Introduction to the Special Collection: Early Earth Environments and the Origins of Life

Questions about our earliest beginnings have filled thinking minds for millennia across cultures, faiths, and wide-ranging frontiers of research. Asking where we come from is as fundamental as astrobiology's driving query of "are we alone?" These days, we often link these questions as we explore life beyond our planet and solar system. Scientific steps toward answers have been big and frequent, but the pathways remain highly varied. Achieving something even close to a consensus has been elusive. The one thing we all can agree on, however, is that our understanding of Earth's earliest stages, and that of our solar system, has advanced by leaps and bounds over recent decades. No longer must we explore life's beginnings with little knowledge of how and when planetary habitability first developed and, more specifically, what the world was like roughly 4.4-4.2 billion years ago-a reasonable time estimate for the initial steps in the progression toward life. The simple distillation of this view is that models for life's earliest chapters, including experimental simulations of prebiotic chemistry, can and should be designed around an increasingly sophisticated understanding of Earth's initial boundary conditions, including the timing and controls on the emergence of oceans, the atmosphere, and tectonics-along with their coupled evolutions.