This past week two reviews of WEIT have appeared, one in the Christian Science Monitor, which includes an attached podcast (click under the cover icon), and one by Eugenie Scott in the scientific journal Nature. Both are pretty positive, I think, though, that the Nature review is quite tepid. I suspect that one reason for this is that I have angered the National Center for Science Education (Genie Scott is its executive director) by claiming that science and faith are largely incompatible. The purported compatibility of these areas is a keystone of the NCSE’s strategy for selling evolution in the public schools, and the organization has a history of being diffident towards scientists who question such religious accommodationism, either in principle or as a tactic for getting evolution into the schools. The NCSE even has a “faith project” for demonstrating that faith and religion are compatible. My own view is that an organization designed to defend the teaching evolution should do just that and only that, and should stay away from religion completely.
There is one issue Genie Scott brings up that I want to respond to. She says this in her review:
A book for the public must simplify, but there lurks the possibility of subsequent distortion. Many people misunderstand evolution as a great chain in which simple forms evolve into more complex ones, rather than the branching and extinction of lineages. Amphibians did not evolve into reptiles, and reptiles did not evolve into mammals and birds. Rather, a population of early tetrapods — four-legged vertebrates — gave rise to a diverse group of organisms that included ancestors of modern frogs and salamanders, and to a separate branch characterized by having an amniotic egg. A primitive amniote gave rise to reptiles and birds on one branch, and mammals on another. Given that the branch leading to mammals preceded that leading to reptiles, it is misleading for Coyne to use the outmoded term ‘mammal-like reptiles’ instead of ‘non-mammalian synapsids’.
Well, this is a dispute about whether the common ancestor of mammals and reptiles could be considered a reptile, which many cladists don’t since the group “reptiles” must include ALL the descendants of a common ancestor. But if the common ancestor has many diagnostic characters of a reptile, then why not call it one? If you followed Scott’s line of reasoning, you could not say that the ancestor of modern amphibians was a fish, since the category “fish” must include the ancestral fish and ALL of its descendants. But everybody calls early lobe-finned fish “fish.” This criticism, I think, is pretty trivial.
Of course her criticism is trivial. That is all that is left when people try to fight against evidence. They pick on obscure, obtuse trivialities.
As far as:
I think you have not gone far enough, since they are absolutely and completely incompatible. One has truth, evidence and logic and the other has faith, fantasies, lies and delusions.
(Following comment by Greg Mayer, not Jerry.)
Scott’s criticism here is not just small beer, it’s really inside baseball. It concerns a recondite dispute among taxonomists as to whether or not named taxa need be holophyletic– i.e consist of a common ancestor and all it’s descendants– or may be paraphyletic– i.e. consist of a common ancestor and some, but not necessarily all, of its descendants. The class Reptilia, as usually conceived, is paraphyletic, because it gave rise to the classes Aves and Mammalia. Scott evidently prefers holophyly, and thus would not recognize the Reptilia (or if she did, she would have to include Aves and Mammalia within the Reptilia). But even given some position on this issue, it says nothing about which vernacular names to use, and which are best to use in a book directed not at specialists, but at the general public. That the familiar vernacular names used by Jerry are best in this instance is nicely illustrated by a line from Todd Wilkinson, a non-biologist, in his review in today’s Christian Science Monitor:
“Even the book’s cover illustrates the descent of birds from dinosaurs millions of years ago.”
Dinosaurs are paraphyletic, and thus, by Scott’s lights, this perfectly clear statement would have to be rendered as some awkward circumlocution akin to the one in her review about amphibians and reptiles. Jerry has not simplified, with a potential for distortion, as Scott would have it. The widely understood vernacular terms used by Jerry may be less congenial to Scott’s preferred position on some technical issue regarding taxon names. But he has chosen the best, and correct, terms to make his points clear. GCM
I see the criticism, but since Jerry wrote this book for the intelligent lay person, and not as a scientific paper, then widely understood vernacular terms were his correct choice.
As a lay person (I do not claim intelligence) I usually see the formal names as two piles of unintelligible consonants until I have read them 50-100 times before ‘worm’ becomes nematode and then becomes Caenorhabditis elegans.
I can sympathize with being less than thrilled with Genie Scott’s critique about “reptiles” etc., particularly when writing for the public, but there is more to be said on behalf of her view.
First, that critique is not just her personal opinion, rather it is a dominant or at least major opinion amongst paleontologists, systematists, and phylogeneticists (I mean the idea “names should be applied to monophyletic groups; this leaves aside details about whether or not the Linnaean system can/should be saved, phylocode, etc., which are more controversial). Certainly that is pretty much what they teach at Berkeley!
The reasons they have this view aren’t just about being annoying and renaming things as much as possible. Instead, the old practice of having paraphyletic taxa caused all kinds of problems:
1. One problem was that scientists & non-scientists alike would make incorrect judgments about the characters possessed by ancestral forms. E.g., if you think mammals evolved from reptiles, then you tend to assume that the common ancestor of mammals and reptiles, and all of those “mammal-like reptiles” up until they stop becoming mammals (whenever that is) had the “diagnostic characters” of present-day reptiles. But this often turned out to be wrong in detail. To find out what the characters really were requires a statistical analysis, i.e. cladistics, and then you often find that the old “diagnostic characters” don’t really define natural groups, and you are in the phylogenetic position again.
