Are viruses the ancestor of all living beings on Earth?

With the recent discovery of a truly monstrous virus, scientists are again casting about for how best to characterize these spectral life-forms. The new virus, officially known as Mimivirus (because it mimics a bacterium), is a creature "so bizarre," as The London Telegraph described it, "and unlike anything else seen by scientists . . . that . . . it could qualify for a new domain in the tree of life." Indeed, Mimivirus is so much more genetically complex than all previously known viruses, not to mention a number of bacteria, that it seems to call for a dramatic redrawing of the tree of life.

"This thing shows that some viruses are organisms that have an ancestor that was much more complex than they are now," says Didier Raoult, one of the leaders of the research team at the Mediterranean University in Marseille, France, that identified the virus. "We have a lot of evidence with Mimivirus that the virus phylum is at least as old as the other branches of life and that viruses were involved very early on in the evolutionary emergence of life."

http://www.sciencenews.org/articles/20060218/mathtrek.asp