i was thinking about what i learned about viruses in school, that they exhibit characteristics of being alive and yet lack other traits in a way that suggests they are not alive.
since i couldn't remember what the rules were for the "are you alive or aren't you" question, i did a google search pretty much just that. according to some middle-school learning website that set things out in simple enough terms, these are the criteria that would make a virus "alive":
- obtain energy
- grow, develop, and die
- respond to the environment
what's interesting is that you'd think it would be a pretty clear answer, either something is alive or it isn't. viruses have their own genetic material, which seems to be a good sign of being alive, but they can't pass it on by themselves. when they latch on to another cell, then they can begin reproducing inside that host cell. they mutate, but they don't grow and so have no need for nourishment until they come in contact with a cell, and then it is that cell that needs the energy, not the virus. they don't move by themselves, and the question as to whether they respond to the environment is debated.
is a virus alive or isn't it? that should be a simple question, yet you can see reasons for both arguments, depending on what information you choose to look at.
hey, that's life.