Authors: Carl Zimmer
This sort of argument swayed some state legislatures to pass laws requiring that creation science be taught alongside evolution. But the Supreme Court struck the laws down in the 1980s because they, in effect, endorsed religion. The Court declared creation science no science at all.
Creationists repackaged their old claims once more. They stripped away all mention of creationism, creation, and a creator. They argued instead that life shows signs of something they called intelligent design. DNA and proteins and molecular machines are simply too complex to have evolved by natural selection, they argued. These molecules were purposefully arranged, and that purpose reveals an intelligent designer at work. Just what or who that designer is they would not say, at least not publicly.
One of the most striking examples of this makeover was the transformation of a textbook originally called
Creation Biology.
A Texas publishing house had started work on the manuscript in the early 1980s, but in the wake of the Supreme Court’s rulings its editors began to replace the words
creationism
with
intelligent design, creator
with
intelligent designer,
and
creationist
with
design adherent.
Otherwise, they barely changed the language. In 1989, the textbook was published. Instead of
Creation Biology,
its publishers named it
Of Pandas and People.
The evidence for creation—including the flagellum—now became the evidence of intelligent design. Richard Lumsden of the Institute for Creation Research waxed rhapsodic about it in a 1994 article published in the journal of the Creation Research Society, a “young-Earth creationism” organization: “In terms of biophysical complexity, the bacterial rotor-flagellum is without precedent in the living world,” Lumsden wrote. “To the micromechanicians of industrial research and development operations, it has become an inspirational, albeit formidable challenge to the best efforts of current technology, but one ripe with potential for profitable application. To evolutionists, the system presents an enigma; to creationists, it offers clear and compelling evidence of purposeful intelligent design.”
While some proponents of intelligent design continued to call themselves creationists, others noisily rejected the name. They claimed that intelligent design is only the scientific search for evidence of design in nature. And for them
E. coli’
s flagellum was also a favorite example. William Dembski, a philosopher at Southwestern Baptist Theological Seminary, put it on the cover of his book
No Free Lunch.
He presented a calculation of the probability that
E. coli’
s flagellum had come together by chance. The number he came up with was spectacularly tiny, which Dembski took as evidence that it must have been produced by a designer. Biologists and mathematicians alike reject Dembski’s argument because it is supremely irrelevant. Mutations may be random—at least insofar as they don’t produce only variations an organism actually needs—but natural selection is not a matter of chance.
Dembski and other proponents of intelligent design claimed that the designer might be an alien or a time traveler. But personally they believed the designer to be God. Dembski wrote that intelligent design is essentially the theology of John’s Gospel in the Christian scriptures. And all the talk of aliens and time travelers did not scare off conservative religious organizations. Instead, they embraced intelligent design. Focus on the Family, for example, a large American evangelical organization, urged its members to demand that
Of Pandas and People
be used in schools whenever evolution was taught. In 2002, Focus on the Family’s magazine ran an article by Mark Hartwig extolling intelligent design. More than twenty years after Bliss’s lecture in Arkansas, creationists were still picking out
E. coli
as one of their prime exhibits.
“Darwinists dismiss the reasoning behind the intelligent-design movement, contending that living organisms were produced by the mindless processes of random mutation and natural selection,” Hartwig wrote. “But advances in molecular biology are shredding that claim. For example, consider the little outboard motor that bacteria such as
E. coli
use to navigate their environment. This water-cooled contraption, called a flagellum, comes equipped with a reversible engine, drive shaft, U-joint and long whip-like propeller. It hums along at 17,000 rpm.” Hartwig pointed out that it took fifty genes to create a working flagellum. If a single gene were disabled by a mutation, the flagellum would be crippled. There were therefore no intermediate steps by which a flagellum could have evolved. “Such systems simply defy Darwinist explanations,” Hartwig declared.
