So, I’ve decided to try a slightly different approach for the next while—one that has these sorts of folks in mind. From time to time, you can still expect those more in-depth, technical articles, or perhaps a discussion of some new research that makes the popular press, or even an analysis of some new argument from the IDM or RTB. These will be breaks from the new routine, however. For the most part, we’re going to stick to the basics, much like you would if you took an introductory evolution course at a university. Don’t worry, though: this course doesn’t have any prerequisites! All that’s needed is a willingness to learn.

What you can expect

The goal of this course is straightforward: to provide evangelical Christians with a step-by-step introduction to the science of evolutionary biology.  This will provide benefits beyond just the joy of learning more about God’s wonderful creation. An understanding of the basic science of evolution is of great benefit for reflecting on its theological implications, since this reflection can then be done from a scientifically-informed perspective. From time to time we might comment briefly on some issues of theological interest (and suggest resources for those looking to explore those issues further), but for the most part, we’re going to focus on the science. For folks interested in the interaction between science and Christianity, I heartily recommend Ted Davis’ recent series as a fabulous introduction to the topic.

You can also expect a slow, patient pace. Since this course is intended for folks with little or no background in biology, we’re going to take our time to make sure no one gets left behind. This might be frustrating to folks who already know a fair bit about evolution. Hopefully even more knowledgeable readers will learn some new and interesting details along the way—but the goal will primarily be to help folks who are less well versed in evolution increase their understanding.

You can also expect a survey of many different areas that have some bearing on evolution. We’ll examine geology, paleontology, biogeography, genetics, and a host of other topics in order to provide a “big picture” overview. This broad-brush approach means that any given individual post will not necessarily be “convincing” to folks who have doubts about evolution. Think about assembling a large jigsaw puzzle: placing any individual piece, on its own, doesn’t convincingly demonstrate what the overall picture will show. This course will be like that. Each topic we cover will put a few pieces in place here and there, slowly building towards the final overall picture.

Since evolution is an active science, this process will also highlight where there are “missing pieces” that are still being sought by scientists. All of this is well and good, since the purpose of this course is not so much to convince anyone of the validity of evolutionary theory, but rather to inform readers about the nature and scope of evolution as a scientific theory in the present day. My goal is to provide readers with a basic understanding of what evolution is and how it works. Given that as the primary goal, if one finds the scope of the evidence ultimately convincing (or not) is somewhat beside the point. The intent here is to provide readers with information they can use to make their own, informed decision.

How you can help

First and foremost, you can help by spreading the word about this series to folks you think would be interested in learning more about evolution in a non-threatening environment. Secondly, you can help me by asking questions in the comments. One of the challenges of being a specialist is having the ability to put oneself in the shoes of someone just starting out. What might seem obvious to me may not seem obvious to you, and I hope you’ll feel that no question is too basic or too simplistic. If you’re wondering about something, it’s almost guaranteed that other folks are, too! So, please don’t be shy. I’ll do my best to answer questions in the comments, though I hope that some of our more skilled commenters will (respectfully!) help out here, as well. Finally, you can help by letting me know what broader areas of evolution you find confusing. I have my own ideas about what areas of evolution are commonly misunderstood, but I’d love to hear from readers about what areas they find difficult to understand. I’ll use this input to shape the topics I will cover as we go forward.

Getting started

In the next post in this course, we’ll dive into the course content by introducing two key areas: how scientific theories work in general, and how evolution in particular works as the current organizing theory of modern biology. 

Good science has an addiction to theories,¹ and for science to be good science, it must deal with good scientific theories.  What constitutes a good scientific theory?  That is a very involved question, but a user’s view of good scientific theories looks something like this:

1.  A scientific theory is not a guess or suspicion.  For example, “I have a theory about who shot President Kennedy,” reflects the colloquial meaning of the word “theory,” and not the meaning conveyed by scientists when they use the word “theory.”  
2. Scientific theories are convincing explanatory frameworks that efficiently integrate a large body of evidence about the world.  Good scientific theories have the capacity to make sense of a wide range of data that made less sense before the introduction of the theory. 
3. In order to be called a scientific theory, it must have been successfully tested and re-tested many times.²
4. A scientific theory must be falsifiable in order to be truly scientific.  The theory has to live constantly at risk from new data.³ 
5. A theory must have predictive power.⁴  Good theories allow scientists to make predictions based on the theory that, when tested, turn out to be at least roughly correct. 

These are not the only characteristics of a scientific theory, but they probably represent the most important features for practitioners of science. 

If we hold contemporary evolutionary theory to these standards, how well does it do?  Since the inception of evolutionary theory by Charles Darwin in 1859 with the publication of On the Origin of Species, there are four characteristics of evolutionary theory that have endured 150 years of further research:

1. Living species are descendants of other species that lived in the past.
2. These past species lived in populations that underwent gradual transformation so that the individuals in these populations changed their appearance, behaviors, metabolisms, and life histories over long spans of time.⁵
3. New forms of life arose by means of a process called speciation in which one lineage splits into two distinct lineages.  This continual splitting of organismal lineages leads to a nested genealogy of species.  This nested genealogy forms a veritable tree of life, whose root represents the first species to arise and whose twigs represent the millions of species living today.  If you trace back any pair of twigs from the modern species you will find that their histories merge at some node on the tree where the two species share a common ancestor.⁶ 
4. This process of biological change that takes place throughout the advance of geologic time, or evolution, occurs by means of variation in organisms (which we know today is due to genetic mutations) that is acted on by either random genetic drift or natural selection. Those individuals with variations better suited to the current environment leave more offspring, thus changing the average appearance of the population over time and making it a better fit to the environment. This improving fit between organisms and their environment gives the appearance of organisms having been well designed for their milieu.⁷ 

What is the evidence for these aspects of evolutionary theory?  The evidence is actually immense, but I will restrict this discussion to just a few items. 

First there is the fossil record. If life results from a natural process such as biological evolution, then we should observe a progression of fossil organisms that proceed from relatively simple, single-celled organisms in the oldest rocks to more complex, multicellular organisms in younger rocks. When paleontologists examine the geologic column, they perceive that some of the oldest and deepest layers of the geologic column contain fossils of microorganisms, and then marine invertebrates in younger layers above those,⁸ and then much later and higher up in the geologic column fish appear, followed later and higher still by amphibians, and then by reptiles, mammals, and birds.⁹  Thus, the general presentation of the fossil record in the rock record comports exactly with what the theory of evolution predicts. 

However, the fossil story gets even better, because scientists can trace evolutionary trends throughout the fossil record.  For example, horses get bigger, fuse their leg bones and toes into a single bone with a thick hoof and grow the thickness of their tooth enamel;¹⁰ Cenozoic brachiopod shells get narrower, decrease their rib numbers and beak angle;¹¹ diatoms get bigger;¹² and primate fossils reduce the size of their teeth and expand the size of their brains.¹³ 

Additionally, Darwin predicted that there should be organisms preserved in the fossil record that possess features found in two different types of creatures. Such organisms are “transitional forms” that bridge the gap between different types of organisms.¹⁴ However, the fossil record of Darwin’s time provided little evidence of such transitional forms.¹⁵ Therefore, Darwin gambled that future paleontological research would provide sufficient evidence to corroborate his theory. How did this gamble turn out? Since Darwin’s time, paleontologists have discovered transitional fossils that are part fish and tetrapod,¹⁶ part amphibian and part reptile,¹⁷ part dinosaur and part bird,¹⁸ and part reptile and part mammal.¹⁹ Once again, we would predict such paleontological trends and the existence of such transitional fossils if life came about through a process of organic evolution. Clearly paleontological research since Darwin’s time has powerfully vindicated his theory. 

Please join us for part two of this post tomorrow, where we will discuss how signs of evolution can be detected in organisms living today, and how evidence from multifarious scientific fields—not just biology and paleontology—have bolstered the theory of evolution and added to our understanding of how natural selection works.

Notes

1. Ratzsch, Del. The Battle of Beginnings: Why Neither Side Is Winning the Creation-Evolution Debate. Downer’s Grove, WI: Intervarsity Press, 1996. pp. 104–119. 
2. Kitcher, Philip. Abusing Science: The Case Against Creationism. Cambridge, MA: MIT Press, 1983. pp. 45–54.
3. Ibid, 42–48.  .
4. Ratzsch, Del. Science and Its Limits: The Natural Sciences in Christian Perspective. Downer’s Grove, WI: Intervarsity Press, 2000. pp. 21–24. 
5. Hall, Brian K., and Benedikt Hallgrimsson. Strickberger’s Evolution. 5th ed. Burlington, MA: Jones and Bartlett, 2013. pp. 19–68. 
6. Kitcher, Philip. Living With Darwin: Evolution, Design, and the Future of Faith. New York: Oxford University Press, 2009. pp. 43–71. 
7. Futuyma, Douglas J. Evolution. 3rd ed. Sundbury, MA: Sinauer Associates, 2013. pp. 281–343. 
8. Valentine, James W. On the Origin of Phyla. Chicago: University of Chicago Press, 2006. pp. 429–464. 
9. Carroll, Robert L. Vertebrate Paleontology and Evolution. New York: W. H. Freeman and Company, 1990. 
10. MacFadden, “Horses, the Fossil Record, and Evolution,” 131–158; McFadden, Bruce J. “Fossil Horses from "Eohippus" (Hyracotherium) to Equus: Scaling, Cope's Law, and the Evolution of Body Size.” Paleobiology 12, no. 4 (1986): 355–69.; Prothero, Donald R., and R.M. Schoch, eds. The Evolution of Perissodactyls. New York: Clarendon Press, 1989. ; McFadden, Bruce J. Fossil Horses. Systematics, Paleobiology, and Evolution of the Family Equidae. Cambridge, Cambridge University Press, 1993. 
11. McNamara, Kenneth J. “Evolutionary Trends.” In Encyclopedia of Life Sciences (New York: Macmillan Publishers Ltd, 2001), pp. 1–7. 
12. Litchman, E., C. A. Klausmeier, and K. Yoshiyama. “Contrasting Size Evolution in Marine and Freshwater Diatoms.” Proceedings of the National Academy of Sciences USA 106, no. 8 (2009): 2665–2670.
13. Tattersall, Ian. The Fossil Trail: How We Know What We Think We Know About Human Evolution. New York: Oxford University Press, 2008. pp. 89–198. 
14. Darwin, Charles. On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life. London: Penguin Books, 1985. p. 292.
15. Hunt, Gene. “Evolution in Fossil Lineages: Paleontology and The Origin of Species.” Supplement American Naturalist 176 (2010): S61–S76. 
16. Clack, Jennifer A. Gaining Ground: The Origin and Evolution of Tetrapods. Bloomington, IN: Indiana University Press, 2002; Daeschler, Edward B., Neil H. Shubin, and Farish A. Jenkins, Jr. “A Devonian Tetrapod-Like Fish and the Evolution of the Tetrapod Body Plan,” Nature 440, no. 7085 (2006): 757–63; Shubin, Neil H., Edward B. Daeschler, and Farish A. Jenkins, Jr. “The Pectoral Fin of Tiktaalik roasae and the Origin of the Tetrapod Limb.” Nature 440, no. 7085 (2006).): 764–71; Downs, Jason P., Edward B. Daeschler, Farish A. Jenkins, and Neil H. Shubin. "The Cranial Endoskeleton of Tiktaalik roseae." Nature 455, no. 7215 (2008): 925–9. 
17. Carroll, Robert L. Vertebrate Paleontology and Evolution. New York: W. H. Freeman and Company, 1990. pp. 156–216. 
18. Shipman, Pat. Taking Wing: Archaeopteryx and the Evolution of Bird Flight. New York: Touchstone, 1998. pp. 169–244.  
19. Prothero, Donald R. Evolution: What the Fossils Say and Why It Matters. New York: Columbia University Press, 2007. pp. 271–297. 

