3.5 billion years ago Earth hosted life, but was it barely surviving, or thriving? A new study led by researchers at the Earth-Life Science Institute of Tokyo Tech provides new answers to this question. Microbial metabolism is recorded in billions of years of sulfur isotope ratios that agree with this study’s predictions, suggesting life throve in the ancient oceans. Using this data, scientists can more deeply link the geochemical record with cellular states and ecology.