Professor of Earth and Planetary Sciences and co-Director of Graduate Studies
Isotope geochemistry and historical geobiology. Re-animating ancient ecosystems and ocean chemistry using stable isotope systems, chemical speciation techniques, modern microbial experiments (for calibration) and theoretical considerations.
I combine approaches from the bio- and geo-sciences to address big-picture questions about the history of life on Earth and the potential for life elsewhere. This research is motivated by a desire to understand how life and the planet have changed together through time to reach the state that they’re at today and how that might be different on other planets where the environmental context for life or evolutionary contingency differ. My primary research goal is to understand the origin and evolutionary history of major metabolic pathways that have defined the primary productivity of the biosphere, such as photosynthesis, methanogenesis, and nitrogen fixation. These metabolisms have fueled life on Earth for most of its history, but were not all present at the origin of life. Instead, evolutionary innovations have accumulated through time, gradually increasing the productivity of the biosphere to what it is today. Understanding the origin of these metabolisms can help us to understand how and when life on Earth became productive and began to drive geochemical cycles, and will help us to predict how life may evolve on other planets.