Evidence and Evolution: A Controversial Theory

— Rob Bartlett

THE IMPORTANCE OF evolutionary theory for biology can hardly be overstated.  An oft-quoted remark by the geneticist Theodosius Dobzhansky captures this: "Nothing in Biology makes sense except in the light of evolution."  The applications of genetics—the foundation of evolutionary theory—are widespread and profound in technology as well as basic biology.

One of the reasons that governments and private industry were willing to sink billions of dollars into sequencing the human genome—then mice, fruit flies, roundworms and other organisms—is that they expect to get big profits from comparing the DNA (basic genetic material) from genes in different species.  One benefit comes from identifying mutated forms of genes responsible for diseases or associated with higher risks of developing diseases, and potentially the development of drug treatments for them.

Yet any casual reader of newspapers cannot fail to have noticed a steady stream of articles dealing with evolution—not articles detailing the research of scientists studying aspects of the history of life, but cases where local or state boards of education or legislators introduce challenges to the central paradigm in biology of evolution, in the name of "teaching the controversy" or allowing the "evidence contradicting evolution."  The recent case most in the news is that of Dover, PA, whose school board was sued by parents who opposed the introduction of Intelligent Design (ID) into their curriculum.  Specifically the board required that teachers read a statement asserting that "because Darwin's theory is a theory it continues to be tested"…and "is not a fact.  Gaps in the theory exist for which there is no evidence."  It then introduces Intelligent Design as an alternative explanation to evolution.

In late December (after the voters in Dover had kicked the "Intelligent Design" proponents off the school board), the judge hearing the case made a sweeping ruling in favor of the plaintiffs, labeling ID not scientific but merely a mutation of "scientific creationism" and thus religious in essence, violating the separation of church and state.  The 139-page opinion declined to rule narrowly, and instead was a historical listing of both the legal antecedents of this case and a detailed refutation of the scientific claims of ID.

Not surprisingly, proponents of ID like the Discovery Institute's associate director, Dr. John West, decried the decision saying that "Judge Jones got on his soapbox to offer his own views of science, religion, and evolution.  He makes it clear that he wants his place in history as the judge who issued a definitive decision about intelligent design.  This is an activist judge who has delusions of grandeur."  Allusions to activist judges are somewhat ironic in this case as the judge is a Republican, appointed by President Bush.

Although this ruling is nothing new, but merely affirms similar rulings of the past, it is clear that the "controversy" over evolution will not go away.  During 2005 there were dozens of other instances where legislators introduced bills supporting the teaching of ID, or where state boards of educations changed their standards to weaken the teaching of evolution, despite widespread unanimity in the scientific community that support the primacy of evolution as a unifying theory in biology.

While much of this legislation is introduced with little chance of it being enacted into law, in some places, like Kansas and Ohio, state boards of education have changed their state science standards to introduce "controversy" over the theory of evolution or allow teaching of "alternative theories" to evolution such as ID.

Even a state like Illinois, which has a standard that reads "Describe processes by which organisms change over time using evidence from comparative anatomy and physiology, embryology, the fossil record, genetics and biochemistry," the "process,"—evolution—is not named.  This could be attributed to either caution or cowardice, but in any case it highlights the chilling effect of opposition to evolution.

Public Opinion on Evolution

Ever since Charles Darwin and Alfred Wallace's independently derived theory of evolution by means of natural selection was publicly read in 1858, there has been opposition.  The vast majority of scientists were quickly won over, while opposition has stubbornly continued to be centered on a religious basis.  So what is public opinion on the question of evolution?

The Gallup Poll in 2004 found that 35% of the U.S. public said that evolution is well supported by the evidence, while an equal number said it was not. On the origin of human beings, 51% stated that humans developed from less advanced life forms, but 38% believed that God guided this process and only 13% thought that God played no role in the process.  On the other hand, 45% thought that God created humans in the last 10,000 years.

Similarly the Harris Poll of July, 2005 found that 54% of adults in the United States do not think that human beings developed from earlier species, compared to 46% in 1994, and 64% agree with the statement "human beings were directly created by god."  Gallup found that 34% of those polled agreed with the statement "the Bible is the actual word of god and is to be taken literally, word for word."  In contrast, a less reliable United Nations poll of Europeans found that only 18% believed that humans were created divinely.

