tecoyah

First we would need to find all the living creatures in the Universe....which we cannot do. Likely we can do so for the Earth, and perhaps the Solar System if we find life offworld. Many theories abound at this point, but I find the Mimivirus Connection quite compelling.....if incomplete.

"Viruses are parasites, so they can rely on the protein engineering of the host cell," Raoult said. He therefore found it "bizarre" that mimivirus would bother carrying around translation genes. The researchers are not yet sure, though, if the virus actually uses them.

Mimivirus’ unique nature may hold some key to the evolution of singe-celled organisms three billion years ago. Although it will likely take time to generate any consensus for it, the researchers advocate a fourth branch of life for mimivirus, and any other giant viruses that may turn up.

"It really is an organism," Raoult said. "You cannot believe it is just a biomolecule."

http://www.livescience.com/animalwor...ant_virus.html

It seems a possibility that something of this sort, allowed for the formation of self replicating cells in the distant past, and could therefore have started the ball rolling for evolution.