…and this is a 
Cuvier, and his British counterpart, Richard Owen, had an argument against evolution that you don't hear very often anymore. Cuvier called it the laws of correlation, and it was the idea that organisms were fixed and integrated wholes in which every character had a predetermined value set by all the other characters present.
In a word, the form of the tooth involves that of the condyle; that of the shoulder-blade; that of the claws: just as the equation of a curve involves all its properties. And just as by taking each property separately, and making it the base of a separate equation, we should obtain both the ordinary equation and all other properties whatsoever which it possesses; so, in the same way, the claw, the scapula, the condyle, the femur, and all the other bones taken separately, will give the tooth, or one another; and by commencing with any one, he who had a rational conception of the laws of the organic economy, could reconstruct the whole animal.
Cuvier famously (and incorrectly) argued that he could derive the whole of the form of an animal from a single part, and that this unity of form meant that species were necessarily fixed. An organism was like a complex, multi-part equation that used only a single variable: you plugged a parameter like 'ocelot' into the Great Formula, and all the parts and pieces emerged without fail; plug in a different parameter, say 'elephant', and all the attributes of an elephant would be expressed. By looking at one element, such as the foot, you could determine whether you were looking at an elephant or an ocelot, and thereby derive the rest of the animal.
Darwin's natural selection broke the narrow interpretation of the laws of correlation. He emphasized natural variation, the obvious observation that not all elephants or ocelots looked alike, and that individual parts can be plastic over time, and exhibit signs of adaptation. The creationism of people like Cuvier and Owen, though, was actually built on a rational, scientific proposition about the nature of organisms, and at least in the 19th century people could make principled, reasonable criticisms of evolution that built on prior science. Of course, one of the results of Darwin's meticulous observations was that there is no one fixed shape for a species — you can hand a skilled anatomist a claw, for instance, and he might be able to derive 'pigeon' from it … but not 'pouter' or 'fantail' or 'rock pigeon'. The results of the Great Formula are not quite so fixed as was thought.
Now some interpretations of Darwin go a little too far in presuming the organism is almost infinitely plastic, that selection can shape any one character in any direction and with a restricted scope — it can mold on part without complicating any other. We can, to a first approximation, pretend there is no Great Formula at all, no laws of correlation, just collections of characters aggregated in the organism that can be freely tweaked. This is going too far. Darwin himself, in The Origin, did not reject Cuvier's Laws of Correlation at all, and actually had a wonderfully modern view of the relationship of the parts of an organism.
In looking at many small points of difference between species, which, as far as our ignorance permits us to judge, seem quite unimportant, we must not forget that climate, food, &c., have no doubt produced some direct effect. It is also necessary to bear in mind that, owing to the law of correlation, when one part varies, and the variations are accumulated through natural selection, other modifications, often of the most unexpected nature, will ensue.
There is a Great Formula for organisms, but it's multivariate. There are many variables in the formula (I would go so far as to say that each gene is a separate variable, along with various environmental influences), the evaluation of the formula is a process called development, and that the final outcome, the organism itself, is the product of the integration of tens of thousands of parameters, each of which can be individually set, but that all contribute to the whole.
In essence, this is the objective of the field of evo-devo: to take the parts list that we're handed by molecular genetics and genomics, to figure out what the Great Formula for an organism is — that is, the relationships between the genetic parts during the development of the embryo — and decipher the permutations possible when the variables are modified by genetic/evolutionary events. We know what the parts are, and we know that many of the parts seem to be held in common from species to species; the next job is to figure out the assembly instructions, how they produced a functional form, and how those rules vary in different species. Cuvier and the scientific anatomists and physiologists of the 19th century could say that the laws of correlation exist, and what we're trying to do now in the 21st is work through system by system and identify what the laws of correlation are, and the molecular mechanisms underlying their operation.
This is a long introduction to a lovely paper that demonstrates the existence of a developmental rule, a law of correlation, in an evolutionarily significant process. I'm going to let you cogitate over the concepts for a little while, and later I'll summarize the details.
Life Science
Comments
Posted by: Blake Stacey | October 6, 2007 1:17 PM
I bet evolutionary psychology would be a lot easier if that were true.
Posted by: TomS | October 6, 2007 2:14 PM
I have tried to track down where Cuvier used this principle of correlation of parts as an argument specifically against evolution. I have no doubt that he held to this principle, and I have no doubt that he was an opponent of "transformation". I just would like to have a good reference where he tied the two together.
