2019 Volume 128 Issue 4 Pages Cover04_01-Cover04_02
The cover figure schematically illustrates the production mechanism of various metallic proteins. Through water–rock interactions, a number of elements in rocks dissolve in water. This process is probably significant in supplying mineral-derived nutrients for proto-life. Such materials can evolve into more complex organic compounds by reacting and mixing with other building blocks of life originating from the atmosphere. The three main rock types exposed on the Hadean Earth were KREEP basalt, anorthosite, and komatiite. These rocks included anhydrous reducing minerals, such as schreibersite (Fe3P) crystallized from the magma ocean. At approximately 4.37 Ga when the ABEL Bombardment (Part I) began, an oxidized atmosphere (CO2–H2O–N2) formed to initiate water–rock interactions. These interactions supplied Fe2+, S, P, Ti, Zn, Mo from KREEP basalt, Ca, Cr, Mg, Fe2+, Mn3+ from anorthosite, and Fe2+, S, Ni, Mg from komatiite. The surface of each type of rock allowed metallic protein to form, utilizing elements extracted from the rock. In an energy-material circulation system driven by a natural nuclear reactor, more complex building blocks of life were generated. Through this process, the first proto-life emerged with the creation of three different types of bio-film-like community on each rock surface (Refer to Yoshiya et al., 2019).