America remains a scientifically ignorant nation for two reasons: the resurgence of fundamentalist religion during the past 40 years, and secondly, the low level of science education in American elementary and secondary schools, as well as many tertiary colleges.
While television ratings for Cosmos may have stunned media critics and your average fundamentalist, “Americans continue to poll more like Iranians or Nigerians than Europeans or Canadians on questions of evolution, scriptural inerrancy, the presence of angels and demons, and so forth."
http://www.alternet.org/education/results-are-america-dumb-and-road-getting-dumber
Below is an explanation why by a knowledgeable PhD
http://www.hulu.com/watch/701699#i1,p0,d1