July 1, 2015

Americans, Politics and Science Issues

Chapter 4: Evolution and Perceptions of Scientific Consensus

This chapter looks at public views about human evolution and perceptions of scientific consensus about evolution and the creation of the universe. Consistent with past Pew Research surveys and other public surveys, religious groups play a central role in beliefs about these topics. Numerous other factors also influence public views about evolution, however, including politics, education and science knowledge. We will examine respondents’ views about the intersection of science and religion and religious groups’ views about science-related topics in more detail in a follow-up report.

Beliefs About Human Evolution

Public Beliefs About Human EvolutionControversy over evolution has been a mainstay of American public life throughout much of the 20th century. The Pew Research survey asked about evolution using a set of two questions. Respondents were first asked whether “humans and other living things have evolved over time” or “have existed in their present form since the beginning of time.” Those who say that humans and other living things have evolved are asked a follow-up question about the processes they believe account for evolution.

Processes Guiding Human Evolution In the most recent survey, 65% of adults say that humans and other living things have evolved, while 31% say humans and other living things have existed in their present form since the beginning of time. Roughly half of those who say that humans have evolved over time believe that evolution has occurred from natural processes, such as natural selection (35% of all adults), while a somewhat smaller share (24% of all adults) believe a supreme being guided the evolution of humans and other living things. Another 5% of all adults are unsure how evolution occurred.

Among the public as a whole, beliefs about human evolution have been roughly stable since first asked in a 2009 Pew Research survey.37 As we show below, there are a number of differences among subgroups of the population in beliefs about evolution, as has also been the case in past surveys.

Gender, Age, Race and Ethnicity

Views on Human EvolutionView about evolution and the processes guiding evolution vary across a number of groups in the population, including gender, race and ethnic groups, as well as age groups. Women are more likely than men to say that humans have existed in their present form since the beginning of time (36% of women say this, compared with 26% of men). Among those who say that evolution has occurred, women are more likely than men to say that evolution was guided by a supreme being.

Younger adults are more likely than older adults to say that evolution has occurred. Those under age 30 are especially likely to say that evolution is due to natural processes (51% of all those ages 18-29 say this). By comparison, just 22% of adults ages 65 and older say that evolution has occurred due to natural processes; 25% of seniors say that evolution was guided by a supreme being and 37% say that humans and other living things have existed in their present form since the beginning.

African Americans are less likely than are whites to say that evolution has taken place.

Education and Knowledge

Views on Human Evolution, by Education and Science KnowledgeThree-quarters (75%) of all college graduates and fully 81% of those with a postgraduate degree believe that humans have evolved over time. By comparison, 56% of those with a high school diploma or less say evolution has occurred.

There are sizeable differences in views about evolution between those with more and less general knowledge about science. About three-quarters (76%) of those with more science knowledge say that humans have evolved, compared with 54% among those with less science knowledge.

Religion

Wide Differences Among Religious Groups on Beliefs About Human EvolutionBeliefs about evolution among the general public also vary by religious group, with white evangelical Protestants especially likely to say that humans have existed in their present form since the beginning (60%). Black Protestants are closely divided in their beliefs on this topic, with 49% saying that humans and other living things have evolved, and a nearly equal share (47%) saying humans and other living things have existed in their present form since the beginning. Those with no religious affiliation (including those who say they have no particular religion or are atheist or agnostic) stand apart from other groups in their beliefs about evolution. Fully 86% of the religiously unaffiliated say that humans have evolved over time, and two-thirds (67%) say that evolution occurred due to natural processes. By comparison, among all those with a religious affiliation, 59% say that humans have evolved and just 26% say that natural processes account for evolution. More analysis of the relationships between religious beliefs and views about science topics is forthcoming in a separate report.

Party and Ideology

Views on Human Evolution, by Party and IdeologyBeliefs about evolution also differ strongly across political groups. Fully 72% of Democrats and independents who lean to the Democratic Party say that humans and other living things have evolved over time, and 46% of this group believes evolution has occurred due to natural processes. By contrast, 57% of Republicans and those who lean to the GOP say that humans have evolved, and just 26% of this group says evolution occurred through natural processes.

