Who I Am and What I Do
The earliest forms of life on Earth were microscopic. I study the evolution of micro-organisms over the long Earth's history, and then compare our findings with the corresponding changes in the Earth's evolution as a planet. To gather samples, our team of scientists goes to places with extreme environments, such as thermal springs and parts of the sea where the salt content is high. In these extreme environments (which in some ways mimic conditions in the primeval Earth), micro-organisms dominate, and scientists can study how they interact with each other. Another approach to studying micro-organisms that lived billions of years ago involves the gathering and analyzing fossil samples.

The organic molecules, proteins, fats, sugars and nucleic acids, that make up all living cells on our planet are made of long chains of the element carbon. My broad research interest focuses on the biogeochemical carbon cycle and the early evolution Earth and its biosphere. I specialize in studying the stable isotope geochemistry of carbon in lunar samples, meteorites, and oceanic basalts, as well as the carbon geochemistry of ancient (Precambrian) carbonates (a carbon containing part of inorganic molecules found, amongst other places, as a major component in the shells of mollusks).

My research interests extend to the new and exciting field of Astrobiology, which seeks to identify life in other planets, and to make predictions about what life forms future space missions may encounter. I am thus interested in current missions to Mars, and the wealth of information these probes are collecting regarding the extent of aqueous (caused by water) alteration of the Martian crust, as well as the search for fossil evidence of a Martian biosphere (that is: life on Mars).

My field work in geology and biology has taken me to Australia, Canada, South Africa, and Mexico, in addition to many locations in the United States. The interesting results of our research have been published in more than 105 peer-reviewed articles and book chapters.

As a Child
Growing up, I enjoyed exploring caves. In high school, I had a great chemistry teacher, whose enthusiasm for chemistry was infectious; I also began learning skills that are important to a scientist: I learned to be inquisitive and to ask questions. Later on, in college, I refined these skills while studying chemistry, physics, and mathematics. During this time I was introduced to the wonders of geology. I learned that many questions that we have about our biosphere and environment require the application of more than one of these disciplines; I also learned the scientific method, which provides a logical approach to finding answers to mysteries that intrigue me.

Career Journey
As a graduate student in the 1970s, I studied earth science (geology), and I remember being fascinated by the lunar samples we were able to study—which were brought to Earth by earlier NASA lunar missions. This experience led to my interest in space science. My thesis advisor revealed how the power of modern anlytical chemistry can unveil the early history of our biosphere. Later on I became involved with biology, which added a new dimension to my research. This led to my later work on how the carbon cycle relates to Earth's history and to astrobiology.

Advice
As an undergraduate, be sure that you get a good foundation in chemistry, physics, and mathematics, because they are the foundation of our efforts to learn the mysteries of life in the universe. Also, try to get some experience in a reseach laboratory while you are in college.

Personal
I enjoy spending my time doing research, but as a senior scientist, I need to make sure that others in my lab can have the resources and support they need to do their own research. This takes me away from the lab; still my leading role is a vital part of the team's research effort. Additionally, I continue to be deeply involved in field trips to coastal marine environments and to regions having ancient rocks, where our teams examine the nature of microbial ecosystems and the fossil remains of their ancestors. These trips are always educational, exciting, and crucially important for our research. My hobbies include: photography, hiking, and mining history. I am married and have two children, a son and a daughter.

Last Updated: August 15, 2001