"Anyone approaching the Resurrection accounts in the belief that he knows what rising from the dead means will inevitably misunderstand those accounts and will then dismiss them as meaningless" (p. 243).

In fact, if Jesus' Resurrection were "merely" coming back to life in any way that we might comprehend, then it would be of little significance.

"Now it must be acknowledged that if in Jesus' Resurrection we were dealing simply with the miracle of a resuscitated corpse, it would ultimately be of no concern to us" (p. 243).

So what then does Resurrection mean? For Benedict it represents a new dimension of reality breaking through into human experience. It is not a violation of the old; it is the manifestation of something new.

"Jesus had not returned to a normal human life in this world like Lazarus and the others whom Jesus raised from the dead. He has entered upon a different life, a new life -- he has entered the vast breadth of God himself..." (p. 244).

Because it is something entirely new, it cannot represent a violation of natural law as understood by science.

"Naturally there can be no contradiction of clear scientific data. The Resurrection accounts certainly speak of something outside our world of experience. They speak of something new, something unprecedented -- a new dimension of reality that is revealed. What already exists is not called into question. Rather we are told that there is a further dimension, beyond what was previously known. Does that contradict science? Can there really only ever be what there has always been? Can there not be something unexpected, something unimaginable, something new? If there really is a God, is he not able to create a new dimension of human existence, a new dimension of reality altogether?" (p. 246-7)

Thus, in this view, Resurrection (as with all true miracles) is not contrary to science, but an indicator that science does not (yet?) describe the full expanse of reality. Indeed, some may argue that science itself contains similar "indicators." The 11 (or so) dimensional universe required by some versions of string theory, the multiverse theory of the universe where ours is but one of an infinite array of universes with variable physical laws, quantum entanglements, "spooky" action at a distance, the mysterious emergence of consciousness from inorganic matter -- all push the limits of human reason and imagination, suggesting to some that reality may be far more complex than the human mind can grasp.

For a moment, let us entertain the possibility that Resurrection is as Benedict interprets it: not a violation of natural law but an indicator of something beyond our scientific understanding of the universe. This has interesting implications for understanding how believers and skeptics approach the issue. If Resurrection does not violate science, then science does not necessarily constitute an impediment to accepting the reality of Resurrection. If the difference between the skeptic and believer is not science, then is it just a matter of imagination? The believer imagines greater possibilities for the universe than the non-believer. While this is possible, it seems questionable. To my knowledge, no research has found differences in imaginative abilities between religious and non-religious people. Moreover, contrarian examples easily come to mind: Isaac Asimov was an atheist but hardly lacking in imagination when it came to science fiction. I tend to think that both believers and non-believers can imagine (with varying degrees of effort, I'm sure) the new possibilities implied by Resurrection.

Thus, if it is neither imagination nor science that prompts skepticism about Resurrection, then what is left? I suggest that it comes down to a question of authority: At what point does one allow imaginative possibilities to have authority over how one lives? To the believer, Resurrection has an authority that science fiction does not. Resurrection is not thought-provoking entertainment. It requires far more than just imagining greater possibilities for the universe. It requires a change of life, here and now. Unlike the microscopic hidden dimensions of string theory, the new dimension implied by Resurrection has "broken though" into everyday reality and demands a response -- even if that response is to actively ignore it.

Now, what convinces the believer that Resurrection merits such authority when other imaginative possibilities such as extraterrestrial life or time-travel do not? The answer here appears to be historical commitment. There's no record of people committing themselves to the point of martyrdom to other imaginative possibilities as they have to Resurrection. The earliest example of such commitment being found, of course, in the dramatic post-crucifixion turn-around of the Apostles. Such an astounding change of heart, followed by an unwavering commitment capable of altering human history demands a categorically unique explanation: Resurrection.

The believer's argument, however, remains unconvincing to the skeptic. However impressive they might be, a change of heart and steadfast commitment do not necessarily add up to a new dimension of reality. Extraordinary claims require extraordinary evidence. Fair enough. So a key question regarding the interpretation of Resurrection is this: Is the post-crucifixion history of Christianity extraordinary? Does it compel the dispassionate observer to concede that a categorically unique event could plausibly be its best explanation?

It ought to be upon questions such as those above that skeptics and believers respectfully engage one another, rather than the simplistic and often acrimonious sloganeering that has increasingly become the norm.

Understanding John Polkinghorne: Theology of Nature

John Polkinghorne’s interest in natural theology is important, but what really sets him apart from most others is that he combines it with an equally strong interest in theology of nature, which is not the same thing. Where natural theology involves, “metaquestions about the pattern and structure of the physical world,” theology of nature involves, “metaquestions about how its historical process is to be understood.” Rather than “looking to the physical world for hints of God’s existence,” we look “to God’s existence as an aid for understanding why things have developed in the physical world in the manner that they have.” (Belief in God in an Age of Science, p. 13)

On this front, Polkinghorne advances a strongly Christocentric theology of creation, stressing Jürgen Moltmann’s notion of The Crucified God . In the context of Polkinghorne’s theology of nature, the point is that the Creator is the crucified and resurrected second person of the Trinity. Since I devoted a column to this before, I won’t say more here, except to alert readers to the singular importance this particular idea has for him—especially when facing the problem of suffering. “The insight of the Crucified God lies at the very heart of my own Christian belief, indeed of the possibility of such belief in the face of the way the world is.” (Belief in God in an Age of Science, p. 44)

Situating John Polkinghorne: The Resurrection of Jesus

Many Christians today see science as posing dangerous threats to their faith, challenging their understanding of the Bible and undermining core tenets such as the bodily Resurrection of Jesus, the historical basis on which the Christian faith stands or falls. “Evolution” is often identified as the problem, but the real danger is unbridled naturalism. A commitment to naturalistic methods, known as “methodological naturalism,” (MN) has been an integral part of science and medicine since the ancient Greeks. Those methods have been highly successful at producing a coherent, often very convincing picture of nature and the history of nature.

Advocates of Intelligent Design and some other Christians reject MN, but many Christians who work in the sciences and related fields (such as engineering, medicine, or the history and philosophy science) support MN as a properly grounded and properly limited way of understanding reality. In their view, a robust Christian faith is consistent with a commitment to MN, provided that the limits of scientific inquiry are not simply equated with the limits of rationally grounded belief. Polkinghorne fits squarely in this category.

To understand more clearly where Polkinghorne lies on the larger landscape of science and religion, let’s consider his approach to the Resurrection. Many contemporary thinkers, including some theologians and clergy, believe that “science” has somehow made it impossible to believe in the Resurrection, the deity of Jesus, and even belief in the transcendent God of the Bible.

A prime example is John Shelby Spong, a retired Episcopalian bishop whose books have sold more than one million copies. Spong sees the bodily Resurrection as a figment of the disciples’ imaginations, a vestige of a theism that now we must throw away like a threadbare suit of clothes. For Spong, Christians today need to go "beyond theism" throwing out the baby of divine transcendence—the fundamental truth of monotheism—along with the bath water of the credulity and mythology of the pre-modern authors of the Bible and the ecumenical creeds. Spong’s message is that “Christianity must change or die,” and all in the name of “science.”

As Spong likes to say, his work is very controversial, and not just among rank-and-file Christians. Scholars have also railed against him. “I have been attacked in books from the religious right by such people as Alistair MacGrath [whose surname is actually spelled McGrath], N.T. Wright, and Luke Timothy Johnson,” he complains (Why Christianity Must Change or Die, p. xvi).

I understand (with much sadness) that we live in a highly polarized age. Nevertheless, it’s difficult for me to grant much credibility to an author who identifies McGrath, Wright, and Johnson as representatives of the “religious right.” Indeed, if anyone here is distorting the news it is Spong, not they. As the (late) great Catholic biblical scholar Raymond Brown once observed, “I do not think that a single NT [New Testament] author would recognize Spong’s Jesus as the figure being proclaimed or written about.” (Birth of the Messiah, note 321 on p. 704)

Matthias Grünewald, The Resurrection (a wing of the
Isenheim Altarpiece, ca. 1515), Unterlinden Museum,
Colmar, France

Polkinghorne certainly understands science far more than Spong does, and his conclusions about the implications of science for Christian beliefs are markedly different. With respect to the Resurrection, he is basically on the same page with his friend Wright, whose profound book, The Resurrection of the Son of God, he cites with appreciation. Belief in the Resurrection is well supported by the evidence, and the Resurrection, itself, is “the pivot on which the claim of a unique and transcendent significance for Jesus must turn.” Considering authors like Spong (although he does not explicitly name him), he adds, “it would be a serious apologetic mistake if Christian theology thought that operating in the context of science should somehow discourage it from laying proper emphasis on the essential centrality of Christ’s Resurrection, however counterintuitive that belief may seem in the light of mundane expectation.” (Theology in the Context of Science, pp. 135-6)

Amen.

Looking Ahead

This is the Easter season, and I’ll return in a couple of weeks to begin examining Polkinghorne’s approach to the Resurrection more fully, using excerpts from the chapter on “Motivated Belief” from his recent book, Theology in the Context of Science.

References

Raymond E. Brown, Birth of the Messiah: A Commentary on the Infancy Narratives in the Gospels of Matthew and Luke. (1992).

John Polkinghorne, Belief in God in an Age of Science (1998).

John Polkinghorne, Theology in the Context of Science (2009). My review for First Things online is here.

John Shelby Spong, Why Christianity Must Change or Die (1998).

A common argument leveled against the theory of evolution is that scientists have not been able to produce the expected transitional fossils that show the change of one species into another. If evolution were true, wouldn’t there be instances of clear intermediary species, like, for example, a species that was half whale and half hippo to show the transition between those two? In this BioLogos podcast, Kelsey Luoma addresses this misconception about what a transitional fossil actually is. Rather than a mix between two related species, transitional fossils point back to the common ancestors that modern species share. The fact is that the number of transitional species is massive and it grows with each passing year. Given the rarity with which organisms are actually fossilized, the amazing thing is actually the completeness of the fossil record, not its incompleteness. The transitional species story strongly supports, and certainly does not disprove, evolutionary theory. ¹

1. To hear the full audio clips which have been referenced go to:

• Rational Response Debate with Kirk Cameron (from Way of the Masters)
• Behind the Scenes with Dr. Neil Shubin (from Cincinnati Museum Center)
• Mark Norell Publishes New Archaeopteryx Findings (from American Museum of Natural Sciences)
• Texas A&M Professor Discusses Findings of Autralopithecus Sediba and its Relationship to Humans (from Texas A&M University)
• Intro/outro music composed by Martin Minor (Minor2Go).

An audio only version of the podcast can be downloaded here.

