History also tells us that scientific issues can become polarized along partisan lines and stay that way. Back in 1998, 48 percent of Republicans and 47 percent of Democrats said that global warming had already begun, according to a Gallup survey. By 2007, after a decade of fighting between Democrats and Republicans on the issue — as well as the release of “An Inconvenient Truth” starring Al Gore — 70 percent of Democrats believed climate change had started. Republican belief in global warming remained relatively steady at 45 percent. Today, even fewer Republicans (40 percent) and even more Democrats (77 percent) believe climate change has already begun.
Evolution has also grown more polarized over the last decade. Back in 2005, the Pew Research Center found that 54 percent of Democrats and 47 percent of Republicans agreed that “humans and other living things have evolved due to natural processes such as natural selection.” By 2014, 67 percent of Democrats believed that humans had evolved because of natural processes. Republicans, however, remained at 47 percent.