Carl, of course, is right in that it wasn’t long ago that biologists scoffed at the idea of bacteria being more than bags of chemistry. Carl’s thoughtful reply to my question included what, for me, is the best distillation of what virus’s “are.” He writes,
“So viruses may or may not be alive, but they are definitely a part of life.”
And as John and several commenters point out, viruses sure as hell evolve!
Still, I find myself in the gotta-have-metabolism camp. To me, that’s the dividing line between chemistry and biology.
As Carl notes in the section “The Shape of Life,” (page 20), “But on their own, genes are dead, their instructions are meaningless.”
I’ve heard viruses described as “escaped genes” … albeit inside nifty protein packages. But as Carl says, MICROCOSM is less about distilling definitions as it is about understanding the rules. In that vein, on page 21, he writes,
“The most obvious thing one notices about E. coli is that one can notice E. coli at all. It is not a hazy cloud of molecules. It is a densely stuffed package with an inside and an outside.”
So life has “boundaries,” an inside and an outside that must be actively maintained.
As cool as bacteriophages look with their lunar lander profile, they are mere snarls of chemicals in and of themselves.