This long-term process set the stage for the evolution of eukaryotes—organisms that encase DNA within their cellular nuclei—which eventually began to breathe oxygen and grow into bigger organisms, said Annie Bauer, an assistant professor of geoscience at the University of Wisconsin–Madison. Whether this happened roughly simultaneously across the globe or in geographically isolated pockets at different times is still being studied. By comparing the timing of oxygenation from place to place, she said, scientists can determine whether these first whiffs arose together as a globally synchronous exhalation or as discrete puffs.
Office of Strategic Communication