A new international study has revealed chemical evidence of life in rocks more than 3.3 billion years old, indicating that oxygen-producing photosynthesis may have emerged nearly one billion years earlier than previously understood.

The international team, led by the Carnegie Institution for Science, combined advanced chemical analysis with artificial intelligence to identify faint molecular traces of ancient biology preserved in Earth’s oldest rocks. Using machine learning, researchers trained computer models to recognize subtle chemical fingerprints left by living organisms, even when original biological molecules had degraded over time.

Among the collaborators was Michigan State University’s Katie Maloney, an assistant professor in the Department of Earth and Environmental Sciences, who studies the evolution of early complex life and its impact on ancient ecosystems. Maloney contributed samples of exceptionally well-preserved one-billion-year-old seaweed fossils from Yukon Territory, Canada. These samples represent one of the first seaweeds known in the fossil record, when most life can only be viewed through a microscope.