Before reading Mary Roach's latest book, Grunt: The Curious Science of Humans at War, a meticulously researched and darkly humorous look at the science of modern warfare, it had never occurred to me that birds could pose a serious threat to a fighter pilot. Like many civilians, my understanding of jets and the mechanics of flight was largely informed by repeated viewings of the film Top Gun, which left me confident that my knowledge of the term "jetwash" would convey to all those in the military that I "understood" the danger they faced in combat (or at the very least demonstrate my status as an aficionado of 1980s pop culture). Roach quickly dispelled this belief in the introduction to Grunt, where she relates in characteristically witty prose the existence of the "chicken gun," the massive yet comical artillery piece that shoots typical grocery store chickens out of its 60-foot barrel to simulate the impacts of birds in flight. A starling, it turns out, can pierce a jet's windscreen like a bullet. Who knew? Mary Roach has built her career on answering the question "who knew?" about some of the most interesting and (at times) disturbing subjects of scientific inquiry. Her first book, Stiff, introduced readers to the life -- or, rather, afterlife -- of human cadavers, and since then, Roach has published six books (one collection of short essays and five full-length works of non-fiction), four of which have similarly whimsical one word titles in Bonk, Gulp, Spook, and Grunt. Considering these one word titles collectively, it seems fitting that all of them can be read as verbs. Each one imparts an energy and vitality to the work that makes Roach's writing thrilling, accessible, and engrossing in the best possible ways. Roach has a unique ability to make the morbid funny. There's a phrase soldiers use in combat situations that can also be used to describe Roach's voice: "going kinetic." This is slang for "people are firing guns at you." It's also a play on the scientific term kinetic (as in kinetic energy, a phrase many readers will recognize from high school physics class). Kinetic energy is the energy of an object while in motion: of a bicyclist flying down a hill, for instance, or of a writer pacing furiously around a room. Roach's writing is kinetic in the sense that it propels its readers forward, maintaining a speed and energy that keeps us turning the page, elongating a state of perpetual curiosity. Why did the military attempt to develop shark repellent? How does one go about reconstructing a penis after it has been damaged in an IED blast? Like most of Roach's work, Grunt is concerned with the bizarre, the intricate, and, ultimately, the temporal. This isn't a book about the science of wars long past (there's nary a mention of German military efficiency, and readers looking for information about the 12th panzer division of armored tanks are advised to look elsewhere). Though Roach makes occasional reference to 19th- and early-20-century wars -- as when she writes that dysentery or diarrhea killed 95,000 soldiers during the Civil War -- Grunt primarily focuses on the present and recent past, rarely examining science older than the Vietnam War. In fact, much of the science Roach reports is currently in the experimental phase of development. WIAMan, for instance, is a Warrior Injury Assessment Manikin the Army has invested in to help them study and (eventually) simulate the injuries sustained by soldiers in IED explosions. Unlike traditional crash test dummies, which have been designed for automobile companies to test head-on or otherwise horizontal collisions, WIAMan will, when it's finished, have a much larger range of motion, with artificial limbs and ligaments that will react the way the human body reacts when an IED blast hits it (as Roach explains, IEDs tend to explode underneath tanks, knocking soldiers in their heels). In some ways, WIAMan is both a testament to modern military innovation, which is capable of engineering high-tech instruments with no real use in the battlefield, and a reminder that the science of warfare is progressing too fast for medicine to keep up. We're not prepared for the wounds that these new weapons inflict. We're still learning to heal the old ones. Unlike Roach's other works of nonfiction, which focus on fascinating but (for the most part) non-lifesaving scientific advancements and discoveries, Grunt shines a light on science that's actively attempting to keep people alive. Perhaps for this reason, it feels less like a survey of new military science -- much or most of which is surely classified -- than it does a masterful work of nonfiction that intends to draw the reader's attention away from the drone strikes reported in the mainstream media and, in so doing, change the national conversation about war. Roach isn't writing about the NSA, the Geneva Convention, or the various ways that science has improved the military and the government's ability to surveil, kill, and torture. That's a subject for another day, another book. In Grunt, Roach sticks to the science most relevant to soldiers: eating, sleeping, defecating. Like the subtitle says, the book is about "the curious science of humans at war," not machines. It's Roach's attempt to humanize war in the best way she knows how: through research. In the hands of a less capable or more sentimental writer, Grunt could read like a heartfelt plea to reallocate military spending and save the troops with science. Instead, Roach takes a no nonsense approach to this very difficult topic and shows the soldiers she writes about in this book the same level of respect and sagacity she would anyone who occasionally has to shit into a little sandwich bag. Without letting the toilet humor overrun the book, Roach acknowledges the frequently gross and often absurd situations soldiers find themselves in (battling diarrhea during a crucial mission, for instance) and treats these soldiers like people with all their idiosyncrasies intact. One man she talks to adamantly refuses to take antibiotics to treat diarrhea. A sailor looks at her funny because she can't imagine peeing in a wetsuit. And then there's the one scientist with the voice like James Spader's who says, "If you don't have a pair of cadaver shoes, you're not doing enough research." (Good shoes, it turns out, will be ruined by the fluids used while experimenting on cadavers.) It's often hard to tell whether Roach's subjects just naturally have a sense of humor about their work, or if she's bringing it out of them, but in the end, it's Roach's snappy writing style and impeccable comedic timing that make Grunt a must-read. I can't imagine another person writing it.