YET ANOTHER REASON to hope that there’s no life on Mars.

UPDATE: Gary Hudson emails:

On the subject of life on Mars, the Fermi paradox, etc., there is another explanation for why we may not see extraterrestrial intelligent life, yet the universe could be crawling with bacteria.

In Power, Sex and Suicide, the Story of Mitochondria, Nick Lane argues that the evolutionary accident of mitochondria being survivably incorporated into a primitive eucaryotic cell happened by accident, and only once. It was this accident (if accident it was) that allowed multi-cellularity to become established. Without mitochondria, bacteria could not grow large enough and could not produce enough energy to form differentiated multicellular life, a prerequisite to intelligence.

If Lane is correct, then the step from non-life to life probably happens all the time, everywhere, using the same biochemistry. But the accidental incorporation of an alpha-proto bacterium into a host cell may have occurred only once in the long history of the universe. In that case, there’s pond scum everywhere but life as we envision it – with more than two cells to rub together – nowhere but Earth. Depressing thought, perhaps. On the other hand, more room for us.

Works for me.