edition

Published April 29, 2025

About the author

Cutter Wood completed an MFA in creative nonfiction at the University of Iowa in 2010, during which time he was awarded numerous fellowships and had essays published in Harper’s and other magazines. After serving as a Provost Fellow at UI and a Visiting Scholar at the University of Louisville, Wood moved to New York. For his forthcoming book, Love and Death in the Sunshine State, he was awarded a 2018 Fellowship from the National Endowment for the Arts. He currently lives in Brooklyn with his wife and daughter.

Reviews

[Rachel · Rating 5 out of 5]

The 5-year-old nose picker in me delighted in Cutter Woods’s attention to all things gooey and gross in EARTHLY MATTERS, while my adult sensibilities reveled in his imminently-readable research of the infinitesimal miracles and machinations of the human body. A must read for popaholics, blood donors, the pee drinking community, and anyone who’s ever been amazed or aghast at what just came out.

[Joanne · Rating 2 out of 5]

Could have been so much better without all the extraneous tangents.

[Jenna · Rating 4 out of 5]

Parts of this don't work for me, mainly dedicating any time to the r/nofap community. But, I think some of the reviews here are a little bewildering--it's clear the structure of this book is 1. definitions of the emission 2. a medical overview, and 3. an essay following that's tangentially related. I think it's pretty obviously set up to be that way, so I'm not sure why people are upset at the structure. I found the writing to be pretty compelling, and I found myself reciting things I read in the essay portions--the history of blood banks, ayahuasca usage, and the dark underworld of baby formula reselling. I liked the way the book made me feel, and on my own tangent, I liked that when a coworker asked what I was reading and I showed him this cover he said: "Oh...cool...well...actually, gross." It's both, Kyle, it's both!

[Eaon · Rating 3 out of 5]

Interesting, but much longer than I feel like this book needed to be. Without all of the anecdotal interludes from Wood that began to feel irrelevant this book may have been much more engaging. Starting on the mucus chapter was so high; learning about the different ways a mysterious substance in our bodies work to better us. The further the book went on, the less of that we got. Disappointing the further it went on.

[Art Enyedy · Rating 2 out of 5]

I read a review of Earthly Materials in Bookpage and it sounded like an intriguing book: the subtitle is Journeys Through Our Bodies Emissions, Excretions and Disintegrations. While we think a lot about what goes into our bodies (food, medicines, supplements, etc) we rarely given any thought to all the materials that we expel. Wood delves into twelve different topics, the chapter titles are: Mucus, Urine, Blood, Semen, Menses, Milk, Flatulence, Breath, Feces, Vomit, Hair, Tears. I expected to read a lot of neat facts about each of these human byproducts. When Wood stays on subject, there is interesting material here. Unfortunately, Wood simply cannot stay on topic and completely flubs this book.

There are 21 different types of mucus in the human body - it is a mystery how mucus determines what molecules to pass (so that we can smell) and which molecules are considered dangerous and trapped in phlegm and expelled. I liked reading about how doctor Charles Drew set up the first blood bank. Did you know only primates menstruate (though it has been recently discovered that the Cairo spiny mouse also menstruates)? In the 17th century, Hennig Brandt boiled down his pots of his urine until only a fine white substance remained, and ended up discovering phosphorous (but Brandt was searching for a way to make gold and did not realize the magnitude of his experiment.)

The chapter on semen describes the long process needed to create a sperm cell (it takes weeks). Interesting! But then Wood inexplicably switches to describing a Reddit channel on masturbation. This goes on for pages, with Wood quoting from random posters and then commenting on them. I couldn't fathom why Wood included this material (it is not funny nor informative, it felt like filler to lengthen the book) and I ended up skipping a good number of pages to the next chapter.

In the Milk chapter, Wood describes how and why evolutionary forces may have resulted in mammals creating milk to nourish their young. Interesting! But then Wood jumps to the story about a crime syndicate that sold stolen baby formula and the ordinary-seeming citizens who were responsible. Maybe a better journalist could have made the story more interesting, but I was wondering: isn't the story about a crime ring that steals baby formula a bit off topic here?

