excerpt – Evolution and Mormonism
There is a certain irony in the fact that the twentieth century in Mormonism begins and ends with the teachings of Joseph F. Smith. He became president of the church in 1901, and from then until his death in 1918, he presided over a major consolidation of doctrines that, up to that time, had not been particularly well defined. This consolidation—or reconstruction, as historian Thomas G. Alexander has called it—was driven primarily by three prominent Mormon writers and doctrinal commentators whose roles in this area have not been fully recognized by the church at large: B. H. Roberts, James E. Talmage, and John A. Widtsoe.
These three were far more sensitive to the life of the mind than were many of their religious contemporaries; they believed deeply that the gospel was too precious to be defended with anything but the best scholarship and honesty the Saints could muster. They believed in an ultimate synthesis of truth, and that God reveals his truths through both prophets and academicians. And their names have come to symbolize that commitment. Talmages two seminal works—Jesus the Christ and Articles of Faith—remain the foundations of Latter-day Saint doctrinal study. Roberts’s Comprehensive History of the Church still stands as the church’s official history for its first century; his priesthood manuals for the years 1907-12 still constitute the high-water mark of our organized doctrinal study courses. Widtsoe’s long history of doctrinal writings (Evidences and Reconciliations) in the church’s official magazine continues to exert considerable influence.
Not to be ignored or forgotten is Nels L. Nelson, an English professor at Brigham Young University who during the early years of the twentieth century enjoyed an unusual relationship with church president Joseph F. Smith. President Smith was known to send drafts of his speeches to Nelson for editing and suggestions, and it was Nelson who produced Mormonism’s first book on that most controversial of issues: science and religion.
The book appeared in 1904 and was considered a missionary tract by both its author and by the church’s governing First Presidency. Nelson envisioned it as the first of at least two books aimed at making Mormonism noticed—and noted—by the world’s academic fraternity. He titled it Scientific Aspects of Mormonism, and aimed to show that not only was Mormonism compatible with then-current scientific thought, but that indeed it had arrived at many of the basic philosophical positions before science did. Of particular interest is his teaching of a rather thorough-going brand of organic evolution—he saw it as fully compatible with Mormon teachings and revelations.
Demonstrating such a consilience of science and religion was necessary, Nelson believed, because “a religion which is not scientific is scarcely worth the credence of our enlightened age.” And while he recognized that he could not deal with all concepts of science, he insisted that he could show that Mormonism’s “basic data are not out of keeping with those general laws of nature on which all the conclusions of scientists rest,” and that “science and Mormonism see things in this world primarily in the same way, and also reason as to the purpose of things in the same way.” For him, the “book of nature” is (like scripture) a direct revelation of God; the laws of the universe are nothing more than the general divine laws of God. Mortality was meant to be “a glorious university—the only real university—for the development of (God’s) sons and daughters.”
Unfortunately, Nelson was not trained in science and his treatise suffers from that fact. His overall outlook was laudatory but ultimately flawed, both by his own limitations and those of the science of the day. For evolution is surely the most controversial philosophical concept of the modern world, and its mechanisms were only dimly seen in 1904. The entire process is founded on the science we now call genetics—but that word was not even coined until the year after Nelson’s book appeared. In 1904 we did not even know if the laws of genetics applied to human beings—the first demonstration of that came also the year after Nelson’s book was published.
So Nelson’s effort was doomed despite the soundness of his overall conceptual scheme that religion must progress along with science or it will quickly become irrelevant for anything other than social niceties. I fear that subsequent developments in the twentieth century have validated that point of view.
Ultimately religions can do only about three things with science. They can, of course, attack it, and many religious concepts now lie in the dust bin of history from that approach. They can ignore it—in which case they progressively become incapable of addressing modem and future problems. Or they can engage it and incorporate the demonstrated truths found thereby into a more productive view of their overall universe.
This latter path is difficult, and to many people of faith it sounds like selling the store, given the past history of science/religion relationships. But that is so only if one takes the view that God reveals himself solely through revelation and scripture, and that scripture is doctrinally complete—or, if not complete, at least sufficient. And that has not been the position of historical Mormonism.
The angel Moroni had spelled that out to church founder Joseph Smith, citing the ancient prophecy of Joel: “And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions” (Joel 2:28; JS-H 1:41). This scripture has been consistently understood by Mormon commentators to refer to the rise of science. Apostle Joseph Fielding Smith (son of President Joseph F. Smith) probably stated this interpretation most succinctly:
… the Lord has already commenced to pour out his Spirit upon all flesh, and we do find even now that the sons and daughters prophesy; the old men dream dreams, and the young men see visions.
Now, my brethren and sisters, I am not going to confine this prophecy to the members of the Church. The Lord said he would pour out his Spirit upon all flesh … (p. 176)
There has never been a step taken from that day to this, in discovery or invention, where the Spirit of the Lord … was not the prevailing force, resting upon the individual, which caused him to make the discovery or the invention … nor did the Lord always use those who have faith, nor does he always do so today. He uses such minds as are pliable and can be turned in certain directions to accomplish his work, whether they believe in him or not. (Doctrines of Salvation, 1:176, pre-1954; emphasis in original.)
I suppose that Joseph Fielding Smith may not have meant to include Charles Darwin and evolution in this sweeping idealism, though in this particular passage he did not qualify his sentiment at all.
But in President Joseph F. Smith’s day, the church began to deal with Darwin and evolution fairly directly. The Nelson book was a beginning. In 1908 President Smith and his counselors in the First Presidency took note of the rising tide of international discussion regarding the implications of evolution for religion and morals. They appointed a committee to formulate a position statement for the church, to be released in November 1909. This was a double anniversary—fifty years to the month since Darwin had published his fundamental work, On the Origin of Species, as well as the centennial of Darwin’s birth.