Focus on the Family was not the only organization trying to get
Of Pandas and People
into public schools. In 2000, a Christian legal organization called the Thomas More Law Center began sending lawyers to school boards around the country. They urged the boards to adopt the book and promised to defend them if they were sued. “We’ll be your shields against such attacks,” Robert Muise, one of the lawyers, told the Charleston, West Virginia, Board of Education. (The Thomas More Law Center calls itself “the sword and shield for people of faith.”) School boards in Michigan, Minnesota, West Virginia, and other states turned them down.
But in 2004 the Thomas More lawyers got a break when they visited the rural community of Dover, Pennsylvania. The Dover Board of Education decided to promote the teaching of intelligent design. One board member arranged for sixty copies of
Of Pandas and People
to be donated to the school library. The local school board added a new statement to the science curriculum. “Students,” it read in part, “will be made aware of gaps/problems in Darwin’s Theory and of other theories of evolution including, but not limited to, intelligent design.”
The board of education also demanded that teachers read a second statement aloud to all Dover biology classes. They were required to say that evolution was a theory, not a fact (confusing the nature of both facts and theories). “Intelligent Design is an explanation of the origin of life that differs from Darwin’s view,” the statement continued. “The reference book
Of Pandas and People
is available for students to see if they would like to explore this view in an effort to gain an understanding of what Intelligent Design actually involves. As is true with any theory, students are encouraged to keep an open mind.”
Dover’s science teachers refused to read the statement. They declared that to do so would violate the oath they took not to give their students false information. The superintendent came to the classrooms to read the statement instead. When curious students asked what sort of designer was behind intelligent design, he told them to ask their parents and walked out.
Two months later, eleven parents filed a lawsuit. Their lawyers argued that the statement violated the First Amendment because it represented the impermissible establishment of religion. And on an autumn day the trial began.
The plaintiffs called parents and teachers to testify how the board of education had pressured teachers not to teach “monkey to man evolution” and promised to bring God back into the classroom. The defense responded by bringing in two biologists as expert witnesses, Scott Minnich of the University of Idaho and Michael Behe of Lehigh University. Like Dembski, Minnich and Behe are fellows at the Discovery Institute in Seattle, the leading organization for the promotion of intelligent design.
Behe has never managed to publish a paper in a peer-reviewed biology journal arguing for intelligent design based on original research. Instead, he has presented his case mainly in op-ed columns, speeches, and books. Behe claims that some biological systems could not have evolved by natural selection because they are what he calls “irreducibly complex.” He asserts that something could be called irreducibly complex if it is “a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.” It would be impossible, in his view, for natural selection to gradually produce an irreducibly complex system, because it would have to start with something that didn’t work. “If a biological system cannot be produced gradually it would have to arise as an integrated unit, in one fell swoop,” he concludes.
Behe uses a few examples to illustrate irreducible complexity. The flagellum is one of his favorites. He claims it is obviously too complex to have evolved from a simpler precursor. Faced with the wonder of the flagellum, Behe writes, “Darwin looks forlorn.”
At the Dover trial, Behe had a textbook illustration of
E. coli’
s flagellum projected on the courtroom screen, and he proceeded to marvel at it all over again. “We could probably call this the Bacterial Flagellum Trial,” a lawyer for the school board said.
Behe inventoried the flagellum’s many parts and told Judge Jones that Darwinian evolution could not have produced its irreducible complexity. “When you see a purposeful arrangement of parts, that bespeaks design,” he said. The flagellum, Behe explained, was built for a purpose—to propel bacteria—and it was built from many interacting parts, just like the outboard motor of a boat. “This is a machine that looks like something that a human might have designed,” he said.
The plaintiffs’ witnesses were eager to talk about the flagellum as well, in order to demolish Behe’s claims about irreducible complexity. Kenneth Miller, a biologist at Brown University, pointed out that Behe’s claims about irreducible complexity could be tested. Behe, Miller reminded the court, had defined an irreducibly complex system as one that would be nonfunctional if it were missing a part. Miller then showed the court a computer animation of the flagellum. He began to dismantle it, removing not just one part but dozens. The filament disappeared. The universal joint vanished. The motor slipped away. All that was left when Miller was done was the needle that injects new parts of the filament into the shaft.
