In 1987, the Supreme Court struck down a Louisiana law that forbade teaching evolution in public schools unless creationism were also taught. The court found creationism to be a religious belief. But evolution's challengers have since adapted their cause to the new legal climate, just like Darwin's famed finches that formed special beaks to survive on the Galapagos Islands.
Their alternative to Darwin's theory is called "intelligent design," which holds that the universe is so complex it had to be designed by an intelligent (unnamed) agent. Last month, a federal court began hearing a case against the school board in Dover, Pa., which decided last year that 9th-grade biology students should be read a brief statement that evolution is "not a fact" and has "gaps." The statement also alerts students to a book about intelligent design. Some parents sued the school board, arguing that intelligent design is just a 21st-century version of creationism.
The case has the potential to reach the nation's high court - perhaps allowing the justices again to move the delicate line between church and state, at a time of rising interest in spirituality as well as rising clout for conservative Christians.
Advocates of intelligent design say it differs sufficiently from creationism by challenging evolution on the basis of science, not biblical creed. It rejects creationism's literal reading of the Bible which would put the age of the universe at less than 10,000 years. And it does accept a limited view of adaptation over time. But proponents don't accept that evolution alone explains biological life.