Geobiology integrates many disciplines, from genomics to paleoenvironmental modeling to paleontology and geochemical analysis. They can be fruitful individually but, when combined, result in profound insights about life—past, present, future and elsewhere.
Geobiology, literally the intersection of geology with biology, is the study of the interactions that occur between the biosphere (living organisms and their products) and the geosphere. Therefore, it necessarily includes elements of the lithosphere, the atmosphere, and the hydrosphere (marine and freshwater). Because such interactions in our natural world are numerous and complex, there are dozens, if not hundreds of ways to approach the study of geobiology—from molecular genetics, to field geology, to geochemistry, to physics and computer modeling.
Since EAPS brings together world-class faculty across all these disciplines and more, our department provides a uniquely rich and fertile intellectual environment for the pursuit of this intrinsically interdisciplinary discipline.
In EAPS, activity under the umbrella of geobiology (and its close relation astrobiology) is broadly led by four principal faculty: Hayes Career Development Associate Professor of Geology Tanja Bosak, Kerr-McGee Career Development Professor of Biogeochemistry Shuhei Ono, and Professor of Geobiology Roger Summons, joined most recently by EAPS' newest Assistant Professor Greg Fournier.
Tanja Bosak studies biosignatures of microbial processes in modern and ancient sediments to understand the parallel evolution of life and the environment. Because microbes shape the environment more than any other life form (multicellular plants and animals are a conspicuous but not so important veneer on the real actors in the biogeochemical cycles of our planet!), and because we know that 85% of Earth’s history was prior to the advent of multicellularity, microbiologists try to understand this Earth-life interaction/coevolution from a microbiology perspective - growing bugs in the lab and seeing how their metabolisms work, what they do, what actually controls the chemistry in different environments - how they shape and are shaped by their environment.
Bosak's work integrates microbiology, sedimentology and stable isotope geochemistry with experimental geobiology to ask how microbes shape sedimentary rocks, how organisms fossilize and how microbial metabolisms leave biogeochemical patterns in sediments. Her lab uses this approach to explore modern biogeochemical and sedimentological processes and to interpret the record of life on the early Earth.
Recent work with EAPS first Crosby Postdoctoral Fellow Giulio Mariotti, and Cecil and Ida Green Associate Professor of Geology Taylor Perron, has resulted in a suite of elegant experiments at the intersection of geobiology and geomorphology demonstrating how microbial mats colonizing sediment surfaces can lead to the small-scale ripple structures often seen preserved in ancient sandstone. You can learn more about this work in the MIT News story Wrinkles in Time as well as the video Life on the Edge: A short film about biofilms.
Shuhei Ono’s research concerns the application of multiple-sulfur isotope systems to study reaction pathways in sulfur biogeochemical cycles. He applies this technique to study the deep biosphere, seafloor hydrothermal systems and deep time earth history. Complementing work in the Bosak lab, a particular focus has been to understand the origin of mass-independent sulfur isotope fractionation as a unique record of early earth’s atmospheric chemistry and microbial evolution.
A new research area for Ono’s group seeks to better constrain the sources and sinks of methane, an important energy source and significant greenhouse gas. His group has developed a state-of-the-art laser spectroscopy technique to measure its rare isotopologue, 13CH3D, and is using it to provide new and critical constraints for sources of methane in atmospheric and geologic environments. MIT-WHOI Joint Program graduate student Danielle Gruen is one of the members of the Ono Lab working on this project. You can get a taste for Gruen's passion for geo- and astrobiology in this video. Their work is reported in Measuring Rare Methane Isotopologues from deepcarbon.net.
Roger Summons is a biogeochemist involved in the study of a dizzying array of topics including the co-evolution of Earth’s early life and environment, microbially dominated ecosystems, the structure and biosynthesis of membrane lipids, biological mass extinction events (and the re-emergence of life thereafter) and the origins of fossil fuels.
Specific areas of interest include lipid chemistry of geologically significant microbes, organic and isotopic indicators of climate change, biotic evolution and mass extinction, age- and environment-diagnostic biomarkers in sediments and petroleum and Archean, Proterozoic and extraterrestrial biogeochemical fossils.
As PI of the MIT NASA Astrobiology Institute, Summons is involved with the Sample Activity on Mars (SAM) instruments aboard NASA’s Curiosity Rover being used to study potential organic material within the rocks on Mars. Through pyrolysis experiments on Mars analog materials, members of his lab attempt to mimic and verify key aspects of experiments conducted on the surface of Mars by the Curiosity rover. Summons talks about this work in a recent video produced for The Mars Lab, an education program geared to engaging high schoolers in the search for life on Mars and the technologies which enable that search.
Joining EAPS as an assistant professor in July 2014 Greg Fournier works at the interface between paleogenetics and the earth and planetary sciences. His research seeks to link early Earth geochemistry with life history using DNA sequences from extant genomes. Specifically, he brings expertise in the use of fossil/biochemical age calibrations of horizontal gene-transfer (HGT or the process of swapping genetic material between neighboring “contemporary” bacteria) events to time-calibrate the “Tree of Life”.
Before joining the department, Fournier had already been collaborating closely with another EAPS professor Dan Rothman (a broad ranging practitioner of theoretical geophysics), Roger Summons, and graduate student Kate French, on the development of a new theory about how microbes respond to mass-extinction events. In that work, the team showed that the die-off associated with the mass-extinction event ~252 million years ago, though triggered by massive volcanism, was most likely caused by a related bloom of methane-producing microbes that led to a deadly shift in climate and ocean chemistry. You can read more about this fascinating study in Ancient whodunit may be solved: The microbes did it! from MIT News.
Images: (Upper right) Biofilm distributions from a selection of Mariotti's ripple tank experiments - Image courtesy: Giulio Mariotti; (Upper left) The TILDAS instrument in the Ono Lab - Image courtesy: Shuhei Ono; (Lower right) Professor Roger Summons stands beside a twin of the Curiosity rover currently exploring Mars - Image courtesy: Roger Summons; (Lower left) A representation of the Tree (coral) of Life - from J.P. Gogarten, courtesy of Greg Fournier.