Evolutionary theory should be taught to science students, but it alone cannot explain complex biological phenomenon, said a biochemistry professor who is a leading advocate of "intelligent design." Lehigh University Professor Michael Behe was the first witness called by a school board that is requiring students to hear a statement about the intelligent design concept in biology class. Lawyers for the Dover Area School Board began presenting their case Monday in the landmark federal trial, which could decide whether it can be mentioned in public school science classes as an alternative to the theory of evolution. The school board is defending its decision a year ago to require students to hear a statement on intelligent design before ninth-grade biology lessons on evolution. The statement says Charles Darwin's theory is "not a fact," has inexplicable "gaps," and refers students to a textbook, "Of Pandas and People," for more information. Eight families sued to have intelligent design removed from the biology curriculum, contending the policy essentially promotes the Bible's view of creation and therefore violates the constitutional separation of church and state. The trial began Sept. 26 and is expected to last up to five weeks. The plaintiffs are represented by a team put together by the American Civil Liberties Union and Americans United for Separation of Church and State. The school district is being represented by the Thomas More Law Center, a public-interest law firm based in Ann Arbor, Mich., that says its mission is to defend the religious freedom of Christians.