The rapid emergence of single-celled life on Earth is not necessarily evidence that it was an easy step for evolution. See the discussion surrounding “condition

The rapid emergence of single-celled life on Earth is not necessarily evidence that it was an easy step for evolution. See the discussion surrounding “conditional on success, all the hard steps, no matter how hard, take about the same time” in this article: http://mason.gmu.edu/~rhanson/greatfilter.html http://mason.gmu.edu/~rhanson/greatfilter.html