Some 3.8 billion years ago, in an era of churning seas and murky skies, a few chemicals combined under the right conditions, and life emerged on planet Earth. From that first cell, life progressed to a myriad of one-celled organisms, to organisms capable of photosynthesis, to multicellular organisms, to simple plant and animal forms, up to the complex life-forms we know today. This book traces these developments and how they may have occurred, through the scientific study of fossils, relationships among organisms, biochemistry of current life-forms, genetic sequencing, and laboratory experiments. Readers will also explore the complexity of cells and the ways science is making use of internal cell mechanisms for new discoveries in sustainable energy sources, cleaning up pollution, improving the food supply, and treating disease.