Liza Gross of the Public Library of Science has written a piece entitled Scientific Literacy an the Partisan Takeover of Biology. Largely a chronicling of the career of Jon D. Miller, Director of the Center for Biomedical Communications at Northwestern University Medical School, the article provides some information that Miller has collected:
Over the past 20 years, the proportion of Americans who reject this concept has declined (from 48% to 39%), as has the proportion who accept it (45% to 40%). Confusion, on the other hand, has increased considerably, with those expressing uncertainty increasing from 7% in 1985 to 21% in 2005.
He has also found that:
One-third of Americans think evolution is "“definitely false"”; over half lean one way or another or aren't sure. Only 14% expressed unequivocal support for evolution" a result Miller calls "shocking."”
Perhaps most depressingly:
And in a 2005 survey measuring the proportion of adults who accept evolution in 34 European countries and Japan, the United States ranked 33rd, just above Turkey. No other country has so many people who are absolutely committed to rejecting the concept of evolution, Miller says. "“We are truly out on a limb by ourselves."”
Miller suggests that the current spate of anti-evolutionism is largely Republican-driven (a conclusion that, I think, has some merit but needs more study). What I have found is that scientific illiteracy knows no political bounds. People from all walks of life tend to be remarkably ignorant of scientific knowledge. I have often thought, though, that if the Republican party links itself to pro-ID side, it will be seen as anti-scientific and anti-intellectual and lose voters like myself, who might vote independent or Libertarian. 2008 is going to be interesting.