Lecture 13: What is Life?

How do we define life? This lecture reviews the six basic criteria for living systems described by biologists: order, reproduction, growth and development, energy utilization, reaction to environment, and evolution that characterize life. The last third of the lecture is an admittedly whirlwind review of natural selection (I got off my stride and got a little rushed for time at the end). The goal is not a complete survey of current biological thought, but to highlight those characteristics of "life" that may best inform us as to how to look for signs of life elsewhere in the Universe. Recorded live on 2009 Oct 12 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.