A vote on science materials promises to re-ignite debate within Texas' State Board of Education over how public schools teach the theory of evolution.

Such votes tend to expose ideological rifts between more conservative board members who are skeptical of Darwinism and more liberal members who defend the theory of evolution and seek to maintain separation of church and state.

Two years ago, the board approved standards that require schools to seriously question the validity of the theory of evolution, and last year it altered social studies and history curricula to endorse American capitalism and challenge the secular principles enshrined in the U.S. Constitution.

This week's vote will likely be less contentious because it concerns online materials, rather than far-reaching standards that would be incorporated into textbooks.

Because Texas is one of the largest buyers of textbooks, its decisions have broad national implications. Legislation passed last month also blunts the influence of the Board of Education by allowing individual districts to purchase instructional materials without being constrained by what the board mandates.

Mainstream science groups have been supportive of the nine submissions to be considered by the board, none of which mentions intelligent design or creationism. The one that did suggest intelligent design may have been responsible for the advent of life on earth was not recommended by Education Commissioner Robert Scott.

None of the mainstream publishers were going to go that far, said Josh Rosenau, policy director at the National Center for Science Education.

Still, Board Chairwoman Barbara Cargill, a Republican, objected to an entry that juxtaposes human and gorilla embryoes in order to demonstrate that they share characteristics and suggest a common ancestor.