The book reveals how a 19th century idea of Charles Darwin transformed modern science - enabling targeted cancer chemotherapy, gene editing with CRISPR, enzyme design with AI, and many more. Part I offers a highly accessible introduction to Darwinian evolution's central ideas, framed through medical puzzles and everyday observations. In Part II, the narrative deepens into the molecular logic of disease, drawing on real-world examples, interviews with physician-scientists, and the author's personal reflections to connect Darwin's ideas with today's biomedical innovations. Part III invites the curious reader to explore the quantitative framework that underlies this evolutionary lens, uncovering the elegant math behind mutation, selection, and fitness. The book concludes with a bold inquiry into the ethical, economic, and societal implications of evolution in the age of biotechnology. Written for students, educators, and curious minds alike, this book is ideal for anyone exploring a future in medicine, biology, or biotechnology - and for all who wonder how an old theory of life continues to shape its newest frontiers.