DOVER, Pa. — When the talk turns to evolution at the high school in this rural south-central Pennsylvania community, biology teachers have to make room for both Charles Darwin and his detractors.

The Dover Area School District is believed to be the first in the nation specifically to mandate the teaching of "intelligent design," which holds that the universe is so complex that it must have been created by an unspecified higher power.

Intelligent design is singled out in a new ninth-grade biology curriculum that requires students to learn about alternate theories to evolution, which holds that Earth is billions of years old and that life forms developed over millions of years.

Critics say it's a veiled attempt to require public school children to learn creationism, a biblical-based view that credits the origin of species to God.

The state American Civil Liberties Union chapter is reviewing the matter. Its Georgia counterpart is fighting a suburban Atlanta district's decision to include a warning sticker in biology textbooks that says evolution is "a theory, not a fact."

"What Dover has done goes much further than what's happened in Georgia," said Witold Walczak, legal director of the Pennsylvania ACLU. "As far as we can tell, Dover is the first school district that has actually mandated intelligent design."

The district enrolls about 2,800 students. It encompasses the small, rural community of Dover borough, about 20 miles south of Harrisburg, and a patchwork of farmland and newer suburban developments in several surrounding townships.

The revision was spearheaded by school board member William Buckingham, who heads the board's curriculum committee. Buckingham said it all began several months ago, when the board began considering the adoption of a new biology textbook.

"I think it's a downright fraud to perpetrate on the students of this district, to portray one theory over and over," said Buckingham. "What we wanted was a balanced presentation."

Buckingham wanted the board to adopt an intelligent-design textbook, Of Pandas and People: The Central Question of Biological Origins, as a supplement to the traditional biology book, but no vote was ever taken. A few weeks before the new science curriculum was approved, 50 copies were anonymously donated to the high school.

Although Buckingham describes himself as a born-again Christian and believes in creationism, "This is not an attempt to impose my views on anyone else," he said.

Two of the dissenting board members in the 6-3 vote to approve the new curriculum, Carol Brown and her husband, Jeff, were so upset that they resigned after the Oct. 18 vote.

"We have a vocal group within the community who feel very strongly in an evangelical Christian way that there is no separation of church and state," Carol Brown said. "Our responsibility to is to represent the viewpoints of all members of the community."

Statewide science-curriculum standards approved by Pennsylvania's state Education Board merely ask students to "analyze data ... that are relevant to the theory of evolution."

When the standards were revised three years ago, the board considered language that would have required students to consider evidence that did not support evolution, but the board dropped the idea after critics alleged it would have led to the widespread teaching of creationism in public schools. During that discussion, intelligent design was never mentioned specifically.

Critics of intelligent design contend it is creationism repackaged in more secular-sounding language.

"Creationism in a cheap tuxedo," said Nicholas Matzke, project information specialist for the National Center for Science Education in Oakland, Calif., which advocates the teaching of evolution.

Even the Seattle-based Discovery Institute, which supports scientists studying intelligent-design theory, opposes mandating it in schools because it is a relatively new concept, said John West, associate director of the institute's Center for Science and Culture.

"We're completely against anyone who says you should downgrade or limit the teaching of evolution," West said.

Dover biology teacher Jennifer Miller said the curriculum changes had left her uncertain about how to approach her evolution lesson. She won't get to it until January, when her semester-long biology class concludes.

"If you put the words 'intelligent design' into my curriculum, then I have to teach it," said Miller, a 12-year veteran. "I'm not sure what that means as to how in-depth we have to go. ... I'm looking for more direction from the school board."

School board member Heather Geesey, who also voted for the curriculum change, said school administrators were working on more-specific teacher guidelines.

Neither Assistant Superintendent Michael Baksa, who oversees the district's curriculum, nor Superintendent Richard Nilsen responded to telephone calls and e-mail requests for comment.

Jonathan Tome, whose three sons attend Dover schools, applauded the measure.

"You can't be hypocritical with these kids, teaching them one thing but not another," said Tome, 43, who was waiting in his truck to pick up his oldest son from the high school.

High school sophomore Courtney Lawton said she didn't have a problem learning only about evolution in biology class last year and didn't see a need for any changes.

"I just think they should keep it the way it is, and they shouldn't add anything about a higher power. People who believe differently, they might feel like they're being segregated," said Lawton, 15.

Questions of evolution vs. creationism rarely arise in Miller's class, she said, because she emphasizes changes in species over time rather than the origins of life.

"We take a look at the species that are here, and look at the process of natural selection. I've never taught that a fish became a frog," she said.