A wide-ranging, occasionally funny, occasionally queasy exploration of the substances our bodies release into the world. There’s plenty here for fans of Mary Roach–style pop science: curious historical tangents, odd cultural superstitions, and accessible summaries of recent research. I appreciated the way Cutter Wood tries to make the “gross” intimate, reframing bodily waste as something both essential and revealing about human life.

Still, the book felt uneven. Some chapters were crisp and engaging, others meandered without much payoff, and the tone sometimes drifted toward quirk-for-quirk’s-sake. I wanted more connective tissue—something that pulled the historical, philosophical, and scientific strands into a clearer throughline. A mixed bag, but one with moments worth underlining.

Thank you to Mariner Books and NetGalley for the ARC in exchange for an honest review.

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 3.5.

I usually love a good science related book but this kept going on tangents and had extra thoughts that I felt weren't needed and distracted overall. I also was hoping for more in depth versus a brief history picked from a period of time then abruptly was a new chapter.

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?

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.]

Thanks so much for the free copy, the book was literally life-changing. I've spent so much time talking about it with various friends and family members; I think my husband is tired of hearing about it! Each chapter was written so grippingly and left me wanting more. I intend to explore more of the author's work!

A pretty accurate representation of how the human body works and operates. Boy, this book is a wild and icky ride through all things body, inside and out. We learn about the bodily functions of: urine, menses, feces, tears, hair, mucus, and many more. The author does a great job outlining the purpose and reason for each category. Very informative and weirdly delightful.

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.

This book is definitely not for the squeamish! The author goes into great detail about the human body and all of the messy but vital substances it produces. Although it's not exactly great reading material just before a meal, it's an enjoyable and informative book that should delight fans of Mary Roach.

Thank you to NetGalley and the publisher for the ARC, which I received in exchange for an honest review.

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.

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.

I thought Earthly Materials would be an interesting aside but, honestly, it wasn't quite as advertised. In hindsight, I can see the blurb alludes to how it actually reads, but it's also clear the blurb writer was dancing around the many deviations the author took from the stated topic.

Chapter one was very strong, probably one of the best chapters (and probably why the editor put it first). It covers the topic of mucous objectively and in depth, as promised in the blurb, and it provides new facts I didn't know. Coincidentally (or maybe not), my newsfeed popped up an article a day later adding a new twist to mucous that the author wasn't aware of. It was probably too new. So far, so good, I thought - we're off to a fine start.

The second chapter was about blood, which I expected to be just as interesting. Instead, I learned very little about blood and a whole lot about the racial bias surrounding the establishment of the first blood banks. After a very brief overview of the primary blood types, the author launched into a long narrative of how and why blood banks were created, and his focus was heavily on the racist aspects of the time. It's unfortunate but not surprising, as that is the way things were. The chapter ended without me learning anything new about blood itself.

Other chapters were even more oblique. Some chapters were farces written as if they were archaic guides to collecting one's breath or historical accounts of flatulence; other chapters were filled with long lists of slang terms amd folklore, and one was the story of a woman who sold powdered milk (not breast milk) illegally. I came away feeling let down - I wanted more on the stated topic and less of all the rabbit holes that filled the book. I suspect the author knew he didn't have enough matieral to write a booklength volume if he stuck to the substances themselves; hence all the sidelines and filler material.

I think there's a good book to be written on the subject of bodily emissions but, for me, this wasn't it.