A breakdown of the respondents in U.S. polls show that the more education people have and the more liberal they consider themselves, the greater the acceptance of evolution, but even among adults with postgraduate degrees 33% reject human development from earlier species.  On the other hand, among those most well educated in science, according to Newsweek in 1987, only 700 out of 480,000 earth and life scientists give credence to creation-science.

This doesn't imply that rejection of "creation-science" is equivalent to disbelief in god, but scientists do tend toward materialist views and only five percent of the members of the National Academy profess a belief in God. In fact many scientists find no contradiction in accepting the results of science in terms of the age of the earth and the evolution of new species from existing ones, and professing a belief in a deity.

On the teaching of evolution and alternative theories, 55% of the U.S. public thought that evolution, creationism and intelligent design should all be taught in schools and only 12% think that only evolution should be taught.  These are not encouraging numbers no matter how they are parsed.

The legal basis of the acceptance of evolution has an equally checkered past.  The most famous trial on evolution was the Scopes trial of 1925 in Tennessee.  This trial, which occurred 60 years after Darwin's theory was accepted by scientists, upheld the right to bar the teaching of evolution.  It was only in 1968 in Epperson v. Arkansas that the United States Supreme Court ruled that prohibiting the teaching of evolution was illegal, and later in 1982 in McLean v. Arkansas Board of Education that a federal court struck down equal-time statutes on the teaching of "creation-science" and "evolution-science," on the basis that "creation-science" is not in fact scientific, but religious in nature.

In 1987, the Supreme Court extended the 1982 decision to the entire country.  Thus, far from being a bastion of intellectual freedom and curiosity, the United States has only recently been dragged kicking and screaming into teaching 19th century scientific theory.  This is best explained not as some sort of Byzantine plot on the part of the powers that be, but as a reflection of the parochialism of rural America coupled with the plethora of religious sects that colonized the country.

This matters, as the beliefs of teachers responsible for scientific education can influence what they teach.  In the August, 2004 issue of The American Biology Teacher, a survey of teachers in Oregon showed a negative correlation between strength of religious belief and acceptance of evolution.  Likewise, the stronger the acceptance of evolution, the more likely it was presented in the classroom.

I can state anecdotally that during the 2004-5 teaching years there has been a thread of discussion among Advanced Placement Physics teachers that questioned evolution.  This was a distinctly minority position which was ably answered by many other physics teachers, but the individuals questioning evolution were extremely obdurate and persistent in their beliefs, not unlike the present day supporters of ID and Creationism.  It is worrisome that teachers educated in the scientific method are swayed by fundamentally unscientific beliefs, a development that brings up questions of the quality of science education in our society.

While it is impossible to speak authoritatively on how evolution is taught in all levels of education, some observations may indicate something of the problem.  The first has to do with how science is taught at various grade levels.  While most teachers are admirably dedicated, the proportion of teachers trained in the particular discipline they are teaching increases at higher levels all the way from elementary to the university.  In high schools, where teachers must have a major in a subject they are teaching, they are also allowed to be certified to teach other subjects as well.

In Illinois, where I teach, I was required to pass a content area test in my major field of study, but then was subsequently certified in other science subjects like chemistry and physics based upon a minimum number of hours of classes in those fields.  While I feel I am a competent physics or chemistry teacher, in no way do I have the depth of knowledge that I possess in Biology.  Biology majors get a well-rounded view of most areas of their subject, including evolution, but not nearly so good a job is done in other science classes that we also take.

The lower down the education food chain one goes, the more teachers are required to wear many hats and the pedagogy of teaching is stressed over the subject content.  This trend also works on a large to small and urban to rural school basis; the smaller the school, the more subjects a teacher has to cover.  This tends to weaken the content of science and especially so in the lowest grades.  When students form their set of learning skills, their exposure to the nature of science is weak.

A second difficulty has to do with the fractured nature of educational standards.  In my school until about four years ago, a student could graduate having taken only two science classes and one of those could have been an applied technology class.  In the state of Illinois different standards existed in different school districts, with the best funded districts (the richest, of course) requiring more classes and providing more resources for the students.  So even among students who graduate, there is a wide difference in their exposure to science and the skills needed to successfully understand the abstract reasoning implicit in science.

