Featured Stories, MIT EAPS, News | May 24, 2018

How the Earth Got its Oxygen

By MIT science writing graduate students Ashley Junger, Heather Mongilio, Kelsey Tsipis, and Fatima Husain

Over 3.5 billion years ago, Earth’s atmosphere was very different: It lacked oxygen. Accordingly, the organisms had metabolisms suited to an anaerobic environment. But around 2.3 billion years ago, oxygen levels began rising, and scientists think this was due to a change in the metabolisms of Earth’s microorganisms. However, when and how this happened remains a mystery, but two MIT scientists are on the case.

MIT Department of Earth, Atmospheric and Planetary Sciences (EAPS) professors Greg Fournier and Tanja Bosak spoke with MIT science writers about how the geological record and genetics preserve fingerprints of Earth’s history. Bosak uses experimental geobiology to explore modern biogeochemical and sedimentological processes in microbial systems and interpret the record of life on the Early Earth. Meanwhile, Fournier addresses the problem from molecular phylogenetics standpoint, looking at genes and genomics within microbial lineages to produce molecular clocks. These clocks can help pinpoint when microbes were first able to produce oxygen and if/how those traits persisted into the future.