OK, I know the answer to this, I just want to hear some reasons. Why isn’t fire alive? It breathes oxygen. It eats wood. It reproduces (sort of). What defines life? How do we know it’s not an advanced non-carbon-based life-form? On that same note, why isn’t a rock alive? If a rock grew at a nanometer every million years, how could we possibly study something like that? –Gwidion15, via AOL
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You know, Gwidion, a lot of people reading this are thinking, that’s what you get for riding a motorcycle without a helmet. Not me. Truth be told, though everybody thinks he knows it when he sees it, there is no widely agreed-upon definition of life. In fact fire is sometimes used as an example of something that obviously isn’t alive but nonetheless exhibits many functional characteristics of living things, e.g., metabolism, growth, reproduction, and so on. But if the functional definition (it’s alive if it acts like it’s alive) won’t cut it, what will? Here are a few other definitions of life:
A more serious objection is that by this definition a virus is alive. A lot of biologist types don’t buy this. A virus is basically a chunk of DNA or RNA (or computer code, for that matter) that succeeds in reproducing itself. But it’s not a cell, which many consider the fundamental unit of life, and it doesn’t do the things cells do, such as metabolize, react to their environment, etc.
Art accompanying story in printed newspaper (not available in this archive): illustration by Slug Signorino.
