Had an experience common among students today - I sat through a 90 minute discussion of a book I hadn't read. (At least I didn't participate in the discussion!) The class, you'll be relieved to hear, was the one I'm taking, not one of those I'm teaching, and I have since done the assigned reading. The book is Robert M. Hazen's Genesis: The Scientific Quest for Life's Origins. It's sort of like what I reconstructed from the discussion...
Did you know that scientists' definitions of life range from "any population of entities which has the properties of multiplication, heredity and variation" to "an expected, collectively self-organized property of catalytic polymers," from "the ability to communicate" to "a flow of energy, matter and information"? NASA's definition, connected to its charge to seek extraterrestrial life, is "a self-sustained chemical system capable of undergoing Darwinian evolution." Our author's bemused by all the definitions, and is arguing instead that there are many steps along the way and what's interesting is that each is an example of emergence.