Tonight and tomorrow, Christians around the world stop to remember and celebrate the birth of Jesus in Bethlehem just over two thousand years ago. The familiar narrative of Joseph leading Mary to the stable to give birth to the Messiah, of the angels telling the shepherds in the fields of the great event that was happening nearby, and of the three men from the east who came to pay homage to the new King of Israel is re-told or acted out in countless churches, schools and homes. And from countless pulpits, the message goes out that those events are not just a quaint story and an excuse to give gifts, but the central mystery of our faith—that God himself became one of us in order to redeem us and the cosmos from our bondage to sin and death. That mystery—that the Creator God is also the Redeemer Christ—has been to focus of our worship since the first days of the church, and is the subject of the 7th-century Latin hymn Conditor alme siderum, presented here in a new setting from Alex Mejias and High Street Hymns.

While this recording includes only verses one and three from the original text (given in full below), it adds a refrain that catches the spirit of the whole hymn and emphasizes the longing we still feel even in our Christmas joy—the “already, but not yet” state in which we find ourselves today, living between that first Advent and the second Advent yet to be: “Come, O come to us!” For while we know that God has come to us in Jesus—that his death and resurrection have redeemed us and the universe—we are still waiting for that final consummation, depending on the Spirit to be working out our salvation even now. Until the time when, as the hymn says, “all hearts must bow,” the entire BioLogos community invites you to join us in the blessed work of declaring, celebrating, and following the Christ who is both Creator and Savior.

Creator of the Stars at Night

Alex Mejias is the founder and director of High Street Hymns, a non-profit music ministry that exists to spread the Gospel and worship the Triune God in spirit and truth through hymns, psalms and spiritual songs. Alex grew up in New Jersey and outside Washington, DC, receiving a BA in Religious Studies from the University of Virginia and a J.D. from the University of Virginia School of Law. For the past 15 years he has been leading worship for churches and ministries, writing and recording both new and old hymns, and touring the east coast as a singer-songwriter. Alex is also committed to the power of the creative arts to advance the Gospel and promote justice and healing in the name of Christ, serving, supporting, and collaborating with several other non-profit ministries.

In 1774, the French chemist Antoine Lavoisier replicated the relevant experiments in more controlled ways to demonstrate that mass was conserved during combustion. He also renamed the part of the air that burned 'oxygène.' English scientists resisted the French scientist's new name, not least because the English Priestly had already published his discovery of the gas. 'Oxygen' nonetheless entered the common English vocabulary in part due to one of the first popular science books, The Botanic Garden (1791), which included a poem praising the gas using the preferred French name. By coincidence, this book also promoted some early ideas about biological evolution (specifically, it suggested that sexual reproduction might be important to evolution, which might help to explain the popularity of a book of poems about science). It was written by Erasmus Darwin, the grandfather of Charles Darwin, who first proposed the modern form of the theory of biological evolution in his 1859 book, On the Origin of Species.

150 years later, we are discovering that the lines connecting evolution and oxygen run deeper than the Darwin family tree. We now know, for instance, that for roughly half of the Earth's 4.6-billion-years of history, there was little to no oxygen in the atmosphere. Instead, oxygen entered the atmosphere in two major pulses, with one between 2.4 and 2.2 billion years ago, and another between 0.8 and 0.54 billion years ago. Recent evidence suggests that the first pulse may have actually been the largest event in a series of fits and starts beginning at around 2.7 billion years ago that finally produced a stable low oxygen atmosphere by around 1.8 billion years ago.

Remarkably, both episodes of atmospheric oxygenation happened just before explosions in biological diversity. We have spotty evidence of unicellular eukaryotes (cells with nuclei) before 2.4 billion years ago, but the first fossil evidence for large, diverse eukaryotic communities comes at 1.5 billion years ago. If you are a human, this is part of your history; humans are multicellular eukaryotes descended from one of these early unicellular pioneers. Multicellular animal life is an innovation that seems to have required more oxygen: animals don't appear in the fossil record until about 0.61 billion years ago, toward the end of the second pulse of oxygen.

It is, perhaps, not surprising that major evolutionary events in the eukaryotic family tree, including the origin and diversification of the animals, would be tied to or even driven by major changes in atmospheric oxygen abundance. Eukaryotes generally, and animals specifically, are oxygen lovers. As the subjects of Mayow and Priestly died to prove, we require oxygen for respiration. In general, the larger and more organizationally complex we are (for instance, a human versus a slime mold), the more oxygen we require.

But where did all the oxygen come from? Ultimately, it was produced by the bacterial equivalents of the plants in Joseph Priestley's experiment, a group of photosynthetic microbes called the cyanobacteria. These bacteria are the first and only organisms to have evolved the ability to produce oxygen by photosynthesis. In fact, plants are able to photosynthesize only because their cells harbor descendants of one of the early cyanobacteria. We call them chloroplasts and think of them as little cellular organs, but they are actually the great-great-great... granddaughters of a cyanobacterium that long ago gave up its independence in exchange for the stable environment inside a eukaryotic cell. In any case, photosynthesis is the only known geological process capable of producing oxygen at the rates required for the two pulses of atmospheric oxygenation. The first pulse was probably largely accomplished by cyanobacteria, while the second pulse was probably mostly associated with the cyanobacterial denizens of eukaryotic algae.

What is remarkable about all of this is the extent to which modern life and the atmosphere are products of each other's evolution. The tiniest of photosynthetic organisms played one of the most important roles in shaping the sky, and the sky helped to usher in the age of animals! As a Christian and a geobiologist, I do not believe that this relationship is anticipated or predicted by the Biblical creation accounts.

But then again, why should it have been? The original audience for these accounts would have found concepts like bacteria or even oxygen incomprehensible. The people for whom the Bible was originally addressed thought about origins primarily in terms of ongoing national conflicts and the current human condition. Faced with a variety of violent creation myths that reinforced national conflicts, Genesis said that the universe was created to be good, peaceful, and orderly by one god. It specifically listed things worshipped by other nations as creatures of that god, and in the climax of the creation account, Abraham was called by the same god to be a blessing to all the nations through Israel.

I am not claiming that the Bible cannot be read in a way that can shape us in real and meaningful ways today. In fact, for those who believe that the Bible is inspired, part of the meaning of inspiration has to be that the Bible is God's powerful word to both those with no concept of modern science (most of the world's population, both today and in the past) and to those deeply engaged in its practice. But, and this is a big but, we contemporary Americans read the Bible best when we are sensitive to the assumptions of the original audience, carefully observe how the Bible transformed those assumptions, and look for opportunities to do the same thing with our thinking.

I think that it is important for Christians to reflect on the view of origins that science has given us in light of the thinking evident in the Biblical creation accounts. We have to do this because science gives us a story that is inherently without philosophical or theological meaning; it is up to us to give it meaning by understanding it in relationship with our beliefs. For instance, some see the evolutionary history of life and the Earth and give that history meaning by elevating chance and necessity to the level of prime actors in their own modern creation account. This meaning is not inherent to the theory of evolution; it is supplied by an atheistic belief system external to the theory. I suggest that this view mistakes created things (chance and necessity) for the Creator.

Others have preferred to see the regularity of the universe as the action of an orderly God. This is an old approach to natural theology that was popular among many early scientists, and saw God as responsible for doing such things as maintaining the planets in consistent paths around the sun. Still others look for God in the unexplained. This is a newer approach that sees God as acting primarily in short bursts not explainable by the regular, orderly function of the universe. Looking for God in these ways is a little like trying to capture him in a bell jar, an approach that worked perfectly well with oxygen for Mayow, Priestley, and Lavoisier, but one that is unlikely to impress the Creator described in the Bible.

I prefer to see the same history in the light of a God who desires to share aspects of his nature with his creation, notably including his creativity. Just as he has made humans to be creators (with a little 'c'), he has given the rest of our world the gift of being instrumental in its own creation through the process of evolution. This surely must have been part of what God saw when he described his creation as good! It is my hope that the modern American church can learn to see the goodness of creation in things like the evolutionary history of life and the atmosphere, as well.

This post first appeared in October 2009

Keeping History Safe

In the cold morning air with the sun not yet over the ridge, the place to begin preparation for summiting Mount Darwin is to ponder the reasonableness of miracles. Many Totalizers would like to ban miracles from university consideration and inquiry. Trouble is: human history is awash with credible people reporting miracles.

Modern academic tradition tends to try and maintain order. For historians it behooves us professionally to avoid accounts of alleged spiritual events. We find comfort in a little logical gymnastics that keeps history safe for us to wander in, a deceptively formulaic avoidance method that helps us avoid what people are telling us about extraordinary events in the past.

David Hume popularly articulated this logical gymnastics in an essay titled “Of Miracles” that was eventually printed in Enquires Concerning Human Understanding (1748). “I flatter myself,” Hume triumphantly proclaimed, “that I have discovered an argument . . . which, if just, will, with the wise and learned, be an everlasting check to all kinds of superstitious delusion, and consequently, will be useful as long as the world endures.”

His everlasting check on superstition begins with a circular argument that because miracles can’t happen, a reasonable person should not even listen to reports of them. Hume taught that though the normal job of a historian was to listen to the testimony that comes down to us from the past, there is a point at which you can close your ears. Hume knew that historical testimony can get wild, so he came up with a way to domesticate the wildness, a way to make history a zoo rather than allow it to be a jungle. His “Of Miracles” has been tremendously influential in the discipline of human history over the last two hundred and fifty years, not because his ideas are strong, but because his ideas are useful. Get rid of “superstitious delusions,” and the discipline of history can be turned from a safari into a form of home economics. Hume’s domestication of history is seductively simple. Instead of following the Aristotelian tradition of linking the credibility of hard-to-believe testimony to the credibility of the testifier, Hume recommended disregarding the testifier and focusing only on the testimony. This effectively removed the persuasive power from hard-to-believe testimony. Miracles need the credibility of an eyewitness in order to have persuasive power. Hume cut the power source from the unwanted testimony.

Essentially, Hume adopted the modeling technique that Darwin later used and is best seen in Global Positioning System (GPS) units. Hume recommended gathering testimony from the past and every region to create a general model of what humans generally experience. Using this mass of information, one should generalize standards of common experience. Now if anyone reports a miracle, the alleged event can’t be true because it does not conform to the generalized standards of common experience. (Of course, Hume had already refused to allow that any reports of miracles could be used even to generalize common experience.) It’s tricky. Its logic is circular. But it works to weed out awkward, quirky information. It is as if a domineering GPS unit created a sphere to serve as an abstraction for the earth, then insisted that the earth can’t have wobbling poles and flattening in the upper latitudes because the sphere in the GPS shows it can’t be true. Given a useful and trustworthy GPS, don’t listen to a scientist who might tell you something different than what the GPS tells you.

The circularity of this argument has been noted ever since Hume first proposed it, but Hume was a good writer and said what a lot of people wanted to hear. Miracles are impossible so miracle reports can’t be true. Don’t even listen to reports of them.

