Science, evolution, and creationismFrancisco J. AyalaDepartment of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA 92697

On December 20, 2005, John E.Jones III, federal judge for theMiddle District of Pennsylva-nia, issued a 130-page-long de-

cision (Kitzmiller v. Dover Area School Dis-trict) declaring that ‘‘The overwhelmingevidence at trial established that ID [intel-ligent design] is a religious view, a merere-labeling of creationism, and not a sci-entific theory . . . ID is not supported byany peer-reviewed research, data, orpublications.’’

In 1984, the National Academy of Sci-ences (NAS) published Science and Cre-ationism: A View from the NationalAcademy of Sciences. A second editionwas published in 1999. A third edition,sufficiently modified to deserve a newtitle, Science, Evolution, and Creationism,published on January 4, 2008 (1).

Science and Creationism was preparedby a committee of the NAS in response tostatutes passed by the legislatures of, first,the state of Arkansas, and shortly thereaf-ter, the state of Louisiana, that requiredthat ‘‘creation science’’ be taught in publicschools together with evolution. The Loui-siana ‘‘Creation Act’’ was appealed all theway to the U.S. Supreme Court, which in1987 (Edwards v. Aguilard) concluded thatthe act’s ‘‘primary purpose was to changethe public school science curriculum toprovide persuasive advantage to a particu-lar religious doctrine that rejects the fac-tual basis of evolution in its entirety. Thus,the Act is designed either to promote thetheory of creation science that embodies aparticular religious tenet or to prohibit theteaching of a scientific theory disfavoredby certain religious sects. In either case,the Act violates the First Amendment’’ (1,p. 45). Science and Creationism was madepart of an ‘‘amicus brief’’ submitted to theSupreme Court in Edwards v. Aguilard bythe NAS, with the endorsement of theAmerican Association for the Advance-ment of Science and other organizations.

Argument from DesignThe ‘‘argument from design’’ for theexistence of God, based on the complexorganization of living things, was elabo-rated by English clergyman William Pa-ley in his Natural Theology, published in1802 (2). Paley’s argument from designis two-tined. The first prong asserts thathumans, as well as all sorts of organ-isms, in their wholes, in their parts, andin their relations to one another and totheir environment, could not have come

about by chance but rather manifest tohave been designed for serving certainfunctions and for certain ways of life.The second prong of the argument isthat only an omnipotent Creator couldaccount for the perfection and func-tional design of organisms. In the 1990s,several authors in the United States re-vived the argument from design butmodified the second prong of the argu-ment by referring to an unspecified ‘‘in-telligent designer,’’ thus avoiding explicitreference to God, so that the argument

from design could be taught in the pub-lic schools as an alternative to evolution.Judge Jones, like so many other inde-pendent observers, saw through thishypocritical subterfuge and determined,moreover, that the argument lacks anyscientific cogency whatsoever.

Science, Evolution, and Creationism con-sists of three main chapters. The firstchapter briefly describes the process ofevolution and the nature of science incontrast to other forms of knowledge. Thesecond chapter surveys the scientific evi-dence that supports evolution from di-verse disciplines that include astronomy,paleontology, comparative anatomy, bio-geography, molecular biology, genetics,and anthropology. The third chapter ex-amines intelligent design and other cre-ationist perspectives so as to point out thescientific and legal reasons against teach-ing creationism in public school scienceclasses. The text concludes with a selec-tion of frequently asked questions andadditional readings.

Evolution and Natural SelectionIn 1973, the eminent evolutionist Theodo-sius Dobzhansky famously asserted that(3). Biological evolution is the central or-ganizing principle of modern biology.Evolution provides a scientific explanationfor why there are so many different kindsof organisms on Earth and gives an ac-count of their similarities and differences(morphological, physiological, and ge-netic). It accounts for the appearance ofhumans on Earth and reveals our species’

biological connections with other livingthings. It provides an understanding of theconstantly evolving bacteria and virusesand enables the development of effectivenew ways to protect ourselves against thediseases they cause. Evolution has madepossible improvements in agriculture andmedicine and has been applied in manyfields outside biology, including forensicsand software engineering; it has stimu-lated chemists, for example, to use theprinciples of natural selection for develop-ing new molecules with specific functions.

Darwin and other 19th-century biolo-gists found compelling evidence for bio-logical evolution in the comparative studyof living organisms, their geographic dis-tribution, and the fossil remains of extinctorganisms. Since Darwin’s time, biologicaldisciplines that emerged more recently—genetics, biochemistry, ecology, animalbehavior, neurobiology, and especiallymolecular biology—have supplied power-ful additional evidence and detailed con-firmation. Accordingly, evolutionists areno longer concerned with obtaining evi-dence to support the fact of evolution.Rather, evolutionary research nowadaysseeks to understand further and in moredetail how the process of evolution occurs.Yet, the evidence from paleontology andthe older disciplines continues to accumu-late, such as the discovery published in2006 and described in Science, Evolution,and Creationism of Tiktaalik, a fish thatlived in shallow freshwater streams andswamps approximately 380 million yearsago (4, 5). Tiktaalik is a nearly preciseintermediate between typical fish and thefirst known four-legged animals fromwhich would evolve all animals that liveon the land from frogs to reptiles, tobirds, and to mammals, including humans.No intermediate fossils between humansand apes were known in Darwin’s time.Now, thousands of remains are knownthat belong to the human lineage after itseparated from the lineage that goes tothe apes.

