How did life begin? Starting with the Big Bang Theory, this book systematically discusses scientific findings and hypotheses on topics such as the origin of chemical elements, formation of life on Earth, evolution of life elements, their subtle chemical reactions and miraculous physiological functions. The content in this book is carefully arranged to focus on major scientific discoveries in various disciplines related to life science, with particular emphasis on the vital relationship between chemical reactions in the human body and health, shedding light on hot issues of public concern such as nutrition and human longevity.