In this New York Times bestseller and longlist nominee for the National Book Award, “our greatest living chronicler of the natural world” (The New York Times), David Quammen explains how recent discoveries in molecular biology affect our understanding of evolution and life’s history.
In the mid-1970s, scientists began using DNA sequences to reexamine the history of all life. Perhaps the most startling discovery to come out of this new field—the study of life’s diversity and relatedness at the molecular level—is horizontal gene transfer (HGT), or the movement of genes across species lines. It turns out that HGT has been widespread and important; we now know that roughly eight percent of the human genome arrived sideways by viral infection—a type of HGT.
In The Tangled Tree, “the grandest tale in biology….David Quammen presents the science—and the scientists involved—with patience, candor, and flair” (Nature). We learn about the major players, such as Carl Woese, the most important little-known biologist of the twentieth century; Lynn Margulis, the notorious maverick whose wild ideas about “mosaic” creatures proved to be true; and Tsutomu Wantanabe, who discovered that the scourge of antibiotic-resistant bacteria is a direct result of horizontal gene transfer, bringing the deep study of genome histories to bear on a global crisis in public health.
“David Quammen proves to be an immensely well-informed guide to a complex story” (The Wall Street Journal). In The Tangled Tree, he explains how molecular studies of evolution have brought startling recognitions about the tangled tree of life—including where we humans fit upon it. Thanks to new technologies, we now have the ability to alter even our genetic composition—through sideways insertions, as nature has long been doing. “The Tangled Tree is a source of wonder….Quammen has written a deep and daring intellectual adventure” (The Boston Globe).
Science writer Quammen (The Song of the Dodo), as he has so often done before, explores important questions and makes the process as well as the findings understandable and exciting to lay readers. Here, he delves into the field of molecular phylogenetics, the process of "reading the deep history of life and the patterns of relatedness from the sequence of constituent units in certain long molecules," namely "DNA, RNA, and a few select proteins." Although the topic might seem arcane, he brings it to life by profiling many of the field's most important players, including microbiologists Carl Woese and Ford Doolittle, and demonstrating how it has changed "the way scientists understand the shape of the history of life." The breakthroughs Quammen describes include Woese's classification of the archaea, a new category of living creatures made up of single-celled microorganisms, and Doolittle's insight, recounted in an interview with the author, that genes can be transferred horizontally, between organisms (and not always closely related organisms) rather than simply between parent and offspring. The cumulative effect is to transform Darwin's famous image of evolution as a straightforwardly branching "tree of life" into a "tangle of rising and crossing and diverging and converging limbs." This book also proves its author's mastery in weaving various strands of a complex story into an intricate, beautiful, and gripping whole.