COLLOQUIUM
Tuesday March 29th, 2011
12:00 P.M.–1:00 P.M.
Room dv 3130 (Council Chamber)
Greg Slater
School of Geography & Earth Sciences
McMaster University
“BIOSIGNATUARES AND ABIOSIGNATURES: FROM THE PAVILION LAKE
MICROBIALITES TO THE TAGISH LAKE METEORITE”
Two of the most basic questions facing science and society today are to understand the origins of life
and whether or not it occurred more than once, that is, are we alone in the universe? The increasing
discovery of exoplanets and new observations within our solar system, on Mars and in the geologic
record on Earth, raise intriguing possibilities for addressing this question. But how do we know whether
our observations are truly evidence of life? Answering this question requires an understanding of the
signatures of both biological processes of life and the abiotic processes that may create similar
signatures but not provide evidence for life. This talk will present research from both ends of this
spectrum. I will discuss the observation of a biosignature of photosynthetic influence preserved in
carbonate minerals currently precipitating within microbial communities living on the Pavilion Lake
microbialites. This will be contrasted to recent work studying abiosignatures of hydrothermal
processing of organic molecules in the Tagish Lake meteorite. While these systems are at either end this
spectrum, understanding the sources and cycling of elements and the potential creation of preserved
signatures is a fundamental component of our ability to assess purported evidence of life and thereby
understand the history of life on earth as well as determine what may represent evidence of life beyond
the Earth.
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