It is in the Vomit chapter that Wood goes completely off the rails. After a few initial pages describing how and why we vomit, Wood begins a long, tedious description of a visit he made to a purging temple to ingest Ayahuasca. Ayahuasca is a drug that induces violent puking and pooping - but people believe that by ejecting everything in their alimentery canal they are thus "cleansed" and this self-induced sickness will result in a new, purged state of mind as well. Ayahuasca is not legal, so the owners of the "Soul Quest Ayahuasca Church of Mother Earth" declare that this grotesque practice is actually a religious ritual, and so in the name of religious freedom, they are allowed to continue. Wood decides he will participate in the ritual, so he signs a form declaring his religion is Soul Quest and pays $800 for the right to participate; apparently he is curious to subject himself this awful ritual.

The Vomit chapter is 60 pages long, almost 20% of the entire book. What was Wood thinking? I couldn't tell if he thought the writing was funny or clever (it is neither) - I ended up skipping at least thirty pages of this tiresome narrative and went on to the next chapter. Wood's editor betrayed him on this book. A good editor would have told him to stick to the subject matter, and would have excised that entire section regarding Wood's visit to the Soul Quest purging temple.

My rating: two stars - there are perhaps 150 pages of good material in this book. But that is not enough to make it worth reading. I will avoid any further book that Wood writes.

[Melki · Rating 5 out of 5]

I was fascinated by physiology long before I learned the high-falutin' term for the subject. As a kid, I remember staring at a medical encyclopedia that belonged to my parents. It had sheets of acetate featuring the muscular, vascular, and other systems of the body that overlaid on the skeleton, slowly forming a human being. Unfortunately, hemophobia (this book's chapter on blood literally made me queasy), kept me from pursuing any sort of medical career. But I'm still curious about the subject, and if you share my interest in our inner workings, you might like this one as much as I did.

Wood presents an involving look at things that are born inside of us but occasionally slip their bounds, and emerge with a trickle, sneeze, or a blast. There's enough about snot and farts here to make your maiden aunt blush, but also some pretty interesting medical facts.

The author doesn't hesitate to make things personal, and he does go off on many a tangent, but that's what I really enjoyed about the book. Many of his little tales seem only slightly related to the chapter heading, but they make for poignant and occasionally hilarious reading.

The Hair chapter includes a sobering essay on how to preserve, and whether or not to display the hair of murdered Holocaust victims

His chapter on menses tells the story of a woman who nearly died from an ectopic pregnancy. Luckily she was able to have an abortion, and later went on to become the author's mother. Then he relates the tale of a friend's mom who was diagnosed with cancer during her pregnancy. She did not have an abortion, and died a few years later, leaving his friend and his younger brother motherless. His anecdotes manage to drive home the fact that there is much more at stake than a fetus when it comes to the abortion decision, which is why the choice should be left to a woman and a medical professional, and NOT far-right religious leaders or politicians.

(Sorry to be preachy, but this seems like common sense to me.)

In all, this was a fascinating book about gross, wet, sticky, and smelly things . . . most of which you probably don't want to think about but really should.



Book Number 8 in the Ross Library Winter Reading Challenge: A Nonfiction Book That Isn't a Biography/Memoir

[Bill · Rating 3 out of 5]

Cutter Wood’s subject in Earthly Materials is our “messy” body and its “emissions, excretions, and disintegrations.” He covers the topic via a series of individual essays on the following:

• Mucus
• Urine
• Blood
• Semen
• Menses
• Milk
• Flatulence
• Breath
• Feces
• Vomit
• Hair
• Tears


Being a series of individual essays, as is often the case with such things, overall it’s a bit of a mixed bag. That said, it’s generally an informative book with an engaging, entertaining voice.

Earthly Materials is peppered with fascinating facts/explorations, not just about the body’s emissions but also at times about the people who study them, ancient historical connections, and at times Wood’s own hands-on experience, as for instance when he ingested a psychedelic substance with, in addition to the tripping effect, is also known to induce epic vomiting. So there’s a lot to learn here in terms of information, some of it extends beyond simple "trivia” type facts and some of it engagingly personal. Where the books falters at times is that while some of the digressions are interesting or compelling and have clear connections to the topic at hand, at other times they feel like unnecessary detours and several simply go on too long. In the section on semen, for instance, we get a lengthy rundown of Reddit forum discussions that just feels interminable. And while I enjoyed some of the vomit-tripping, it too went on too long.

