Linnaean quanta
The thing about Phylums and Classes and Orders and all,
They don’t really mean very much, from a-one to another –
They don’t show a definite border or wall,
Except that each member within is a brother.
But how shall we simply compare, say, a Fam’ly of fishes
With Fam’lies of insects or fungi, or some other race –
For nature won’t readily yield to our wishes
For systems and schemes with all life in its place.
What’s needed are rankings that indicate something specific,
Like maybe the age when such clades were diverging anew –
There must be a way to be more scientific
That merely to shrug and decide “this’ll do”.
Then maybe some Kingdoms or Phylums will prove to be hoarders,
While others lack class in their Classes, now under-supplied.
So finally, let’s bring an order to Orders,
And give ev’ry Genus some Family pride.
It always struck me that the Linnaean ranks would be more useful if either all of their inhabitants shared a minimum percentage of genes, or alternatively that they were diverging at roughly the same time as all the others of that rank.
Note that in the old method, species is the only rank which has some actual science behind it and isn’t just vibes-based. Except…it turns out that the concept of a biological species is far murkier and less discrete than we used to think, so even this is not really true any longer. Hybrids, it seems, just keep popping-up…
But this will cause its own oddities, such as Cheliserates (arachnids & horseshoe crabs) diverging from the other arthropods in the Cambrian before all of the currently-recognised phylums had appeared, meaning these would need to be recognised as their own phylum too. So we are back to (hopefully) common-sense rough collectives showing nested sub-groups within – but this only makes real sense when we examine the specific heirarchy, but not much when we compare the same level from different heirarchies.
But either way, the idea of the phylums being the major body-plan divisions is well-established, at least in the animals. And having four intermediate levels between there and species feels about right – we now know that there have been an order of magnitude more branches (mostly petering-out in extinction), but we don’t need to capture all the complexity of the Shrub of Life, this is intended to be a layman’s tool, not a PHD.
Yet I do wish when talking of, say, the Order of Proboscidea, they would add when the split occurred – in this case, in the early Paleocene. You’re welcome.
Rhyming Couplets 