The committee’s work appeared over the signatures of Joseph F. Smith and his counselors. It has been reprinted many times by critics of evolution in the church, for it is easily interpreted as having an anti-evolutionary tone. Its major argument is that man is composed of both body and spirit, and it labors long to establish that the human spirit results from a spirit birth to a Heavenly Father and a Heavenly Mother. The origin of the human body is less clear, however. After stating that Adam, “like Christ, took upon himself an appropriate body,” the statement turns briefly to other matters, then dismisses evolution and concludes by saying that humans are capable of evolving into Gods.
Numerous questions from church readers prompted a clarification just five months later. In April 1910, in their official columns in the church magazine, the First Presidency took a more detailed stance. They identified three possible options for the origin of the human body, listing evolution by “natural processes … through the direction and power of God” as one acceptable view. No First Presidency since then has ever clarified the details of this issue any further. I find it regrettable that the church’s study manual for 2000-2001 includes only the 1909 statement, with no context whatever nor any evidence of the subsequent clarification.
Commentary on evolution continued cautiously from that time on. The next major LDS book dealing with the subject was written by geologist Frederick J. Pack in 1924 and is decidedly pro-evolution. As this present book details, that guardedly favorable attitude in the church continued for some time. A major discussion among the general authorities in 1931 resulted in a First Presidency ruling that the church had no doctrinal position on either side of the two most controversial issues: whether there were human-like beings on Earth before the time generally ascribed to Adam, and whether there was death on Earth prior to the fall of Adam. So for several decades, beginning with Joseph F. Smith’s administration, the church remained open on the subject of evolution, though aware of possible pitfalls. The chosen course was one of minimal engagement, little attempt at accommodation, but certainly not one of rejection.
All that changed, however, at mid-century, as a couple of books claiming to be authoritative took a decidedly antagonistic stance toward evolution. That story is well known. Less well known is that those works have not found substantive support from church history, and none whatever from ever-advancing science. A careful study of the subject clearly demonstrates that the anti-science position espoused by some in the church is untenable. Perhaps consequently, some recent writers have decided to take refuge in the third option outlined above and ignore science altogether. Lacking the training and discipline to adequately study science, they have asserted that science is irrelevant to matters of interest to religion. If we give scientists any credence at all, they argue, we would be making them into rival prophets—a clearly intolerable thought.
What does this new stance do to Mormonism’s long history of claiming that “no man can be saved in ignorance,” or that “man can be saved no faster than he gains knowledge”? What, to be more precise, does it do with Nelson’s view that mortal life is a “glorious university—the only real university”? Perhaps Nelson and his sponsoring First Presidency were simply wrong. Mortality, says the new wisdom, is really not a university in which we learn divine natural laws. Rather it is a testing center where we learn ordinances and obedience, not science and natural laws.
Of course, this is self-defeating. It produces a mentality ever more incapable of dealing with modern issues, a people progressively “irrelevant” to discussing and resolving society’s challenges. For if science is irrelevant to religion, perhaps religion is equally irrelevant to science. And since science is incontestably the force that shapes modern society, both by its technology and its increasing understanding of natural laws, we clearly run the danger of defining ourselves right out of relevance to modern life.
So, as a new century dawns, we find ourselves studying once again the teachings of the prophet who opened the twentieth century. And the present book serves as a fine introduction to the idealism found in the broader church literature of that earlier day.
Trent Stephens and Jeff Meldrum are both established research scientists. Their undergraduate careers at Brigham Young University exposed them early to the details of Mormonism’s history with science and religion. Their own interests in the field were evident even then to members of their faculty. Some students in biology “muddle through,” while others do well but with their sights set either on technical details of research or on a disciplined preparation for professional careers in, say, medicine or dentistry or wildlands management. Rare indeed are those who address the broader philosophical issues, who want to “engage” the issues rather than shrink from the fray. Trent and Jeff were clearly members of this latter group.
After completion of their own doctorate training, both joined the faculty of a state university whose student body is largely composed of Latter-day Saints. These students’ predictable questions forced continued consideration of the issues by Trent and Jeff. Their active church involvement brought additional questions and insights to bear on the topic. One of their students, Forrest Peterson, eventually convinced them that it was a worthy effort to share their thoughts with a broader LDS audience. Thus the present book was born.
This work should not be seen as a final synthesis of Mormonism and science, much less of science and religion in general. We Latter-day Saints have fallen too far behind the discussion to envision any such synthesis; the first thing we need to do is a lot of catching up. We have no significant ecclesiastical tradition dealing with the substance of either science or scripture on the majority of science/religion issues.
In December 1910 President Joseph F. Smith and his counselors laid down a critical criterion to guide church members in discussions of this sort. “Our religion is not hostile to real science,” they attested. “That which is demonstrated we accept with joy.” Demonstrated. A key requirement. What in evolutionary science can be said to be “demonstrated”? This book attempts some initial answers.
Beyond these concepts from the First Presidency, the authors return to the philosophical stance of traditional Mormonism, to Nelson’s insight that mortality is a glorious university. They have labored hard to render the fundamentals of modern genetic and evolutionary science understandable to anyone willing to expend a modicum of serious effort. “Thy mind, O man!” exclaimed Joseph Smith, “if thou wilt lead a soul unto salvation, must stretch as high as the utmost heavens, and search into and contemplate the darkest abyss, and the broad expanse of eternity” (qtd. in Smith, History of the Church, 3:295).
