Frequently Asked Questions

Aren't evolution and religion opposing ideas?

Newspaper and television stories sometimes make it seem as though evolution and religion are incompatible, but that is not true. Many scientists and theologians have written about how one can accept both faith and the validity of biological evolution. Many past and current scientists who have made major contributions to our understanding of the world have been devoutly religious. At the same time, many religious people accept the reality of evolution, and many religious denominations have issued emphatic statements reflecting this acceptance.

To be sure, disagreements do exist. Some people reject any science that contains the word "evolution"; others reject all forms of religion. The range of beliefs about science and about religion is very broad. Regrettably, those who occupy the extremes of this range often have set the tone of public discussions. Evolution is science, however, and only science should be taught and learned in science classes.

Isn't belief in evolution also a matter of faith?

Acceptance of evolution is not the same as a religious belief. Scientists' confidence about the occurrence of evolution is based on an overwhelming amount of supporting evidence gathered from many aspects of the natural world. To be accepted, scientific knowledge has to withstand the scrutiny of testing, retesting, and experimentation. Evolution is accepted within the scientific community because the concept has withstood extensive testing by many thousands of scientists for more than a century. As a 2006 "Statement on the Teaching of Evolution" from the Interacademy Panel on International Issues, a global network of national science academies, said, "Evidence-based facts about the origins and evolution of the Earth and of life on this planet have been established by numerous observations and independently derived experimental results from a multitude of scientific disciplines" (emphasis in original).

Many religious beliefs do not rely on evidence gathered from the natural world. On the contrary, an important component of religious belief is faith, which implies acceptance of a truth regardless of the presence of empirical evidence for or against that truth. Scientists cannot accept scientific conclusions on faith alone because all such conclusions must be subject to testing against observations. Thus, scientists do not "believe" in evolution in the same way that someone believes in God.

How can random biological changes lead to more adapted organisms?

Contrary to a widespread public impression, biological evolution is not random, even though the biological changes that provide the raw material for evolution are not directed toward predetermined, specific goals. When DNA is being copied, mistakes in the copying process generate novel DNA sequences. These new sequences act as evolutionary "experiments." Most mutations do not change traits or fitness. But some mutations give organisms traits that enhance their ability to survive and reproduce, while other mutations reduce the reproductive fitness of an organism.

The process by which organisms with advantageous variations have greater reproductive success than other organisms within a population is known as "natural selection." Over multiple generations, some populations of organisms subjected to natural selection may change in ways that make them better able to survive and reproduce in a given environment. Others may be unable to adapt to a changing environment and will become extinct.

Aren't there many questions that still surround evolution? Don't many famous scientists reject evolution?

As with all active areas of science, there remain questions about evolution. There are always new questions to ask, new situations to consider, and new ways to study known phenomena. But evolution itself has been so thoroughly tested that biologists are no longer examining whether evolution has occurred and is continuing to occur. Similarly, biologists no longer debate many of the mechanisms responsible for evolution. As with any other field of science, scientists continue to study the mechanisms of how the process of evolution operates. As new technologies make possible previously unimaginable observations and allow for new kinds of experiments, scientists continue to propose and examine the strength of evidence regarding the mechanisms for evolutionary change. But the existence of such questions neither reduces nor undermines the fact that evolution has occurred and continues to occur.

Nor do such questions diminish the strength of evolutionary science. Indeed, the strength of a theory rests in part on providing scientists with the basis to explain observed phenomena and to predict what they are likely to find when exploring new phenomena and observations. In this regard, evolution has been and continues to be one of the most productive theories known to modern science.

Even scientific theories that are firmly established continue to be tested and modified by scientists as new information and new technologies become available. For example, the theory of gravity has been substantiated by many observations on Earth. But theoretical scientists, using their understanding of the physical universe, continue to test the limits of the theory of gravity in more extreme situations, such as close to a neutron star or black hole. Someday, new phenomena may be discovered that will require that the theory be expanded or revised, just as the development of the theory of general relativity in the first part of the 20th century expanded knowledge about gravity.

With evolutionary theory, many new insights will emerge as research proceeds. For example, the links between genetic changes and alterations in an organism's form and function are being intensively investigated now that the tools and technologies to do so are available.

Some who oppose the teaching of evolution sometimes use quotations from prominent scientists out of context to claim that scientists do not support evolution. However, examination of the quotations reveals that the scientists are actually disputing some aspect of how evolution occurs, not whether evolution occurred.

What evidence is there that the universe is billions of years old?

This is an important question because evolution of the wide variety of organisms currently existing on Earth required a very long period of time. Several independent dating techniques indicate that the Earth is billions of years old. Measurements of the radioactive elements in materials from the Earth, the Moon, and meteorites provide ages for the Earth and the solar system. These measurements are consistent with each other and with the physical processes of radioactivity. Additional evidence for the ages of the solar system and the galaxy includes the record of crater formation on the planets and their moons, the ages of the oldest stars in the Milky Way, and the rate of expansion of the universe. Measurements of the radiation left over from the Big Bang also support the universe's great age.

