Investigating the rise of oxygenic photosynthesis
About 2.4 billion years ago, at the end of the Archean Eon, a planet-wide increase in oxygen levels called the Great Oxidation Event (GOE) created the familiar atmosphere we all breathe today. Researchers focused on life's origins widely agree that this transition event was caused by the global proliferation of photosynthetic microbes capable of splitting water to make molecular oxygen (O2). However, according to Tanja Bosak, associate professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences (EAPS), researchers don’t know how long before the GOE these organisms evolved. Bosak’s new research, published today in Nature, suggests it might now be even harder to pin down the emergence of oxygen-producing microbes in the geologic record. A signal in the rocks The first microbes to make oxygen did not leave a diary behind, so scientists must search for subtle clues of their emergence that could have survived the intervening few billion years. Complicating things...