Exaltation is not, said Joseph and traditional Mormonism, a matter of marching lockstep through mortality; it is instead a conscientious, dedicated, disciplined, and rigorous search for truth, for an understanding of the laws that make this world and universe run. And the study of those laws need not be seen as a threat to one’s religious commitment. Quite the contrary. God himself seems to have asserted that a study of nature’s laws leads only to a greater understanding and appreciation of him and his ways: “all things are created and made to bear record of me, both things which are temporal, and things which are spiritual; things which are in the heavens above, and things which are on the earth, and things which are in the earth, and things which are under the earth, both above and beneath: all things bear record of me” (Moses 6:63).
This book is a much-needed attempt to get us back on the road to pursuing that ideal. It was that ideal that fired Nelson, Roberts, Talmage, and Widtsoe in the early years of this century. Now, a century later, we have come, in a sense, full circle, with a book that stems from the same commitment. But where they (Nelson particularly) struggled with high ideals but inadequate science, the present authors have at their command a century of the most spectacular advances in knowledge—demonstrated knowledge—ever to be possessed by the human race. To the extent that knowledge fulfills the prophecy of Joel, it is God’s knowledge and is an integral part of our religion. It is clear that the twenty-first century will bring even more of that type of knowledge, knowledge which takes us right to the fundamental principles of life itself and the management of those principles both in humans and in other organisms. Such knowledge most certainly is “relevant” to religious concerns. Knowledge of the natural laws is essential to the wise stewardship of God’s creations and creatures. We must bring ourselves into a position to deal with this massive outpouring of truth. In my opinion, we can no longer afford to ignore it. Active, honest, and rigorous engagement is the only response worthy of those who would uphold the ideals that fired the Restoration. The present book is a major step in that direction.
Over the past few hundred years, a variety of issues has created seeming conflicts between science and religion. One of the major points of disagreement has to do with the origin and nature of humankind. On one side is the revealed word and particularly its interpretation, which indicate that humans were created by God, in his image, and are unique and separate from Nature. On the other side are the scientific data and their interpretation, which indicate that we evolved from other preexisting life forms by random processes, and that we are related to all of Nature. Church leaders and other members have sometimes expressed strong opinions on both sides of the issue. Some members of the church have even alleged that a person cannot be in good standing in the church and “believe” in human evolution. Yet LDS students are presented with compelling data and persuasive arguments in their biology, geology, and anthropology classes that support the theory of evolution. Can a person acknowledge these data and accept these arguments while remaining an active member of the church? Can the theory of organic evolution and the doctrines of the LDS church be reconciled?
There is a relatively common experience among LDS students who enter colleges and universities. Some, perhaps many, of these students have been taught that evolution is false and, even more, that it is evil and not God’s way. Enrolled in a college biology course, these students become confused when faced with a body of well-established evidence that supports the theory of evolution and seemingly contradicts previous religious education. Students who pursue a health-sciences profession or attend a graduate biology program often major in biology as undergraduates. They are required to take advanced courses in genetics and evolution and become acquainted with even more compelling evidence for evolution. Such a student is then faced with a difficult dilemma: “Do I believe what I’ve been previously taught in spite of what seems to be convincing evidence, or do I accept the evidence of science and discount the ideas of my family and former teachers? If I discount what they have told me about evolution, what about other church teachings?” Must students be forced to choose between science and their faith? We think not.
Every year students come to us when they discover we are active members of the LDS church and also evolutionary biologists and ask, “How do you reconcile your faith with the theory of evolution?” We discuss our opinions with these students, but when our discussion has ended, we have found that we cannot refer them to any good book on the subject because most are at least twenty years old, very dated, and often out of print. (An exception is a short but well-written section on evolution and the church in Paul, Science, Religion, and Mormon Cosmology, 180-8 1.) We have written this book to fill that void. We attempt to resolve the apparent discrepancies between the theory of evolution and the concept of the creation as taught in the LDS church.
In one of only two official First Presidency statements concerning the origin of Adam, President Joseph F. Smith and his counselors stated in November 1909: “The Church … declares man to be the direct and lineal offspring of Deity. … Man is the child of God, formed in the divine image and endowed with divine attributes.” (This statement, which remains the official church position, is reprinted in this book’s appendix; see also chap. 2.) This statement has been interpreted by some members of the church to mean that our physical bodies, as well as our spirit bodies, are the lineal offspring of deity. Because the 1909 First Presidency statement stimulated “several High Priests’ quorums” to wonder, “In just what manner did the mortal bodies of Adam and Eve come into existence on this earth?” an editorial in the Improvement Era entitled “Priesthood Quorum’s Table” addressed the issue in April 1910. “Whether the mortal bodies of man evolved in natural processes to present perfection, through the direction and power of God,” it stated; “whether the first parents of our generations, Adam and Eve, were transplanted from another sphere, with immortal tabernacles …; whether they were born here in mortality, as other mortals have been, are questions not fully answered in the revealed word of God.” (The entire editorial is also reprinted in the appendix.) Even though many people continue to debate the issue of Adam’s origin, the Improvement Era editorial clearly allows for the possibility of a natural process employed by God in the physical creation of humankind.
Two major problems contribute to the perceived rift between evolution and some commonly held LDS beliefs: (1) If evolution is an entirely random process, as many evolutionary biologists say, how then can there be order in the universe? How could God have been in control of the process if the outcome was unpredictable? How could we have been created in God’s image as the result of a random evolutionary process? (2) If Adam and Eve came into being as the result of evolutionary processes, how then could they have been immortal? If they were not immortal, how do we explain the Fall? If there was no Fall, what was the mission of Jesus? If there was no Fall and Atonement, is there then no Christianity?