I think that this would be perhaps the first example of "irreducible complexity" being used as an argument against evolution. And I would like to add it to the Wikipedia article on "Irreducible complexity".
By the way, I happened across a reference to the correlation of parts in the Sherlock Holmes story, "The Five Orange Pips":
Posted by: Russell | October 6, 2007 3:28 PM
Did Cuvier spend much time in the field? That sounds much more like a desk theory than a naturalist's theory.
Posted by: travc | October 6, 2007 3:50 PM
I believe that "non-linear" is the appropriate term, not just multivariate. It is those annoying cross terms that account for so much of the complexity and wonderfulness of evo-devo (developmental gain and such).
Posted by: Stanton | October 6, 2007 3:52 PM
I think Cuvier did, he did explore some of the gypsum mines around Paris, and discovered several kinds of Eocene mammals.
Cuvier was also the reason why people thought the paleotheres were proto-tapirs for the last 200 years or so.
Posted by: Torbjörn Larsson, OM | October 6, 2007 4:20 PM
Cogitating ...
Cogitating ...
Cogitating ...
Ah, yes: One is of course free to chose what one would like to consider variables and parameters in a model. And it is certainly the case that alleles are variables in population genetics models.
But in evo-devo, genes are selected by the environment, expressed through the environment (development), expression changed by the environment (plasticity), and expression contingent on the environment (ie, fins are poor ambulatory devices on land).
To me it seems natural to consider the environment as variables and the genes as parameters. It is also consistent with them being less changeable than the environment and giving structure to genetic processes.
Posted by: inkadu | October 6, 2007 4:21 PM
I remember some genius writing in Seed about this very topic, using some funky beetle for an illustration... ;)
Posted by: David Marjanović | October 6, 2007 4:28 PM
One famous case is when such an Eocene mammal was discovered, Cuvier saw its teeth or something, and said it was a marsupial. A marsupial? In France? The fossil was prepared further, and lo, it had epipubic bones, which are absent in placental mammals* and were long thought to support the pouch in marsupials.
No wonder Cuvier is considered the founder of comparative anatomy.
* Later turned out to be present in many -- as the penis/clitoris bone.
Jim brought it up in the "Wells lies. Again." thread.
Posted by: Torbjörn Larsson, OM | October 6, 2007 4:28 PM
Cogitating some more: Another, perhaps more natural view, is to consider both environment and genes as variables with different time scales, placing the role of parameters on constraints. (Such as smallest and largest possible sizes.)
Hmm. Back to where I started, on a minor point no less. Now I understand why they describe it as "turn over in one's mind". :-P
Posted by: RamblinDude | October 6, 2007 4:47 PM
TomS: I read that Sherlock Holmes passage back in 1970(?), and I vaguely remember it because it had an impact on me!
Posted by: windy | October 6, 2007 5:05 PM
I bet evolutionary psychology would be harder, since we'd need to evolve a "evolutionary psychology" module first :)
Posted by: Thony C. | October 6, 2007 5:15 PM
Russell wrote:
Formed by a strict Protestantism, Cuvier's work ethic was steeped in an equally strict empiricism. He rejected speculative thought and in its place searched for "positive facts" accessible to accurate description.
Quoted from Georges Cuvier (1769 - 1832) by Oliver Rieppel in Darwin & Co. Eine Geschichte der Biologie in Portraits Ed. Ilse Jahn und Michael Schmitt. (My translation)
Posted by: obscurifer | October 6, 2007 5:22 PM
The foot bone's connected to the ankle bone.
The ankle bone's connected to the leg bone.
etc.
Posted by: tristero | October 6, 2007 6:09 PM
As the perenially interested layperson, I need to ask a really dumb question:
"you can hand a skilled anatomist a claw, for instance, and he might be able to derive 'pigeon' from it ... but not 'pouter' or 'fantail' or 'rock pigeon'."
Isnt' that exactly what a paleontologist does - infer the possibility (or not) of a new species from fragmentary fossils of an organism? What am I missing here?
Posted by: PZ Myers | October 6, 2007 6:36 PM
Yes -- you can hand a good paleontologist a fragment of a skeleton and he'll use his knowledge of other organisms to come up with a good idea of what it is. If you find a vertebra, though, there's nothing implicit in the structure of that one bone that will tell you what kind of skull is on top of it.