Similarly, liberals are more likely to say that humans have evolved and most believe evolution has occurred due to natural processes. Conservatives are closely divided over whether or not evolution has occurred (48% to 47%). Moderates fall in between these two groups, with 71% saying that humans have evolved over time; 38% of moderates say evolution is due to natural processes and 29% say a supreme being guided evolution “for the purpose of creating humans and other life in the form it exists today.”

Both political and religious differences underlie beliefs about evolution. For example, partisans who are more religiously observant, measured by frequency of attending worship services, hold distinct views about evolution, as compared with fellow partisans who are less observant.

Differences Among Religiously Observant Partisans on Beliefs About EvolutionAmong Republicans (including those who lean to the Republican Party) who attend church services at least weekly, fully 53% say that humans have existed in their present form since the beginning and just 9% say that evolution has occurred through natural processes. By contrast, a two-thirds majority (67%) of Republicans and leaning Republicans who attend worship services less often say that humans have evolved over time; 37% of this group says that evolution is due to natural processes.

A similar divide occurs among Democrats and leaning Democrats who regularly attend worship services and those who do not.

Multivariate Analyses

To look at the relative influence of these factors on beliefs about evolution, we conducted a series of multivariate regression analyses. The models shown here included religious affiliation and frequency of worship service attendance. The results underscore the importance of multiple influences on beliefs about evolution, especially religious tradition and church attendance, but, also, party and ideology, education and knowledge about science, age, gender and race. Belief that scientists generally agree that humans have evolved over time is also an independent predictor of beliefs about evolution.

We turn, first, to predicting the view that the humans and other living things have evolved over time (whether due to natural processes or guided by a supreme being) as compared with the view that humans and other living things have existed in their present form since the beginning.38

We find religious tradition strongly associated with beliefs about whether or not humans have evolved. Evangelical Protestants are 30 percentage points less likely to say that humans have evolved over time and mainline Protestants are 18 percentage points less likely to say this than are the religiously unaffiliated. Other Christians (a small group in the sample composed primarily of Mormons) have a high predicted probability of saying that humans and other living things have existed in their present form since the beginning (+0.69). Catholics tend to be less likely than the religiously unaffiliated to say that humans have evolved, although this factor does not reach statistical significance once other factors are controlled. Black Protestants are closely divided over whether or not humans have evolved over time; a majority of black Protestants identify as evangelical and the remainder are included with mainline Protestants in the model. There is no statistically independent effect of being black on views about evolution once religious tradition, frequency of attendance and other factors are controlled, although the effect approaches customary levels of statistical significance.

Regular worship service attendance, regardless of tradition, also predicts a lower likelihood of saying that humans and other living things have evolved (-0.09 compared with seldom or never attending worship service).

In addition to religious factors, education and science knowledge play a role. Those who generally know more about science (+0.12) as well as those holding either a college degree or a postgraduate degree are more likely to say that humans have evolved (+0.10 and +0.08, respectively). Specifically, those with a high school degree or less science knowledge on this measure have a predicted probability of 0.64, those with a college degree and more science knowledge have a predicted probability of 0.85, and those with a postgraduate degree and more science knowledge have a predicted probability of 0.87 of saying humans evolved over time.

Those who believe there is scientific consensus about evolution are also 18 percentage points more likely to say that humans have evolved over time, compared with those who do not see broad scientific consensus on this issue.39

Conservatives are less likely than liberals to say that humans have evolved over time (-0.18). And Republicans and independents who lean to the GOP are 10 percentage points less likely than are their Democratic counterparts to say that humans have evolved, after controlling for religious affiliation, service attendance and other factors.

Next, we show the results of a logistic regression predicting the view that humans have evolved due to natural processes, as opposed to other views (either that evolution was guided by a supreme being or that humans have existed in their present form since the beginning). A similar set of factors predicts this belief including religious, political, education level and other demographic differences. Those with a Christian religious affiliation (including evangelical Protestant, mainline Protestant, Catholic and other Christian) are less likely than the religiously unaffiliated to say that humans have evolved through natural processes. Those who attend services at least weekly are also less likely to believe that natural processes guided evolution (-0.14).

