Did viruses precede other life?

[iansmith]

Structural studies on ancient virus reveal clues about the evolution of life on Earth | By Cathy Holding



Viruses share a common ancestor that existed over 3 billion years ago and may even have preceded cellular forms of life, according to a report in the May 3 PNAS by George Rice and colleagues at Montana State University.

Based on a comparison of known virus types and an icosahedral virus isolated from a hot spring in Yellowstone National Park, the team found that coat proteins in all viral types that inhabit the three domains of life—Eukarya, Bacteria, and Archaea—have conformational similarities even though the genetics underlying them is quite different.

Nearly all of the Yellowstone virus' 36 predicted open reading frame products showed no significant similarity to proteins in public databases, and so basic structural and assembly principles in this virus were compared instead, revealing an “astounding” similarity with all virus types, according to the authors.

“This suggests that this type of coat protein arrangement preceded the split of the three domains of life over 3 billion years ago,” Mark A. Young, the team's leader and coauthor of the paper, told The Scientist.


http://www.biomedcentral.com/news/20040506/01

[mee]

How would they reproduce without a working cell to invade? My guess is that cells came before viruses and viruses are actually descended from cells that became more and more efficient at their processes until they shed most cellular function relying on their prey to reproduce for them.

[catch.yossarian]

Yeah, I agree with mee.

Viruses need organisms to live off of. Therefor viruses couldn't have existed before other life.

[iansmith]

Technically the viruses do not need an organism to live rather a molecular machinery is need to be provided. The first cell had the same challenge than the viruses, they require some kind of machinery to replicated their protein and genetic code. You have to wonder were the machinery came from. The cellular orgnization was not as it is nowadays, it was probably a loose and choatic system. Therefore some DNA particle could "borrow" the machinery of the loose entities, replicated and spread. These loose DNA particles then probalby evolve intoviruses and adapted to more organize and stringent entities which probably ressemble cell found nowadays.