All across the country — most recently, in the state of Texas — local battles over the teaching of evolution are taking on a new complexion. More and more, it isn’t just evolution under attack, it’s also the teaching of climate science. The National Center for Science Education, the leading group defending the teaching of evolution across the country, has even broadened its portfolio: Now, it protects climate education too.

How did these issues get wrapped up together? On its face, there isn’t a clear reason — other than a marriage of convenience — why attacks on evolution and attacks on climate change ought to travel side by side. After all, we know why people deny evolution: Religion, especially the fundamentalist kind. And we know why people deny global warming: Free market ideology and libertarianism. These are not, last I checked, the same thing. (If anything, libertarians may be the most religiously skeptical group on the political right.)

And yet clearly there’s a relationship between the two issue stances. If you’re in doubt, watch this Climate Desk video of a number of members of Congress citing religion in the context of questioning global warming:

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Indeed, recent research suggests that Christian “end times” believers are less likely to see a need for action on global warming.

And now new research by Yale’s Dan Kahan further reaffirms that there’s something going on here. More specifically, Kahan showed that there is a correlation (.25, which is weak to modest, but significant) between a person’s religiosity and his or her tendency to think that global warming isn’t much of a risk. Perhaps even more tellingly, Kahan also found that among highly religious individuals, as their ability to comprehend science increases, so does their denial of the risk posed by global warming. Here’s some data he presented:

Among the highly religious, more science comprehension translates into less concern about global warming.

Dan KahanAmong the highly religious, more science comprehension translates into less concern about global warming. Click to embiggen.

“I have to say, those effects are bigger than I would have expected,” wrote Kahan of his findings. The researcher went on to say that he isn’t sure why greater religiosity predicts greater denial of climate change. But in his data — with a representative sample of over 2,000 Americans — it clearly does.

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There are two major possibilities. And there is probably some truth to both of them.

There is the “the enemy of my enemy is my friend” theory. In other words, anti-evolutionists and climate deniers were both getting dumped on so much by the scientific community that they sort of naturally joined forces. And that makes sense: We know that in general, people gather their issue stances in bunches, because those stances travel together in a group (often under the aegis of a political party).

But there’s also the “declining trust in science” theory, according to which political conservatives have, in general, become distrustful of the scientific community (we have data showing this is the case), and this has infected how they think about several different politicized scientific issues. And who knows: Perhaps the distrust started with the evolution issue. It is easy to imagine how a Christian conservative who thinks liberal scientists are full of it on evolution would naturally distrust said scientists on other issues as well.

Further research will no doubt unravel what’s going on here. In the meantime, we can simply observe: In the political science wars that have wracked America for well over a decade, both sides are consolidating their forces.

This story was produced by Mother Jones as part of the Climate Desk collaboration.