A recent Pew Research study found a significant increase in just the past four years in the number of Republicans who say they do not believe in evolution.
When asked whether humans and other living things have evolved over time or existed in their present form since the beginning, 48 percent of Republicans answered "existed in present form since the beginning," compared to 39 percent of Republicans who answered the same in 2009, a statistically significant and large difference.
There are a number of possible explanations as to why there has been such a large change in only four years. In a Jan. 3 blog post, Cary Funk, Pew Research Center senior researcher, took a closer look at the data and offered some intriguing possibilities.
One hypothesis examined by Funk was whether the Republican Party is more religious today than in 2009. It could be, for instance, that people with higher levels of religiosity have gravitated toward the GOP while less religious Republicans have left the party.
Funk found, though, that the Republican Party looks demographically about the same as it did in 2009. It has about the same distribution of religious adherents and looks similar in terms of religious participation, gender and race or ethnicity. The only demographic difference is the Party is slightly older.
Funk did find, though, that the shift in attitudes on evolution came among less religious Republicans.
Views on evolution remained about the same among Republicans with high levels of religiosity (measured by frequency of attendance at religious services). In 2009, 56 percent of Republicans who said they attend religious services weekly or more answered that humans have existed in their present form since the beginning. Today, that number is about the same, 59 percent.
Among Republicans attending religious services less than weekly, though, there was a more significant shift. In 2009, 23 percent answered that humans have always existed in their present form. That number has now increased 12 percentage points to 35 percent.
Among Democrats, views on evolution have not changed much, regardless of frequency of church attendance.
Funk also notes that there may have been a "priming effect" that explains the differences in the two surveys. Sometimes a poll question can produce different results based upon the question that was asked directly before it. The previous question "primes" the respondent to think a certain way in how they should answer the question.
There could be several reasons for the shift in Republican attitudes on evolution found by Pew, according to Funk. In the future, she says, Pew will ask a broader range of questions to better understand beliefs about evolution.