Book excerpt: All humans share three origins: the beginning of our individual lives, the appearance of life on Earth, and the formation of our planetary home. Life through Time and Space brings together the latest discoveries in both biology and astronomy to examine our deepest questions about where we came from, where we are going, and whether we are alone in the cosmos. A distinctive voice in the growing field of astrobiology, Wallace Arthur combines embryological, evolutionary, and cosmological perspectives to tell the story of life on Earth and its potential to exist elsewhere in the universe. He guides us on a journey through the myriad events that started with the big bang and led to the universe we inhabit today. Along the way, readers learn about the evolution of life from a primordial soup of organic molecules to complex plants and animals, about Earth’s geological transformation from barren rock to diverse ecosystems, and about human development from embryo to infant to adult. Arthur looks closely at the history of mass extinctions and the prospects for humanity’s future on our precious planet. Do intelligent aliens exist on a distant planet in the Milky Way, sharing the three origins that characterize all life on Earth? In addressing this question, Life through Time and Space tackles the many riddles of our place and fate in the universe that have intrigued human beings since they first gazed in wonder at the nighttime sky.