In the end, the book is a mostly enjoyable read, and you’ll come away knowing more. It’s not as fully informative or well-crafted as a Mary Roach or Bill Bryson work of non-fiction on the similar topic; it feels a bit rougher in terms of structure, writing, and balance, but it’s a good addition to the field.

[Elisa · Rating 4 out of 5]

This is not the book to bring to the lunchroom. It is pretty gross but it is also fascinating. Everything humans try to do discreetly is brought to the spotlight and explored in graphic ways. From snot to tears, the author offers different perspectives on everything our bodies shed. Part of it is approachable science, like what are the chemicals in urine; there is also a historical perspective but it mostly approaches the subjects in surprising ways. Some parts fell a little flat for me, like the pages about flatulence in a boy from Pennsylvania, or the detailed part about catching someone’s last breath. Others were truly entertaining and surprisingly poignant (hair, tears). The account of an ayahuasca ceremony is a little random but very interesting (I’ve never considered doing drugs but this will guarantee I never, ever, ever even go near them). But the part that shocked me was the epilogue. I hadn’t considered where the author was going and it surprised and moved me.
I chose to read this book and all opinions in this review are my own and completely unbiased. Thank you, NetGalley/Mariner Books.

[Rose · Rating 4 out of 5]

3.5 rounded up. Don't go into this thinking you're going to get a book that comprehensively looks at each of these bodily functions; instead, it's best when the chapters are treated as "wow look at this wild shit about mucus." These chapters are where the book shines. The chapters on farts, breath, and vomit (for the most part, the longest chapters) were particularly weak because the author either tried to use narrative structures that weren't helpful (farts and breath) or went on a journey that didn't seem to elucidate the topic at hand (he went to do ayahuasca so he could vomit, but his body like really doesn't have the ability to vomit, yet this is still how he chose to tell the story of vomit?). The other chapters were really interesting. Of note, the debate on whether to include an exhibit of hair taken from Holocaust victims at the US Holocaust Museum, a stolen formula ring and how we came to use formula instead of milk anyway, and the explanation of the blood bank system and its history of racism were particularly interesting.

[Book Club of One · Rating 4 out of 5]

What is the body? In this book that winds up being so much more about death than you'd expect from the title, Cutter Wood shares twelve body themed essays. Earthly Materials: Journeys Through Our Bodies' Emissions, Excretions, and Disintegrations will inform, disgust, entertain and surprise readers with its free ranging approach and provide lots of statistics and alternate names or slang for the chapter subjects.

Each chapter opens with a list of the nicknames or slang for that section's subject. Then Wood details a summary of its purpose in or out of our bodies before going off on a related tangent that becomes the focus. For example, the chapter about vomit follows Wood's experience at a New Age weekend retreat focused on consuming ayahuasca. The chapter on milk focuses on Formula Mom, a Floridian who established a baby formula selling business that was busted for how it sourced the formula.

It is a work of popular science that also delves into the deeply personal or occasionally, investigative journalism.

Recommended for readers of health or medical science, nonfiction or fans of Mary Roach and Bill Bryson.

I received a free digital version of this book via NetGalley thanks to the publisher.

[Sierra · Rating 2 out of 5]

I read this because the author is a Brown alum, and so am I. This is a terrible reason to read a book. The content and stories were fascinating, but the way it was put together felt like he was trying to be pretentious. There were lots of endless lists of facts with no further elaboration, interspersed with very long stories about one thing ad nauseam, with no balance. Every chapter had the same biological prelude, but after that the format and types of stories were all over the place, and not in a way that worked. He admits in the beginning that he doesn't plan on drawing any sort of grand truths from these stories or even trying to tie them together, so why keep it as one book?

ARC provided by NetGalley in exchange for an honest review.

[Stacey · Rating 5 out of 5]

"While capturing breath from the mouth and nose is fairly easily accomplished, the anus, socketed away between the buttocks and the perineum like a still in a brambly Appalachian holler, requires a great deal of Mylar and ingenuity."

If you like this sentence, I predict you'll enjoy this book. If you don't like it, what kind of prude are you?