In this book we hope to discuss these and other questions in a way that will benefit students and other members of the church. We also hope to compare science and faith as ways of knowing about the universe and our place in it. Science is limited to questions that can be addressed through observations; conclusions and theories must be consistent with those observations. Faith, on the other hand, is based on revelation. We are confident that religious truth and scientific truth do not conflict. Our opinions are based on years of study, both in the fields of theology and biology. We recognize the distinct but complementary roles that knowledge in each field plays in our understanding of life. We believe that God created the earth, but we also believe that as scientists we can begin to understand some of the processes God employed and interpret the prehistoric record of “creation.” We believe we are the spirit children of God, but we also believe that we can discover the laws of Nature which brought our bodies into being. We believe that by gaining greater knowledge and understanding, the perceived rift between evolution and LDS theology can be bridged and disagreements dispelled.
When Charles Darwin introduced the theory of evolution by natural selection, the mechanisms of inheritance (genetics) were a mystery. The subsequent discovery of Gregor Mendel’s work explained the mechanism of inheritance but did not seem to allow for variations, which Darwin’s theory required. During the first three decades of the twentieth century, many scientists viewed Darwin’s theory of natural selection as having been supplanted by the newly discovered principles of Mendelian genetics, with its precise statistical assortment of discrete genes. However, in the 1920s H. J. Muller demonstrated the principle of mutation, which provided the variations necessary for natural selection. The combination of Darwin’s natural selection, Mendel’s genetics, and Muller’s mutation theory in the late 1930s and 1940s has been called by biologists the “modern synthesis” (sometimes called Neo-Darwinism). The modern synthesis has reaffirmed the integral role of evolution by natural selection in the biological sciences. Many statements made by scientists during the decades of skepticism regarding evolution were quoted by critics of evolution for many years after their obsolescence, and they are repeatedly cited by some individuals (mainly fundamentalist) to this day.
An impressive amount of new scientific data has accumulated in the past twenty-five years, data that were unknown when the previous generation of science and religion books was published. Many writers addressing the subject of evolution and creation have not considered the modern synthesis and its implications, let alone the more recent molecular evidence. The entirely new field of molecular biology has added its enormous weight to the discussion.
Concerning Adam’s origin, the First Presidency under Heber J. Grant stated in a meeting of general church authorities in 1931, “Our mission is to bear the message of the restored gospel to the world. Leave geology, biology, archaeology, and anthropology … to scientific research” (reprinted in the appendix). As scientists who are also active in the church and have strong faith in the gospel of Jesus Christ, we, in the spirit of that admonition from the First Presidency, present this book in the hope that it will help readers in their quest for understanding.
* * * * *
One of the most basic issues dividing science and religion is the notion that our physical bodies are, or are not, related to the rest of nature. Many people believe that if we are the spirit children of God, then our physical bodies must be unique. They believe that if our bodies are in any way related to those of other animals, such a relationship is in some way degrading. We see a striking parallel between this belief and the medieval concept that if humans are the center of God’s creation then Earth must be the center of the universe. Even though this notion seems odd today, it was adamantly adhered to in previous generations (up to about 300 years ago). Eventually, the scientific data became so overwhelming that the notion of an Earth-centered universe had to be abandoned, even by religious leaders and the lay public. The idea that because we are at the center of God’s attention we should also be at the center of the physical universe was an error of logic which ultimately could not be supported by observation. But the discovery of our world’s true position in the universe does not negate God’s existence or diminish his love for each of us his children.
Likewise, the modern molecular data, which have accumulated over the past twenty-five years, overwhelmingly support the notion that we are genetically related to other animals and completely contradict the idea that we are genetically unique. As with an Earth-centered universe, the idea that because we are spirit children of God and are created in his image our physical bodies should be unique is an error that is not supported by the data. In fact, there are far more data supporting the concept that humans are related to other animals than to support the idea that Earth is not the center of the universe. As with the evidence that eventually led all people to accept the notion that Earth is not the center of the universe, the evidence that humans are biologically connected to other animals is overwhelming and cannot be dismissed. If humans were created by some means that made us unique (i.e., by “special creation”), then what is the basis of the demonstrable biological connection?
Some of the most powerful data supporting the theory of evolution in general and, specifically, the notion that all of nature, including humans, are related come from the relatively new field of molecular biology, the study of living things at the level of DNA and its associated molecules. DNA, or deoxyribonucleic acid, an acidic molecule within the cell nucleus which contains the sugar deoxyribose, is the genetic material of cells and is the template for protein synthesis. DNA provides the master pattern for the structure of all proteins (this is described in more detail below). In order to understand the magnitude of these molecular data, it is important to understand something about the field of molecular biology itself. Furthermore, in order to contrast our current level of knowledge in biology with that of even the very recent past, a brief overview of the history of molecular biology is necessary.
This chapter deals with these very issues. Many people may worry that they cannot understand molecular biology. However, it is important to realize that much of what is understood in modern biology about evolution requires a basic knowledge of the subject. We believe that some of the most elementary concepts of biochemistry and molecular biology can be readily grasped by the non-scientist.
We have designed or borrowed analogies which we believe will help readers understand some of the fundamental and important issues.
All living things are made up of cells, the basic functional units of life. It is important to know that the life of a single cell does not necessarily depend on its presence in the body. Cells can be removed from the body and kept alive for days, weeks, or even years.
Cells are very tiny. Approximately 10,000 of them could fit comfortably, in a single layer, on the head of a pin. As small as they are, each cell is a virtual microcosm of activity and contains millions of individual molecules, whose interactions are the basis of the cell’s function. Molecules are composed of atoms and range in size from 1/1000 to 1/200,000, the diameter of the cell. At the very heart of the cell, within the nucleus, is a group of relatively large molecules, the DNA, the master controls of the cell. Functional DNA is what distinguishes living things from non-living things. DNA is also the basis of inheritance of genetic information from one generation to the next.