Biological evolution is part of a com-pelling historical narrative that scientistshave constructed over the last few cen-turies. The narrative begins with the for-mation of the universe, the solar system,and the Earth, where conditions occursuitable for life to evolve. There are the-ories that seek to account for how lifeoriginated on Earth, but none of them

@ 2008 by The National Academy of Sciences of the USA

‘‘Nothing makes sense inbiology except in thelight of evolution.’’

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has gathered enough supporting evi-dence to be generally accepted by scien-tists. But natural selection, discoveredby Darwin, has been convincingly dem-onstrated as the process that accountsfor the adaptive configuration and func-tion of organisms (for their ‘‘design’’).Darwin’s greatest contribution to sci-ence is not that he accumulated evi-dence demonstrating the evolution oflife, but that he discovered natural se-lection, the process that accounts for thedesign of organisms and their wonderfuladaptations to survive and reproduce inthe environments where they live, in-cluding wings for flying, legs for run-ning, eyes to see, and kidneys thatregulate the composition of the blood.

Evolution and ReligionScientists and religious authors havewritten eloquently about their awe andwonder at the history of the universeand of life on this planet, explainingthat they see no conflict between theevidence for evolution and their beliefin God (ref. 1, p. 15; ref. 6). Authoritiesof diverse religious denominations havealso issued statements affirming thecompatibility between the tenets of theirfaith and the acceptance of biologicalevolution (ref. 1, pp. 13 and 14; ref. 6).Science and religion concern differentaspects of the human experience. Scien-tific explanations are based on evidence

drawn from examining the natural worldand rely exclusively on natural processesto account for natural phenomena. Sci-entific explanations are subject to em-pirical tests by means of observation andexperimentation and are subject to thepossibility of modification and rejection.Religious faith, in contrast, does not de-pend on empirical tests and is not sub-ject to the possibility of rejection basedon empirical evidence. The significanceand purpose of the world and humanlife, as well as issues concerning moraland religious values, are of great impor-tance to many people, perhaps a major-ity of humans, but these are matters thattranscend science.

Many people have questions aboutbiological evolution. They may havebeen told that scientific understandingof evolution is incorrect or at leastdoubtful. They may be skeptical that anatural process could account for theastonishing diversity of the living worldand the marvelous adaptations of organ-isms to their ways of life. People of faithwonder whether accepting evolution iscompatible with their religious beliefs.Science, Evolution, and Creationismspeaks to these questions. It is written toserve as a source of information and asa resource for people who find them-selves embroiled in debates about evolu-tion. It should be helpful to ‘‘schoolboard members, science teachers and

other education leaders, policy makers,legal scholars, and others in the commu-nity who are committed to providingstudents with quality science education.’’Moreover, as stated in the preface, Sci-ence, Evolution, and Creationism ‘‘is alsodirected to the broader audience ofhigh-school and college students as wellas adults who wish to become more fa-miliar with the many strands of evidencesupporting evolution and to understandwhy evolution is both a fact and a pro-cess that accounts for the diversity oflife on Earth.’’

A related document, You Say You Wantan Evolution? A Role for Scientists in Sci-ence Education, recently has been madepublic (7). This document is sponsored by17 scientific societies, representing thephysical, chemical, biological, and socialsciences and science teachers’ communi-ties. It presents the results of a recent ex-tensive survey of the public acceptance ofevolution as a function of the level of edu-cation and other variables. The documentconcludes with a determined call ‘‘for sci-entists to become involved in promotingscience education. . . . If our nation is tocontinue to develop the talent necessaryto advance scientific and medical research,we must ensure that high standards inscience education are maintained and thatefforts to introduce non-science into sci-ence classes do not succeed.’’

1. National Academy of Sciences and Institute of Medicine(2008) Science, Evolution, and Creationism (Natl AcadPress, Washington, DC).

2. Paley W (1802) Natural Theology (R Fauldner, London).3. Dobzhansky Th (1973) Nothing makes sense in biology

except in the light of evolution. Amer Biol Teacher 35:125–129.

4. Daeschler EB, Shubin NH, Jenkins FA, Jr (2006)A Devonian tetrapod-like fish and the evolu-tion of the tetrapod body plan. Nature 440:757–763.

5. Shubin NH, Daeschler EB, Jenkins FA, Jr (2006) Thepectoral fin of Tiktaalik roseae and the origin of thetetrapod limb. Nature 440:764–771.

6. Ayala FJ (2007) Darwin’s Gift to Science and Religion(Joseph Henry, Washington, DC).

7. Coalition of Scientific Societies (2007) YouSay You Want an Evolution? A Role for Scien-tists in Science Education (evolution.faseb.org/sciencecoalition). Accessed on December 15,2007.

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