Research by a University of Minnesota Duluth (UMD) graduate student Mojtaba Fakhraee and Associate Professor Sergei Katsev has pushed a major milestone in the evolution of the Earth’s environment back by about 250 million years. While oxygen is believed to have first accumulated in the Earth atmosphere around 2.45 billion years ago, new research shows that oceans contained plentiful oxygen long before that time, providing energy-rich habitat for early life. The results of the two UMD scientists and their co-author Sean Crowe from the University of British Columbia have been published in the peer-reviewed journal Science Advances.