The nucleus may be thought of as a library containing hundreds of books (the DNA) with information about the cell, including much of its structural and functional information, that will be passed on to the next generation. The books in this library also contain information about the history of the cell and about its relatedness to other cells in other animals. This recorded history has been stored in the cell’s library for thousands of generations, just waiting to be read and comprehended. Today, for the first time, those books are being opened and read at an incredible pace.
When Darwin published The Origin of Species in 1859, biologists knew nothing about DNA or the other molecules making up the cell. They knew very little about the cell itself. The “cell theory,” which states that all living things are made up of cells, was just emerging. Biologists of that time did not know how traits are inherited. Darwin realized that a major obstacle to his theory of natural selection was explaining how these are passed from one generation to the next.
The problem of inheritance was partly solved when the work of Gregor Mendel was discovered at the turn of the twentieth century. His work established the field of genetics but, at the same time, brought to light another mystery: What was the basis of the genetic code? What was a gene made of? What molecules were responsible for storing and transmitting the encoded information; what was the nature of the code itself? And, of critical importance to Darwin’s theory, can genes change?
One of the objectives of biology in the first half of the twentieth century was to “crack” the genetic code. By mid-century, it had been established that genes are made of DNA, but critical questions remained: what is the structure of DNA and how does it replicate? During the early 1950s, James Watson and Francis Crick were working from x-ray diffraction photographs taken by Maurice Wilkins and Rosalind Franklin. They deduced that DNA molecules form a double helix, referring to their shape which resembles a minute ladder twisted into a spiral. The discovery of this structure allowed Watson and Crick and others to establish how the genetic code works at the chemical level, thus “cracking” the elusive code and ushering in a whole new era for biology. The “molecular age” was born. For their discoveries, Crick, Watson, and Wilkins shared the 1962 Nobel Prize for “Physiology or Medicine.” (Sadly, Franklin had died of cancer before the prize was awarded, and did not share in the success her work had made possible.)
In 1965 Watson wrote a book entitled Molecular Biology of the Gene. This influential work outlined the new field of molecular biology. Before its publication, the term “molecular biology” was seldom used. By the time his book was published, the codes for a few small proteins had been deciphered, but few comparisons between the encoded sequences (similar to the order or sequence of letters making up words) for proteins had been made between species or classes of plants or animals. Furthermore, the techniques for rapidly sequencing DNA (discovering the sequence of the base units) were not developed until the early 1970s. Therefore, essentially all of what we know about animal interrelatedness at the molecular level has been discovered since 1970. It is important to remember that most of the books that have been written concerning the Mormon church and the theory of evolution were published before any of the molecular data, which are some of the most convincing supporting the theory of evolution, were available.
The first gene was isolated from a bacterium in the summer of 1970, and no genes had yet been sequenced. We have now sequenced thousands in hundreds of species of plants and animals. The entire DNA sequence is known for the bacterium E. coli, from which the first gene was isolated. The complete DNA sequence is also known for several other species. More rapid techniques are being developed all the time, such as the polymerase chain reaction (PCR) which has allowed us to produce millions of copies of a given stretch of DNA in a matter of hours. We have gone so far in the past quarter of a century that by the year 2003, less than thirty-three years after the first gene was sequenced, we will have sequenced the entire human genome (a genome is the entire complement of genes contained in every cell in the body), comprising approximately 80,000 genes in all. Every normal human has the same number of genes, but differ in the precise details of their DNA sequence. That is what makes each of us unique.
DNA is composed of basic building blocks called nucleotides. Only four types of nucleotides exist in DNA, represented by the letters A, G, C, and I. Early researchers thought that DNA, with an alphabet consisting of only four letters, was not sufficiently complex to store all the information needed by a living cell. However, with the advent of computers, we now recognize that even a binary code (consisting of only two numbers, 1 and 0) can store and transmit tremendous amounts of information.
The DNA alphabet spells out a code (codon) for particular amino acids. They combine to form proteins, which are in turn the building blocks and machinery of the body. A gene is a portion of DNA that codes for a particular protein product, something like a single word in a sentence or an ingredient in a recipe. Other sequences of DNA serve a regulatory function, controlling the expression of the recipe. (A gene, like the recipe in a book, may remain untranscribed. When it is transcribed and translated, like making a cake from a recipe, the process is called expression.) Also present are stretches of non-coding DNA, which may be thought of as blank spaces between the genes.
As cells continually grow and divide, the DNA library is replicated. During the process of copying millions of nucleotides every time a cell divides, errors are introduced into the new sequences. Such errors may simply be the substitution of a single nucleotide (say an A for a T), or the deletion of a portion of the sequence (e.g., the sequence ATACCGTT being reduced to ATACCG), or the duplication of a segment of DNA (e.g., the sequence ATAC becoming ATACATAC). These errors are called mutations. Most mutations are repaired by enzymes in the cell with that specific function; not all errors are repaired, however. Some occur within genes, whereas others occur in non-coding DNA and are inconsequential. Some occur in the cells of the body, which result in diseases such as cancer. When a mutation occurs in reproductive cells, it may be passed on to the offspring, making it different in some way from its parent. A mutation in a gene involved in the pathway for producing color may result in a person who does not produce skin and eye color. Most mutations reduce survival—but some are beneficial to the organism in the face of changing conditions. For example, mutated insects can become resistant to pesticides, prompting the development of more powerful and more toxic chemicals. Mutations in bacteria may make them resistant to antibiotics. In fact, the overuse of antibiotics has precipitated the emergence of resistant bacteria—posing an international medical crisis.
