How did life become complex? Not through competition, but through merger. Lynn Margulis, one of the most brilliant and controversial scientists of the twentieth century, saw collaboration where others saw conflict. She proved that the foundation of complex life-our very cells-is a living monument to ancient, successful alliances. This idea, the Serial Endosymbiotic Theory, became the basis for a worldview that stretched from the petri dish to the entire planet. Providing the biological foundations for the Gaia Hypothesis, Margulis argued that Earth is not merely a collection of rocks and organisms, but a single, interactive, self-regulating system. This is the definitive biography of the fearless iconoclast whose defiant, cooperative vision changed modern biology and forced us to acknowledge our deep, intimate relationship with the microbial world. Approx.160 pages, 28500 word count