life with c & j

Canto: Hi, what's new?

Jacinta: Well I've been wondering about life, in a shallow sort of way.

Canto: What brought that on?

Jacinta: Some reading, of course. What else? Sparks to brighten the imagination.

Canto: To set it aflame.

Jacinta: The analytic imagination.

Canto: Bien entendu. So what about life?

Jacinta: Well, questions lead to more questions. What's the most basic form of life you can think of?

Canto: Hmmm. A virus? A chromosome? Is a chromosome alive? Remember the selfish gene theory? Was it a theory? To be selfish you have to be alive, don't you?

Jacinta: That's a lot of questions. Well done. Generally, I'm not sure that genes are considered to be alive, though they're obviously essential components of life. As we know it.

Canto: Probably depends which microbiologist you're talking to.

Jacinta: They've developed rules about what constitutes a living entity. Or someone has. But rules are made to be broken.

Canto: Let's hear them.

Jacinta: Well, first [but not necessarily first], such an entity has to metabolize. That's to say, it has to absorb something and burn it as fuel to maintain and grow itself. I mean, to provide it with energy. Which rules chromosomes out, maybe?

Canto: I haven't accepted any rules. Anyway, what is a chromosome? Tell me that.

Jacinta: Shit Canto, you gorgeous thing, don't sidetrack me. Let's just spell out these rules first, okay. The second rule is that life has complexity and organisation.

Canto: Right. No living thing that we know of, none that is uncontroversially accepted, prokaryotic or eukaryotic, is simple.

Jacinta: Absolutely. Bacteria are anything but simple. Third rule, but they're not in any order. All living entities reproduce.

Canto: That's almost too obvious. They produce again. Not quite the same as replicate. They don't produce replicas.

Jacinta: Well, near enough.

Canto: Near enough, indeed. Like two circles, neither of them exact.

Jacinta: Exactly. Fourthly, living entities develop. They grow, they absorb, they move, they struggle and suffer.

Canto: Death?

Jacinta: Let's not go there. Fifth, they evolve. That brings us back to those imperfect reproductions of course.

Canto: Like Chinese whispers, they change with changing conditions. They adapt. They want to preserve their identities and they strive for something fresh.

Jacinta: Worth exploring, but not now Canto, not now. Last rule, living entities are autonomous. They're not directed by or entirely dependent on any other living entity.

Canto: Ooh, that's a tricky one. Remind me never to make babies with you Jacinta. You'd see it as a living entity and therefore autonomous, and I'd be stuck with all the feeding, arsewiping, example-setting, obstacle-reducing, etc etc.

Jacinta: As if. But you're right, this is the most troublesome rule, and maybe the weakest. Where would a bacterium be without a colony - or an ant, for that matter?

Canto: A rough and ready set of rules.

Jacinta: Makeshift.

Canto: A starting point. So what is life?

Jacinta: I'm not sure, but here's to it loverboy.


Sources:
Peter Ward, Life as we do not know it: the NASA search for [and synthesis of] alien life. Viking, 2005