Balancing Likelihoods

Also embedded in Hume’s essay is the awkward “rule of logic,” most often called “Balancing Likelihoods.” By combining math and logic in an odd way, Hume’s “Of Miracles “ offered another way for historians to avoid thinking about miracles. Balancing Likelihoods has many names but is probably best stated by David Hackett Fischer, in his Historians’ Fallacies: Toward a Logic of Historical Thought, as “the rule of probability:”

“[A]ll inferences from empirical evidence are probabilistic. It is not, therefore, sufficient to demonstrate merely that A was possibly the case. A historian must determine, as best he can, the probability of A in relation to the probability of alternatives. In the same fashion he cannot disprove A by demonstrating that not-A was possible, but only by demonstrating that not-A was more probable than A. This is the rule of probability.”

This seems to be practical but is impossible. Balancing Likelihoods, in the way described by Fischer, cannot be used by historians in any normal practice. It is a talisman to keep history mentally safe from the wildness that is reported to exist. Logicians, especially mathematicians, have long criticized intellectual constructions like this. The “probability” that Fischer writes about is seemingly mathematical, but the math is simply implied to give a sense of strength to human feelings.

Before Hume wrote “Of Miracles” probabilistic logic had been advancing rapidly and there was a great hope that mathematical analogies would strengthen human thinking—even Christian apologetics. “Pascal’s Wager,” the most famous mathematical apologetic from the seventeenth century, equated eternal salvation with mathematical infinity and then applied it to a gambling formula. Antoine Arnauld, in The Port-Royal Logic (1662), and John Locke, in his Essay Concerning Human Understanding (1690) and Discourse on Miracles (1706), carried probabilistic math and logic into the handling of reported miracles. A half-century later, however, Hume reacted against Arnauld and Locke’s teachings that mathematical analogies could help in the discussion of the credibility of miracles. Hume insisted that to handle a reported miracle, a historian had to create two separate ratios, pro and con, for believability. The ratios were then to be weighed against each other. This is Fischer’s “rule of probability” quoted above. In the language of Hume’s era, this was proclaimed as the “calculus of good sense.”

Lorraine Daston, in Classical Probability in the Enlightenment (1988), offers an excellent study of Hume and the many eighteenth-century mathematicians who wanted to help bring rigorous quantitative thinking to what today would be called the humanities. Daston writes that by the 1840s, mathematicians realized that “the ‘calculus of good sense’ had become antithetical to good sense,” and that today most of what these early probabilists were trying to do is considered “patently absurd.”

In 1901, one of America’s preeminent philosopher-mathematician-logicians, Charles Sanders Peirce, wrote three essays attacking the way historians had adopted Hume’s bad logic: “A Preliminary Chapter, Toward an Examination of Hume’s Argument Against Miracles, in its Logic and in its History,” “Hume’s Arguments Against Miracles, and the Idea of Natural Law,” and “On the Logic of Drawing History from Ancient Documents especially from Testimonies.” Peirce showed that historians are in error when they talk of judging testimony by balancing probabilities because “in a scientific sense, there are no ‘probabilities’ to be judged.”

Probability, Peirce wrote, “is the ratio of the frequency of occurrence of a specific event to a generic event.” A testimony “is neither a specific event, nor a generic event, but an individual event.” Peirce further pointed out that what people were justifying by claiming Balancing Likelihoods was really simply relating “what they prefer to do” to what they don’t prefer. “Likelihood is merely a reflection of our preconceived ideas.”

Historians like me who teach in universities about the reasonable credibility of Jesus’ resurrection need to be students of Peirce not Hume on the subject of assessing the credibility of reports that come down to us from ancient history. Dealing wisely with reports of events verging on the incredible is just part of the normal job of being grounded in the social study of our complex human past.

“Come to history as a doubter,” Richard Marius advises in a historical methods manual. “Skepticism is one of the historian’s finest qualities. Historians don’t trust their sources. . . . Nothing is quite so destructive to a historian’s reputation as to present conclusions that prove gullibility.”

But Marius is wrong. In practice, historians have to trust more than doubt. In practice, historians, especially ancient historians, can’t rely on doubting. Historians have to be close listeners, discerning listeners, wise listeners, who sometimes have to make harmonies and stretch for belief.

There are several different kinds of arguments that people bring along these lines; I want to talk about just one. So first… the Heidelberg catechism, one of the forms of unity of the church I go to (the Christian Reformed Church), says

Providence is the almighty and ever-present power of God, by which he upholds as with his hand heaven and Earth and all creatures and so rules them, that leaf and blade, rain and drought, fruitful and lean years, food and drink, health and sickness, prosperity and poverty. All things, in fact, come to us not by chance, but from his fatherly hand.

And part of the way it comes to us—not by chance, but from his fatherly hand—part of the way God has designed our world, is that there is a great deal of regularity and dependability in our world. Of course, if it were not for this regularity and dependability, we couldn’t do the things that we actually do. I mean, for example, if I just wanted to walk off the stage—if, for example, all the sudden those stairs over there suddenly turned into a ladder going up—well, that would make it really difficult.

If you are trying to build a house, for example, you have this hammer, but all the sudden the hammer turns in to a goose or a pigeon. Again, that would make things really difficult…or if the nail turned into a worm…or if you get in the car and turn the key and the car turns into a camel, things would be really hard, much harder than they are. This regularity and dependability in our world is an essential condition of our being able to live in the world in which we actually do.

If the world were irregular enough, we would not even be able to live in it, but there are also, according to classical Christianity here (the Heidelberg catechism, for example) there are also special divine actions; sometimes God does things specially. There are miracles in Scripture: the parting of the Red Sea, for example, Jesus walking on water, Jesus changing water into wine. There are miraculous healings: Jesus rising from the dead, Jesus raising Lazarus from the dead, and so on. And according to classical Christians, many of them, perhaps most of them, are special divine actions. God, for example, responds to prayers. He works in the hearts and minds of his children to effect sanctification. There is, what Calvin called, the internal testimony or witness of the Holy Spirit, and there is what Thomas Aquinas called the internal instigation of the Holy Spirit. So, these things are all special actions on the part of God. God constantly causes events in the world. Ok, so far fair enough—what is the problem?

Many theologians seem to think there is a science-religion problem here. I don’t think any of the theologians of Biola think this, (I don’t know, but I doubt it) but many theologians do. For example, Rudolf Bultmann says, “The historical method,” which of course he thinks that is the method we should use, “includes the presupposition that history is a unity in the sense of a closed continuum of effects in which individual events are connected by the succession of cause and effect. This continuum, furthermore, cannot be rent by the interference of supernatural, transcendent powers.”

That’s what he says. Alright, there is this continuum that cannot be rent by the interference of supernatural (that would be God) or transcendent powers. So, it is a little bit like the laws of the Medes and Persians. You probably remember Daniel. Daniel was a favorite of King Darius, and well, the other courtiers became jealous of Daniel (they didn’t like it that the king liked him so well). So, they came to the king and said, “Oh king, live forever, we think it would be a great idea if you passed an edict to the effect that you alone can be worshipped. Everybody has to worship you and nothing else.” Well the king thought that over for a minute, and that sounded pretty good to him so he said, “I guess that it is a pretty good idea.” So he made this edict; he made this declaration: “Only King Darius is to be worshipped—no one else, nothing else.”

These courtiers knew that Daniel worshipped God, and they thought probably Daniel would keep right on worshipping God despite this edict. So they were watching Daniel, and he was, in fact, worshipping God. So they came to the king. Now the penalty for worshipping something else was to be thrown into the lion’s den and they said, “Well, king live forever, looks like Daniel has been violating this edict. You have got to throw him in the lion’s den.”

Well, the king didn’t want to do this because he really liked Daniel. He thought this was a miserable way to proceed, and he didn’t want to do it, but then they said to him, “O king live forever, and remember a law of the Medes and Persians cannot be abrogated, even by the king himself.” So once it’s put in place, not even the king himself can change it or abrogate it or go against it.

That is sort of the suggestion that you get here from Bultmann. Bultmann thinks, “Maybe God created the world and set it up in a certain way, but once he did that, not even he can interfere in it”—he uses that word interference—“not even he can do anything in it. He just has to keep hands off.” It is like the law of the Medes and the Persians.

Another theologian who agrees is John Macquarrie, who says,

The way of understanding miracle (and that would be one kind of special divine action) that appeals to breaks in the natural order and to supernatural intervention belongs to the mythological outlook, and cannot commend itself in a post-mythological climate of thought. The traditional conception of miracle is irreconcilable with our modern understanding of both science and history. Science proceeds on the assumption that whatever events occur in the world, can be accounted for in terms of other events that also belong within the world, and if on some occasion, we are unable to give a complete account of some happening, the scientific conviction is that further research will bring to light further factors in the situation that will turn out to be just as imminent and this worldly as the factors already known.

Ok again, no room there for special action. And the third thinker here, Langdon Gilkey (still another theologian), says something similar, but I will pass. I will not read that one in the interest of saving a little bit of time, but these three theologians, plus many others want to assert that there is something wrong with the idea of God acting in the world, acting in the world in a way that goes beyond creation and sustaining, or creation and holding things in existence. So they think, “Ok, God created the world; God sustains it in existence”…that is ok with them, but anything beyond that, God performing any miracles, raising Jesus from the dead, or for that matter working in somebody’s heart and mind in a special way, that, they say, is a real problem. The question is, what is the problem?

Well, the next little bit here…according to the Christian and theistic idea, God is a person; he has knowledge, loves, and hates. He has aims and ends. He acts on the basis of his knowledge to achieve his ends. He is all-powerful, all-knowing, and wholly good. Thirdly (noted above by the Heidelberg catechism), God has created the world. Fourth is God conserves and sustains and maintains in being this world he created, but fifth, at least sometimes, God acts in a way going beyond creation and conservation in miracles, but also in his providential guiding of history, his working in the hearts of people, his internal instigation of the Holy Spirit, and so on, and it is with that fifth category that these people have a problem. It is God’s special action in the world—action beyond conservation and creation—and miracles would be an example.

So we might think of these theologians as endorsing what we could call hands off theology. God has got to keep his hands off. God could create the world. God conserves the world, sustains it in being, but he can’t do anything else—that is as far as he could go. It is hands off theology, and Bultmann, even in this context, even talks about interfering. I mean if God did something in the world that would be interfering, which, when you think about it, is a sort of strange thing to say—I mean if God created the world, he is the omnipotent, omniscient, holy, good creator of the world—when you accuse someone of interfering, you are saying they are doing something they should not be doing, right?

So Bultmann thinks if God did something in the world that would be interfering, and he should be ashamed of himself. Ok, now why is this a problem? Their suggestion is that somehow it is contrary to science. It is contrary to science the suggestion that God acts specially in the world. I didn’t read that bit, but Gilkey says, "The causal nexus in space and time which the enlightenment science and philosophy introduced into the western mind is also assumed by modern theologians and scholars. Since they participate in the modern world of science, both intellectually and existentially, they can scarcely do anything else.”

From a presentation sponsored by Biola University’s Center for Christian Thought, and delivered February 12, 2012 at EV Free Church, Fullerton, CA. Used by permission.

In his essay for that series, Jeff Schloss addressed the question of whether animal death is a natural evil, but also noted that such theological considerations aside, death does not actually “drive evolution” in the way most people imagine—especially when they think of violence in the natural world. This more complicated sense of death’s role is partially the result of modern evolutionary science recognizing the importance of cooperation and inter-relation among species, rather than just direct competition. But just as important is the knowledge that evolution is significantly shaped not by the deaths of individual creatures, but by extinction, the loss of species over time. In this post, we explore some aspects of how extinction acts as both a destructive and creative force in evolutionary history, including the evolutionary history of mammals.