Mutations that occur in the non-coding regions of DNA (in the blank spaces) have little or no effect on the individual or his or her offspring (i.e., such mutations do not change structure or function of the individual). However, the pattern of accumulated mutations within the non-coding regions results in a relatively unique identity in the DNA of each individual and his or her close relatives. To illustrate, imagine yourself in a shooting gallery. There are targets and blank spaces between the targets. When a bullet hits a target, the target falls over, but if the bullet misses and strikes the space in between, nothing happens. However, the pattern of hits in the space between the targets leaves a unique record of the shots fired. The back walls of no two shooting galleries are exactly alike. In the same way, mutations that “hit” genes can directly affect the individual or his or her offspring; but in the non-coding regions between genes, or “targets,” they have no effect on the individual. Still, the “hits” in the non-coding regions, the “spaces between the targets,” are recorded, with no two individuals having exactly the same pattern. The pattern of hits in the non-coding regions is passed on to the offspring, providing a unique record of the offspring’s heritage.
The discovery that DNA sequences are unique among individuals and families has led to the development of a technique for identification. This technique, called DNA fingerprinting, permits a profile of key “landmarks” to be compared between samples. The procedure takes advantage of the fact that many cells are equipped with a defense mechanism to protect against invasion by foreign DNA. This defense consists of proteins, called restriction enzymes, that recognize specific short sequences of DNA, attach to those sites, and snip the invading foreign strand into two. By exposing a sample of DNA to a select battery of restriction enzymes, the strand will be snipped into a collection of variable-length fragments. The resulting fragments are applied to an electrophoresis gel and the electrical current causes the fragments to spread along the gel, the shorter fragments moving farther than the longer ones. Once this gel is labeled with a dye, it produces a characteristic “fingerprint” of the individual, a relatively unique banding pattern produced by the restriction fragments.
The use of DNA fingerprint evidence has become an important forensic tool in criminal investigation. DNA samples collected from a crime scene can be used to virtually establish the presence or absence of a suspect at the scene. Such evidence is also employed to settle questions of paternity, as in the cases of infants switched at birth in a hospital.
Questions of family relatedness can also be determined. Recently, the DNA of an unknown Vietnam soldier in Arlington National Cemetery was tested and compared to blood samples of presumed family members, the dead soldier was identified, and his remains were returned to his family. As a result of this case, the Pentagon plans to take DNA samples from every soldier to create a registry. This future registry will make it nearly impossible for there ever again to be an unknown soldier.
Similarly, when nine skeletons were found in a shallow grave in July 1991, it was possible to identify the remains of the tsar, his wife, three of their five children, the royal physician, and three servants. Even though the cells had been dead for seventy-five years, DNA fragments were still intact. Analysis revealed an exact match between the wife, the three children, and a living maternal relative. Similar results were achieved with the remains of the former tsar and two living maternal relatives. This forensic evidence supported the hypothesis that the remains were those of the executed Romanov family. On the other hand, DNA analysis refuted the claim of a woman who had claimed to be the surviving Anastasia Romanov.
Similar techniques are currently being used to identify family relations among the ancient pharaohs, who lived 5,000 years ago. DNA has been extracted from 10,000-year-old human bones and teeth, and from 135 million-year-old amber-imbedded insects. DNA from Neandertal fossils, 30,000-100,000 years old, has also been sequenced. The data from this study suggest that Neandertals, although human-like in appearance, were not direct ancestors of modern humans (see Krings, “Neandertal DNA sequences,” 19-30).
This new science has taken the witness stand in cases of homicide, paternity, and issues of family relatedness. DNA fingerprinting can identify an individual and tie him or her to living or dead relatives. These same techniques are used by biologists to investigate the interrelatedness of various species. For example, a controversy has existed among botanists for most of this century as to whether yews, which have flat needles and berry-like fruit, should be classified with conifers, which are needle-bearing evergreens with typical cones, or whether they should be classified as a separate class or even as a separate phylum. Until recently, this controversy was unresolvable. However, molecular data collected within the past ten years clearly indicate that yews, for all their apparent morphological differences, are closely related to the other conifers (see Li, Molecular Evolution, 160-63).
What do the molecular data reveal about humans’ closest relatives in the animal kingdom? The question of which, if any, African apes share a common ancestor with humans has also been investigated using DNA sequencing. Mounting evidence indicates that humans and chimpanzees are the most closely related (see Bailey, “Hominoid trichotomy,” 100-108). These findings have independently borne out the conclusions of earlier comparative anatomists that humans are more closely related to the chimp and gorilla than either the chimp or gorilla are related to the third great ape, the orangutan. When the DNA sequences of two humans selected at random are compared, they may differ on average by as much as one out of every 200 nucleotides. In other words, they are about 99.5 percent similar. If the DNA sequences of a human and a chimpanzee are compared, 1.45 out of every 100 nucleotides are found to be different—about 98.5 percent similar. Human DNA is 97 percent similar to that of orangutans and 92.5 percent similar to that of rhesus monkeys. Likewise, chimpanzees are only 92.5 percent similar to rhesus monkeys but 97 percent similar to orangutans. Animals that are more distantly related have even greater DNA sequence differences.
These differences can be seen not only in the DNA but in proteins as well. Proteins are made from the DNA template by a process which we will describe later in this chapter. Because of this relationship, amino acid (amino acids, incidentally, are carbon-containing acids that have an amine group [NH2] and a “side group,” which ranges from a single hydrogen atom to larger, more complex groups of atoms) sequences in proteins can be used for comparisons across species. We can compare, for example, the human protein cytochrome c amino acid sequence to that of any other plant or animal. We find that all 100 amino acids in human cytochrome c are identical to those of the chimpanzee, 99 percent are identical to those of monkeys, 90 percent to those of a dog, 88 percent to a horse, 85 percent to a chicken, 83 percent to a snake, 82 percent to a frog, 79 percent to a fish, 72 percent to a fly, 57 percent to wheat, and 52 percent to yeast. The list goes on, confirming the validity of the hypothesis that more closely related plants and animals have more closely related amino acid sequences and that more distantly related plants and animals have less similar sequences. Even though there are up to 50 percent differences in amino acid sequences in cytochrome c, the cytochromes from one plant or animal can substitute for those of another. (See, for example, Ernst, “Substitutions of proline 76,” 13,225-36; and Tanaka, “Amino acid replacement studies,” 477-80.)
