Belief in evolution is seeing an increased partisan divide, according to an analysis released Monday by the Pew Research Center.
Meanwhile, 67 percent of Democrats said they believe in human evolution, a slight increase from 64 percent who said so in 2009. Combined, the two shifts mean a 10-point gap in 2009 has grown into a 24-point chasm in 2013.
Overall, 60 percent of Americans believed in human evolution, while 33 percent denied it, with the rest unsure.
The large party gap in part reflects significant differences in party make-up. The religiously unaffiliated, who tilt Democratic, are among the most likely to believe in evolution, while white evangelical Protestants, who are overwhelmingly Republican, are by a significant margin the religious grouping least likely to accept it.
However, according to Pew, a partisan gap remains even after controlling for these factors, suggesting that partisanship itself may be related to beliefs regarding evolution.
The survey, conducted between March 21 and April 8, had a sample size of 1,983 and a margin of error of +/- 2.9 percentage points.