Possible impact of cosmochemistry on terrestrial biology: historical introduction

Abstract

Until the middle of the nineteenth century most philosophers, scientists and theologians assumed that life, even intelligent life, was not confined to Earth. Few of them, however, assumed that these organisms affected, or had affected, life here. The absence of human remains in ancient strata led, at the beginning of that century, to the suggestion that people were late intruders: later it was suggested that all life had come from Space. These speculations now seem quaint; our own may seem as quaint to our descendants. A few thoughtful scientists pointed out that these ‘explanations’ did not explain anything: they merely transferred problems. The presence of organic matter in meteorites was well known in the nineteenth century. There is now abundant quantitative evidence that molecules of many different types come here from Space; there is no unequivocal evidence that any have a biological origin. Nor is there evidence for the arrival of molecules of types that could not have been synthesized in the probiotic environment here by non-biological processes.