2. With paraphyletic groups like “reptiles”, the borders between reptiles and birds, or reptiles & mammals, were arbitrary. As more transitional fossils were discovered, the “diagnostic characters” became less and less meaningful. E.g., there is a big debate over whether a key step producing the 3-bone mammalian middle ear happened once or twice — if the answer is “twice”, then “mammals” on the diagnostic character definition evolved twice.
3. The fusion of traditional & phylogenetic systems also causes problems. E.g., as scientists moved towards making groups monophyletic, they tended to “lump” any fossil closer to a living clade A than other living clades into group A. These “groups” then get counted as “phyla” or whatever, leading to the appearance of an “explosion” of “phyla” in the Cambrian. But actually many of those fossils, outside of the modern clade, and are located down on the stem where they have some but not all of the features uniting the living clade. I.e., they are transitional, but the ranked classification system obscures that, leading to lots of confused talk (and creationist quote mines) based on a taxonomic artefact rather than reality.
There are other issues but those are some of them. I will admit that it is a difficult problem to figure out how to talk about evolution to the public, when the scientists are using modern systematics and the public & many popular writers are using the older system. A lot of creationist mileage has been gotten out of this confusion. Maybe the best we can do is erect some “common names” like “fish” and “reptiles”, admit they are paraphyletic and arbitrarily defined, and be done with it. But there might be some useful work to do for educators & scientists in this area.
Cheers!
Nick
(From Greg Mayer)
Nick–
All your points are well-taken, and are among the real scientific arguments made not just by Eugenie Scott (I didn’t want to imply her view was idiosyncratic) but by all who favor cladistic classification. But there’s also a standard and real set of counter-arguments (e.g., the border between mammals and non-mammalian amniotes, or between any holophyletic group nested within a larger clade and the rest of the clade, is arbitrary, regardless of what name or rank is used [if rank is used at all]). The very incomprehensibility of this argument and counter-argument to the average reader suggests that a book for the general public is not the place to conduct this debate.
I would add that I think that a classification comprising only holophyletic taxa is a drawback in explaining evolution to the public, because under such a system no taxon has given rise to any other taxon, and this blunts the claim of ancestry and common descent, thus allowing creationists to say that biologists don’t include these concepts in their classifications. This of course is not true, even for cladists (except some of the early ones, who, like the pheneticists, wanted classification and phylogeny to be unrelated, or related only coincidentally). The idea of ancestry is so firmly rooted in everyday experience and common knowledge– my grandfather is an ancestor of me and my cousin; wolves are ancestors of dogs; Latin is ancestral to Spanish and Italian– and so important a part of evolution, that it would be foolish to eliminate talk of it in our discussions of evolution, especially evolutionary history.
Greg
I don’t read Dr. Scott’s comment as criticizing Dr. Coyne’s systematics, but instead as criticizing the common problem of assigning paleospecies to modern taxa. She isn’t accusing Dr. Coyne of making this error, but instead expressing a wish that he would have done more to emphasize the non-directed branching nature of the evolutionary process than he did.
Perhaps we could rewrite the critic to say:
“Modern amphibians did not evolve into modern reptiles… Rather, a population of ancient amphibians gave rise to both modern amphibians and modern reptiles. The evolution of amphibians did not grind to a halt after reptile and amphibian lineages diverged; both lineages are evolutionarily liable and have continued to modify the features they inherited from ancestral forms.”
Matthew,
The nondirected nature of branching is precisely what I describe in the first chapter, which tells what a common ancestor really is–I say something very like what you suggest in Chapter 1! I am sure that this is an accusation of misrepresentation–and (to a cladist) it is. I just feel that it’s completely trivial.
I completely agree that it is a trivial criticism, but people often feel compeled to make trivial criticism.
And, of course, she does explicitly say your wording is ‘misleading,’ and
I concede that she really is saying that your usage of ‘outmoded’ nomenclature contributes to a misunderstanding, but regardless…
I suppose if you can’t say something critical, then you might as well not say something at all. 😉
Oh well…
Slightly off topic question, but could you give me the reference(s) for the horse limb (hoof) development stuff that is referenced in WEIT (vestigial organs, atavisms, etc)?
Two issues here; one is the tendency for non-biologists to interpret terms like “amphibians” and “monkeys” to mean extant amphibians ans monkeys, without realizing the incredibly rich diversity of extinct “amphibians” that a biologist might be referencing.
Second is the silly (IMO) insistence of clade-only taxonomists on scrubbing the vernacular of paraphyletic group-names, or of using the “inside baseball” revised (monophyletc) meaning of such terms without clueing in nonspecialists. Paraphyletc group names are very handy and not at all misleading if used correctly and if their use is understood by all parties involved. I get so tired of hardcore monophyletic zealots criticizing the vernacular use of perfectly meaningful terms like reptiles, algae, monkeys, lizards, fishes, prokaryotes, etc. Formal taxonomy is one thing (and I too insist on monophyletic formal taxa), but talking in everyday English is quite another. IMO.