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Last Updated on September 1, 2019, by eNotes Editorial. Word Count: 413

Published in 2018, The Tangled Tree: A Radical New History of Life is written by science journalist and nonfiction writer David Quammen. The book traces the history of evolutionary genetics and molecular biology, while explaining the role of horizontal gene transfer in shaping genomes. Quammen states that this form of gene transfer, in which genes are transferred between different types of organisms rather than vertically from parent to offspring, plays a far greater role in evolution than previously hypothesized. He writes that this form of exchanging genetic material complicates the "tree of life" proposed by Darwin to explain the evolutionary relationship between different species. Under Darwin's hypothesis, speciation occurs slowly, as small genetic changes are passed down generation to generation. Horizontal gene transfer accelerates this process; genes can be transferred quickly between organisms to drastically change genomes. Quammen uses bacterial resistance to highlight the speed of this form of genetic exchange; bacterial species can rapidly become resistant to certain antibiotics by quickly transferring resistance genes between each other. Horizontal gene transfer occurs most often between microbes, but it can also occur in multi-cellular organisms (such as humans) through viruses and plasmids. He explains that this complicates the tree of life, making it more of a web with interwoven parts.

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The Tangled Tree is written in Quammen's typical style, in which he weaves complex scientific concepts with personal and historic anecdotes to make those concepts easily understood by the average reader. He highlights the changes made to the "tree of life" hypothesis over the last three centuries: the development of our understanding of microorganisms, endosymbiotic theory ,...

(The entire section contains 413 words.)

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