I do enjoy a good mind stretching read and this article (only a fragment here, I get the whole issue as a PDF each month), gave me lots to think about.
I've seen many a text book which describe viruses as the smallest living thing. So small that they can 'infect' bacteria, but are they alive? Well they do reproduce although they are so simple that they can't even do that by them selves. They infect a cell and then modify the cells own DNA so that it then turns out copies of the virus. Dose this make them not alive? I'm not so sure. Strictly speaking we (humans) are similar in that it takes two to tango as it where. Not much of an argument, but there are other definitely living things in nature that are in symbiotic relationships with other species. Lichen is one that springs to mind, fungi and algae living together. Now I'm not sure if these two NEED to live together of if it's just useful for them, but it doesn't make them less alive.
Simplicity is another argument used to prove that they are non-living. They are just very simple chemical reactions, true, but then so are we, just on an much larger and almost infinitely more complex scale. Dose the scale change the fundamental concept? Well actually yes it must, other wise we would have to classify me putting bleach in my loo as creating life! But where to draw the line? Where ever the line is viruses are very close to it.
The problem is life is very difficult to define. We know what is alive and what isn't (mostly) but to put hard and fast scientific rules to that is hard. I sort of covered this on my cellular automata pages the digital ant hill (which was also inspired by an other scientific american article).
Oh and I've just got to say very cool cover artwork. Looks like we have a beholder on the cover!