KANSAS CITY, Mo. -- How evolution is taught in Kansas schools is sparking controversy again.

KMBC's Micheal Mahoney reported that Kansas is revising its science standards and there is a dispute over how to teach the theory of evolution. It is not the first time science and religion have clashed in the state.

"It's a theory. It is not fact," one woman said recently a hearing on the issue.

Mahoney said that some Kansans want science classes to start questioning the theory of evolution.

"If it's such a robust theory, then we ought to be able to criticize it," said Dr. William Harris, discussing the theory of intelligent design.

Harris is a medical researcher.

"It is a challenge to Darwinism. Let's see if they're up to the challenge," Harris said.

Critics claim Charles Darwin's theory -- that life evolves through natural selection -- has gaps, like gaps in the fossil record, which they say fails to show the dramatic changes evolution claims. From deep space to the basic cells, life is too complex to originate naturally without design.

"Basically, all of the data to support evolution can also be used for an intelligent design," Harris said.

Who or what that is is not important, Harris said.

"No surprise because if they name it, it's going to be God. And they can't say that, so of course they're going to be coy," said Dr. Edward Wiley of the University of Kansas Natural History Museum.

Wiley calls evolution the best natural explanation -- tested and supported by science, while intelligent design is not.

"Because what it does is tell the students that supernatural explanations are appropriate for science, and they're not," Wiley said.

But the intelligent design advocates charge science cannot prove the natural origin of life.

"Why is anybody spending time on this? Why are they spending money and devoting careers to this? For what purpose, when 50 years of experiments show it didn't work?" Harris asked.

"Would that kind of attitude have led us to antibiotics? Would that have led us to genetic breakthrough that have led us to better crops?" Wiley asked.

Wiley believes the intelligent design advocates have a hidden agenda for Kansas classrooms.

"I think intelligent design is just creationism dressed up in a cheap tuxedo," Wiley said.

Harris is a member of a committee of teachers writing the science standards. At a recent meeting, he led an unsuccessful effort to include some challenges to evolution in the updated standards, Mahoney reported.

Ultimately, it will be the state school board, where there's a 6-4 conservative majority, that will decide the new standards.

Mahoney said that a majority of scientists accept evolution as the best evidence available on how life started. Some add that students don't have to believe in evolution, but they need to understand it.

A poll late last year showed that 55 percent of Americans believe God created humans in their present form.