Today, a century and a half after Charles Darwin published "On the Origin of Species by Means of Natural Selection," the overwhelming majority of scientists in the United States accept Darwinian evolution as the basis for understanding how life on Earth developed. But although evolutionary theory is often portrayed as antithetical to religion, it has not destroyed the religious faith of the scientific community.
According to a survey of members of the American Assn. for the Advancement of Science, conducted by the Pew Research Center in May and June this year, a majority of scientists (51%) say they believe in God or a higher power, while 41% say they do not.
Furthermore, scientists today are no less likely to believe in God than they were almost 100 years ago, when the scientific community was first polled on this issue. In 1914, 11 years before the Scopes "monkey" trial and four decades before the discovery of the structure of DNA, psychologist James Leuba asked 1,000 U.S. scientists about their views on God. He found the scientific community evenly divided, with 42% saying that they believed in a personal God and the same number saying they did not. Scientists have unearthed many important fossils since then, but they are, if anything, more likely to believe in God today.
The scientific community is, however, much less religious than the general public. In Pew surveys, 95% of American adults say they believe in some form of deity or higher power.
And the public does not share scientists' certainty about evolution. While 87% of scientists say that life evolved over time due to natural processes, only 32% of the public believes this to be true, according to a different Pew poll earlier this year.
Given that scientists are much less likely than the general public to believe in God, it's not surprising that the percentage who are affiliated with a particular religion is also lower. Nearly half of U.S. scientists say they have no religious affiliation -- describing themselves as atheist, agnostic or nothing in particular -- compared with 17% of all Americans.
Among scientists there are far fewer Protestants (21%) and Catholics (10%) than in the general public, which is 51% Protestant and 24% Catholic. And while evangelical Protestants make up more than a fourth of the general population (28%), they are only a tiny slice (4%) of the scientific community. One notable exception is Jews, who make up a larger proportion of the scientific community (8%) than the general population (2%).
But the Pew poll found that levels of religious faith among scientists vary quite a bit depending on their specialty and age. Chemists, for instance, are more likely to believe in God (41%) than those who work in biology and medicine (32%). And younger scientists (ages 18 to 34) are more likely than older ones to believe in God or a higher power.
If a substantial portion of the scientific community is made up of believers, why do so many people think evolution and religion are incompatible? It may be because some of our most famous and prolific scientists, such as American evolutionary biologist Stephen Jay Gould and British physicist Stephen Hawking, were or are atheists and agnostics. But what about Francis Collins, the former head of the Human Genome Project, who was recently appointed as director of the National Institutes of Health by President Obama? Collins is an evangelical Christian who speaks passionately about his faith -- and also thinks evolution is an established scientific fact.
As for Darwin, his letters indicate that he was probably an agnostic who lost his faith not because his groundbreaking theory was incompatible with religion, but because of his grief after the 1851 death of his favorite child, his 10-year-old daughter, Annie. And even then, he may not have completely rejected the idea of a higher power. The concluding sentence of "Origin of Species" speaks of a "Creator" breathing life "into a few forms or into one." The passage raises at least a little doubt as to how the father of modern evolutionary theory might have responded to the question on belief in Pew's recent survey of scientists.
David Masci is a senior researcher at the Pew Forum.