In his introduction to Flush: The Remarkable Science of an Unlikely Treasure, author Bryn Nelson relates a Siberian folktale that tells how as the First Bird (a raven) flew through the void, he would, as birds do, occasionally excrete. The more solid parts became the land (the hardest parts turned into mountains) while the more liquid parts formed rivers and lakes. It’s been a long time, then, that people have described the word as full of shit. For Nelson, though, and for that matter the Siberians, that description is less a pejorative and more an opportunity. In Flush, Nelson takes the reader on an exhaustive tour of all the ways our waste product is, well, going to waste.

Early on, Nelson gives us the biological basics on the how and what of what we flush, along with tidbits that will either fascinate the reader or make them wish for a little less detail, such as different transit times for digestible material between men and women, weight differences in the “final product” between Americans and other nations (our lack of fiber means our poop is much lighter) and how amazingly wide the range of transit time and other factors can be from individual to individual (some, perhaps many, might be more likely to mumble “TMI” when Nelson offers up his own details thanks to the trio of apps he used for a while to track his own waste product and how his diet affected the product). We also get some historical information, such as how the ancient Scythians dipped their arrowheads in a fecal slurry to infect and kill those whom the arrow didn’t kill immediately.

Once the how and what is covered, Nelson moves into why simply flushing our waste down the drain might not be the best option. What else might we do instead? Well, we could use it for fecal transplants, which have been shown to decisively help treat irritable bowel syndrome and c-diff infection (the later a major health issue that kills many Americans annually and which fecal transplant has been shown to cure at a stunning 94 percent rate). Nelson does an excellent job of showing the long, difficult road it took to get FTs accepted (believe it or not, the first recorded one took place in 4th century China), with individuals performing their own at-home ones via online tutorials until the medical establishment finally caught up.

Another medical reason we might want to pay more attention to our poop is for diagnostic purposes. For individuals to some extent, but more importantly, Nelson details how various communities have turned to wastewater examination as a means of learning what illnesses are circulating and also where to best, most effectively target resources.

In other sections, Nelson explores non-medical applications, using our waste as “bio-solid” fertilizer, turning into transport or cooking fuels, using to detoxify contaminated land, and even turning it into potable water. The last is not speculative tech – reclaiming waste into water has been done on the International Space Station for years and a number of cities have turned to doing the same. As one might imagine, the concept turns a lot of people off (a significant minority say they would never drink such water). But psychologists have found that if the reclaimed water is added to natural water sources, such as reservoirs or rivers, the public is far more accepting of the idea, considering the “tainted” water is “cleansed” by the natural water.

Nor is it just our current waste that is useful. Nelson also points to how anthropologists, historians, and archaeologists are mining old, even fossilized (called “coprolites”), waste for a ton of information to reconstruct ancient illnesses and diets. This is such a recent usage that one scientists is quoted by Nelson explaining how they thought such material was so useless they used to have contests with it to see how far they could throw it in daily games of “Frisbee throwing.”

As noted, the book is thorough; it’s hard to imagine that Nelson left anything out in terms of possible applications and for the most part, it’s all fascinating (one of the most unexpected and interesting elements is a discussion of huma gut bacteria being threatened with extinction and attempts to use the waste of hunter-gatherer societies to “replenish” the evolutionary well). Possibly Nelson might be a bit too thorough in spots, with the details threatening to overwhelm some readers. And as mentioned above, if not overwhelming in terms of data, some readers might wish for a little less personal info. But mileage will certainly vary on both of those, and I’m willing to guess that anyone who picks up a book about shit is willing to go a pretty good distance with the author.

If I had one complaint, it would be that at times I wanted Nelson to offer up a bit more of the counter-arguments, a little more explanation of how much is still in the prototype/non-scaled stage. For instance, biosolid fertilizer has been called into question as to its safety, and at one point Nelson refers to the impact on serotonin and thus depression, but more recent research has questioned that linkage.

But in the end, the positives greatly outweigh any issues, which are both few in number and minor in impact. The depth of information and the fluidity of its delivery, combined with Nelson’s conversational tone and willingness to place himself in the midst, along with its relatively unusual subject matter, make Flush a strong example of popular science. Anyone who tells you differently is full of, well, you know.

My thanks to both NetGalley and the publisher Grand Central Publishing for an advanced copy of this new book on the many uses and science behind the waste that we leave behind..

I grew up in a time when certain things were not just brought up in polite conversation, they were never even a part of any conversation. Procreation probably lead the never discussed subject list, intoxication was mentioned about certain members of the family, never our own. Defecation maybe when sick, but even in jest it was a subject that was considered, well for others, or maybe HBO comedy specials. As I got older I began to notice the health of guts and everything that went in or out was becoming more conversational, but still it was not a subject I wanted to share. Thankfully Bryn Nelson, PhD has no problems with discussing the subject in every way shape and form. Flush: The Remarkable Science of an Unlikely Treasure is an examination of what according to the children's book everybody does, along with the science and knowledge that can be gained both for ourselves and the environment.

The book begins well at the beginning, answering the age old question of what a bear does in the woods. Turns out the giant short- faced bear ate plenty of plants and animals, which relieving itself helped the growth of plants and trees in North America through the natural fertilizer over 20,000 years ago. The book then focuses on humans and the science and biology involved in breaking down what we eat, what this shows of our health and where said wastes go. There is a large interest in human waste as it can tell the health of a city, seeing what diseases or even COVID traces, tracking the higher breakout areas and allocating resources based on what they find. One of the big problems with the study of human waste is getting past the shame and disgust that humans feel for their own bodies a lot of the time. The benefits, however, seem to outweigh these feelings of human taboo, and that is also discussed.

The writing is very good taking a subject that is not one that people like to discuss and makes it interesting and the reader left wanting to know more. The balance of humor to science I think helps a lot. Get ready for Dad jokes is my only warning. Nelson has a, I hate to say, good feel for th subject, and even in sections that readers might think, echh, has the ability to make it both interesting and educational. The science on the environment and disease was fascinating I feel that I have more of an interest in a subject that I never gave much thought about.

Recommended for fans of Mary Roach or Bill Bryson's latest book on the human body. The writing is very good and will leave the reader fairly flushed at the end. I kid. I enjoyed this far more than I thought I would, and found that I have more or an appreciation for all the little things our bodies do for us everyday.

While I generally tear through books, it took me quite awhile to read Flush by Bryn Nelson. It is extremely well-written- combining historical facts, humor, and current/future “poop” medical use and research. It is bursting with so much information that there were many times I needed to put it down and give my brain a little time to absorb it all. Shorter chapters may have made it a breezier read, yet it is highly worth your time.

I learned a lot more than I thought I would, including a whealth of information on the miracle of fecal transplants, how covid (temporarily) ruined forward momentum on research application, and how the heck humans began to think of a natural and healthy body function as taboo and disgusting.

This is fascinating stuff. I’m not sure if I’ll find many patrons who wish to discuss it with me, solely due to its topic. However, I literally read parts out loud to my husband (who would not have chosen this as a topic he wanted to learn more about) and we had some lively chats about it. I can’t wait to find more people who want to discuss this book!

My thanks to NetGalley and Grand Central Publishing for access to a digital ARC.