The study may be trying to make some mischievous causation claim for all I know (why was it commissioned in the first place?), but the obstinate bit of science that needs applying here is that, as ever, correlation does not imply or prove causation. The results can form nothing more than the basis of a hypothesis that needs a great deal more investigation. Another point: taking a heterogeneous behemoth such as the US as a single state and sticking it alongside tiny states such as Iceland for comparison is very suspect. It would be interesting to see a similar graph plotting just the 50 states of the US. Even then there would be cavils.

I wonder how a graph of evolution belief versus beer-drinking would look. Or evolution belief versus sunscreen use. I'd like to know what germ of a notion suggested this study to its author. Unfortunately, I ain't paying good money to access the article to find out. By far the most worrying aspect of it all is that less than half of US citizens accept that evolution takes place (watch out - there's a gastropod about...) Seems like there's a lot of very bad education about.