Sporadic extinction

Extinction is actually a common feature of life on earth when viewed over long (e.g. geological) timescales. By some estimates, over 99% of the species that have ever lived have gone extinct. One factor that promotes extinction is the fact that evolution does not produce species that are optimally adapted to their environment, but only better adapted than their local competitors. Invasive species testify to this fact: local (endemic) species are not always the best-adapted species for their own environment. Examples abound where species from other environments are actually better-suited to out-compete endemic species. Here in my own province, the invasive Himilayan blackberry (Rubis discolor) easily outcompetes many endemic species. If endemic species were optimally adapted to their environment, this would not be possible, as they would outcompete all exotic species. Instead, exotic species, by chance, might be better adapted to an ecosystem they did not evolve in. These exotics may be capable of eliminating endemic species altogether.

Such an extinction event (of a single species, or perhaps a handful of species) alters the environment of other remaining species in an ecosystem. This, in turn, may influence the ability of some of these remaining species to reproduce compared to other species. For example, the extinction of a competitor might allow a species to increase in population size. Conversely, the extinction of a species that provides a benefit (such as a pollinator) may reduce a species in number. As the ecosystem landscape shifts due to loss of species, new biological opportunities, or niches, might arise. These new niches are then available to support new species to fill them.

Extinction, en masse

One way to appreciate how extinction opens up new niches is to examine mass extinction events – geologically brief periods where large numbers of species go extinct at the same time. Over the history of life on our planet there have been several mass extinction events. The largest such event, at the end of the Permian (~250 million years ago) appears to have been caused, at least in part, by intense volcanic activity over several hundred thousand years. This activity likely shifted CO2 levels and eventually led to a “runaway” greenhouse effect that dramatically raised global temperatures and led to anoxic (i.e. oxygen-depleted) oceans, though the exact contributions of these varied factors remains an area of scientific debate. What appears certain is that during this period environmental changes were too rapid for most species to keep evolutionary pace with, and as a result over 90% of the world’s species alive at that time went extinct. Obviously this represents destruction of biodiversity on an unimaginable scale, and the destructive effects of this event are with us to this day.

Speciation, en masse

This destruction, however, is not the whole story. Following on from the Permian mass extinction, we observe a steady increase in new species. These are species previously unknown in the fossil record. In fact, this pattern (a “radiation” of new species following an extinction event) is the rule, not an exception – we see the same effect after every mass extinction in the fossil record. Extinction is a driving force for novelty.

Perhaps the most famous mass extinction event is the Cretaceous – Paleogene (KPg) extinction, and it too follows this standard pattern. This mass extinction took place 65 million years ago when an asteroid ~10 kilometers in diameter struck the Yucatan peninsula. (Note: this event was formerly known as the Cretaceous – Tertiary (K-T) extinction, but that terminology is in decline within the scientific community). This extinction event is famous since it is the one that eliminated the dinosaurs (with the exception of the ancestors of modern birds). As with the Permian extinction, the elimination of so many species shifted the evolutionary landscape for the remaining species, and the result was a burst of speciation that appears rapid when viewed in geological time. Significantly for our own species, following the KPg extinction event is a burst in mammalian speciation, as small mammals that survived the event diverge and fill niches left empty by the dinosaurs. Without this event, the trajectory of mammalian evolution would certainly look very different.

Clearing the deck, and re-filling the niches

One interesting fact to note is that biological features that make a species resistant to usual, sporadic extinction are not necessarily the same features that will be useful during a mass extinction event. While species are continually under selection at the local level, there is no mechanism for (pre) selection to survive a mass extinction. As such, only species that happen to have the right combination of traits will survive, and often spread widely after a mass extinction. These so-called “disaster species” are usually generalists, and will later be displaced by more specialized species as they arise. As such, where sporadic extinction allows for more gradual turnover in species, mass extinction events are major “resets” of evolution that can radically shift what constitutes “well adapted” in a geological eyeblink. For mammals at the KPg boundary, small body size and an omnivorous diet (including the ability to scavenge detritus) were the “winning” combination of traits that allowed them to survive where larger, more specialized animals (think Tyrannosaurus rex) could not. From this rather humble station, mammals would come to dominate the world’s ecosystems over the coming eons – including a lineage that would someday lead to our own species. Far from only a destructive force, extinction is a powerful mechanism to allow evolutionary innovation, and one that was of significant importance to us.

For further reading:

Meredith, R.W. et al (2011). Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification. Science 334; 521-524.

Fastovsky, D.E. (2005). The Extinction of the Dinosaurs in North America. GSA Today (15); 1052-5173.

Benton, M.J. and Twitchett, R.J. (2003). How to kill (almost) all life: the end-Permian extinction event. TRENDS in Ecology and Evolution (18); 358-365.

In my previous essay, I discussed “Darwin’s finches” and how surprisingly little Charles Darwin himself had to say about them. In fact, it was actually the British ornithologist David Lack (1910-1973) who conducted the critical research that immortalized the finches in biology textbooks and popular lore. In 1973, the eminent German zoologist Ernst Mayr wrote:

Already well known among professional ornithologists, his work on the Galapagos finches gave David Lack world fame… There is no modern textbook of zoology, evolution or ecology which does not include an account of his work.¹

Ernst W. Mayr

Decades have passed since Mayr wrote these words, and David Lack’s name has largely faded from public discourse. On the other hand, the Galapagos finches have become one of the most recognized symbols of evolution in the world today. Does it really matter whether Lack or Darwin gets credit for describing the evolution of these remarkable birds?

Insofar as evolutionary theory contrasted with religious belief, it makes a big difference. In a culture that is eager to equate evolution with atheism, it should come as no surprise that these birds are only known as “Darwin’s finches”. Darwin’s personal struggles and ultimate rejection of Christianity are well documented, and people are eager to link his loss of faith to his evolutionary theory. David Lack, on the other hand, began his scientific career as an agnostic, but shortly after publishing his famous book on the evolution of Galápagos finches, he converted to Christianity! ²

A Christian at the forefront of evolutionary biology

Lack’s Christian conversion did not mark the end of his scientific achievements, either. In fact, he continued as a prolific researcher until just weeks before he died. Among his many achievements, he was Director of the Edward Grey Institute of Field Ornithology (1945-1973), Fellow of the Royal Society, and President of both the International Ornithological Congress (1962-66) and the British Ecological Society (1964-65). His fellow scientists held him in great esteem:

He was described as one of the most outstanding among world ornithologists; he was certainly this, but he was also one of the world’s leading evolutionists. All the time one saw developing his use of birds as material for the study of wider, deeper, biological problems.³

David Lack at the International Ornithological Congress, 1962.

Clearly David Lack was an outstanding scientist, and his commitment to Christianity did not tarnish, hinder, or undermine his research on evolution. But we might also ask, what was Lack like as a Christian? Did he keep his faith hidden from view, afraid that it might compromise his reputation as a scientist? Ernst Mayr, who interacted with David Lack professionally and personally for nearly 40 years, had this to say:

I have known only few people with such deep moral convictions as David Lack. He applied very high standards to his own work and was not inclined to condone shoddiness, superficiality and lack of sincerity in others. This did not always go well with those who preferred to compromise in favour of temporary expediency. David had been raised in an environment in which great stress was layed on moral principles and this attitude was later reinforced by his Christian faith. This explains his extraordinary unselfishness and modesty, and his great devotion to his family, to his students, to his friends, and to all the things that he lived for. The equanimity, indeed serenity, with which he faced death after his terminal cancer had been diagnosed is further evidence of the strength which his faith gave him.⁴

Like Asa Gray⁵ before him, and Francis Collins⁶ after, David Lack was an sincere, devout Christian, as well as a leading scientist who employed evolutionary theory to make brilliant discoveries about the natural world. Though Lack did not see any conflict between his scientific and Christian beliefs, he was sympathetic to the concerns of his fellow Christians. Therefore, ten years after publishing his masterpiece on Darwin’s Finches, Lack wrote another book entitled Evolutionary Theory and Christian Belief: The Unresolved Conflict.

Originally published in 1957, this book deals with the very same science and faith questions that Christians struggle with today— topics like randomness and chance, death in nature, miracles, and evolutionary ethics. While it would be unreasonable to expect anyone to completely resolve these matters, Lack offered numerous insights both as a devout Christian and one of the world’s leading biologists.

Let’s take a brief look at how Lack addressed some of these questions.

Blind Chance or Divine Plan?

Evolutionary theory does not invoke supernatural forces in explaining the history of life on Earth; instead, it relies on naturally-occurring processes to account for the vast diversity of life. Additionally, it explains animal behavior largely in terms of survival and reproduction, without appealing to any higher purpose of life. Taken together, does this imply that God is absent, and that our lives are ultimately meaningless?

David Lack responded,

Behind the criticism that Darwinism means that evolution is either random or rigidly determined lies the fear that evolution proceeds blindly, and not in accordance with a divine plan. This is another problem that really lies outside the terms of reference of biology. It is true that biologists have inferred that, because evolution occurs by natural selection, there is no divine plan; but they are being as illogical as those theologians whom they rightly criticize for inferring that, because there is a divine plan, evolution cannot be the result of natural selection.⁷

When rendering judgment on the ultimate meaning of life, biologists are speaking from their person beliefs, not from scientific authority. Moreover, Lack pointed out that many science enthusiasts have employed the concept of “randomness” in ambiguous and misleading ways:

Mutations are random in relation to the needs of the animal, but natural selection is not. Selection, as the word implies, is the reverse of chance.⁸

In support of his view, Lack pointed out that convergent evolution has produced uncanny resemblances between distantly-related species across the world, notably among marsupials in Australia. Different evolutionary trajectories can lead to very similar results.⁹

Death in Nature

After addressing concerns about the seeming “randomness” of evolution, Lack turned to another great concern, the role of death in natural selection:

Various writers–some Christian and others agnostic–have been troubled about natural selection not only because it seems too random, but also because it is so unpleasant.¹⁰

Image courtesy John Marsh Photography via Flikr

Genetic mutations are generally harmful, and for evolution by natural selection to produce new forms of life, an awful lot of organisms must die. For many Christians, it is inconceivable that a loving and merciful God would allow death on such a vast scale.

But Lack also pointed out that rejecting evolutionary theory doesn’t actually get rid of the problem of death. Regardless of what we think about evolution, the brute fact of mass extinction remains. Fossils of innumerable animals, plants, and microorganisms clearly demonstrate that the vast majority of species that have ever lived are now dead. It may be quite troubling for us to observe that our planet is a giant graveyard of natural history, but rejecting evolution will not change this fact.

Some Christians conclude that death could not have been part of the divine plan; instead, it must be the work of the devil, or the result of human sin. But this interpretation contains an implicit assumption that death is always evil. Is this really true? David Lack offered two intriguing insights:

Blue-cheeked Bee-eater (Merops persicus) pair in
courtship, seen in Basai, Gurgaon, India.
Image courtesy Koshy Koshy.

1. For a population to maintain a stable size, all births must be balanced by a corresponding number of deaths. A world in which no animals die is a world in which no animals are born. That means no reproduction, no courtship, and by implication, no singing birds—much to the dismay of ornithologists and people in love!

