Friday, March 11, 2011

Koala bears

Admit it: You're thinking "But koalas aren't bears, they're marsupial!"

Fair enough.  This is, after all, the response we've all had drilled into our heads since grade school.

But why should it matter whether a koala is a marsupial and not an ursid?  Lots of things we call bears aren't members of family Ursidae.  For example:
  • Teddy bears
  • Chicago Bears football players
  • Statues of bears
  • Final exams
  • Goldilocks' Three Bears
It would generally sound silly to point out that teddy bears aren't really bears, or that bears don't actually talk, eat porridge and live in houses, or that "That test was a bear!" is just an expression, so why the urge to point out that koalas aren't in Ursidae?

Given the regularity with which it is pointed out that koalas "aren't really bears", it hardly adds much to point it out again.  There is, however, a fairly plausible explanation based not on some fundamental need taxonomic accuracy, but on normal rotten human nature: It serves to make known that, yes, you went to school and you, too, know that koalas are marsupial (or at least "not real bears" if "marsupial" escapes you at the moment).  You thus mark yourself as belonging to the "in" group (albeit not a particularly exclusive one) of Those Who Know Koalas Aren't Closely Related To Those Other Animals We Call "Bears".

Behind this is a more general notion: The "technical" definition is the "right" one and anything else is "incorrect" or, more cynically, "If I had it drummed into my head, so should you".

Again, fair enough.  I have no doubt that such balding-ape behavior is at work here, but what triggers it? Once more, why do we not feel compelled to mark ourselves as belonging to Those Who Know That The Chicago Bears Are Not Really Hairy Carnivores (well, actually ...)?

It seems this sort of behavior only comes out in borderline cases, where there is some chance that the listener isn't one of Those Who Know.  Koalas look and act a fair bit like ursids.  It's perfectly understandable that a European encountering a koala would think "That's a funny-looking bear," and so they did.  But now we know better, or at least Some of Us do.

It has been said that academic disputes are bitter precisely because the stakes are so low.  Just so, quibbles over usage are most heated precisely when they are inherently least consequential, that is, when the distinction in question makes little difference.  If I say "koala bear", you won't think I'm talking about a squid.  You'll know exactly which animal I'm talking about, but feel a strong urge to whisper "He doesn't know it's not really a bear" to the first Person in the Know that you can find.

The perfect in-group marker, evidently, is content-free.



One might be tempted to think that when it was discovered that koalas weren't actually placental at all and thus were not on the same taxonomic branch as the Ursidae, all educated persons began calling them by their right name and "koala bear" fell into immediate disuse.   Not so.  Search Google books for "marsupial koala bear" in quotes and you'll find at least three books, clearly written by trained biologists.  Why would a biologist say "koala bear"?  Why not?  From a biological point of view common names carry no particular weight.  If you want to be clear and unambiguous, you say Phascolarctos cinereus (or P. cinereus for short).


This sort of thing seems to happen a fair bit -- those who would presumably know best tend to be more casual in their usage than those who wish to appeal to them for authority.  It has been said, for example, that the term "tide" can only be properly applied to phenomena due to gravitational gradients, centuries of usage before and after Newton's gravitational explanation of the tides notwithstanding.  This does not, however, keep atmospheric scientists from studying "atmospheric tides".

These small daily fluctuations in air pressure, due to heating from the sun and in no significant way related to the moon, are nicely analogous to the usual oceanic tides.  Three possible explanations for this presumably "incorrect" name come to mind:
  • Whoever coined the term "atmospheric tide" mistakenly thought they were caused by the moon's gravity.
  • Whoever coined the term was unaware of the rule that anything called a "tide" or "tidal" must have a gravitational cause.
  • No such rule exists.
I'm going with the last of these.

2 comments:

  1. I know I'm playing the game by saying this but: That the tides are caused by gravity has nothing to do with their being called tides. They're called tides because they're regular in occurance. "Tide" is cognate with Ger. "Zeit," and meant (and in some contexts still means) "time."

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  2. Yep ... a couple of days ago I ran across "tidal volume" to do with the amount of air one breathes in and out. Perfectly sensible, unless you buy the "gravity" theory.

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