The nature of life on Earth

Abstract

We are, of course, very familiar with life on Earth — its variety, its distribution, its behavior. This is the only sample we have of life in the Universe, and so we look to it for guidance as to what it is we should look for beyond the Earth, and where we are most likely to find it. This cannot be achieved in a few words, which is why I’ve devoted theree chapters to life on Earth — its nature in this chapter, its origin in the next, and its evolution in the one after. Throughout Chapters 3–5 I will concentrate on what is needed for discussing extraterrestrial life in later chapters.