NASA recently sent two probes to Mars to look for water.  They must either find existing life, evidence of past life, or conditions that allow life to evolve outside of earth if they hope to convince people that life on earth also evolved from non-living chemicals by chance.  Thinking people may ask, if this story is true then where is all the life?  Everywhere we look and as far as we can sense with our best instruments, there is no life.  There are elements, energy, even water - but no life.  So who exactly would E.T. call? Uplook Magazine, January-February 2005, p.29. References: Ward, P.D. and Brownlee, D. Rare Earth: Why complex life is uncommon in the universe. Copernicus. Springer-Verlag, 2000