Knowledge of Science and Beliefs About Evolution

Data from within US and between US and other countries.

Posted May 09, 2012

What is the relationship between scientific knowledge and belief in evolution? I have recently been reviewing data that explores this issue and am sharing what I found. There clearly are some significant relationships between scientific knowledge and belief in evolution, although not as strong as I would have predicted.

But before I get into the results, why should we care? From my perspective, a cosmic evolutionary view is essential to understand and organize scientific knowledge. More specifically, Darwin’s theory of evolution is central to understand biology and by extension psychology and sociology. Furthermore evolutionary theory is at the heart of one of the great socio-political schisms of our time, the split between a Christian, social conservative worldview and an academic, evolutionary worldview (see an earlier blog exploring the issue in greater depth). [The other great socio-political schism pertains to economics and the role of government in economic policy and society in general—think  Paul Ryan v. Paul Krugman.]

Let’s start by looking at beliefs about evolution in the United States. Gallup polls have been tracking this issue since 1982. Specifically, Gallup has surveyed Americans regarding their beliefs about human origins with the following: "Which comes closest to your views: 1) God created humans as is within the last 10,000 years; 2) Humans developed over millions of years, guided by God; 3) Humans developed over millions of years, God had no part." The results have been remarkably consistent over time. Between 40 percent and 47 percent of Americans endorse the creationist view that God created human beings pretty much in their present form at one time within the last 10,000 years or so, whereas between 35 percent and 40 percent endorsed the claim that humans evolved over millions of years with God guiding the process, and 9 percent to 16 percent have endorsed the secular evolutionary perspective that humans evolved with no guidance from God. (There has been a slight trend in the last few years to see an increase in the purely naturalistic account, and may be a decrease in the creationist account). Here is an even more detailed examination of American’s beliefs about creationism and evolution.There is a strong relationship between education and belief in evolution, as shown in the graph below. (Note that less than 5 percent of scientists in general and less than 0.1 percent of life and earth scientists doubt evolution, broadly defined).

How do beliefs Americans have on these issues line up with other countries? A recent National Academies of Science publication (found here) reported on data comparing countries in their responses the question asked in 2005, “Human beings, as we know them, developed from an earlier species of animals”. Here are the data from 34 countries (percent who answered ‘true’ is in blue, ‘false’ in red, ‘unsure’ in beige). Note that the United States ranks 33rd  out of 34 (or 2nd out of 34 depending on your beliefs!), with approximately 40% believing the answer is ‘true’, 40 percent believing it false, and 20 percent unsure.   

I was curious about the relationship between scientific performance and beliefs in evolution across nations. I predicted there would be a significant, positive relationship between scores on measures of science and numbers of individuals who believed humans evolved from other animals. I could not find any direct data on this issue, so I did some basic data gathering and entering myself. I went to the Programme for International Student Assessment (PISA) and found the scores in science for the 2009 year here.

I then did a simple correlation between percent who believed humans evolved from earlier animals and scores on the PISA science section. For 33 nations (one was not listed on PISA), the correlation was significant and moderate (r = .385; p = .027) but less than I would have guessed. Here is the plot of the relationship.

On my travels around the web searching the above data, I stumbled upon a similar plot looking at the relationship between belief in evolution by Gross Domestic Product per capita. (See also these somewhat more humorous but interesting graphs here and here).

Finally, I went back into the US to see if there was a more specific relationship between performance on standardized measures of science and beliefs about evolution across the states. I found an article on the web addressing this issue here. The authors, Charlie Belin and Brian Kisida at the University of Arkansas, noted that there was not a strong, general relationship between beliefs in evolution, science standards, and science performance, as shown by this graph.

They did, however, find a moderately strong relationship between student science achievement and the views the public holds towards evolution after controlling for other variables. Specifically, they found “For each increase in the percent of residents that believes in teaching evolution exclusively, a state’s average science score on the NAEP for 8th graders rises about .06 standard deviations, equivalent to half a mean scale point”.

In sum, there is a relationship between education, knowledge of science, and beliefs in evolution, although the relationship is only moderate, at least when examined through the rather broad correlational lens taken here.