2. Some people, taking cues from Isaiah 11:6-7, suppose that in a perfect world, animals only eat plants. But in fact, plants themselves depend on the bacterial decay of dead organisms. If animals didn't die, then essential nutrients would disappear from the ground, and plants could not continue to grow. Eventually, there would be nothing left for animals to eat, and all life would cease.¹¹

Miracles

Many Christians are uncomfortable with evolutionary theory because it denies a miraculous, supernatural origin of life. They fear that if those miracles are denied, it might lead people to reject the possibility of miracles altogether, including the central feature of the Christian faith—the resurrection of Jesus from the dead.

As a devout Christian, David Lack certainly affirmed the fundamental tenets of the gospel. But at the same time, he explained to his readers that invoking miracles to account for unusual features of the natural world is not particularly helpful when trying to deepen our understanding of God’s great multitude of creatures:

[The biologist's] research depends on repeated observations. It need not, as popularly supposed, consist solely, or even mainly of measurements and experiments, but unless events are repeated, they cannot be assessed by science. Hence truly unique events come outside the domain of science, though biologists are not usually convinced when told they must, therefore, leave such problems as miracles to others. For one of the chief ways in which research has advanced is through the discovery of apparent exceptions to the known rules, and if further study shows the exceptions to be replicable, new regularities are revealed from which modified rules can be propounded. This method has been so successful that the biologist tends to doubt whether there are any types of irregularity, or seeming irregularity, that will not yield to it.¹²

But just because a scientist cannot repeat a particular event doesn’t mean it didn’t happen. Both natural history and human history contain unique events that only happened once. As we peer into the past, the difficulty of discerning fact from fiction inspires us to further investigate the mysteries that surround us.

Conclusion

David Lack’s book Evolutionary Theory and Christian Belief was quite insightful, but his enduring achievements took place in evolutionary biology, a place where many Christians are afraid to tread. While it is significant that he himself found no contradiction between his faith and his science, perhaps the greatest testament to the compatibility between Christian faith and evolution is the life he led as a believer in both. As we saw in Ernst Mayr’s candid praise, Lack reflected the light of Christ through both his personal and his professional relationships.

Today, many voices in our culture still insist that evolution is incompatible with a sincere faith in Jesus, but a careful look at history demonstrates otherwise. In the future, perhaps more people of faith will have confidence to study biology knowing that one of the most iconic symbols of evolution—the Galapagos finches—owe their fame in large part to a devout Christian named David Lack.

Notes

1. Mayr (1973) “David L. Lack.” Ibis: 433.
2. Larson, E. J. Evolution's Workshop: God and Science on the Galapagos Islands. New York, Basic Books, 2001: 218. See also Lack, David. (1973) “My life as an amateur ornithologist.” Ibis: 431.
3. Alister C. Hardy (1973). "David L. Lack." Ibis: 436.
4. Mayr (1973) “David L. Lack.” Ibis: 433.
5. For more about Asa Gray, see the BioLogos FAQ “How have Christians responded to Darwin’s Origin of Species?”
6. See Francis Collins’ autobiography The Language of God: A Scientist Presents Evidence for his Belief (New York: Free Press, 2007) (book info)
7. Lack, David. Evolutionary Theory and Christian Belief: The Unresolved Conflict. Methuen & Co., 1957: 67.
8. Lack, p65.
9. For more on convergent evolution and the possibility that evolution could be compatible with some form of divine purpose, see the work of Simon Conway Morris, especially The Deep Structure of Biology: Is Convergence Sufficiently Ubiquitous to Give a Directional Signal? Templeton Press, 2008.
10. Lack, p72.
11. Lack, pp75-76.
12. Lack, p82.

There are two opposite errors which need to be countered about the fossil record: 1) that it is so incomplete as to be of no value in interpreting patterns and trends in the history of life, and 2) that it is so good that we should expect a relatively complete record of the details of evolutionary transitions within all or most lineages.

What then is the quality of the fossil record? It can be confidently stated that only a very small fraction of the species that once lived on Earth have been preserved in the rock record and subsequently discovered and described by science.

There is an entire field of scientific research referred to as "taphonomy" -- literally, "the study of death." Taphonomic research includes investigating those processes active from the time of death of an organism until its final burial by sediment. These processes include decomposition, scavenging, mechanical destruction, transportation, and chemical dissolution and alteration. The ways in which the remains of organisms are subsequently mechanically and chemically altered after burial are also examined -- including the various processes of fossilization. Burial and "fossilization" of an organism's remains in no way guarantees its ultimate preservation as a fossil. Processes such as dissolution and recrystallization can remove all record of fossils from the rock. What we collect as fossils are thus the "lucky" organisms that have avoided the wide spectrum of destructive pre- and post-depositional processes arrayed against them.

Soft-bodied organisms, and organisms with non-mineralized skeletons have very little chance of preservation under most environmental conditions. Until the Cambrian nearly all organisms were soft-bodied, and even today the majority of species in marine communities are soft-bodied. The discovery of new soft-bodied fossil localities is always met with great enthusiasm. These localities typically turn up new species with unusual morphologies, and new higher taxa can be erected on the basis of a few specimens! Such localities are also erratically and widely spaced geographically and in geologic time.

Even those organisms with preservable hard parts are unlikely to be preserved under "normal" conditions. Studies of the fate of clam shells in shallow coastal waters reveal that shells are rapidly destroyed by scavenging, boring, chemical dissolution and breakage. Occasional burial during major storm events is one process that favors the incorporation of shells into the sedimentary record, and their ultimate preservation as fossils. Getting terrestrial vertebrate material into the fossil record is even more difficult. The terrestrial environment is a very destructive one: with decomposition and scavenging together with physical and chemical destruction by weathering.

The potential for fossil preservation varies dramatically from environment to environment. Preservation is enhanced under conditions that limit destructive physical and biological processes. Thus marine and fresh water environments with low oxygen levels, high salinities, or relatively high rates of sediment deposition favor preservation. Similarly, in some environments biochemical conditions can favor the early mineralization of skeletons and even soft tissues by a variety of compounds (eg. carbonate, silica, pyrite, and phosphate). The likelihood of preservation is thus highly variable. As a result, the fossil record is biased toward sampling the biota of certain types of environments, and against sampling the biota of others.

In addition to these preservational biases, the erosion, deformation and metamorphism of originally fossiliferous sedimentary rock have eliminated significant portions of the fossil record over geologic time. Furthermore, much of the fossil-bearing sedimentary record is hidden in the subsurface, or located in poorly accessible or little studied geographic areas. For these reasons, of those once-living species actually preserved in the fossil record, only a small portion have been discovered and described by science. However, there is also the promise of continued new and important discovery.

The forces arrayed against fossil preservation also guarantee that the earliest fossils known for a given animal group will always date to some time after that group first evolved. The fossil record always provides only minimum ages for the first appearance of organisms.

Because of the biases of the fossil record, the most abundant and geographically widespread species of hardpart-bearing organisms would tend to be best represented. Also, short-lived species that belonged to rapidly evolving lines of descent are less likely to be preserved than long-lived stable species. Because evolutionary change is probably most rapid within small isolated populations, a detailed species-by-species record of such evolutionary transitions is unlikely to be preserved. Furthermore, capturing such evolutionary events in the fossil record requires the fortuitous sampling of the particular geographic locality where the changes occurred.

Using the model of a branching tree of life, the expectation is for the preservation of isolated branches on an originally very bushy evolutionary tree. A few of these branches (lines of descent) would be fairly complete, while most are reconstructed with only very fragmentary evidence. As a result, the large-scale patterns of evolutionary history can generally be better discerned than the population-by-population or species-by-species transitions. Evolutionary trends over longer periods of time and across greater anatomical transitions can be followed by reconstructing the sequences in which anatomical features were acquired within an evolving branch of the tree of life.

(Written by the BioLogos editorial team)

In a recent lecture in Washington, D.C., Intelligent Design advocate Stephen Meyer noted that scientists and theologians are generally uncomfortable with the idea of "supernatural intervention" in natural processes such as evolution. He then posed the question, “What's so bad about supernatural intervention?” Meyer’s comment touches on a point of particular tension among Christians engaged in understanding how our science and our theology interact: the nature of divine action.

Much of the confusion in this area, however, stems from the inexact meaning of intervention, which—like evolution or Darwinism—implies different things to different people. All Christians affirm that God works powerfully in the world, doing extraordinary acts of creation and salvation. In common conversation, then, intervention tends to mean simply “acts that are recognizably or obviously God’s,” whether as dramatic as the parting of the Red Sea or as subtle as an individual believer hearing a clear call to repentance or to mission from the Lord. Even in this most casual sense, intervention tends to mean special occasions of God’s providential care, rather than his ordinary sustaining work.

But to Christian scientists and philosophers trying to understand God’s action in creation—especially how he might go about his sustaining role—intervention has another connotation: namely, that recognizing something as “divine action” requires it to be in violation of the natural laws which God himself established. Put another way, many Christian thinkers associate the word intervention with the idea that to act in the world God “must” act from outside the world. That view is a central tenet of deism, not Christianity. One response to Meyer’s comment, then, is to ask whether intervention is the only (or even a helpful) way of thinking about God’s work in biological creation. Is there another way of talking about “divine action” that does not restrict God's work to only extraordinary events? Can we conceive of divine action in a way God is never absent, distant, or in any way removed from the creation he sustains at every moment?

Finding such an alternative vocabulary to talk about the different ways God acts in his creation is the purpose of this short series introducing the work of theologian and physicist Robert John Russell. Russell’s book Cosmology: From Alpha to Omega explores the history of Christian thinking about divine action and proposes one model for how we might understand it in light of Scripture, the traditions of the church, and contemporary scientific explorations of the material world.

To be clear, Russell argues that God does unmistakably act in the world. He singles out the bodily resurrection of Jesus not only as a prime example, but as a truly unique event distinct even from Christ’s other miraculous acts during his ministry on earth. That is, the resurrection was an in-breaking of God’s new reality into the present one, something “beyond miraculous.” This series, though, offers his perspective on the more basic issue of how God might be at work in what we have called the “ordinary processes” of his world.

We begin our three-part series below with Professor Russell’s description of how views of divine action have changed throughout history (excerpted from Chapter 4 of Cosmology: From Alpha to Omega).

Historical background to the problem of divine action

The notion of God’s acting in the world is central to the biblical witness. From the call of Abraham and the Exodus from Egypt to the birth, ministry, death and raising of Jesus and the founding of the church at Pentecost, God is represented as making new things happen. Through these “mighty acts,” God creates and saves. Rather than seeing divine acts as occasional events in what are otherwise entirely natural and historical processes, both the Hebrews and the early Christians conceived of God as the creator of the world and of divine action as the continuing basis of all that happens in nature and in history.

The view that God works in and through all the processes of the world continued throughout Patristic and Medieval times. For example, God was understood as the first or primary cause of all events—where all natural causes are instrumental or secondary causes through which God works. The conviction that God acts universally in all events, and that we act together with God in specific events, was maintained by the Reformers and the ensuing Protestant orthodoxy. John Calvin (1509-1564) argued that God is in absolute control over the world and at the same time maintained that people are responsible for evil deeds. Questions about human freedom and the reality of evil were seen more as problems requiring serious theological attention than as reasons for abandoning belief in God’s universal agency.

