The kangaroo is the first organism, but the fungus is not the biggest

So the record for the "world's largest organism" has again been claimed for a fungus, something Stephen Jay Gould wrote about in his wonderfully titled essay "A Humongous Fungus Among Us" back in 1992, and which was included in his volume A Dinosaur in a Haystack.

The previous fungus, Armillaria gallica, is now replaced by a related mushroom stand, Armillaria ostoyae, in Oregon's Blue Mountains. But I have my doubts. The term "organism" here has a meaning rather different to "relatively undifferentiated mass of related stands". In fact, I want to talk about the notion of an organism, and how it has developed over the years.

It may surprise folks to learn that for the bulk of western history, there was no such concept as an "organism". Sure, there were things that grew, and things that could move, and so on, but until around 1800 or so there was no general category of living things as such. Instead, the prior classification began with unmotivated matter, as it were, and rising through Aristotle's levels of "soul", shown below as "mineral" (e.g., petra, or rock), "vegetable" (grows and reproduces; arbor or tree), "sensible" (reacts to its environment and moves of its own accord; equus or horse), and "rational" (is capable of using reason; homo or human). The moral equation to these souls is shown on the right hand side: in descending order, virtue (studiousness), luxury (sensuality), gluttony (feeding) and despair (like a rock - literally, "stoned").

You can see the addition: things have being (est), and perhaps growth or life (vivit), and perhaps sentience (sentit) and perhaps thinking (intelligit).

This was the view bequeathed to the renaissance from the middle ages (the figure is from the 16th century). By the end of the 18th century, however, something had happened. It began with Francis Bacon asserting in The New Organon that final causes - accounts of things in terms of what they are there to do - were barren except when dealing with life and mind, and in particular human life and mind.

Shortly after this, the tradition that came to be known as natural history (the word "history" comes from the Greek term historia, which means "investigations"; the sense of it being about the past is due to the use of the word in the opening words of Thucydides' History) began, but even here, no great distinction was made between living and other things, and "natural history" was used indifferently for geology, biology, meteorology, and psychology.

The medieval view held sway until the end of the 18th century - it's last great exponent was Charles Bonnet in 1764; Lamarck adopted it but turned it on its side to form a temporal sequence. But by this time, it was becoming clear that life was sui generis - its own kind. Lamarck himself, independently of Treviranus, in 1802 coined the term "biologie", and life took on an independent intellectual history, although many of the subsequent researchers, including Charles Darwin, thought themselves to be geologists first and naturalists second for some time, until geology had become a separate discipline.

Bonnet is crucial for another reason - he is the fellow who begins to talk about "les corps organisées" (organised bodies) when referring to living things, in an 1762 book. Bonnet was a preformationist, and believed that the germ (the term for that which germinates in living things) had to be at least as complex as the final adult form of an organism, and so for him, organisation was central.

About this time, in the early 19th century, then, logicians began to speak of "natural beings", or "organised beings" to distinguish between them and inorganic objects. Richard Whately, in a text that is the great reviver in English of the treatment of formal logic, Introduction to Logic, referred to "organized beings" when talking about living things (Bk IV ch5 §1, p309 this edition). "Human beings" is of course a subset of this category of things that have organs, or are organised. By 1833, the word "organism" was being used to refer to these sorts of beings, according to the Oxford English Dictionary [subscription required], in a paper [JSTOR subscription needed] in the Philosophical Transactions of the Royal Society of London, by Richard Owen, on the generation of marsupials. I like the Antipodean connection here, and this is what gives the first part of my title (that, and Paul Griffiths' suggestion). Owen writes

[p]erhaps it is more philosophical to consider generation as having reference rather to the whole nature of the thing generated, and its relative perfection as compared with other species, than to partial modifications of the mother.

and goes on to say

Now it is in the Mammalia that the brain is perfected: we can trace through the different orders the increasing complication of this organ... And if the introduction of new powers into an organism...

And so it is that "organism" means, and has always meant, that which has organs, or is organised.

In recent years E. O. Wilson among others has used the term "superorganism" to mean a colony or group of organisms in which there is a differentiation of role. It may suprise him (although given his erudition, perhaps not) that the term "organism" itself has meant exactly that in the years since Owen used the term. The much older doctrine of the macrocosm/microcosm, which used analogy between the organisation of the organism and the cosmos to argue that the entire universe was a kind of organism is also relevant here. And today, of course, some argue that earth itself, under the rubric Gaia is also an organism.

All of this notwithstanding, I think that it is at best loose talk to call the gallica stand an "organism". You can chop off almost any sized part of that mass and grow from it. This means that it lacks the kind of coherence and differentiation of parts that a (classical) organism has. This is not true, however, of plants that can be vegetatively propagated - not all parts of a tree can be encouraged to grow. But there are enough contrary cases to test our intuitions and exemplars.

In botany, clonal stands are not called "organisms", but neither are they called a mass. Instead, special terminology has been devised to deal with these border cases - the entire clonal stand is a genet, while the individually viable "organisms" are called ramets. You can divide a genet into many ramets (this is how the Wollemi pine is being propagated for commercial sale); it is hardly fair, then, to call the entire ramet an "organism". And the divisibility of early stage embryos into viable individuals is itself an indication that they are not yet organisms either. This may have implications for the abortion debate, but I won't enter into that quagmire here.

So, what is the biggest organism in the world? I think it has to be the sequoia trees - they function as a whole, are differentiated into organs, and have a threshold of damage that will kill them. Apologies to Gould and to Oregon.