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Since Darwin, people have speculated about the evolutionary relationships among dissimilar species, including our connections to the diverse life forms known as microbes. In the 1970s biologists discovered a way to establish these kinships. This new era of exploration began with Linus Pauling s finding that every protein in every cell contains a huge reservoir of evolutionary history. His discovery opened a research path that has changed the way biologists and others think about the living world.

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