What's wrong with teaching critical thinking or "controversies" with regard to evolution?

Nothing is wrong with teaching critical thinking. Students need to learn how to reexamine their ideas in light of observations and accepted scientific concepts. Scientific knowledge itself is the result of the critical thinking applied by generations of scientists to questions about the natural world. Scientific knowledge must be subjected to continued reexamination and skepticism for human knowledge to continue to advance.

But critical thinking does not mean that all criticisms are equally valid. Critical thinking has to be based on rules of reason and evidence. Discussion of critical thinking or controversies does not mean giving equal weight to ideas that lack essential supporting evidence. The ideas offered by intelligent design creationists are not the products of scientific reasoning. Discussing these ideas in science classes would not be appropriate given their lack of scientific support.

Recent calls to introduce "critical analysis" into science classes disguise a broader agenda. Other attempts to introduce creationist ideas into science employ such phrases as "teach the controversy" or "present arguments for and against evolution." Many such calls are directed specifically at attacking the teaching of evolution or other topics that some people consider as controversial. In this way, they are intended to introduce creationist ideas into science classes, even though scientists have thoroughly refuted these ideas. Indeed, the application of critical thinking to the science curriculum would argue against including these ideas in science classes because they do not meet scientific standards.

There is no scientific controversy about the basic facts of evolution. In this sense the intelligent design movement's call to "teach the controversy" is unwarranted. Of course, there remain many interesting questions about evolution, such as the evolutionary origin of sex or different mechanisms of speciation, and discussion of these questions is fully warranted in science classes. However, arguments that attempt to confuse students by suggesting that there are fundamental weaknesses in the science of evolution are unwarranted based on the overwhelming evidence that supports the theory. Creationist ideas lie outside of the realm of science, and introducing them in science courses has been ruled unconstitutional by the U.S. Supreme Court and other federal courts.

What are common ideas regarding creationism?

"Creationism" is a very broad term. In the most general sense, it refers to views that reject scientific explanations of certain features of the natural world (whether in biology, geology, or other sciences) and instead posit direct intervention (sometimes called "special creation") in these features by some transcendent being or power. Some creationists believe that the universe and Earth are only several thousand years old, a position referred to as "young Earth" creationism. Creationism also includes the view that the complex features of organisms cannot be explained by natural processes but require the intervention of a nonnatural "intelligent designer." The "Additional Readings" section following these questions contains several books that describe the various ways in which the word "creationism" is used.

Wouldn't it be "fair" to teach creationism along with evolution?

The goal of science education is to expose students to the best possible scholarship in each field of science. The science curriculum is thus the product of centuries of scientific investigation. Ideas need to become part of the base of accepted scientific knowledge before they are appropriately taught in schools. For example, the idea of continental drift to explain the movements and shapes of the continents was studied and debated for many years without becoming part of the basic science curriculum. As data accumulated, it became clearer that the surface of the Earth is composed of a series of massive plates, which are not bounded by the continents, that continually move in relation to each other. The theory of plate tectonics (which was proposed in the mid-1960s) grew from these data and offered a more complete explanation for the movement of continents. The new theory also predicted important phenomena, such as where earthquakes and volcanoes are likely to occur. When enough evidence had accumulated for the concept of plate tectonics to be accepted by the scientific community as fact, it became part of the earth sciences curriculum.

Scientists and science educators have concluded that evolution should be taught in science classes because it is the only tested, comprehensive scientific explanation for the nature of the biological world today that is supported by overwhelming evidence and widely accepted by the scientific community. The ideas supported by creationists, in contrast, are not supported by evidence and are not accepted by the scientific community.

Different religions hold very different views and teachings about the origins and diversity of life on Earth. Because creationism is based on specific sets of religious convictions, teaching it in science classes would mean imposing a particular religious view on students and thus is unconstitutional, according to several major rulings in federal district courts and the Supreme Court of the United States.

Does science disprove religion?

Science can neither prove nor disprove religion. Scientific advances have called some religious beliefs into question, such as the ideas that the Earth was created very recently, that the Sun goes around the Earth, and that mental illness is due to possession by spirits or demons. But many religious beliefs involve entities or ideas that currently are not within the domain of science. Thus, it would be false to assume that all religious beliefs can be challenged by scientific findings.

As science continues to advance, it will produce more complete and more accurate explanations for natural phenomena, including a deeper understanding of biological evolution. Both science and religion are weakened by claims that something not yet explained scientifically must be attributed to a supernatural deity. Theologians have pointed out that as scientific knowledge about phenomena that had been previously attributed to supernatural causes increases, a "god of the gaps" approach can undermine faith. Furthermore, it confuses the roles of science and religion by attributing explanations to one that belong in the domain of the other.

Many scientists have written eloquently about how their scientific studies have increased their awe and understanding of a creator. The study of science need not lessen or compromise faith.

From Science, Evolution, and Creationism, National Academy of Sciences and Institute of Medicine. © 2008 National Academy of Sciences