Читать книгу IN THE BEGINNING - Welby Thomas Cox Jr. - Страница 15

One other point of contention is the presence or absence of ultraviolet (UV) light. This could be a strong influence in a terrestrial origin scenario with no protective ozone layer on the early earth, but completely absent in the deep-sea theory. The relative UV stability of RNA nucleotides suggests selection occurred in UV light – on the earth’s surface not in the sea.

This would also support the groundbreaking 2009 synthesis of RNA proposed7 by John Sutherland of the UK’s Medical Research Council Laboratory of Molecular Biology in Cambridge and his 2015 suggested synthesis of nucleic acid precursors starting with just hydrogen cyanide (HCN), hydrogen sulfide (H2S) and UV light.8 Illumination with UV light over 10 days enriched the yields of the biological nucleotides, adding weight to their selection being advantaged in UV light. Mulkidjanian has also suggested zinc sulfide precipitates could have acted as catalysts for carbon dioxide reduction using UV light – an early form of photosynthesis which he calls the ‘zinc world’ scenario

But according to Lane, ‘There is a big problem with life evolving with UV light, which is to say no life today uses UV as an energy source – it tends to destroy molecules rather than promote biochemistry.’ He also argues that the synthetic chemistry proposed in such terrestrial scheme just doesn’t look like life as we know it. ‘It starts with cyanides or with zinc sulfide photosynthesis and you end up with a kind of Frankenstein chemistry,’ Lane says. ‘The chemistry might work but to join that up with life as we know it, I would say is borderline impossible.