This could be overcome if resources were made available in the form of science specialists to strengthen science programs throughout all levels of education, but that should be the subject of another article.

So why does this matter when the overwhelming number of people doing science, scientists, accept evolution?  The easy answer is that although obscurantist beliefs may have little effect on the research programs of scientists at universities or corporations who use evolutionary insights, the general public is being deprived of the ability to think critically about nature and, by implication, about society.

The Nature of Science

Underlying this problem is a lack of knowledge about the nature of science, leading to confusion over competing "theories."  This needs to be addressed, as one of the main tools that opponents of evolution use is a misunderstanding within the public of the nature of science, and an appeal to the sense of fairness in people by asking for equal time to present "opposing theories."

A key semantic argument involves the misuse of the term "theory."  A "theory" in popular parlance is equated with an idea or an opinion: You have your theory and I have mine.  In scientific terms this sort of usage would best be called an "hypothesis."  In any event scientific hypotheses must be more than simply opinion, but also be plausible, fitting the available evidence.  They must also be testable through a series of experiments designed to compare predictions based upon the hypothesis.

A rather silly example might be over the existence of Santa Claus.  A child might think that Santa exists, based upon the statements of parents and the indisputable evidence of presents at Christmas, the disappearance of milk and cookies left out for him, etc. On this level "Santa science" has one thing going for it that's lacking in "creation science" or "intelligent design"—evidence that supports the hypothesis of Santa.  Secondly, this hypothesis fits another hallmark of science—its testability and ultimately the possibility to be disproven.

A more scientific example might be as follows: If species have indeed evolved and share common ancestors through descent with modification, then those species which are most closely related (share the most recent common ancestor) should also share more anatomical or morphological characteristics than species which are more distantly related.

The rise of molecular biology has allowed the testing of predictions of evolutionary relationships based upon comparative anatomy, through testing proteins like hemoglobin or those involved in cellular respiration.  These proteins, while having a common function, show differences in structure that can be attributed to mutations of single DNA nucleotides (DNA is made of four different nucleotides).  This can result in no change in a protein due to the redundancy of more than one codon (three nucleotides make up a codon, hence there are 64 possible codons, which form 20 amino acids and serve as start and stop signals) coding for a particular amino acid; or it can result in an entirely new amino acid being inserted into a protein.

This can either have little effect on the protein if the new amino acid has similar chemical properties and doesn't alter the shape and hence the function of the protein, or it may have profound and disastrous effects like the mutation that is responsible for sickle-cell trait where the substituted amino acid changes the shape of the hemoglobin molecule.  Mutations like the one responsible for sickle cell trait are unlikely to persist in a population unless they provide another evolutionary advantage (in this case, resistance to malaria).

The point is that neutral (i.e. neither harmful nor beneficial) mutations can be assumed to happen at similar rates within related groups, and can be used as a measuring stick of evolutionary time between the divergence of species or groups.  Examination of this sort of data allows scientists to have reasonable assurance that chimps are the closest living relative to humans.  While this is interesting, from an evolutionary standpoint it supports the previously hypothesized relationships between groups of mammals like new and old world monkeys or even more closely related groups like the 13 species of Darwin's finches.

In short, tools like molecular biology not only tend to confirm evolutionary relationships and fill in the details of evolution, but they allow scientists to begin to study the effects of natural selection from the population level to that of molecule.

The problem with alternative explanations such as creationism or intelligent design is that by their very nature of being part of a belief system, not based on the natural world, they are inherently untestable.  This is not simply a matter of people with religious views having one set of beliefs, versus scientists having a belief in the scientific method.  The scientific method is superior to appeals to the supernatural, because experiments based upon this method get results.  While scientists frequently dispute the interpretation of data and put forward alternative hypotheses—the debate over the causes and extent of global warming come to mind—real science is tested in the real world using reproducible experiments.

Even theories which attempt to unify the forces of physics (e.g. string theory) are not drawn of thin air, but are based upon mathematical models, which to ultimately gain acceptance must find a way to make testable predictions consistent with the natural world.

