What did the Earth and the biosphere look like billions of years ago? And how did microbes and the environment coevolve?

I am a geobiologist with a deep love of microbes and a curiosity about microbial life on early Earth. My research centers around microbial-environmental interactions and how the biosphere and geosphere have co-evolved throughout Earth history. I am particularly interested in taphonomy – the study of the fossilization processes – and what taphonomy can tell us about ancient environments, early life, and the biological and abiotic processes that have shaped the Earth for billions of years.  

I am interested in both the impacts that microbes have on their environments and, in parallel, the impacts that environmental conditions have on microbes, their evolution, and their preservation in the rock record. The history of this coevolution of the biosphere and the geosphere is recorded both in the sedimentary record and in modern microbes and environments. I use a range of field based, experimental, and analytical techniques that tap into these modern and ancient records. With these tools, I hope to paint a more complete picture of ancient environments and the early biosphere and better understand how the biosphere and geosphere together shaped our planet over the course of Earth history.

Recently, I have extended my interests to the search for evidence of life outside of the Earth. On the Mars 2020 team, I became interested in understanding ancient environments on Mars, their past habitability, and their preservation potential. In my research, I continue to ask not only how we can identify and interpret biosignatures on Earth, but also how we will find evidence of past life on Mars, if it ever existed.