Love a writer — read him carefully and closely — and you’ll pick up on his pet words, the ones he reaches for repeatedly, like a baseball player with a trusted bat. Nabokov famously had “mauve.” Elizabeth Hardwick had “motive.” Edward St. Aubyn has “gasp.” The statistician Ben Blatt has called these “cinnamon words” (after Ray Bradbury’s fondness for the names of spices), and they’re often hilariously telling, revealing the essence of a writer, something idiosyncratic in his perception of the world and himself. Is it any wonder that Dickens, that cash-strapped father of 10, was so crazy about “pinch” as noun, verb — even name? For the science writer David Quammen that word is — sublimely — “noodle.” The verb pops up all over his work — and could any word suit him better? He is our greatest living chronicler of the natural world yet was never formally trained in the sciences. He started out as a novelist, a protégé of Robert Penn Warren, and stumbled into nonfiction, his boyhood passion for rooting around in forests now taking him to the canopies of the Amazon and the cliff lines of Komodo island. (The root of “amateur,” remember, is Latin for “lover.”) As he follows scientists into thickets, real and rhetorical, he keeps an eye not only on the rigor demanded by science, but on the wonder and play and curiosity — the noodling — of serious creativity. These are the very qualities that infuse and leaven his own work, making unlikely page-turners out of burly books on zoonotic diseases and biogeography. Nonfiction ought to be “artful, imaginative, accurate,” Quammen has written. “This combination of adjectives is not contradictory.” His new book, “The Tangled Tree,” is the biography of an idea — a heretical, groundbreaking idea — and its many midwives, chief among them Carl Woese, “the most important biologist of the 20th century you’ve never heard of.” You have 3 free articles remaining. Subscribe to The Times In 1977, Woese and his colleagues at the University of Illinois announced their discovery of a “third domain” of life — single-cell microbes they called archaea — genetically distinct from what were thought to be the only two lineages of life: prokaryotes, which include bacteria, and eukaryotes, which include plants and animals. (It’s O.K., I might have missed the memo, too.) Image David Quammen CreditLynn Donaldson Quammen surveys the field pioneered by Woese: molecular phylogenetics (“wrinkle your nose at that fancy phrase, if you will, and I’ll wrinkle with you”): “reading the deep history of life and the patterns of relatedness from the sequence of constituent units in certain long molecules” — this means DNA, RNA and a few proteins — “as those molecules exist today within living creatures.” He plunges into how various findings have upended our conception of stately Darwinian inheritance, represented in the notion of the tree of life — of species branching out, evolving separately from each other. EDITORS’ PICKS War Without End The Unlikely Activists Who Took On Silicon Valley (and Won) China Seeks Influence in Europe, One Business Deal at a Time ADVERTISEMENT Genes, as it happens, do not merely flow vertically from parent to child. They can move horizontally (known as horizontal gene transfer). They can move between species. “Roughly 8 percent of the human genome consists of the remnants of retroviruses that have invaded our lineage — invaded the DNA, not just the bodies, of our ancestors — and stayed,” Quammen writes. The gene that gives us the human placenta came to us from a retroviral infection. Since Anton van Leeuwenhoek scraped the plaque off his 17th-century teeth and observed it under the microscope (“there were many very little living animalcules, very prettily a-moving,” he wrote to the Royal Society), we have known that we teem with living organisms. But this new knowledge — that we are genetically a mosaic — challenges our conception of human identity. What does it mean to be an “individual,” if we are such composite creatures? Quammen raises and rushes past these existential questions; like the White Rabbit, he spends some sections in a bit of a mad rush. There’s a “Montana blizzard of facts” he wants to shepherd us through; a dizzying array of scientists, past and present, he must introduce. (Please don’t ask me if I can tell my Norton Zinder from my Oswald Avery.) But Quammen is generally an exemplary guide; there are few writers so firmly on the side of the reader, who so solicitously request your patience (“Trust me, this is leading to a point”) and delightedly hack away at jargon (“Brace yourself for a fancy bit of lingo…”). He keeps the chapters short, the sentences spring-loaded. There are vivacious descriptions on almost every page — precellular life on Earth, he writes, was a “a world of primeval twitching.” Each section ends with a light cliffhanger. Quammen has the gift of Daedalus; he gets you out of the maze. And maybe to a bar. When not in the field, you can find Quammen and his subjects talking over a drink or two, over a combo sushi platter, over Turkish food, Chilean steaks and beers or just over a coke and pizza. It’s a book born out of appetite and conviviality, an unpretentious delight in food and conversation — in being and thinking with others. Quammen doesn’t just give us stories of solitary toil and triumph. Every discovery is couched in a life with its particular constraints and spurs — not least the power (or catastrophe) of personality. For all Woese’s brilliance, it can be argued that he stood in the way of his success; he was a disinterested lecturer, a collector of petty grievances. We see how women scientists in the field were mocked and marginalized — even those with some standing, like Lynn Margulis, whose groundbreaking theory revealed how eukaryotic cells (which include most cells in the human body), developed symbiotically with bacteria. She was blunt about the professional and personal burdens on women: “It’s not humanly possible to be a good wife, a good mother and a first-class scientist.” She eventually opted for the latter two. Quammen can sometimes be too gentle on his subjects. Later in life Margulis became a 9/11 truther, which he presents as a kind of quirkiness. And there is a large, strange silence around Woese’s personal life — his relationship with his wife and children is understood to be strained but he never delves into it. The focus of the book, however, isn’t biography, but how the work is tinged by the life. “Science itself, however precise and objective, is a human activity,” he writes. “It’s a way of wondering as well as a way of knowing. It’s a process, not a body of facts or laws. Like music, like poetry, like baseball, like grandmaster chess, it’s something gloriously imperfect that people do. The smudgy fingerprints of our humanness are all over it.”