Scientists frequently test the validity of a hypothesis or theory by trying to extend the insight of the hypothesis or theory to cover more circumstances and see if the evidence is consistent.  The assumption is that our knowledge may be incomplete or imperfect, but in all cases changes to our ideas are based upon evidence and not our own desires.

While the discovery that matter is made of elements whose smallest units are atoms made of varying numbers of protons, neutrons and electrons certainly put an end to the ancient Greek idea of matter composed of earth, air, fire and water, the further elaborations of physicists that these subatomic particles are also made of even smaller units like quarks has not ended the careers of chemists.  So while all theories are subject to change, modification, even complete revision, the process by which this takes place is a generally incremental one of continual testing and refinement using the hallmarks of science—data from reproducible experiments.

Proponents of "ID" make much of what they call "gaps" in evolutionary theory, but have come up with no alternative set of facts or evidence that contradict evolution.  The fact that scientists acknowledge the imperfection of their knowledge of all details of evolution no more negates it than, say, the theory of special relativity.  Before we examine the supposed new evidence that contradicts evolution, it may be useful to briefly sketch out what the evolution is.

Tenets of Evolutionary Theory

Evolution, or change over time, is not an idea that originated with Charles Darwin and Alfred Russell Wallace, but they were the first to find a plausible mechanism, natural selection, for the evolutionary process.

Darwin began with: 1) the fact that variation exists in all populations (Darwin spends his first two chapters detailing the variation in domesticated and non-domesticated species and the artificial selection of animal breeders); 2) the premise (inspired by Malthus) that species produce far more offspring than can possibly survive, leading to what he called a "struggle for existence;" 3) the observation that this struggle is mediated by ever changing ecological conditions, which influence the "struggle for existence" through those variations which are present and give one organism an advantage over its competitors.

While conditions may change, first favoring one then another variation in a population, the essence of speciation is the collection of enough genetic variations in a population that eventually prevent the modified population from mixing with the parent population (genetic isolation) or when they are capable of reproducing hybrids who are less "fit" than either individual parent.  This change can result either from isolation of populations from each other, or through the differential reproduction of individuals within a population with inheritable variations.

Natural selection is the constant competition between individual organisms and their environment, both living and non-living.  Nature acts on the raw material of variation, be it physical, behavioral, or metabolic within populations.  Thus Darwin refers to evolution as descent with modification.

This explains why organisms of similar lineages share so many common features, such as the homologies of the vertebrate body plan with the same number of bones in the limbs (the radius and ulna in the forelimb along with the humerus and the tibia and fibia in the hind limb, with the femur vastly changed as the form is modified to fit the function of different forms of locomotion from flying, walking or swimming).

This also explains why nature is not always the "best designer."  As structures suitable for, say, walking on four limbs (the spine) are modified for upright bipedal movement, inherent design flaws can result in "back problems."

Most tellingly, all life shares the same basic genetic code and amazingly large numbers of common genes, such as the hox family, which control the sequence in which genes are turned on and off during the course of development.

That in much too small of a nutshell is what natural selection is all about.  Readers wishing to investigate the topic in much greater depth can find many excellent sites on the internet, but one of note is the talk.origins archive at http:// www.talkorigins.org/.

Does New Evidence Challenge Evolution?

Back in the 1980s religious opponents of evolution labeled their view "creation science."  It wasn't trying too hard to masquerade as science, and courts ruled that it was a religious belief and not scientific in nature.  This mutated in the 1990s with the publication of Michael Behe's book Darwin's Black Box: The Biochemical Challenge to Evolution, which attempted to give a scientific veneer to creationism.

Behe's book begins with the argument that with the deepening knowledge of molecular biology it was discovered that the molecular machinery of life was far more complex than previously understood—so complex in fact that the micro and macro structures that make up cells are unlikely to have arisen through a random process like evolution.

Behe introduces the idea of "irreducible complexity," his example being that of a mouse trap.  This is made of relatively simple parts, a base, a hammer, a spring, and a metal catch to hold the hammer, yet take away any one part and it no longer functions.  How is it possible to imagine that these components, so exquisitely fitted for their function, could have evolved into this simple, yet elegant, machine?

Such a machine is truly simple compared to some of the chemical cascade reactions that mediate the life of a cell, and one is then left to wonder how those could possibly have evolved randomly.  In short, the intelligent design proponents declare, if a structure seems to function as if it is designed, it probably was. Who the designer was is not specified, but the meaning is clear.