I laughed and laughed, and I learned a lot about crying, as well as all my other bodily functions.

[Marika · Rating 4 out of 5]

13 chapters detailing the types of materials that the human body sheds. From innocuous types like mucus, blood, tears to the more taboo topics such as vomit, urine and flatulence. Written in a scientific manner, yet easily readable about a topic that we all experience.


*I read an advance copy and was not compensated.

[M Dubielak · Rating 4 out of 5]

This is an entertaining book in multiple ways. The topics are anything that physically comes out of the human body - the good, the bad, and the ugly - so it's a wild ride. Luckily, Cutter Wood is a good writer and while using facts - not alternative facts - he is also entertaining and funny. A great way to learn!

[Jane]

On the meaning of tears:

“I suspect it’s part of what’s going on behind Marin Čilić’s towel on Centre Court. We’re going to die. It’s no great metaphysical statement. It’s crying. Baby mammals do it all the time.

[…]

The big man has glimpsed something you’re not supposed to glimpse while playing tennis, and now we’ve all glimpsed it too”

[kylie · Rating 4 out of 5]

Such a fun and only a bit gross read. My one complaint is the gratuitousness of the flatulence chapter. It had more references than the rest of the book combined. We get it, guys like farts.

**I received my copy from Netgalley.

[Christina Marta · Rating 3 out of 5]

Entertaining bits, but I don't think the chapter on emesis needed to be 50 pages long, mostly about his ayahuasca experience. Nor is menses something experienced from a male point of view (btw, an ectopic pregnancy is treated with salpingectomy, not "abortion." Honestly!) Mary Roach did it better.

[Mike Taylor · Rating 2 out of 5]

I gave up about half way through. Based on title and subtitle, I expected more biology and scientific information. Instead book does a nice job of replaying historical vignettes and anecdotes. If you like those, then you'll like this book.

[Jesse · Rating 5 out of 5]

I love science, weird trivia, and good writing so I loved this book. I laughed out loud so many times. I frequently have to remind myself that the entertaining facts I learned in this book actually aren't appropriate dinner conversation with some people.

[Haley Williamson · Rating 5 out of 5]

Five stars for the first chapter. He lost me by the middle of the book tbh but just all around interesting!

[Kyle · Rating 2 out of 5]

More science less political science please. C

[Karen · Rating 5 out of 5]

this was so excellent!! literally life-changing. thanks so much to the publisher for the free eARC!

[Left Coast Justin · Rating 2 out of 5]

Maybe the most fundamental question in flatulence is who authored a particular flatus.

Given that Wood is himself an author, one cannot help wondering whether he’s maybe having a little fun at his own expense. Having read this book in its entirety, I come away a full believer in his sense of fun. Locking stentorian authoritative prose into a wrestling match with fart jokes is just one of the tools at his disposal.

We tour the whole toolbox here. This book is all over the place. I grew up believing it axiomatic that authors wish to leave a permanent impression on their readers’ minds. A smarter and better-educated literary scholar than I could doubtless write a treatise on how times have changed; in our modern stimulus-soaked atmosphere, an author’s only goal is to keep you paying attention, changing topics, styles and viewpoints as often as necessary to keep you from wandering off. Whether you remember any of this next week does not appear to be a primary goal.

To Wood's credit, several of these essays -- the ones on milk, on menstruation and on tears spring to mind -- were quite good, unfortunately offset by equally bad ones on urine, vomit and semen. The human body is a messy organism, and so it is a messy book, he writes in the intro. That's one way of letting yourself off the hook.

Let's suppose you have an interest in semen. Going to a book whose subtitle is 'Journeys through our bodies' emissions, excretions and disintegrations' and flipping to the chapter titled 'Semen' might seem a rational act. But alas, what we find here is the longest chapter of the book, at 34 pages, providing a deep dive into a Reddit discussion of men who are trying to stop masturbating to porn. It's really, truly something I could happily live without knowing about, and completely unrelated to semen as such.

Or vomit: We learn of his trip to a tacky Ayahuesca church, where he takes the powerful hallucinogen but fails to vomit, and learn little else. He notes early on in the Urine chapter that "unlike popular belief, urine is far from sterile," but fails to follow up on that thought entirely, instead believing what his readers really want to know is the history of Roman plumbing.

