A high-temperature origin of life (80°-110°C) is widely favored (1-6) because hyperthermophiles, which grow at temperatures between 80° and 110°C, are claimed to be the oldest organisms on the Earth (7), although there are dissenting opinions (8-11). Added support for this theory comes from atmospheric models depicting an early warm (
85°-110°C) Earth (12, 13). Models for an even higher temperature origin include proposals that life arose in the 350°C submarine vents (14-17) or between 150° and 250°C involving temperature and pH gradients (18).
For a compound to be used in the first living organism it needs to be sufficiently stable so that the balance between synthesis and degradation does not result in vanishingly small concentrations. Previous studies have shown that a major problem with an origin of life between 250°-350°C is the stability of the presumed components of the first organisms, where the half-lives for decomposition are at most a few minutes (19-22). These data, however, do not deal with an origin of life between 80°-110°C, where problems with the stability of RNA previously have been pointed out (23).
We show here that the rapid rates of hydrolysis of the nucleobases A, U, G, C, and T at temperatures much above 0°C would present a major problem in the accumulation of these presumed essential compounds on the early Earth. A high-temperature origin of life involving these compounds therefore is unlikely. These results are applicable to any origin-of-life theory in which life begins with the evolution of a self-replicating genetic system capable of undergoing Darwinian evolution. A high-temperature origin of life involving compounds other than those discussed here or involving the evolution of metabolic cycles before the evolution of the first genetic material may be possible, but also would be subject to stability criteria.
Answers to all your Biology Questions
