For the John Templeton Foundation, I wrote the role of minerals as a precursor to life.
Our planet teems with life in even the most improbable places such as deep caves, undersea vents, or acidic hot springs. But is Earth the norm in the universe or the exception? Scientific and philosophical discourse on the prospects for life beyond Earth has long tended to gravitate towards two poles: on the one hand, viewing life on this planet as a sign of a cosmic imperative; or on the other, as a fluke unlikely to have been repeated anywhere else. For Robert Hazen, an astrobiologist and mineralogist based at the Carnegie Institution for Science in Washington, D.C., neither pole offers a satisfying paradigm. Instead, Hazen and a group of colleagues are applying a new set of statistical methodologies to map the continuum of probabilities for the chemical reactions related to life’s origin — giving insights into how and where to look for evidence of life outside of Earth’s bounds.
“You can think of the origin of life as a sequential number of chemical reactions leading from the geosphere to the biosphere,” Hazen says. To understand the probability of finding those reactions on a given planet, he says, we need to know both the probability that an individual reaction will occur in any instance and the probability that, given the surface area and time scale of an Earth-like planet, the reaction will have occurred at some point, somewhere.