John Scopes attended high school in Salem, Ill., where his commencement speaker was the town's most famous native son, William Jennings Bryan. Their paths would cross again.

Eighty years ago Scopes, 24, a high-school football coach and general-science teacher, attended a meeting in Robinson's drugstore in Dayton, Tenn. There, to the satisfaction of community leaders who thought that what was to come would be good for business, Scopes agreed to become the defendant in a trial testing Tennessee's law against teaching "any theory that denies the story of the divine creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals."

So began "the most widely publicized misdemeanor case in American history." That is Edward J. Larson's description of the "monkey trial" in his 1997 Pulitzer Prize-winning "Summer for the Gods: The Scopes Trial and America's Continuing Debate Over Science and Religion." With that debate again at a rolling boil, that book by Larson, professor of history and law at the University of Georgia, demonstrates that the trial pitted a modernism with unpleasant dimensions against a religious fundamentalism that believed, not without reason, that it was faithful to progressive values.

By 1925, many Christian geologists were comfortable with the fact that Earth has a long geologic history. They saw God immanent in the dynamic of appearance and disappearance of life forms. What most distressed some Christians was not the fact of evolution but the postulated mechanism--a nature-red-in-tooth-and-claw randomness that erased God's purposefulness and benevolence.

Since the publication of Charles Darwin's "Origin of Species" in 1859, religiously motivated critics of the theory of evolution by natural selection had stressed the supposed failure of paleontology to supply the "missing link" that would establish continuity in the descent of man.

Darwinism did not ignite a culture war until the 1920s, when high-school education became common in the rural South, where Christian fundamentalism was strong. When school seemed to threaten children's souls, fundamentalists sought and found a champion in Bryan, a three-time Democratic presidential nominee and star of the prosecution team in Scopes's trial.

Scopes's defense, led by Clarence Darrow, stressed individual rights--academic freedom. The prosecution stressed the community's right to control the curriculum of public schools. As a young man, Bryan had been a force for progressivism understood as, Larson says, a "sunny faith in the curative power of majoritarian reforms," such as popular election of U.S. senators. So the vocabulary of progressivism served Bryan's argument that the issue was not what should be taught, but who should decide.

He, like many anti-evolutionists, believed that the idea of natural selection fueled merciless social Darwinism in domestic policies and militarism and imperialism among nations, justifying the survival of the fittest nations or races, and their dominion over lesser breeds. Modernists considered World War I a progressive crusade. Bryan resigned in protest as President Wilson's secretary of State.

Many scientists at the time were, Larson says, receptive to the idea that we could channel human evolution through selective breeding. Some believed that acquired human characteristics could be inherited, hence improvement of the human race could be engineered. And many evolutionary biologists embraced eugenics. By 1935, 35 states had laws compelling the sexual segregation and sterilization of people considered unfit--the mentally ill and retarded, habitual criminals and epileptics.

Today's proponents of "intelligent design" theory are doing nothing novel when they say the complexity of nature is more plausibly explained by postulating a designing mind--a.k.a. God--than by natural adaptation and selection. By 1925, Larson's book notes, "Christian apologists had long regarded the intricate design of the eye as a 'cure for atheism'."

The problem with intelligent-design theory is not that it is false but that it is not falsifiable: Not being susceptible to contradicting evidence, it is not a testable hypothesis. Hence it is not a scientific but a creedal tenet--a matter of faith, unsuited to a public school's science curriculum.

The Dayton jurors were eager to get on with their lives--"The peach crop will soon be coming in," one said--and did not even sit down before deciding that Scopes was guilty. But Bryan did not believe penalties should be attached to anti-evolution laws--"We are not dealing with a criminal class"--and offered to pay Scopes's $100 fine.

Bryan died five days after the trial. Scopes left to study geology--how fitting--at the University of Chicago and became a petroleum engineer. The argument about science, religion, the rights of communities' majorities and academic freedom rolled on, but not everywhere. When an anti-evolution bill was introduced in the Rhode Island Legislature, it was referred to the Committee on Fish and Game.