Origins of Life: A Proposal for an Alternative Approach

The only possibility of obtaining information about what we will call the “objects” present in our environment is through our sense organs. They cannot detect life per se, but they are able to divide the objects they detect into two categories: non-living and living. Life can then be defined by “life is present where there is at least one living object”. The transition “non-living → living”, termed “spontaneous generation”, is impossible on the Earth as it is at present. By contrast, the transition “living → non-living”, termed “death”, is currently observed. A “criterion of life” can be obtained by observing the behavior of an unknown object under isolation vs. free contact with the outside. Since it is not possible for a living object to arise from a non-living object on the Earth as it is today, the beginning of the processes that were to lead to the first living object(s) must have occurred at the birth of the Earth (the epoch when it differed the most from what it is now). It was then much too hot for organic molecules to have existed there. Therefore, it is likely that the processes thus set in action first involved only mineral substances then evolved towards the acquisition of organic compounds as the Earth cooled. Hence it would have taken several hundred million years for the acquisition of the first protocells, finally followed over billions of years by their evolution into bacteria, animals and plants.