Sunday, September 02, 2007

A Lesson In Creationist "Kinds"

My current edition of American Scientist has a wonderful article by Elaine Ostrander entitled “Genetics and the Shape of the Dog”. The piece generally focuses on the results of the dog genome project and its implications for understanding the genetics of canine diseases and potential changes to dog breeding programs. More specifically, the article discusses how an understanding of the dog genome demonstrates how tiny genetic changes lead to tremendous physical variation within the species.

In reading the article I could not help but be struck by the potential implications for creationism (both kinds – young-earth and intelligent design). Most creationists trot out the “kinds” argument for explaining the differences they see between different species: God created the basic kinds of animals (dogs, cats, horses, etc.) and all the species we see today are essentially variations on a theme. In other words, they can accept the relationship between genotypic change and phenotypic change only to the extent that these changes are limited to the same “kind” of animal. Dog variation (stand a Chihuahua next to a Great Dane, for example) can easily be the result of minor fluctuations in the genome – but the differences between a Chihuahua and a Siamese cat are the result of God’s creative separation of the species.

Creationists engaged in a cursory reading of Ostrander’s article (and can we expect creationists to engage in anything but a cursory reading?) will find the vocabulary necessary to proudly proclaim that “science” has verified the “kind” hypothesis of speciation. Of course, the “kind” hypothesis can only be supported if your knowledge of the animal world is extremely limited. Scientists working with either morphological (physical) or genetic variation among species understand that this discrete categorization of animals doesn’t work. One can easily envision the variation among dogs (most of us own one or more) and think that the “kind” hypothesis makes sense; but how many completely understand the range of variation within the genus Canis? The Family Canidae? The Order Carnivora? It’s easy to envision the “kind” separation between cats and dogs, but where does one “kind” end and another begin?

Ostrander provides an interesting figure showing the phylogenetic grouping of “dogs” based on a comparison of genetic sequences. Our domestic dog is grouped with an impressive array of wild species and the question to creationists begs itself: when is a dog not a dog? Wolves are clearly “dog-like”, as are coyotes. That’s easy. What about dholes and jackals? How about foxes? Certainly dog-like, but clearly some differences (to make it easier on our creationist friends reading this, we’ll follow their preferred methodology and ignore the morphological differences that don’t quite “fit” the “kind” hypothesis – foxes are dogs!). But we’re not even close to the end of the dog-like animals within the Canidae. Hyenas? What “kind” would they fall under? How about mustelids (mink, ermine, weasel, ferret)? Mephitids (skunks)? – are skunks more like dogs or cats? Or are they a separate “kind”? On Ostrander’s diagram “raccoon dogs” are listed. What about raccoons? Are they dogs…or are they bears? Some bears are awfully dog-like (particularly the smaller ones).

Of course all of my evolutionary biology friends understand this dilemma perfectly – and it is one reason we buy into evolution as an explanation for this huge variety of life we see around us. Taxonomy, like Sesame Street, certainly reflects the human propensity for grouping animals that are not like another. Very basic groups (dogs and cats) are simple to understand. But when you have knowledge of the entire range of animals represented in a group (Carnivores, for example) you spend a lot of time scratching your head (or arguing in the literature!) over a huge number of animals that do not quite fit in one group or another. And here I am just talking about living species. Add in the fossil record and (contrary to creationist claims) transitional species – species that don’t easily fall within one group or another because they share characteristics of both - are suddenly a dime a dozen. Of course the Ken Hams of the world are not interested in explaining the totality of the evidence – their only interest is in sifting the data for the few nuggets that support their own ideas. Contrary to Ham’s claims, creationists and evolutionary biologists are not looking at the same set of data!

In my college courses I generally prohibit students from writing papers on creationist ideas (unless it is from a strictly historical comparative perspective). I sometimes wonder if that is not a mistake. If the idea is to get a creationist student to “think outside the box”, then perhaps allowing a paper on creationism would be a better learning tool, provided it adhered to strict scientific guidelines. Could a creationist student learn something from the following assignment?...

Write a term paper on the creationist “kind” model. Compare and contrast a minimum of three family level groups of animals within the same order (Ursidae, Canidae, Procyonidae, for example). Re-group all genera and species from these families according to biblical “kinds” and then justify, in detail, the characteristics you used to organize them into separate kinds and why these characteristics are discrete for each kind.

For the intelligent design creationists out there I would modify the essay requirements:

Write a term paper on the creationist “intelligent design” model of species origins. Compare and contrast a minimum of three family level groups of animals within the same order (Ursidae, Canidae, Procyonidae, for example). Discuss, in detail, the mechanism for species divergence within each. At what taxonomic level is the designer likely to have intervened to define a new group of organisms (what criteria would you use to define the point at which a designer intervened? What drives the mechanism for the divergence (why did the designer intervene at this particular point and not another?).

It would certainly be interesting to see the results of such an exercise.


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The idea of "Kind" is psudoscience! said...

Wow, this creationist "kind" business sounds kind of hypocritical. Its basicaly the same as evolution with a few made up barriers thrown in isn't it?

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