Physico-chemical and evolutionary constraints for the formation and selection of first biopolymers: towards the consensus paradigm of the abiogenic origin of life.

During the last two decades, the common school of thought has split into two, so that the problem of the origin of life is tackled in the framework of either the 'replication first' paradigm or the 'metabolism first' scenario. The first paradigm suggests that the life started from the spontaneous emergence of the first, supposedly RNA-based 'replicators' and considers in much detail their further evolution in the so-called 'RNA world'. The alternative hypothesis of 'metabolism first' derives the life from increasingly complex autocatalytic chemical cycles. In this work, we emphasize the role of selection during the pre-biological stages of evolution and focus on the constraints that are imposed by physical, chemical, and biological laws. We try to demonstrate that the 'replication first' and 'metabolism first' hypotheses complement, rather than contradict, each other. We suggest that life on Earth has started from a 'metabolism-driven replication'; the suggested scenario might serve as a consensus scheme in the framework of which the molecular details of origin of life can be further elaborated. The key feature of the scenario is the participation of the UV irradiation both as driving and selecting forces during the earlier stages of evolution.