Back to the Beginning: The Miller’s Tale

Image: Wikimedia Commons.
Image: Wikimedia Commons.

Twentieth-century scientist and modern-day Promethean Stanley Lloyd Miller was famous for his ‘spark of life’ experiments of the 1950s. In those studies he subjected a mixture of H2S, CH4, NH3 and CO2 to electrical discharge in an attempt to mimic conditions on the early Earth prior to the evolution of life. However, it seems that Miller never got around to analysing some of the results of one of his 1958 investigations and the samples lay hidden away in a cardboard box for decades. Using modern-day analytical techniques – high-performance liquid chromatography and time-of-flight mass spectrometry, which are up to 1000 times more sensitive than those of the 1950s – Eric Parker and co-workers (PNAS 108: 55265531, 2011) have analysed some of Miller’s archived samples. Twenty-three amino acids and four amines, including seven organosulphur compounds, were detected in these vials, which marks the first synthesis of sulphur amino acids from spark discharge experiments designed to imitate primordial environments. Although this does not prove how the building blocks of life – still less life itself – were created, the simulated primordial conditions used may serve as a model for early volcanic plume chemistry and provide insight to the possible roles such plumes may have played in abiotic organic synthesis. Intriguingly, Parker et al. note that the overall abundances of the synthesised amino acids in the presence of H2S are very similar to the abundances found in some carbonaceous meteorites, suggesting that H2S may have played an important role in prebiotic reactions in early solar system environments. This will no doubt spark renewed interest in theories of how life began on Earth, and fuel further notions of panspermia and extraterrestrial influence on terrestrial biota and evolution. Sticking with this evolutionary theme, the next item takes the story a few hundred million years closer to the present day…