When he wrote The Origin, Darwin did not know the basis of inherited variation. He knew nothing about DNA, cytochrome c, or amino acid sequences. Nonetheless, the theory of descent by natural selection predicted in 1859 the relationship in DNA and amino acid sequences that we observe today. No more powerful evidence exists for any scientific theory than that it clearly and precisely predicts the data obtained from future experiments and observations, especially in fields of science that do not yet exist.
The use of DNA data in forensic science and questions of animal interrelatedness have only become possible in the past three decades and, on a larger scale, only within the past ten years. However, in spite of the relative youth of the molecular biology field, the data which have accumulated are:
(1) Massive. There are literally thousands of volumes of DNA sequences now available. It is also equally important to know that the human genome contains huge regions of non-coding DNA. The sequence similarities and differences in these non-coding regions provide the most powerful information about relatedness among humans (such as in homicide and paternity cases) and between humans and other animals.
(2) Rapidly accumulating. Newer and faster sequencing techniques are being developed all the time, cutting by factors of hundreds or thousands the time required to sequence a gene compared to the early days of sequencing. Several new genes are being sequenced every day. By the year 2003, the entire human genome, consisting of approximately 80,000 genes will be sequenced, and large portions of the genomes of other plants and animals will be known. The entire DNA sequences of several viruses, bacteria, and yeast are already completely known.
(3) Consistent. The DNA sequences discovered for similar genes in different plants and animals have been found to be remarkably alike, demonstrating that there is an impressive similarity in structure and function at the molecular level.
(4) Supportive of the concept of relatedness. When we examine DNA sequences to determine how closely or distantly two plant or animal species are related, it is not the conserved (similar) portion of the DNA sequence that is important; rather it is the portion of the sequence that is different (variable, often non-coding regions) that matters most. In every organism studied to date, there is a remarkable correlation between the amount of similarity in those variable regions of DNA and the proposed relationship between the plants or animals examined. The differences between sequences apparently reflect the accumulation of mutations in separate biological lineages derived from a common ancestor. It is important to emphasize, once more, that this information, which is the most powerful information available for examining questions of interrelatedness between living things, was not available twenty-five years ago. This same type of information is used in courts of law to determine DNA matches in paternity or homicide cases. Some people readily accept DNA data as evidence for relatedness among humans yet reject the same data indicating our relatedness to other animals.
These data powerfully support the theory of evolution and its prediction that closely related species exhibit closely related DNA sequences. Because of the consistency of these data, we can confidently predict that anyone reading this book can go to any college or university library, pick up any scientific journal containing published DNA sequences, and verify the relatedness of the species presented. These data are powerful because they directly address the forces of creation, the motive cause that forms each plant and animal. They are also powerful because they are objective and do not depend on the subjective comparisons of early systematics.
We present here a demonstration you can try yourself, which is an analogy of the relatedness of DNA sequences among species. All you need for this demonstration are four different colors of paper clips, about thirty of each. From a mixed box with all four colors, select ten paper clips at random and link them together to form a chain. This chain will be made up of the four colors of paper clips in random order. Lay this chain of ten paper clips onto a table so that you can see the pattern.
Now construct a second chain of ten paper clips that is identical to the first. After this second chain is constructed, pick one additional paper clip at random from the box of assorted colors. Then pick at random one link in the second chain. This may best be done by laying out the chain, closing your eyes, and pointing to one link. Once that link has been identified, replace it with the new link you selected from the box. There is a 25 percent chance that the link you are replacing will be the same color as the new link.
Now construct a third chain identical to the second and repeat the process of replacing one link. Once more the link and color of the replacement will be random. There is a 10 percent chance of replacing the same link and a 25 percent chance of replacing the same color as was there before. That does not matter; go ahead and complete the exercise. Repeat this process until you have a total of ten chains of ten paper clips each, with slight color variations. Once all ten chains are formed, place them into a box or some other container, and mix them up. Now dump out the ten paperclip chains onto a table and sort them out by degree of similarity (it works better if one person makes the chains and another person sorts them out). Organize the chains according to some order that you decide upon. How did you organize the chains? What was the basis of your decision to organize them the way you did? What are the implications of the organization you chose? There may be some chains that are identical and cannot be distinguished. What factors might result in identical chains?
The results of this demonstration are similar to what molecular biologists obtain in examining DNA sequences. We can consider these data relative to at least two alternative hypotheses: (1) The theory of evolution predicts that species are related to each other by descent; or (2) each species was created independently and uniquely, and therefore the species are not related. The DNA sequence data powerfully and consistently support the theory of evolution by indicating that species are related and just as powerfully and consistently refute the hypothesis of special creation. If each species was created independently and uniquely, and the species are not related, then some reasonable explanation must be advanced to explain the apparent relationship in DNA sequences. Science does not preclude the advancement of such an alternative hypothesis; rather, alternative hypotheses are encouraged. There is no conspiracy in science to suppress reasonable alternative hypotheses. The fact is, no reasonable alternative hypothesis has yet been proposed.
