[OGD] The problem of taxonomy

  • From: "Peter O'Byrne" <oberonia@xxxxxxxxx>
  • To: orchids <orchids@xxxxxxxxxxxxx>
  • Date: Thu, 12 Nov 2009 00:05:33 +0800

I support what Finn N Rasmussen and Oliver Sparrow said in OGD V2 #321
(well, not Oliver's crack about Dendrobium), but I suspect that many people
are going to find the scientific jargon hard to swallow. Maybe this analogy
will help.

What taxonomists are trying to do is make a map. Now I don't know the USA
well enough to provide an example, so let's use London instead.

London has an underground railway system, popularly called the "Tube"
("subway" in Usan). Millions of citizens use it each day, and navigate round
it by means of simplified, colourful, highly-stylized maps. In my analogy,
each Tube station is a species, and you can tell which genus the species
belongs to by the colour of the line that joins the species ..... so all
stations on the red line could be Dendrobium species, all those on the blue
line are Cattleyas, etc. In this mapping system, each species is an entity
which is totally distinct from all the others ... and there is a blank (no
overlap) in the space between them. The citizens who use these Tube maps are
like most ordinary orchid growers .... they want to keep things simple, and
are quite happy with the idea that species are separate entities connected
by a genus.

But this isn't the only way of drawing the map. A different group of people
never use the Tube ... they want a map that allows them to navigate between
the stations using the roads at surface level. Obviously, their map will be
totally different to the Tube-users map, although the stations shown will be
the same. Both maps depict the same territory, but in different levels of
detail. One major difference is that the above-ground map acknowledges that
each station has a surrounding area .... analogous to the variation that we
see in any one orchid species in the wild population. And this is where the
taxonomic problems start ..... on the above-ground map, the surroundings of
one station overlap with the surroundings of the next. And people have to
decide which station any nearby particular building should be grouped with.
In my orchid analogy, the traditional taxonomists are the people who decide
this. Except, of course, they don't seem agree with each other.

Why is this a surprise ? Different people have always used different
groupings according to the things that they think are important. So while a
Tube-using tourist might think of St Paul's Cathedral as being near St Pauls
Tube station (which it certainly is), a road-using postman would probably
classify it under Blackfriars Station, because that is the nearest
post-office depot. My beer-loving friend Jim would classify anywhere in
London according it's proximity to a pub that sold real ale. We are all
familiar with using different mapping or grouping systems, and this doesn't
usually cause problems in everyday life. So why do we make it such a big
issue when it comes to orchids ?

Let's introduce the DNA-analyst people as "The Society for Evolutionary
Accuracy in Mapping", or SEAM for short. SEAM say that you cannot understand
the nature of the city without taking the historical context into
consideration. [Visitors from the colonies are often surprised just how much
historical context there is in London]. And of course, we all know they are
right ... after all, you'll have a much deeper understanding of St Paul's
Cathedral if you know about Christopher Wren, 2nd World War bombing raids,
and post-modern carbuncles. So SEAM have re-drawn the map of London. To do
this they ignored any roads or buildings constructed since 1950. Their map
reflects the evolution of the city from it's pre-Roman origins, and it has
revealed that the locations of our Tube stations have a really ancient
origin ... they lie at the intersections of invisible force-lines called
"ley lines". [Hey, if you think I've totally lost my marbles, try googling
"ley lines".]  Of course, the SEAM map ain't much use if you are just using
the Tube to get from A to B, but no Tube-user is ever going to bothered by
that. They'll keep on using their same old map, same as always, because it
works. And if SEAM decide that it would be more accurate to change "St
Paul's Cathedral" to "Caractacus Catuvellauni Fort", well .... good luck to
them. Maybe the new name will stick, maybe not. While the postman will
pretty soon get used to delivering mail to CCF, the taxi-driver will be able
to drop you at SPC for years to come. As long as people know they are the
same place, it doesn't matter too much which name you use.

In one sense, are these maps all accurate. In another sense, none of them
are. Is it worth getting so worked-up about them ? Surely the important
thing is to be able to use them (better if you can use several different
sorts) in the knowledge that they can never be more than approximations.


Peter O'Byrne
In Singapore, where buildings and roads change so fast that any map is out
of date before it is published.

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