In addition, party and ideological factors significantly predict views about evolution with Republicans or leaning Republicans and those with no party affiliation or leaning less likely than Democrats and leaning Democrats to say that humans have evolved through natural processes (-0.14 for each). Conservatives are 12 percentage points less likely than are liberals to hold this view.

In addition, older adults (-0.21) and women (-0.12) are less likely to say that humans have evolved over time due to natural processes.

Those with a postgraduate degree are more likely to take the view that humans have evolved through natural processes (+0.13) as are those who say there is scientific consensus on this issue (+0.18).

Factors Associated With Views About Evolution

Perceptions of Scientific Consensus About Human Evolution

Do Scientists Generally Agree About Evolution?As mentioned above, beliefs about whether scientists tend to agree about evolution are strongly related to respondent’s views about evolution. These beliefs are independent predictors of views about evolution even after accounting for other factors.

Overall, two-thirds of adults (66%) say that scientists agree that humans have evolved over time, while 29% say that scientists do not agree about this.

Perception of Scientific Consensus by Personal Beliefs About EvolutionAbout half (47%) of those who personally believe that humans have existed in their present form since the beginning of time also say scientists agree that humans have evolved. Three-quarters of those who believe humans have evolved also see scientists as largely in agreement about evolution.

Gender, Age, Race and Ethnicity

The perception that scientists generally agree about evolution is related to a number of respondent characteristics. Younger generations (ages 18 to 49) are more likely than older ones to see scientists as in agreement about evolution. There are no differences in perception of scientists between men and women or among whites, blacks and Hispanics, however.

Education and Knowledge

Perceptions of scientific consensus on evolution tend to vary by education and science knowledge. About three-quarters of college graduates (76%) say scientists generally agree about evolution, compared with 58% of those with a high school education or less. Fully 79% of those with more science knowledge say that scientists generally agree that humans have evolved; this compares with 54% among those who have less knowledge about science. There are no differences in perception of scientists’ beliefs about evolution between college graduates with degrees in a scientific field and those with degrees in some other field, however.

Religion

Those who are religiously unaffiliated are also more inclined to say that scientists generally agree that humans have evolved over time: 78% do so compared with 62% among those with a religious affiliation. White evangelical Protestants are especially likely to say scientists disagree about evolution; 49% believe scientists do not agree that humans have evolved, while 46% say otherwise. However, a majority of black Protestants (63%) say scientists agree that humans have evolved over time. Those who attend services regularly are less likely than those who attend less often to see scientists as being in agreement about evolution.

Party and Ideology

Perceptions of scientific consensus about evolution are related to party affiliation and ideology. Six-in-ten Republicans and leaning Republicans say that scientists generally agree that humans have evolved compared with 72% among Democrats and those who lean to the Democratic Party. Conservatives are less likely than either moderates or liberals to say scientists generally agree that humans have evolved; 55% of conservatives say scientists agree, compared with 67% of moderates and 79% of liberals.

Multivariate Analyses

Factors Associated With Belief There Is Scientific Consensus About Human EvolutionA multivariate logistic regression predicting the view that scientists generally agree that humans have evolved over time finds those with more science knowledge (+0.20) and postgraduate degree holders (+0.11) are more likely to believe there is scientific consensus about evolution. Those with a postgraduate degree and more science knowledge on this index are predicted to be 31 percentage points more likely to say that there is a scientific consensus on evolution than those with a high school degree or less and less science knowledge. Older adults are less likely than younger adults to say scientists are in agreement on this issue (-0.23). Conservatives (-0.12) and moderates (-0.09) are less likely than are liberals to say this. And, those who attend church services regularly (at least weekly) are less likely to believe that scientists are generally in agreement about human evolution (-0.13). There is no statistically independent effect of religious tradition in views of scientific consensus when it comes to evolution, however.

Perceptions of Scientific Consensus About the Creation of the Universe

The Pew Research survey included one question of perceived scientific consensus about the creation of the universe. Some 42% of the public as whole says that scientists generally agree the universe was created in a single event often called “the Big Bang,” while 52% say that scientists are divided in their views about creation of the universe.

