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The properties of RNA make the idea of the RNA world hypothesis conceptually plausible, though its general acceptance as an explanation for the origin of life requires further evidence. [21] RNA is known to form efficient catalysts, and its similarity to DNA makes clear its ability to store information.
The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, [178] [179] [180] including in comets, [181] and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA ...
An origin-of-life theory based on self-replicating beta-sheet structures has been put forward by Maury in 2009. [76] [77] The theory suggest that self-replicating and self-assembling catalytic amyloids were the first informational polymers in a primitive pre-RNA world.
In any case, the problem lay buried in the catch-all rubric "origin of life"--where, because it is a biological not a (bio)chemical problem, it was effectively ignored. Scientific interest in cellular evolution started to pick up once the universal phylogenetic tree, the framework within which the problem had to be addressed, was determined.
Support for the theory persisted, however, with Fred Hoyle and Chandra Wickramasinghe using two reasons for why an extra-terrestrial origin of life might be preferred. First is that required conditions for the origin of life may have been more favorable somewhere other than Earth, and second that life on Earth exhibits properties that are not ...
Antonie van Leeuwenhoek. Traditional religion attributed the origin of life to deities who created the natural world. Spontaneous generation, the first naturalistic theory of abiogenesis, goes back to Aristotle and ancient Greek philosophy, and continued to have support in Western scholarship until the 19th century. [15]
Viruses may even have multiple origins and different types of viruses may have evolved independently over the history of life. [52] There are different hypotheses for the origins of viruses, for instance an early viral origin from the RNA world or a later viral origin from selfish DNA. [52]
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...