The theory of evolution has long generated controversy in American society, but Americans’ attitudes about human evolution are often neglected in studies of “culture wars” and the nature of mass belief systems more generally (Berkman and Plutzer 2010; Freeland and Houston 2009). Gallup and other survey organizations have polled about evolution, but offered limited response categories that mask complexity in public opinion (Bishop 2006; Moore 2008). The main problems concerning the leading survey questions about evolution are: first, questions measure only a single dimension, thus they ignore the potential for multidimensionality in people’s attitudes. Second, depending on question wording and response options, the results of public opinion surveys vary by polling groups. This is an example of measurement error which misleads the interpretation and impression of American public opinion on the origin of humankind.
A number of studies have analyzed Americans’ beliefs about evolution and hypothesized about the influential effects of several factors (Deckman 2002; Mazur 2005; Mooney 2005; Miller et al. 2006; Newport 2006; Forrest 2007;Nisbet and Goidel 2007;Scott 2009). However, there remains a lack of complete understanding of what Americans know and believe about human evolution. Given the salience of this issue and the significant influence of public opinion on policy-making in America (Page and Shapiro 1992; Stimson 2004; Newport 2004), the measurement error and explanation of polling results on controversial issues related to this topic are in need of clarification.
In this study, I address these deficiencies with analyses of data from a 2008 national survey by Harris Interactive (n= 4,626) that included numerous measures of factual knowledge and beliefs about evolution. The items offer more nuanced response options than the standard three-category question asked for decades by the Gallup poll. The Harris survey also had multiple measures of religiosity and the Right-Wing-Authoritarianism personality scale. Using this uniquely rich data set I develop a model of the nature and organization of these various attitude structures.
Data analyses on explanation of public acceptance or rejection of evolution indicate that the Right-wing-authoritarianism and religious factors including beliefs in God’s existence, views of the Bible, frequency of church attendance, and Evangelical Protestant affiliation are significant predictors across all measures. Scientific literacy, genetic science knowledge and familiarity, in general, are another contributor to prediction of public attitudes toward evolution. On measurement validity, consistency of measurement and responses are examined. The results from data analyses reveal the effect of question wording form and context is at play. In addition, public beliefs and knowledge about evolution are not consistent, rather contradictory, and are susceptible to framing effects. As scholars of public opinion warn, we should avoid the referendum view of polls on controversial issues (Schuman 2008; Moore 2008; Bishop 2005).
Findings from this research lead to two key conclusions. First, great caution should be taken interpreting poll results on human evolution. Second, for better understanding of public opinion on this issue, a modified standard question should replace the current question.