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Last Reviewed on June 19, 2019, by eNotes Editorial. Word Count: 321

While most people are familiar with the idea that DNA is the building block of life, relatively few probably contemplate how knowledge of genetics has changed our fundamental understanding of the ways that life forms change slowly over time. A principal theme of David Quammen’s book is how scientific advances of the last half century have reshaped our understanding of what constitutes life. An additional theme is the predominant role of molecular biology in that intellectual transformation. Quammen also reiterates the theme of the practical impact of these discoveries; he shows how science is embedded in daily life and why the theoretical changes matter in the everyday material world.

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Quammen begins with the familiar image of the branches on a tree, showing how such an apparently straightforward symbol must be rethought in the light of recent changes. If one thinks of the flow not only in one direction through time—from trunk to branch or from parental to children’s generation—but instead laterally, between branches of species, how does that affect one’s vision of what a species is? Such re-envisioning of species, he helps the reader understand, requires our altering our basic concepts of how to put lifeforms into categories. Rather than a tree, the image becomes a web.

Science, Quammen continually alerts the reader, is not a set of abstract rules that are simply applied by practitioners. Rather, he offers numerous insightful portraits of individual scientists and the cooperation and competition between them. Notably, he showcases Carl Woese for his identification of the “third domain.” Moreover, Quammen explores the influence of the social construction of scientific communities. Important influences on conducting original research and getting that research involved in practical applications include the gendering of science. Quammen stops short of exploring reasons for male dominance in the hard sciences, but he includes prominent women, such as Lynn Margulis, who have played crucial roles in the recent advances.

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