Did life arise out of some primordial soup containing the brown organic sluge found in the Miller type experiments or were the foundations instead laid in the realm of inorganic chemistry?
Producted in a reducing atmosphere, thiolesters contain sulphur instead of oxygen groups
The atmosphere of the early Earth would have been very different from the present day, with an oxygenless swirling turmoil shot with volcanoes and lightning. This view of Earth's beginning would have had a highly reactive atmosphere containing S, ammonia NH4, and compounds like urea and Formaldehyde leading to the production Alderhydes and ketones i.e. sugars and other such organic compounds.
This was the atmosphere being reproduced in the Miller experiments, which produced the amino acids, these however are not particularly complex and the formation of peptide bonds which are essential for protein synthesis where still lacking. It now thought by some scientists that the reason for this is that the development of complex hydrocarbons and therefore life, as we know it, may not be due to the organic molecules themselves but templating and catalysation of inorganic minerals!
The cells of all organisms on the Earth today show remnants of this with the use of metal ions in metabolism. Due to the reducing atmosphere many minerals, which would be oxidised today, remained on the ancient beaches as sand grains. These minerals such as sulphides, iron pyrite etc…can act as catalysts for polymerisation of organic compounds, this is important as without the complex structures of protein enzymes these reactions would not occur and you end up with a chicken and egg scenario.
Another problem is that the Earth's early atmosphere may not have been as highly reactive as previously believed; instead it may have been a relatively inert atmosphere of N2 and CO2. If this was the case then mineral catalysts may well have been the only way to produce the more complex hydrocarbons.