Biology and Philosophy 20 (4):633-671 (2004)
Life appears to be a natural property of matter, but the problem of its origin only arose after early scientists refuted continuous spontaneous generation. There is no chance of life arising ‘all at once’, we need the standard scientific incremental explanation with large numbers of small steps, an approach used in both physical and evolutionary sciences. The necessity for considering both theoretical and experimental approaches is emphasized. After describing basic principles that are available (including the Darwin-Eigen cycle), the search for origins is considered under four main themes. These are the RNA-world hypothesis; potential intermediates between an RNA-world and a modern world via the evolution of protein synthesis and then of DNA; possible alternatives to an RNA-world; and finally the earliest stages from the simple prebiotic systems to RNA. The triplicase/proto-ribosome theory for the origin of the ribosome is discussed where triples of nucleotides are added to a replicating RNA, with the origin of a triplet code well-before protein synthesis begins. The length of the code is suggested to arise from the early development of a ratchet mechanism that overcomes the problem of continued processivity of an RNA-based RNA-polymerase. It is probable that there were precursor stages to RNA with simpler sugars, or just two nucleotides, but we do not yet know of any better alternatives to RNA that were likely to arise naturally. For prebiotic stages (before RNA) a flow-reactor model is suggested to solve metabolism, energy gradients, and compartmentation simultaneously – thus the intense interest in some form of flow reactor. If an autocatalytic cycle could arise in such a system we would be major steps ahead. The most likely physical conditions for the origin of life require further clarification and it is still unclear whether the origin of life is more of an entropy (information) problem (and therefore high temperatures would be detrimental), rather than a kinetic problem (where high temperatures may be advantageous).
|Keywords||origin of life RNA world origin of the ribosome Darwin-Eigen cycle flow reactor|
|Categories||categorize this paper)|
References found in this work BETA
The Spontaneous Generation Controversy From Descartes to Oparin.John Farley - 1979 - British Journal for the Philosophy of Science 30 (1):93-96.
Where is the Root of the Universal Tree of Life?Patrick Forterre & Hervé Philippe - 1999 - Bioessays 21 (10):871-879.
Early Evolution: Prokaryotes, the New Kids on the Block.Anthony Poole, Daniel Jeffares & David Penny - 1999 - Bioessays 21 (10):880-889.
Citations of this work BETA
Prebiotic World, Macroevolution, and Darwin's Theory: A New Insight.Luis Boto, Ignacio Doadrio & Rui Diogo - 2009 - Biology and Philosophy 24 (1):119-128.
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