Pew found that 43 percent of Republicans said they believed humans and other living beings had evolved over time, down from 54 percent in 2009. More (48 percent) said they believed all living things have existed in their present form since the beginning of time.

The percentages for Democrats and independents were considerably more stable: Democratic belief in evolution went from 64 percent in 2009 to 67 percent in 2013; independent belief dipped from 67 percent in 2009 to 65 percent in 2013.

More: Poll: Republican Belief in Evolution Has Plummeted in Recent Years

I think it would be important to note this doesn’t necessarily mean more Republicans stopped believing in evolution. I think that a more likely scenario is that as more extreme beliefs have been picked up by the GOP, more people who believe in evolution have decided that they no longer wish to be Republicans.