Word of the day: "feculant emesis"

Sometimes, his unexpected detours work. The chapter on blood, in which some key emotional connections were made, was a nice piece of work, though it focused more on blood donation than blood per se. The Milk chapter was hijacked by a criminal case in Florida against an infant-formula theft ring, but I'm grateful he pointed out the prosecuter was Pam Bondi, current Attorney General of the United States of Trump's America, "who declined to pursue a fraud investigation of Trump University after receiving a $25,000 donation from the Trump Foundation." And up until yesterday I was unaware of a family of shrews that live on the large Caribbean islands of Cuba and Hispaniola called solenodons whose nipples are located next to their anuses. This is an evolutionary outcome whose advantage I simply cannot work out.

Other parts are simply puzzling. On page 12, the MIT scientists he's interviewing note that the freeze-dried, purified mucus they're working with "is worth ten thousand to twenty thousand dollars a gram," while two pages earlier he notes that the same gram can be purchased from Sigma-Aldrich for $500. And he describes a high-school sweetheart, a softball player, this way:

She knew how to split wood, plow snow, drive stick, paint a watercolor of nasturniums on a windowsill. She could sling an errant foul to second with enough pace it left a lump on your palm.

At the end of the day, I can forgive the obsession with Reddit users, the factual inconsistencies and the failure to get to the essence of puke. But: Why in the hell would you throw a foul ball to second base? Messing with baseball is a step too far.

I did laugh at some of the fart jokes, though.

[Allyson Dyar · Rating 4 out of 5]

The premise of the book sounded interesting, so I requested the book and added it to my NetGalley’s list to read. After all, not much attention gets paid to the more problematic bodily functions, such as flatulence or vomit.

I thought the chapter on mucus was quite enlightening, as I hadn’t really given it much consideration through my studies of human anatomy and physiology, and I learned a lot.

What is depressing is that, as of this writing in May of 2025, the current United States administration seems hell bent on destroying any advantage America has in scientific advancements, so I read the chapter realizing that the investigation detailed in the chapter might already be discontinued.

If I have any complaints about the book, it’s that the author feels it necessary to take pages upon pages of one aspect of a subject and literally beat it to death. For example, in the chapter on semen, there is an extensive and rather boring discussion of a Reddit “subreddit” on Fapping.

Reddit can be described as a social media platform with subreddits serving as forums dedicated to one subject. I’m not a prude by any means, but after a few pages of the discussion on fapping, I got the gist and basically skimmed the rest.

Also, on the chapter dedicated to Milk, specifically breast milk, the author meanders into a long story about a woman who was reselling baby formula. I remember there was a major problem with the availability of baby formula, but honestly, the whole discussion of the rise and fall of Alicia Tondreau-Leve could have been distilled down to a few paragraphs, not the multiple pages that were dedicated to the subject.

I did like reading the author’s adventures with ayahuasca, as I had heard quite a bit about it but hadn’t delved into the matter. As with other portions of the book, this section did go on a bit long, but I was interested, which makes me think that my concerns above about the meanderings of the chapters on milk and semen might be of interest to others, despite my feeling that it went on too long.

I do have mixed feelings about “Earthly Materials: Journeys Through Our Bodies' Emissions, Excretions, and Disintegrations,” as I felt the author could have concentrated more on the subjects he was writing about rather than taking all those side trips. There were also times when the author used terms that were not adequately explained, such as “xanthinuria”—a disease where the body cannot break down xanthine (for a more detailed explanation, Google is your friend)—and this makes it difficult to recommend this book to a more lay audience.

In general, I did enjoy reading the book, though I often found myself skipping through the many side stories that I felt really didn’t enhance the subject. Someone who is interested in the various subjects covered may get something valuable out of the book; others may find it a wee bit tedious.


3.5/5 stars

[Thank you to NetGalley and the author for the advanced ebook copy in exchange for my honest and objective opinion, which I have given here.]

[Livia Van workum · Rating 5 out of 5]

one of the most fantastic and intriguing books ive read in a long time
especially good for the squeamish for some good exposure to how very normal and nuanced it can all be