Studying ancient Earth is not new in astrobiology, but elucidating general principles – selection rules – has not been a focus. This needs to change in the coming decade as astronomers and astrobiologists are broadening their search strategy beyond an exclusive framework of “life as we know it” on “Earth 2.0”. Geochemical records of ancient Earth, and our increased understanding of factors that drove the chemical origins of life, permit us to explore alternate possibilities. In this talk, I will introduce our new experimental systems focusing on an astrobiologically important question: Would the coevolution of life and the Earth environment have worked out differently if we “replayed the tape” of evolution under slightly different conditions — as seems inevitable on other worlds? Should we expect that surprisingly small deviations to lead to biospheres that are radically differently from Earth to complicate our abilities to detect or interpret? In what ways will these biospheres differ, and hence, how should our knowledge of extrasolar planetary environments shape our search strategies? I will specifically focus on our recent efforts as a part of the newly funded NASA “MUSE” ICAR in understanding elemental selection and evolution across geologic time using laboratory and natural systems, and how lessons from our planet’s deep past may guide life search and detection strategies in the decades to come.

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