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Last Reviewed on June 19, 2019, by eNotes Editorial. Word Count: 331

In The Tangled Tree: A Radical New History of Life, author David Quammen provides a history of the discovery of horizontal gene transfer (HGT) through the lens of the scientists involved in this discovery. These "characters" include Carl R. Woese, an American microbiologist responsible for the discovery of archaea. Archea are microorganisms that differ from other forms of bacteria in that they are anaerobic, often existing in extreme aquatic or terrestrial environments devoid of oxygen. This anaerobic quality provided evidence for a missing link in traditional Darwinism—the notion that all life essentially evolved from a single cell, and a model that suggests that all cells compete with one another for survival and only the fittest endure. Rather, Woese conjectured, life evolved from several cells working in correlation with one another, freely exchanging biological information as was mutually beneficial to previously independent cells.

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In a similar fashion, Woese's HGT theory supported the work of second character, Lynn Margulis. Margulis, an American biologist, was responsible for the theory of symbiosis, a model of evolution in which two organisms work in association with one another to form an original organism. For example, Margulis proposed that nucleated cells—eukaryotic—were the result of a cross-gene transfer between previously non-nucleated cells, coined as the serial endosymbiotic theory (SET). In her now highly respected publication, Symbiosis in Cell Evolution, Margulis provided another example of HGT in which eubacteria and Woese's archaea evolved into cytoplasm.

The revolutionary work of Woese and Magulis culminated in Tsutomu Wantanabe—a Japanese biologist at the University of Tokyo—discovering a strain of bacteria resistant to antibiotics as a direct result of horizontal gene transfer. This discovery supports the notion that single cells and their corresponding organisms are made stronger by working in correlation with one another, versus the Darwinian notion of ruthless competition. The works of these characters thus becomes a biological model for how we, as members of the human species, might better further our evolution via cooperation versus competition.

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