The origin and nature of life on earth: the emergence of the fourth geosphere, by Eric Smith and Harold J. Morowitz

摘要

We now know a great deal about the nature of life on Earth. We understand how it functions and, in many cases, how it can be modified; but how it arose here in the first place remains an enduring mystery. It is well established that life in some form, probably akin to bacteria, was already flourishing about 3.8 billion years ago, i.e. almost as soon as the young Earth had cooled enough for it not to be cooked. Once life had appeared, it is not difficult to envisage how the combination of random mutation and Darwinian evolution (survival of the fittest) has brought us and the Earth to where we are today. There remain some notable residual problems, e.g. the seemingly improbable appearance of the complicated eukaryotic cell which forms the building blocks for the higher forms of life like plants and people but, in a rough-and-ready kind of way, the story seems clear and convincing. Unfortunately, however, no evidence remains about how the process got started.