What does tell you is empirical knowledge. There are features of the vertebra that will tell you by comparison with other vertebrae whether it is from a bird, or a fish, or a reptile, or a mammal. There may even be some attributes specific enough to tell you what the likely family or genus might be.
Cuvier was an excellent comparative anatomist. He mistook his breadth of knowledge of known forms for the existence of deep rules for the relatedness of morphological features, a regularity of pattern that Darwin would come along and explain more simply as a consequence of lineage.
Posted by: Keith Douglas | October 6, 2007 7:40 PM
Does this have anything to do with Goethe and the sort of Platonic approach to form? (Urplane, I think.)
Posted by: Nebularry | October 6, 2007 11:14 PM
I think Cuvier may have been onto something, therefore, I'm making an intense study of Catherine Zeta Jones's parts. I'll get back to you on that.
Posted by: Thony C. | October 7, 2007 6:05 AM
Actually it's what a palaeozoologist does and it was Cuvier who founded the discipline of palaeozoology.
Posted by: hoary puccoon | October 7, 2007 10:27 AM
The beginning of this post leaves the misimpression that Georges Cuvier actually voiced criticisms of Darwin's theory. That would have been some trick, as The Origin of Species was published in 1859 and Cuvier died in 1832.
Posted by: Reginald Selkirk | October 7, 2007 1:49 PM
Extra! Extra! Cuvier predicted somatic cell cloning!Posted by: Thony C. | October 7, 2007 1:51 PM
Only if you think that Charles Darwin invented the theory of evolution. This of course not the case, both his grandfather Erasmus and Lamarck had put forward theories of evolution long before Charles and it was Lamarck who Cuvier attacked because Lamarck's theory contradicted Cuvier's own catastrophe theory of species development
Posted by: hoary puccoon | October 7, 2007 2:43 PM
Thony C-- yeah, notice how I carefully said Darwin's theory. It should really have been Charles Darwin's theory, to exclude Erasmus Darwin's theory of evolution.
The catastrophists had a kind of pseudo-evolution built into their theory, in which the major breaks in the fossil record represented total die-offs, followed by repopulation under God's new, improved plan. Geologists are now sure the breaks really were created by catastrophic die-offs (followed by adaptive radiation of survivor species) so the catastrophist's theory did have some solid evidence behind it and wasn't all that much worse as science than Lamarckianism. If Cuvier had lived to see the theory of evolution by natural selection, who knows how he would have reacted to it?
Posted by: David Marjanović, OM | October 7, 2007 4:09 PM
What you are talking about is that paleontologists -- just like other biologists -- look for consistent similarities differences between species or other groups. These can be quite obscure details of anatomy. If they occur on a vertebra, an isolated vertebra (or fructification or cuticle pattern...) or half of one or even less will be enough to tell you, with reasonable certainty, whether you're dealing with a known "species" (and which one) or not.
If not, it won't, though. It does often happen that fragmentary or poorly preserved fossils are indeed undiagnostic "at the species level" or even at higher levels. For example, isolated mammal teeth, especially molars and premolars, can often be referred to a single species and jaw position (like "right first upper molar"). Isolated hadrosaur teeth... IIRC it's possible to distinguish hadrosaurines and lambeosaurines that way, but that's all, leaving you with at least 10 species and hundreds of jaw positions in each.
Careful measurements and statistics can do wonders. Did you know there are two surviving species of tuatara, Sphenodon punctatus and S. guntheri? For a long time it was thought they could only be distinguished by molecular methods. Not so. Recently someone sat down, measured lots of specimens, and found consistent, if small, differences.
Posted by: Thony C. | October 7, 2007 5:00 PM
I wasn't criticising your post but rather supplementing it as you have in turn supplemented mine with your reply to which I would add one further comment. You wrote:
Neither Lamarck's nor Cuvier's science should be regarded in any way as bad. Both were excellent scientists who made very important contributions to the development of the life sciences, contributions without which Darwin's work would not have been possible. Both of them made errors and propagated theories that are now known to be false but so did every scientist who ever lived. I find it sad that many people, including many biologist who should know better, regard Lamarck as some sort of idiot who tried to steer biology in the wrong direction an error from which the great Charles Darwin saved biology! This is of course a total perversion of the history of biology.
Posted by: David Marjanović, OM | October 7, 2007 5:17 PM
Lamarck has a statue in Paris, next to one of the museum buildings :-)