The theory of evolution is right up there with the theory of gravity in terms of its universal acceptance among scientists. But, as we’ve learned from the climate change debate, politics has the power to trump science — and, according to a new Pew poll, it seems like political partisanship may be starting to take its toll on evolution. While a comfortable majority of Republicans accepted human evolution as fact in 2009, Pew finds a plurality now reject it — an astonishing 19 point reversal in four years.
It’s a finding that tells us a lot, both principally about the (ahem) evolution of the Republican Party in the past fours. In short, the kind of person who doesn’t believe in evolution is much more likely be a typical Republican today than four years ago — for reasons that have only a bit to do with the debate over evolution itself.
There are two keys to understanding what the Pew poll teaches us about Republicans. First, the drop in belief in evolution is among Republicans and, more or less, Republicans only. Acceptance of human evolution was basically the same among Democrats and independents in 2013 as it was in 2009. Second, the share of the total population that believes in evolution hasn’t changed at all. The drop in Republican belief doesn’t appear to be people changing their minds about evolution so much as people who already didn’t believe in evolution becoming Republicans.
Why might that be? The obvious explanation is the changing character of the Republican base. When Republicans win in recent years, those victories are won on the backs of old voters, white voters, and religious voters. While race isn’t super-important in predicting views on evolution, age and religion are. Each generation of Americans, Pew found, is increasingly more likely to accept natural human evolution; Americans 18-29 do so by a 68-27 margin, while the number for seniors (65+) is 49-36. Likewise, white evangelical protestants are the group most likely to reject evolution, while the religiously unaffiliated are by far the most likely to accept it.
The winnowing of self-identified Republicans to these demographic groups has been dramatic in recent years. The overall number of Americans who identify as Republicans hovered around 29 percent from from 2008-2012 as American seniors became dramatically more Republican, the pro-GOP margin shifting from 35-34 in 2008 to 39-29 in 2012. White evangelicals have become similarly more Republican at the same time.
So on one look, the decline in Republican belief in evolution is perfectly consistent with one of the most fundamental trends in American politics: a greying, born-again Republican Party increasingly out of step with the rest of America’s political views.
The Republican base’s increasing hostility to evolution could very well explain the rash of recent state-level debates on teaching evolution in schools. In the past four years, we’ve seen a slate of state controversies over school textbooks and curricula that teach creationism alongside evolution. States like Texas, Tennessee, Louisiana, Oklahoma, Kentucky, and New Mexico have all had versions of this fight — all controversies sparked by conservative state leaders that have heated up in the past two or three years. All of this anti-evolution activity makes much more sense if understood as Republican representatives and activists responding to incentives created by their increasingly homogenous base.
If that explanation is right, then we should expect to see similarly base-tailored legislation coming out of Republican state representatives in 2014 and beyond. The demographic trends concentrating the Republican base don’t appear to be slowing, which means that Republicans will have even stronger incentives over time to push legislation that appeals to the older, whiter, more religious demographic. This means that more issues like creationism in schools that don’t play on the national level, but can help local Republicans make a name for themselves inside the party, might make their way into state capitols in the coming year.
But the demographic explanation isn’t everything. Pew cautions that “differences in the racial and ethnic composition of Democrats and Republicans or differences in their levels of religious commitment do not wholly explain partisan differences in beliefs about evolution.” Put more simply, Republicans are more skeptical of evolution than you would expect even when you take into account the demographic character of its base.
This suggests another, more subtle effect at work. A wealth of research into political psychology shows that people’s partisan affiliations affect their beliefs on basic facts. Republicans are overwhelmingly more likely to think the economy is doing well when Republicans hold the Presidency, and ditto with Democrats when their guy holds the White House. A recent experiment found that even basic math is contaminated by politics; people are much more likely to correctly solve basic math problems when, in context, solving them correctly helps rather than hurts their party.
In the evolution context, this suggests a feedback effect at work among Republicans. As the GOP becomes more associated with the creationist cause as a consequence of demographic shifts, Republicans start to feel more like being skeptical of evolution is their “team” position. So even Republicans who are demographically more likely to accept the basic science of evolution start to reject it, because that belief best harmonizes their beliefs with the perceived interest of their political party.