Studies shed new light on ideal environments for origin of life
Two independent yet connected studies provide new insights into Archean terrestrial geochemistry, contributing to the search for the origins of life on Earth.
Co-authored by Dr Terry Kee, Reader at the School of Chemistry, the studies involved twelve research groups from seven countries, working in partnership to investigate how sedimentary hydrothermal systems served to influence the range of key chemicals available for early life to thrive.
It’s generally agreed that the complex chemistry that led to biological life probably took place in a geological environment where rocks, water and chemicals could interact – such as hydrothermal vents beneath the ocean, and the hot pools surrounding volcanoes.
However, one key question is how phosphorus, a vital component of biological life, became involved in the earliest life forms. The compound phosphate is both chemically unreactive and insoluble in water, making it difficult to determine how it could have travelled around geological environments.
Now, these studies indicate that a hydrothermal sedimentary environment may have offered ideal conditions for both making and distributing the chemicals necessary for life.
In the first study (Astrobiology, doi.org/10.1089/ast.2017.1680), sedimentary hydrothermal environments are proposed to have acted as fluidized bed reactors in the processing of carbonaceous material, exemplified by deposits located in the 3.5–3.3 Ga Barberton Greenstone Belt, South Africa.
The second paper (Nature Communications, doi.org/10.1038/s41467-018-03835-3) describes the processing of ferruginous phosphate deposits within SH systems such as those of the 3.8-3.7 Ga Akilia enclave, western Greenland.
Terry Kee, a co-author on both studies, explained: “Sedimentary hydrothermal systems have hitherto been only lightly sketched as environments for the diagenesis of key life elements on the early Earth. These two studies demonstrate how our picture of Archean geochemistry may change profoundly as a result of such processing.
“What the Nature Communications paper shows is that iron minerals and phosphate minerals can combine in hydrothermal sedimentary environments to make a new form of phosphorus called phosphite, which is both chemically more reactive and more water-soluble, making it far easier for early life to have used.
“This phosphite would have been easy to make and easy to distribute, and could have had a profound role in how phosphorus became to be used in all life on earth.”