The idea that all life on Earth is related through a nested hierarchy of branching evolution, occurring over billions of years through entirely natural processes, is one of the biggest ideas ever to emerge from human science. It did not just emerge whole cloth from the brain of Charles Darwin, it had been percolating in the scientific community for decades. Darwin, however, put it all together in one long compelling argument. Alfred Wallace independently came up with essentially the same conclusion, although did not develop it as far as Darwin.

On the Origin of Species was published in 1859, and it quickly won over the scientific community, with natural selection acting on variation becoming the dominant working hypothesis. But that, of course, was not the end of the story, only the beginning. If Darwin’s ideas were wrong, they would have slowly withered from lack of confirming evidence. But they were largely correct, even insightful. The last 162 years of research and observation have confirmed to an extraordinary degree the core ideas that life is related through branching connections, and that natural selection is a primary driving force of evolution. The theory has also evolved quite a bit, and is now a mature and complex scientific discipline sitting on top of mountains of evidence, including fossils, genetics, comparative anatomy, developmental biology, and direct observation. The basic fact of evolution could have been falsified thousands of times over, but it has survived every time – because it is essentially true.

Acceptance of the basic tenets of evolutionary theory, therefore, is a good litmus test for any modern society. Of what, exactly, is another question, but certainly something is going wrong if the population does not accept this overwhelming scientific consensus. The US ranks second from the bottom (only Turkey is worse) in terms of accepting evolutionary theory. Researchers have been tracking the statistics for decades, and now some of the lead researchers in this field have published data from 1985 to 2020 (sorry it’s behind a paywall). There are some interesting details to pull from the numbers.

The lead author is Jon Miller, who studies scientific literacy. One co-author is Eugenie Scott, a fellow skeptic, who we interviewed on the SGU this week about the study. The big news is that between 1985 and 2007 US public acceptance and rejection of evolutionary theory were in a statistical dead heat, each hovering between 40-45%, with  “don’t know” varying between 10-20%. Then since 2007 the lines have started diverging, by 2019 with more people accepting evolution. (54%) than rejecting (36%). It’s too early to say how long this trend will hold or where it will stabilize, if it does, but this is a significant difference from the prior several decades. What is going on?

If we delve into the data we can see some predictors of accepting vs rejecting belief in evolution. The overwhelmingly most predictive factor is the degree to which one holds fundamentalist religious views. When it comes down to it, that is most of the phenomenon of evolution denial. All other factors are either minor or derive from fundamentalism. For example, political affiliation also correlates with belief, but this can be entirely explained by the fact that fundamentalists are mostly Republicans.

These numbers also explain much of the recent increase in evolution acceptance. In 1988 those ranking lowest on the fundamentalism scale accepted evolution at 78%, while the highest at only 8%. In 2019 the numbers were 91% and 32% respectively – a third of the most fundamentalist people now accept evolution. That is a significant change. In addition evangelical protestants (the main group of Christian fundamentalists in the US) have been slowly declining as a share of the US population (now down from 25% to about 14%).

If we look at the age data this might provide a partial explanation for the increased acceptance among fundamentalists. The 18-24 age group accept evolution at 68%, 25-34 at 64%, while the 55 and over are only at 45%. So there is a generational phenomenon happening here, and perhaps fundamentalist denominations, in order to appeal to younger age groups and slow their demographic decline, are moderating their views. I know it doesn’t feel like that in the current political climate, but these are the numbers.

The second most predictive factor in terms of evolution acceptance is having a civic level of scientific literacy. These numbers have essentially not changed over 35 years, with those who are not scientifically literate accepting evolution at 45%, and those who are at 74%. This remained an independent predictive factor, even when controlling for other factors, but was about half as powerful an effect as being a fundamentalist. There are so many interacting factors that this correlational data is difficult to interpret in terms of cause and effect. But optimistically this might suggest that education can have an effect.

If we further look at level of education, this has no effect until we get to full college degree and beyond. Having a high school education or even associates degree has no effect on acceptance of evolution. Once in college, the number of college level science courses one takes also has a positive correlation. Again, the arrow of causation may be going from accepting evolution to having a greater interest in science rather than the other way around, and education was not much of an independent predictive factor.

Pessimistically this is all compatible with the conclusion that we cannot make a significant dent in evolution denial through education alone. The “knowledge deficit” model simply does not apply here, because rejection of evolution is not about science or facts. It is about identity and world-view. However, the optimistic view is that there is some wiggle room here. Education may move the needle, but only if it is good enough to foster actual scientific literacy. This is basically not happening at the high school level.

If there is an action-item from all this data, it’s that we can do a better job of science education in K-12. This means better science training for teachers, and incorporating overall scientific literacy, critical thinking skills, and media savvy into the curriculum. Students need to be taught not just the facts of science, but epistemology (how we know what we know), and how to recognize and deal with misinformation, pseudoscience, and science denial.

But also, cooling the culture war will also be massively helpful. I don’t know exactly how to do this, but the goal is to decouple acceptance or rejection of science from personal belief systems and values. This has always been the approach I have taken to science communication – you can believe what you want and have your personal value system, but empirical facts exist in a separate realm. In a modern society we should recognize this and be able to agree on the facts. Then we can have a friendly conversation about belief systems and values. One can dream.