Gender, Age, Race and Ethnicity

Do Scientists Generally Believe in ‘Big Bang’?As with perceptions of consensus about evolution, the belief that scientists generally agree about the creation of the universe is related to age. Younger generations (ages 18 to 49) are more likely than older ones to say scientists are in agreement about how the universe was created. Men are somewhat more likely than are women to say that scientists generally believe the universe was created in a single, violent event (48% of men say this, compared with 36% of women). There are no differences among whites, blacks and Hispanics in views about this.

Education and Knowledge

About half of those with at least a college degree (52%) and fully 61% of those with a postgraduate degree say that scientists generally believe the universe was created in a single, violent event compared with 33% of those with a high school degree or less who say the same. Similarly, those with more knowledge about science are more likely to view scientists as generally in agreement about the creation of the universe. There are no differences in perception of scientists’ beliefs about the Big Bang between college graduates with degrees in a scientific field and those with degrees in some other field, however.

Religion

A 61% majority of the religiously unaffiliated say that scientists generally believe the creation of the universe occurred in a single, violent event. By contrast, a majority of those who identify with a religious tradition say that scientists generally are divided about how the universe was created (56%). A majority of white evangelical Protestants, black Protestants and Catholics hold the view that scientists are divided about the creation of the universe. White mainline Protestants are more evenly split, with 47% saying that scientists generally agree and 46% saying that scientists are divided about the Big Bang. Those who regularly attend worship services are less inclined than less frequent attenders to believe scientists are generally in agreement about the creation of the universe.

Party and Ideology

Partisan and ideological groups tend to hold differing beliefs about the Big Bang. A majority of Republicans and independents who lean to the GOP (61%) say scientists are divided in their views about the creation of the universe. By comparison 46% of those who identify with or lean to the Democratic Party say scientists are divided in their views about how the universe was created; a similar share (48%) says scientists generally agree that the universe was created in a single event. Close to half of moderates (47%) and liberals (50%) say scientists generally believe the universe was created in a single violent event. By contrast, a third (33%) of conservatives hold this view.

Multivariate Analyses

Factors Associated With Saying Scientists Believe Universe Created in Big Bang EventA multivariate logistic regression analysis finds science knowledge and education to predict views of scientific consensus. Those with more knowledge about science are 22 percentage points more likely than those with less knowledge to say that scientists generally believe the universe was created in a single, violent event. Those with a postgraduate degree are more likely than those with a high school degree or less schooling to say there is scientific consensus on this issue (+0.19). Controlling for other factors, adults with a high school education who also have less science knowledge have a predicted probability of 0.28 of saying that scientists believe the universe was created in a “Big Bang” event, compared to a predicted probability of 0.67 for those with a postgraduate degree who also have more science knowledge.

Other Christians (i.e., those who are Mormon or Orthodox Christian) are 35 percentage points less likely than the religiously unaffiliated to say that scientists generally agree about the universe was created in a single, violent event. Republicans and leaning Republicans are less likely than their Democratic counterparts to see scientists as in agreement about this issue (-0.16). Women are less likely than men to say that scientists believe the universe was created in a single, violent event (-0.10), controlling for other factors.

  1. Surveys in 2005 and 2006 asked a similar set of questions about evolution beliefs. Those findings are not directly comparable to the questions discussed here due to differences in the question wording. In addition, the earlier surveys preceded questions about evolution with a question about personal belief in God. That survey context may also influence responses to questions about evolution beliefs. See Pew Research Center’s 2006 report “Many Americans Uneasy with Mix of Religion and Politics.”
  2. We also conducted a series of multinomial logistic regression analyses predicting one of three positions: whether respondents say humans and other living things have existed in their present form since the beginning, humans and other living things have evolved with the guidance of a supreme being, or that humans and other living things have evolved due to natural processes. Those who were unsure whether evolution has occurred or where unsure of the processes of evolution were omitted from this analysis. For ease of interpretation, we show the results of separate logistic regressions above.
  3. We also ran these analyses without including beliefs about scientific consensus to test that the findings shown here hold regardless of this difference in model specification. Details are available upon request.