Marilyn Fogel

A vast reservoir of carbon lies beneath the Earth's surface. It is composed of organic material millions of years old that has a mass many times larger than that of all living animals and plants combined. It is critical to us because it is the source of all of our fossil fuels -- oil, gas, and coal. Carbon is also critical because within it, and in the organic molecules that give rise to it, are the keys to understanding the biological and geological evolution of our planet. Understanding the coevolution of biology and geology is essential for management of our resources and predictions of climate change in the next century.

Fogel's aim is to unlock the secrets within the Earth's carbon record through a unique combination of methodologies and techniques. She applies advanced biochemical, isotopic, and spectroscopic techniques -- some borrowed from the medical community -- to learn how and why biochemicals survive and transform into other molecules on the Earth's surface to eventually become part of the carbon reservoir below. She is interested to learn, for example, how carbohydrates make up such a large fraction of the organic matter in geological samples, when for years it was believed that carbohydrates were destroyed early in the decay process. She wonders how nonbiological complexes of carbohydrates with proteins and nucleic acids become structurally complex and stable geopolymers that withstand the test of time. To investigate such puzzles, her work straddles the territory between geochemistry and molecular biology.

Fogel is also interested in studying past global change by reconstructing ancient environments using tools of isotopic analysis. Her rationale begins with the dictum "You are what you eat." An organism's tissues retain the nitrogen, carbon, and oxygen isotopic signatures of its diet and environment. These signatures are retained over millions of years in fossils, particularly in shell or tooth fragments, and can be measured in the laboratory. Fogel has analyzed ancient emu eggshell, for instance, to learn how the practice of large-scale burning by ancient humans in the Australian Outback has altered the climate on a continental scale. Learning how such ancient environments have been changed by humans can help scientists better understand how humans now and in the future alter the global landscape.

Fogel is currently working in a new direction with fellow Staff Members George Cody, Douglas Rumble, and Bob Hazen. They and others at the Geophysical Laboratory are members of NASA's Astrobiology Institute, which is involved in studies searching for evidence of early forms of life on Earth, on other planets, and outside our solar system.

Fig. 8. Fogel and colleague Gifford Miller discuss their ideas and data in their field camp on the shores of Lake Gregory, located within an Aboriginal reserve in the Great Sandy Desert of Western Australia.