Re-animating the chemistry of Precambrian oceans: new perspectives on the environmental backdrop to early life (lecture)

Dr Nick Tosca, Oxford University

The Precambrian era, representing ~90% of Earth’s history, witnessed some of the most critical biological milestones in the history of life. From the origin and evolution of prokaryotic and eukaryotic cells, to the advent of multicellular and complex animals, these transitions each irreversibly altered the course of biological evolution. But what role did the environment play in ushering in biological innovation? Answering this question requires that we understand how the details of climate and marine chemistry are written in the sedimentary rock record. We have used experimental, theoretical, and analytical approaches to unravel chemical and mineralogical clues in Precambrian rocks that, in turn, lend special insight into the chemical dynamics of Precambrian seas. We are discovering how chemical element cycles such as Fe, Si, and C were connected to one another, and how oceanography exerted a strong control on the availability of key nutrients in Precambrian seawater. Together, these results are painting a new detailed picture of the physical and chemical structure of Earth’s most ancient oceans and how they set the environmental stage for the evolution of ancient microbial life.

Nick is a Fellow and Tutor in Earth Sciences at St Peter’s College, Oxford and an Associate Professor in Sedimentary Geology. He has been a Fellow of St Peter’s since 2014, appointed after a Lectureship in Earth Sciences at the University of St Andrews, and Postdoctoral Research Fellowships at Churchill College, Cambridge, and Harvard University. His research is focused on how Earth’s climate has evolved through its early history and how this impacted biological evolution.