Oklahoma has joined a list of states questioning the teaching of evolution by requiring a disclaimer in school science textbooks that evolution is a "controversial theory," education officials in Oklahoma City said. The state education board confirmed that a textbook committee imposed the requirement last week because members thought teaching evolution is too one-sided. The disclaimer reads in part: "This textbook discusses evolution, a controversial theory which some scientists present as scientific explanation for the origin of living things. No one was present when life first appeared on Earth. Therefore, any statement about life's origins should be considered as theory, not fact." Committee member John Dickmann told the Tulsa World newspaper it was added because biology texts do not give enough attention to alternate explanations of the development of life.