Moreover, faith in God the creator was articulated through two distinct but interwoven doctrines: creation and providence. The doctrine of creation asserts that the ultimate source and absolute ground of the universe is God. Without God, the universe would not exist, nor would it exist as “universe.” Creation theology, in turn, has often included three related but distinct claims: 1) the universe had a beginning; 2) the universe depends absolutely and at every moment on God for its sheer existence; and 3) the universe is the locus of God’s continuing activity as Creator. The first two have traditionally been grouped in terms of creatio ex nihilo(creation from nothing), and the third in terms of creatio continua (continuing creation).

The doctrine of providence presupposes a doctrine of creation, but adds significantly to it. While creation stresses that God is the cause of all existence, providence stresses that God is the cause of the meaning and purpose of all that is. God not only creates but guides and directs the universe towards the fulfilling of God’s purposes. These purposes are mostly hidden to us, though they may be partially seen after the fact in the course of natural and historical events. The way God achieves them is hidden, too. Only in the eschatological future will God’s action throughout the history of the universe be fully revealed and our faith in it confirmed. General providence refers to God’s universal action in guiding all events; special providence refers to God’s particular acts in specific moments, whether found in personal life or in history.

Divine intervention arises in the Enlightenment

The rise of modern science in the seventeenth century and Enlightenment philosophy in the eighteenth, however, led many to reject the traditional views of divine action. Although Isaac Newton (1643-1727) argued for the essential role of God in relation to the metaphysical underpinnings of his mechanical system, and in this way defended the sovereignty of God in relation to nature, Newtonian mechanics depicted a causally closed universe with little, if any, room for God’s special action in specific events—and then only by intervention: that is, by acting as from outside that closed system. A century later, Pierre Simon Laplace (1749-1827, pictured left) combined the determinism of Newton’s equations with epistemological reductionism (the properties and behavior of the whole are reducible to those of the parts) and metaphysical reductionism (the whole is simply composed of its parts), to portray all of nature as a causally closed, impersonal mechanism. This in turn led to the concept of interventionism: if God were really to act in specific events in nature, God would apparently have to break the remorseless lock-step of natural cause and effect by intervening in the sequence and violating the laws of nature in the process.

The eighteenth century also saw the rise and fall of deism, in which the scope of divine agency was limited to an initial act of creation. According to deism, the universe was like a clock which, once built and set in place, proceeded to run on its own. David Hume (1711-1776) challenged the deistic (and theistic) arguments for God as first cause and as designer. In response, Immanuel Kant (1724-1804, pictured right) constructed a new metaphysical system which emphasized the mind’s role in organizing sense-data through universal categories of intuition and forms of sensibility. According to Kant, the sphere of religion lies not in our knowing (the activity of pure reason) but in our sense of moral obligation (the activity of practical reason). It is our ethical system, not our knowledge of nature, that requires us to postulate God, freedom and the immortality of the soul. The consequence of Kant’s thought for the West was the philosophical separation of the domains of science and religion into “two worlds”—a move which was to have an immeasurable effect on Christian theology up to the present.

Theology splits into conservative and liberal interpretations of divine action

As a consequence of the philosophical division of science and religion, theology in the nineteenth century was faced with a fundamental challenge not only to its contents and structure, but even to its method. The variety of responses to this challenge tend to fall into two groups: “liberals” largely accepted and worked within the terms of the discussion that modernity dictated while “conservatives” upheld traditional formulations and tended to reject “modernity.” The earliest and most influential figure among liberals was Friedrich Schleiermacher (1768-1834), who responded to Kant by locating religion as neither a knowing nor a doing. Instead religion is grounded in personal piety—the feeling of absolute dependence.

Schleiermacher held that theological assertions emerge from the immediacy of the religious self-consciousness. He understood God’s relation to the world in terms of “universal divine immanence” [the idea that God is present to the entire cosmos at all times], and he blurred the distinction between creation and providence by collapsing the later into the former. In a famous move he defined miracle as “. . . simply the religious name for event. Every event, even the most natural and usual, becomes a miracle, as soon as the religious view of it can be the dominant.” Schleiermacher’s arguments became characteristic of liberal Protestant theology throughout the nineteenth century and continued into much of twentieth century theological work.

The second half of the nineteenth century saw the rise of Darwinian evolution, which combined random variation and natural selection to explain biological complexity. To some in the nineteenth and twentieth centuries, the fundamental role of chance in nature seemed to undercut any notion of divine action in the world; to others, such as the Anglo-Catholic liberal movement in Britain and America, Darwinian evolution could be accommodated and even integrated into theology without interventionism, since God works immanently in and through the very processes of nature. In contrast, religious conservatives tended either to reject evolution as a whole or give it a limited acceptance with the proviso that the objective acts of special providence constitute divine interventions in nature.

The rise of neo-orthodoxy in the twentieth century

Protestant theology in the first half of the twentieth century was largely shaped by Karl Barth. In his rejection of nineteenth-century liberal theology, Barth returned theology to its biblical roots and focused it on the God who is “wholly other.” Recognizing that a religion founded exclusively on subjective experience is vulnerable to the critiques of Feuerbach and Freud, Barth and his followers held fast to the objective action of God in creating and redeeming the world. “The Gospel is . . . not an event, nor an experience, nor an emotion—however delicate! ... It is a communication which presumes faith in the living God, and which creates that which it presumes.” The ‘God who acts’ became a hallmark of the ensuing “biblical theology” movement which arose in the 1940s and 1950s. To many this movement seemed to offer a tertium quid between liberal and conservative theologies.

But do Barthian neo-orthodoxy and the biblical theology movement actually produce a credible account of divine action? On the one hand neo-orthodoxy attempts to distance itself from liberal theology by retaining biblical language about God acting through wondrous events and by viewing revelation as including an objective act. Yet on the other hand, it, like liberalism, accepts the modern premise that nature is a closed causal system, as depicted by classical physics. The result is that neo-orthodoxy seems to assert a contradiction: God does act objectively in nature (as conservatives believe) and God does so without intervening, violating, suspending or obstructing the ordinary processes of nature understood as a closed causal system (as liberals believe).

A third way between liberal and conservative theologies

Any purported “third option” will require an intelligible concept of objectively special providence which does not entail divine intervention. Such a concept could serve as a genuine tertium quid to conservative and liberal notions of special providence, combining strengths borrowed from each. Specifically, we will seek to speak about special divine acts in which God acts objectively in an unusual and particularly meaningful way in, with, and through events which serve to mediate God’s action. We will seek to do so without entertaining—in fact by refusing—the additional claim that God must intervene in, or at least suspend, the laws of nature. Those laws are themselves the result of and description of God’s continuous creation, after all. I call this type of divine action Non-Interventionist Objective Divine Action (NIODA).

In part 2 of this series, Tom Burnett will explore in more depth what Russell takes to be wrong with the Enlightenment concept of “supernatural intervention.” Part 3 will explain and clarify Russell’s theory of NIODA.

From Chapter 4, “Does ‘The God Who Acts’ Really Act? New Approaches to Divine Action In Light Of Contemporary Science,” in Cosmology: From Alpha to Omega by Robert John Russell, copyright © 2008 Fortress Press. Reproduced by permission of Augsburg Fortress Publishers. All rights reserved. No further reproduction allowed without the written permission of the publisher.

This ongoing series grew out of a conversation that Kenneth Keathley, the Senior Vice President for Academic Administration at Southeastern Baptist Theological Seminary and I had last year. We agreed that he would solicit a set of essays from scholars at Southern Baptist Seminaries who would specifically identify their concerns about what they perceive to be the BioLogos view of creation. In response to this request, Dr. William Dembski of Southwestern Baptist Seminary submitted the essay “Is Darwinism Theologically Neutral?” Although I do not consider my view Darwinian, I am sure that my view and that of others associated with BioLogos is perceived that way by some, so this gives me an opportunity not only to respond to his analysis, but to clarify my position on creation and how I think it is distinct from what Dembski calls “Darwinism."

God’s Activity in Creation

I will begin by summarizing my view of the nature of God’s activity in creation. I think that God created all living organisms, including humans, through the evolutionary process. Acceptance of creation through evolution does not mean that I reject the notion of a miracle-working God. On the contrary, I believe in the miracles of Scripture, and I believe that we’ve experienced God’s supernatural activity in our own lives. I stand in awe of a personal God whose activity is not constrained by natural laws, but also includes supernatural acts.

But what are the natural laws? Are not the the laws of nature simply a description of God’s ongoing and non-ceasing activity in the universe? The Law of Gravity, for example, is not something that God set up in the beginning, thereafter recusing himself from further involvement and exiting from the scene. Instead, the Law of Gravity works as it does because of the ongoing activity of God’s Spirit in the universe. So consistent is that activity that it can be described mathematically through scientific analysis. If God ceased to be active, however, then not only would the matter of this universe no longer function in a way which enables a mathematical description of gravity, matter itself would cease to exist. Paul, referring to Christ, writes “All things are created by him and through him.” Continuing, he goes on to state that “He himself is before all things and in him all things hold together” (Colossians 1:17). So he created in the beginning and, indeed, “…without him not one thing came into being.” (John 1:3) But it doesn’t end there: his ongoing activity is necessary for the universe to function. As the writer to the Hebrews declares “He sustains all things by his powerful word.” (Hebrews 1:4) The laws of nature, then, are simply a description of the ongoing activity of God which—because it is so consistent, dependable, and pervasive—points to the trustworthiness of God. Put another way, the activity of God is not restricted to that which we call the supernatural; it is all God’s activity. It is just that some aspects of God’s activity are so consistently repeatable that we can develop laws which describe the regularity of the divine activity which “holds” and “sustains” the universe. This latter type of activity is no less magnificent just because God does it continuously. Indeed, the Psalmist marveled at God’s natural activity and worshipfully reflected upon it.

On the other hand, the God we know through Scripture and personal experience also works in ways that are not mathematically predictable. We call this aspect of God’s action supernatural, and we seem to think of this facet of God’s work—this law-defying activity—as being more God-like. Indeed calling it super-natural suggests we think of it as God’s “turbo-charged” activity. But are not miracles simply a reflection of God choosing to work in a unique, non-customary manner to accomplish God’s purposes in God’s time? (See here for more detail.) When God works in this way, Scripture generally presents such activity in the context and purpose of God’s desire to enter into or renew a relationship with an individual or with a community of people. For example, God’s miraculous involvement in the lives of the elderly couple, Abraham and Sarah, led to the birth of their son, Isaac, and marks the beginning of God’s very special relationship with their descendents. God’s interaction with Moses through the burning bush initiated a new phase of God’s relationship with the Hebrew people as they moved out of slavery and back into the Promised Land. And of course, the supreme examples of miraculous activity are the incarnation, the empty tomb, and the resurrected Body. We worship a personal God whose desire for an ongoing loving relationship with humankind is first laid out in the early chapters of Genesis, but does not end there. In all divine activity—supernatural and natural—God is just being who God is: Creator, Sustainer, and loving Father. There are not two sets of activities, even though we label them “super” and “ordinary.” All are “super,” because all describe the activity of our supernatural God. Some are regular, predictable and ongoing, while other activities of God are not, for reasons often based in the fact that God is lovingly responsive and relational.

