Earth's 4.5 billion year history is a complex tale of deterministic physical and chemical processes, as well as "frozen accidents". Most models of life's origins also invoke chance and necessity. Recent research adds two important insights to this discussion. First, chance versus necessity is an inherently false dichotomy--a range of probabilities exists for many natural events. Second, given the astonishing combinatorial chemical richness of early Earth, events that are extremely rare may, nevertheless, be deterministic on time scales of a billion years.

Robert Hazen, Geophysical Laboratory, Carnegie Institution for Science