Major area of research is highly interdisciplinary with three major thrusts. I use stable isotope biogeochemistry to study modern environments on Earth from the tropics to deserts to the Arctic. Armed with this knowledge, I use what I’ve learned to study the biogeochemistry and paleobiology on Earth including how life originated and interacted with major geological forces over time. As an extension of this research, I participate in the study of astrobiology attempting to figure out the signatures of life that are robust enough to determine if and how life might have originated and functioned on other solar system bodies like Mars. B. S. in Biology, Penn State University (1973) and Ph.D. in Botany (Marine Science), University of Texas at Austin, Port Aransas Marine Lab (1977). Carnegie Corporation Fellow (1977-1979) and senior staff scientist at the Carnegie Institution of Washington’s Geophysical Laboratory (1979 to present). Visiting scientist at Carnegie’s Dept. of Plant Biology (1985-1986), Dartmouth College (1995), University of Maryland (2003-2005). Adjunct professor at Univ. of Delaware and Fellow at Smithsonian Environmental Research Center (2003-2009). Director of Geobiology and Low Temperature Geochemistry program at NSF (2009-2010). Member of AGU and the Geochemical Society. Principal Investigator (2007-2011), W. M. Keck Foundation, Investigating the Biosphere’s Roots in Deep Earth Geochemistry, studying the origins of biogeochemical cycles on earth and Mars and life in extreme environments. Member of NASA’s Astrobiology Institute since 1998. Published over 150 papers in refereed journals and books. Publications of note include: (l987) Depletion of 13C in lignin and its implications for stable carbon isotope studies, Nature; (1993) Photosynthetic fractionation of the stable isotopes of oxygen and carbon, Plant Physiology; (2005)Ecosystem collapse in Pleistocene Australia and a human role in megafaunal extinction, Science; and (2012) A Reduced Organic Carbon Component in Martian Basalts, Science. Elected Fellow of the Geochemical Society (2003). Served recently on the Geochemical Society’s Treibs Medal Committee, organized a recent session in Biogeosciences jointly with Planetary Science.