The DNA sequence data do not disprove creation, they simply help us explore possible mechanisms and patterns in the course of evolution. One of the most beautiful parts of God’s creation is the elegantly simple DNA molecule. That graceful spiral contains the possibility for storing almost infinite amounts of information. DNA is copied and transferred from one generation to the next with almost perfect fidelity. Hence, in the short term, likes beget likes. The “almost” part of the process of DNA replication allows for the variation that is a critical part of the creative process. Variation permits species to adapt in the face of a changing environment. That variation is certainly one of God’s most profound laws.
Some people argue that it comes as no surprise that the “blueprints” for similarly appearing organisms are likewise similar. That would be a fair assertion if the DNA of an organism was anything like an architect’s blueprint, but such is not the case. Rather than a blueprint, an organism’s complement of DNA is more like a “recipe” in a scrapbook of family history. In addition to the instructions for the unfolding development of the organism, there are bits and pieces, souvenirs and memorabilia, from far-flung predecessors. Stretches of non-coding DNA–interons, tandem repeats, satellite DNA–have little or no effect on the outcome of development. Mutations accumulate in these stretches of DNA that are invisible to natural selection and therefore provide a relatively unskewed evolutionary record of the lineage like the pattern of bullet holes on the wall of the shooting gallery. When examined in conjunction with more conservative genes that code for functional proteins, these provide a means for determining which organisms share a most recent common ancestor.
The information contained in DNA may be compared to a cake recipe. Suppose you want to bake a very special cake using a recipe available in only a very limited number of cook books. Suppose, also, that the only cook book you can find containing the recipe is in the reference section of the local library and cannot be checked out. The recipe book could be thought of as the DNA sequence for a given plant or animal and the cake recipe itself would be the DNA sequence of a gene for a given protein. The library can be thought of as the nucleus of a cell within the plant or animal. Just like a reference book, which cannot be removed from the library, DNA is too large a molecule to leave the nucleus.
If you want a copy of the cake recipe, your only choice is to copy it from the recipe book. You may choose to copy it onto a card, which you can then take home and use to make the cake. You transcribe the recipe from the recipe book onto the card. In the nucleus of an actual cell, a given stretch of DNA is transcribed as a sequence of ribonucleic acid (RNA), a molecule closely related to DNA. The RNA used to transcribe information from DNA that will be used to make proteins is called messenger RNA (mRNA). You may not choose to copy the recipe exactly as written in the book, but may choose to abridge some passages. For example, the recipe may state, “Add one cup of sifted all purpose flour.” You may write on your card, “Add one cup of flour.” In molecular terminology, the phrase that you transcribed is called an exon. An exon is the part of the DNA actually used to make a protein. That portion of the recipe you did not copy, “sifted all purpose,” is called the intron. An intron is the portion of a given DNA sequence not used to make the protein.
Once you have transcribed the recipe onto a card, you are ready to leave the library and go to your kitchen. You place the card on your kitchen counter or table, which may be thought of as the ribosome of the cell, where proteins are assembled. You then gather up all the ingredients for the cake and place them onto the counter. These are the amino acids from which the protein is to be made. You put the ingredients together according to the instructions in the recipe. Because you are now changing from a written recipe to a cake, the process is called translation. In molecular biology, translation is the process of making proteins from an mRNA template. The cake recipe provides the information for whether this will be a chocolate or lemon cake. Likewise, the DNA and mRNA sequences provide the information for the amino acid sequence in a given protein, and this sequence determines the structure and function of it.
Now let us consider changing the letters of the recipe, much like we did the paper clips in the previous demonstration. The original recipe states:
Add one cup of sifted all purpose flour.
The italicized words are the intron. Now change one letter, as though a typo had occurred in the recipe book:
Add one cup of sifted all purpose flour.
This change in the exon is referred to as a functional mutation, which makes the recipe nonfunctional as it can no longer be read correctly. Mutations occur randomly in nature, much like in the exercise of randomly replacing colored paper clips in a chain. Plants or animals with functional mutations rarely survive because the mutation tends to destroy some critical function. However, let us consider a change in the intron:
Add one pup of sifted all porpose flour.
In this case, the functional meaning of the recipe is not changed. This type of mutation is called a neutral mutation because function is retained. Neutral mutations can continue to accumulate (in nature, they accumulate at measurable rates). Let us say that the cook book goes through several editions without the accumulated errors being corrected. The page containing the publication date is lost from each book and you want to reconstruct the publication order of five editions of the book. Here is the phrase from each of the five editions:
Add one cup of sifted all pompose flour.
Add one cup of sufter all pompose flour.
Add one cup of sifted all porpose flour.
Add one cup of sufted all pompose flour.
Add one cup of sifted all purpose flour.
Assuming that no errors were corrected from edition to edition, which phrase came from the oldest, original cook book? Which came from the second edition, which from the third, fourth, and fifth? What is the basis of your conclusions?
Biologists use the same logic to determine not only relationships between plants or animals but also to determine the order of descent. Data obtained from such observations strongly agree with similar data obtained from other sources, such as the fossil record. All of the data combine to powerfully support the theory that all plants and animals are related by descent with modification from common ancestors.
The “witnesses” have testified; the evidence has been presented; the merits of the case rest upon the accumulated data. The fingerprint of our common biological heritage with animals appears self-evident. The same techniques employed in courts of law to settle disputes of paternity, or to research the history of genetic diseases in family genealogies, demonstrate our close relations to the rest of nature. Their validity as tools to elucidate genealogical relationships is unquestioned; why would their application to elucidate relationships between animal species be disputed?
We believe that these data provide insights into the processes used by God to create the plants and animals on this earth, including our own bodies. We must remember again that in science there is always the opportunity for alternative hypotheses to be advanced which better explain the observed data. However, in nearly 150 years of exhaustive study, no one has advanced a testable alternative hypothesis to explain the data that even begins to demonstrate the predictive power of evolutionary biology.<