But this leap from incredulity at the intricacies of nature to the conclusion that all is the product of some designer is neither understandable nor supportable.  The basic flaw in reasoning is to propose that a biological structure must arise fully formed and functional for that purpose alone.  If that were the case then the difficulties of the evolutionary process would be formidable.

In the case of the mousetrap, each part can be used either individually or in combination to make other devices—like a clipboard or a hook.  The proteins that are involved in complicated biochemical systems can likewise be adapted and modified for different functions.  The proteins that make up the blood clotting mechanism, for example, have been shown to be variations of proteins involved in the digestive system.

The alleged science behind intelligent design boils down to an argument that if we can't imagine how such complex structures could evolve, therefore they must have been designed.  Numerous critics of this argument have pointed out that if that is the case, then the designer must be a rather poor or cruel one, as many organisms suffer from poor designs such as the vermiform appendix, whose only function seems to be to occasionally become infected and rupture, killing the unfortunate person.

The scientific explanation of organs like the appendix is that they are vestigial or remnant structures, ghosts of evolution past.  Clearly intelligent design fails the test of science: it makes no predictions that can be tested, carries out no research program, and has no body of evidence to support itself.  Yet why does it so persistently raise its criticisms?

The Genesis of Intelligent Design.

It would be a mistake to look at ID as an idea out of the context of those who present it. In the Dover case the somewhat hapless school board proponents of ID were exposed as being rather naïve, with deep religious beliefs capable of being manipulated by more sophisticated forces like the Discovery Institute, an intelligent design "think tank" and represented legally by the Thomas Moore Law Center of Ann Arbor.  The latter was funded by the Domino's pizza founder Thomas Monaghan, who is well known for his anti-abortion and extreme right-wing views.

The purpose of the Discovery Institute (DI) is best understood by examining a position paper titled "The Wedge Project," issued by the Center for the Renewal of Science and Culture, which was launched by the DI in 1996.  This was posted anonymously on the web and its stated mission is to "defeat scientific materialism and its destructive moral, cultural and political legacies" and "replace materialistic explanations with the theistic understanding that nature and human beings are created by God."

The wedge refers to their attempt to split "materialistic science" at its perceived weakest point, Darwinian Evolution.  The court in the Dover case cites the wedge document and its "Five Year Strategic Plan Summary" which is divided into three phases: Phase I for scientific research and publicity; Phase II for publicity and opinion making, which focuses on influential opinion-makers and strives "to build up a popular base of support among our natural constituency, namely, Christians;" and Phase III for cultural confrontation and renewal including legal assistance "in response to resistance to the integration of design theory into public school science curricula."

Both the Discovery Institute and similarly ideological groups like the Thomas Moore Law Center clearly have an ambitious agenda.  They have also clearly tapped into the U.S. evangelical movement.  While most of the members of the evangelical movement who are the targets of intelligent design are unlikely to have the same messianic mission as the DI, their numbers would seem to assure that the Dover ruling is no stake through the ID movement's heart.

This movement's capacity for political mobilization may also play into why it receives support from people who should perhaps know better, like President Bush and Senator Frist of Tennessee, both of whom have publicly gone on record urging the teaching of both ID and evolution in public schools.

While these views are embarrassing to scientists, including Bush's science advisor John Marburger who stated in response to Bush's remarks that "evolution is the cornerstone of modern biology" and "intelligent design is not a scientific concept," they may serve another purpose of muddying the water when a scientific consensus builds on highly charged issues—like the human causes of global climate change, and the ruinous effect of the ruthless extraction of natural resources around the world.

A political agenda with economic aims that denies the link between greenhouse gases and global warming can be more easily furthered when the public is both uneducated in the intricacies of science and ignorant of what is really known, as well as capable of being manipulated by appeals to the supernatural.  Both factors, sadly, promise to keep this debate in the public view for the foreseeable future.


Rob Bartlett teaches high school biology and physics at Morton West High School in Berwyn, Illionois.  The author owes a debt of gratitude for the critical comments of Ansar Fayyazuddin on an earlier draft.  His comments helped even though he may still disagree with some of the author's characterizations.

ATC 121, March-April 2006