Miller had removed a great deal of an irreducibly complex system. By Behe’s definition, what remained should no longer be functional. But it is. The ten proteins that make up the needle are nearly identical in both their sequence and their arrangement to a molecular machine known as the type III secretion system. This is the needle used by
E. coli
O157:H7 and other disease-causing strains to inject toxins into host cells.
“We do break it apart, and lo and behold, we find—actually we find a variety of useful functions, one of which I have just pointed out, which is type III secretion,” Miller testified. “What that means, in ordinary scientific terms, is that the argument that Dr. Behe has made is falsified, it’s wrong, it’s time to go back to the drawing board.”
Behe tried to play down Miller’s testimony. When Behe said that a system became nonfunctional when it lost a part, he now claimed, he had meant that it lost its
particular
function. By removing part of the flagellum, Behe argued, Miller was left with something that could not propel a microbe. “If you take away those parts, it does not act as a rotary motor,” Behe said.
He then claimed that most people would assume Miller was implying that a type III secretion system evolved into a flagellum, something evolutionary biologists were not agreed on. Some had raised the possibility that the flagellum had evolved into a type III secretion system or that both structures evolved from a common ancestor. Yet Miller had not said anything of the sort. He had simply tested Behe’s claims, carefully hewing to Behe’s own words. And Behe’s claims had not held up to the evidence.
Over the course of the trial it became clear that Behe had some strange demands for scientists who would explain how the flagellum—or any other supposedly irreducibly complex systems—evolved. “Not only would I need a step-by-step, mutation-by-mutation analysis,” he said, “I would also want to see relevant information such as what is the population size of the organism in which these mutations are occurring, what is the selective value for the mutation, are there any detrimental effects of the mutation, and many other such questions.”
For the flagellum, Behe offered evolutionary biologists an idea for an experiment to overturn irreducible complexity. “To falsify such a claim, a scientist could go into the laboratory, place a bacterial species lacking a flagellum under some selective pressure, for mobility, say, grow it for 10,000 generations, and see if a flagellum, or any equally complex system, was produced. If that happened, my claims would be neatly disproven.”
Behe was cross-examined by Eric Rothschild, one of the lawyers for the Dover parents. Rothschild pointed out the inconsistencies riddling his testimony. Behe’s proposal for evolving a flagellum in the lab revealed an indifference to the scale of evolution. A 10,000-generation experiment might last two years, whereas bacteria have been evolving for well over 3 billion years. In a typical experiment a scientist might study several billion microbes. But the world’s population of microbes is inconceivably larger. A microbe’s failure to evolve in a laboratory would offer no evidence of intelligent design.
While Behe issued absurd demands to evolutionary biologists, he demanded little of himself. He felt no need to offer his own step-by-step account of how an intelligent designer created the flagellum (or when, or where, or why). Intelligent design, he informed the court, “does not propose a mechanism in the sense of a step-by-step description of how those structures arose.” The only feature that Behe needed to find in those structures to call them intelligently designed was the appearance of design. “When we see a purposeful arrangement of parts, we have always found that to be design,” he testified. “What else can one go with except on appearances?”
This sort of testimony persuaded Judge Jones that intelligent design was scientifically empty. In December 2005, he ruled that
Of Pandas and People
had no place in the Dover classroom. “The evidence at trial demonstrates that ID [intelligent design] is nothing less than the progeny of creationism,” Jones declared in his decision. He chose the flagellum as an illustration of how seamlessly creationism and intelligent design were connected. “Creationists made the same argument that the complexity of the bacterial flagellum supported creationism as Professors Behe and Minnich now make for ID,” he wrote.