Thursday, June 17, 2004

Teach the Controversy? The journal Trends in Ecology and Evolution has recently hosted an exchange of editorials and letters to the editor on the issue of “Teaching the Controversy”. This is the rallying cry of ID proponents; doggone it, they just want to present leigitmate scientific controversies over the Neo-Darwinian theory of evolution, you know, so students will be better informed. Of course, such controversies as exist have nothing to do with the validity of anything that is taught at the high school level. When pressed for examples of weaknesses in evolutionary theory that students are currently not hearing about, they invariably come up with examples that are exaggerated, misinterpreted, and usually just plain wrong.

It is worth noting that “Teaching the Controversy” is hardly original with the ID crowd. It was also a favorite demand of the young-Earthers, and, to be blunt, of holocaust deniers.

The exchange began with this article by Eugenie Scott and Glenn Branch of the National Center for Science Education. Here's an excerpt:

Although 'teaching the controversy' sounds fair, it is unfair to pretend to students that a controversy exists in science where none does. It is unfair to students to miseducate and confuse them about the nature of the scientific process. Furthermore, there is a fundamental unfairness about the antievolutionist position, which, in essence, is trying to circumvent the normal process of peer review by which scientific ideas work their way into the science curriculum. As Lawrence Krauss, a physicist at Case Western Reserve University who was prominent in the recent struggle to protect the Ohio state science standards from antievolutionist attack, described his opponents, ‘They use language that sounds sensible. “We just want fairness,” they'll say. “We just want an equal playing field for our ideas.” The point is they already have an equal playing field – the field of science. They can submit their ideas to journals, and get peer reviewed, and if their ideas are any good they'll make it into the scientific canon, and make it down into the high schools. What they want is something completely unfair, to bypass the whole process and go directly to the high school students’

Two letters were published in reply. The first was this letter from Clarkson University biologist Tom Langen:

In an important recent Opinion article in TREE [1], Eugenie Scott and Glenn Branch propose five criteria for evaluating whether it is appropriate to teach a controversy in a public school science class. They argue that antievolutionary alternatives to the standard science account of organic evolution fail on most of the five criteria and, therefore, should not be discussed within the framework of a science course.

I propose a sixth criterion: the controversy should be taught if it clarifies the demarcation between science and other ways of knowing about nature. Most introductory biology texts (e.g. [2, 3 and 4]) begin with a chapter that reviews both the foundational assumptions about nature that underlie science (e.g. natural phenomena have natural causes, natural ‘laws’ operate everywhere and for all time), and the ethical ideals that the scientific community recognizes as being essential for scientific knowledge to progress (e.g. detailed public reporting of scientific research so that peers can accurately evaluate and replicate it, all accepted scientific claims are provisional and therefore might be revised or rejected upon further review). US national science education standards direct high-school science teachers to cover the assumptions and ethics of science [5].

Langan's letter is quite good. As Scott and Branch point out in reply, however, what Langen is proposing (and what he elaborates on in the rest of his letter) is a different sense of “teach the controversy” than what they were discussing in their original essay. Contrasting evolution with alternative, nonscientific theories, for the purpose of giving students a better udnerstanding of what science is and why scientists believe the things they do is entirely appropriate. That is not what the ID folks want, alas. Rather, they want to bamboozle students with enough false and misleading information to make them think that evolution is bad science.

Next came Stephen Meyer of the Discovery Institute. He offers a more hard-core response here:

Scott and Branch deny the existence of any significant scientific controversies about the ‘validity of evolution’. But the credibility of their position depends on definitional equivocation. All reputable scientists agree that ‘evolution happened’, they insist. Overwhelming evidence reinforces this opinion. And, of course, they are right if they equate ‘evolution’ with ‘change over time’ or ‘descent with modification’ (as they do when pressed).

Yes, life has changed over time. But, of course, neo-darwinism affirms a good deal more than that. In particular, it affirms that: (i) that an undirected processes, principally natural selection acting on random mutations, is sufficient to generate biological complexity; and (ii) all organisms have descended from a common ancestor.

Scott herself acknowledges significant scientific debate about the sufficiency of the neo-darwinian mechanism. Recently, in a public forum at the University of San Francisco, she also acknowledged that many evolutionary biologists now disagree about the truth of universal common descent. Our position, radical though it might seem, is that students should be informed about such dissenting opinion and, furthermore, that they should be told why some scientists doubt aspects of neo-darwinism.

Both of Meyer's points (i) and (ii) are misleading at best.

Scott and Branch offer their reply here:

The crucial phrase in clause (i) of Meyer's definition of ‘neo-darwinism’ [2] is ‘undirected processes’, the alternative to which is, presumably, directed processes. But directed by what? In spite of the CSC's nods in the direction of extraterrestrial aliens and time travellers from the future [5], God is clearly the favored candidate, as reflected in the CSC's original logo, featuring Michelangelo's God from the Sistine Chapel [6]. Is there, as Meyer implies, a scientific controversy about whether ‘directed processes’ are responsible for ‘biological complexity’? We are unaware of such a controversy, and we are confident that readers of TREE are too.

In clause (ii) of Meyer's definition, it is perhaps sufficient to observe that he conflates the undebated idea of common ancestry in general with the actual debate about whether it is possible to identify a single universal common ancestor. Woese's work (e.g. [7]), to which Scott was alluding in the forum that Meyer mentions, contributes to the latter debate. There is no reason not to sketch Woese's basic idea in a pre-university biology class. However, it would be scientifically inappropriate and pedagogically irresponsible to pretend that it challenges the common ancestry of primates, tetrapods, or eukaryotes, or that it constitutes evidence for a special creation of the three domains, or that it is anything but a necessary refinement of the idea of common ancestry.

Just in case you're not up on Carl Woese's work, the issue here has to do with horizontal gene transfer in ancient bacteria. Woese uncovered important evidence that some of the genetic commonalities among bacteria are due not to common descent, but rather to horizontal gene transfer, in which genetic material from one organism is, well, transferred directly to another. A more detailed description is available here.

The point is that such transfer makes it effectively impossible to identify the universal common ancestor, because the genetic relationships among the most primitive organisms are confounded as a result of genetic transfers. Such transfer, however, is only thought ot be significant in simple, prokaryotic organisms. As Scott and Branch point out, it has nothing to do with the common descent of, say, mammals from reptiles. And even if it were to turn out that such transfers are possible among complex organisms as well, that would hardly constitute an argument for supernatural intervention in natural history.

Incidentally, I learned about this exchange from the website of the pro-ID Discovery Institute. They had a link to Meyer's letter, but they linked to neither of Scott and Branch's essays, nor did they link to Langan's letter. Rather childish of them, don't you think?