Feb. 19, 2019
Research Highlight
Productivity of Earth's Biosphere before Oxygenic Photosynthesis
Researchers have integrated estimates of primary production by early anaerobic organisms into a model to provide a better understanding of the productivity of Earth’s biosphere prior to the advent of oxygenic photosynthesis. On Earth today, photosynthesis ultimately fuels most life, and the raw materials used by organisms that perform photosynthesis are readily available. Prior to photosynthesis, it is unclear how productive the biosphere could have been.
The team of researchers looked at compounds that would have been required for early metabolisms on the ancient Earth, including iron and hydrogen compounds. Such compounds could have acted as electron donors, and would have been limited on the Earth due to the fact that they would be supplied geologically over long periods of time. This means that before life evolved the ability to use water as an electron donor in photosynthesis, productivity of the biosphere would have been magnitudes of order lower than today. The study has implications for understanding ancient life on Earth, and could also be relevant in understanding potential biospheres on worlds with subsurface oceans, where photosynthesis would not be possible.
The study, “Primary Productivity Was Limited by Electron Donors Prior to the Advent of Oxygenic Photosynthesis,” was published in the journal JGR Biogeosciences. The work was supported by NASA Astrobiology through the Exobiology Program.