The Genesis narrative gives us no details about the mechanism by which God brought the universe and life into existence. God gave the charge: “Let there be lights in the dome of the sky..., “ “Let the waters bring forth…,” “Let the land bring forth…,” “Let the birds multiply…,” and, in response, we are told, it happened. Scripture does not explain how it happened, although as we read God’s other book—the book of nature—we see that God’s work extended over a long period of time. In these details, the Bible does not say whether the “bringing forth” was fulfilled through God’s natural activity (that which is regular, ongoing, and can be described by science) or God’s supernatural activity (that which is not regular and predictable). Given the many examples of supernatural activity in Scripture, we human beings tend to expect that for something as special as creation of stars or new species, supernatural activity would have been required. But we cannot derive this from the scriptural account and, therefore, it is wise not to second-guess how God might have worked based on the Scriptures.

Indeed, the distinction is softened by Scripture itself, which often speaks of God’s natural activity in ways that sound supernatural. For example, the Psalmist writes of God opening his hand to feed the living creatures (Psalm 104:28). We know how God does this and so did the Psalmist—he did it through natural means—but it was still God’s process and God’s provisions. Job speaks of thunder as being the voice of God (Job 40:9). We know God’s natural activity produces thunder and we can describe the laws that are responsible for it, but the fact that we know how it works certainly doesn’t negate the point being made in the book of Job. When the Psalmist describes the heavens as being the work of his fingers (Psalm 8:3), this does not negate astronomy’s description of the regular and ongoing processes that give rise to stars in God’s universe. Those processes are natural, but they are every bit as much God’s activity as if he were to take huge balls of matter and miraculously fashion sparkling stars with his hands.

Still, given that there is extensive supernatural activity exhibited in God’s interaction with Israel and in the life of Jesus, it is entirely possible that he did work supernaturally in fulfilling the creation command, as well. Even though the miracles described in the Bible primarily serve some theological or pastoral purpose that stems from God’s earnest desire to make his presence known and to deepen his relationship with humankind, we should reserve judgment about whether only God’s natural activity was responsible. It is not clear though, that supernatural activity would often be God’s chosen mode of action millions of years before humans had arrived. Thus, we should not assume with certainty that God would choose to use supernatural flurries of activity if his ongoing regular activity—that described through natural laws—would accomplish the same end, albeit over a longer period of time. For all we know, God may prefer slowness, even though we seem to be inclined to think that faster is better. After all, in the history of Israel and the church, God gave no new prophecy for 400 years before the coming of Christ, and it took the early church five centuries to come to a clear—albeit mysterious—understanding of the Trinity. Even now, two thousand years after Christ, we wait for his return.

In the next part, Darrel responds to Dembski’s lists of non-negotiables and clarifies how he sees BioLogos as different from “Darwinism”.

Evolution: just a theory

One game that my (young) children like to play is a guessing game where both players select a character from among many choices, and by process of elimination, tries to guess the character the other has selected. Questions like “does your character have red hair? glasses?” etc., are used to narrow down the possibilities. Once you have guessed correctly which character your opponent has selected, you can perfectly predict the answer to every question thereafter (and a good many parents likely prolong the questioning to keep the hopes of victory alive for their children). When considered separately, the individual features of each character—glasses, brown hair, purple hat, and so on—mean almost nothing, since they could be features shared with other characters in the game. Only the convergence of multiple features is indicative of a good guess, and the accuracy of that guess is put to the test every time a new question is asked.

A good theory is something like this: an educated guess, based on and consistent with all past work on the topic to date. It allows you to predict how future tests should pan out. In the guessing game, there are limited options to choose from (so the analogy, like all analogies, eventually breaks down). In science, we don’t really know the true way things actually work. What we have are theories—broad explanatory frameworks supported by experimentation, that make sense of our current collection of facts—that we can use to make testable predictions about the natural world. All theories in science are provisional in that they are not complete descriptions of how the world actually works and are subject to future revision; but at the same time they are robust frameworks that can be used to predict how experiments should behave with almost boring regularity. So, far from the colloquial usage of “theory” as speculation, “just a theory” is high praise in science.

The current understanding of evolutionary theory in all its scope and diversity is far more complex than Darwin himself could have ever envisaged. (As a geneticist, I’ve often wished I could have a cup of tea with him to show him how far his theory has grown, especially given his confusion about how heredity worked.) Our understanding of how evolution works has grown by leaps and bounds since the 1850s. What is remarkable is just how much Darwin got “right” given his time and place. His main hypotheses—that species descend from ancestral forms through descent with modification, that and natural selection acting on heritable variation is a significant force in that process—remains the core of modern evolutionary theory. We’ve added a lot of detail since then (population genetics, kin selection, neutral evolution/genetic drift, symbiosis, horizontal gene transfer, molecular exaptation, and so on), but Darwin’s core ideas have produced a wealth of successful predictions. They were a very good “guess” that continues to pay rich scientific dividends.

Whale evolution: an example of converging lines of evidence

One of the things I personally find quite enjoyable about evolutionary theory is the counter-intuitiveness of some of the predictions it makes. One example that is a personal favorite, and one I often use to illustrate how evolution makes sense of converging lines of evidence, is cetacean (whale) evolution. Let’s set up the “problem” that evolutionary biology forces upon us:

• Modern cetaceans are mammals – they nourish their young in utero through a placenta, give birth to live young, and feed newborns with milk – all features of standard mammalian biology.
• Mammals are tetrapods – organisms with four limbs. Mammalian life shows up in the fossil record as an innovation within tetrapods, so mammals are “nested within the set” of tetrapod forms. Not all tetrapods are mammals (amphibians, for example) but all mammals are tetrapods.
• Tetrapods are by and large terrestrial creatures. Having four limbs for locomotion is a distinctly land-based adaptation.

The “problem”, of course, is that modern whales are emphatically not terrestrial, nor do they have four limbs – they have two front flippers and a tail, with no hind limbs in sight. Yet they are mammals, which forces evolution’s hand as it were. Evolution thus is dragged, under protest, to the prediction that modern whales, as mammals, are descended, with modification, from ancestral terrestrial, tetrapod ancestors. Instantly this prediction raises a host of uncomfortable questions: where did their hind limbs go? How did they acquire a blowhole on the top of their heads when other mammals have two nostrils on the front of their faces? How did they transition to giving birth in the water? What happened to the teeth of the baleen whales? What happened to the hair characteristic of mammals? and so on. In some ways, evolutionary thinking about whales creates more difficulties than it appears to solve.

And yet, these difficulties are the stuff of science. If indeed our “educated guess” of terrestrial, tetrapod ancestry for whales is correct, the evidence will show that these transitions, challenging though they may seem, did indeed occur on the road to becoming “truly cetacean”.

Going out on a limb

Anyone who has seen a modern whale skeleton in a museum and noted it carefully may have noticed that though whales lack hind limbs, they do have a bit of bone back there where the hind limbs ought to be. While this is suggestive of a vestigial characteristic (a feature in a modern organism that has a reduced role relative to the role the structure played in an ancestral species), it’s hardly a smoking gun for evolution. Still, it’s consistent with the idea.

When we look at the cetacean fossil record, we also see forms suggestive of a progressive loss of hind limb function and structure over time, as David Kerk and Darrel Falk have elegantly explained before. Again, if one were resistant to evolutionary explanations, it would be possible (if a bit strained) to interpret these creatures as having been created directly as we find them in the fossil record. The facts that we do not see these forms in the present day, and that they seem to blur the distinctions between terrestrial tetrapods and whales might make one a bit uncomfortable, however.

Recent work on cetacean embryogenesis (how whales and their relatives develop from fertilized eggs into fully-formed baby whales) has shed even more light on the issue for modern species, however. Dolphin embryos actually have four limbs early in their development, as well as a few facial hairs, just as any good mammal should have. The hind limbs and hairs are lost later in development, and work on the molecular signaling events that halt hind limb growth and cause the limb bud to regress into the body wall have now been worked out in some detail. Moreover, early in dolphin development the nostrils are distinct and on the front of the face, and only fuse into a blowhole and migrate to the top of the head later in development. Early dolphin embryogenesis is distinctly mammalian and uncannily tetrapod-like.

… and passing the test

Taken in isolation, these facts about whales are interesting trivia. Taken together, however, they begin to form a picture entirely consistent with the prediction that modern whales are derived from terrestrial ancestors. The true strength of evolution as a scientific theory for the origin of whales is this: not that we can prove it, (for no theory is ever proven in science due to its permanently provisional nature), nor that we have full access to every bit of data we would like (consider how fragmentary the fossil record is, for example), but rather that we haven’t been able to disprove it yet, despite our best efforts. Descent with modification remains a productive educated guess that grows stronger with each investigation.

In the next post in this series, we’ll explore some additional lines of evidence for cetacean evolution that further illustrate the predictive power of evolutionary theory.

For further reading

Evidences for Evolution, Part 2a: The Whale's Tale

Evidences for Evolution, Part 2b: The Whale's Tale
J. G. M. Thewissen, M. J. Cohn, L. S. Stevens, S. Bajpai, J. Heyning, and W. E. Horton, Jr. (2006). Developmental basis for hind-limb loss in dolphins and origin of the cetacean bodyplan. Proceedings of the National Academy of Sciences 103 (22), 8414–8418. available freely online.

In our last two BioLogos podcasts, we looked at the question of transitional fossils and the genetic evidence for evolution. In our final installment of this three part series, we move on to the question of speciation and macroevolution. A common challenge to evolutionary theory is that while life does indeed change over time (what is known as microevolution), no one has ever seen one species evolve into another species (macroevolution). For example, no one has seen a dog evolve into something other than a dog. Because speciation has never been observed, and because science is based on observation, evolution cannot be considered scientific.

In fact, examples of speciation have been observed by scientists. We must also remember that we are able to observe just a tiny window of the long history of life on Earth, and the fact that any speciation has been noted at all is impressive indeed.

Transcript

It’s pretty clear to most of us that life can change over time. For those who aren’t convinced, just take a quick trip to your local animal shelter. Each of the dog breeds there, from the Great Dane to the Chihuahua, descended from a single ancestral population. As you probably already know, that ancestral group was a wolf-like species. -How did these drastic changes take place? Well, basically, genetic variation within that original population was acted upon by selective forces. Now, just to be clear, the selection at work here wasn’t natural. It was the result of breeding done over hundreds of years. But the basic principle is the same. Genetic variation plus some sort of selection results in genetic change. This is evolution.

For the most part we are ok with accepting this. Yet many people still have a problem with the Theory of Evolution. Those suspicious of evolutionary Theory generally split evolution into two categories. Instead of arguing that evolution is completely impossible, they will say something like, “I know microevolution is real, but I just can’t accept macroevolution.”

Kent Hovind, an especially outspoken opponent of evolutionary theory, often makes this argument in his presentations:

“Maybe you’re talking about macroevolution. That’s where an animal changes into a different kind of animal. Nobody’s ever seen that. Nobody’s seen a dog produce a non-dog. I mean you may get a big dog or a little dog, I understand, but you’re going to get a dog, okay?” (source)

But what does this mean? What is the difference between micro and macroevolution anyway, and why is one of them ok while the other is condemned?

Well, like many terms used in the evolution debate, the definitions tend to differ depending on who you talk to. This can make rational discussion difficult. Most opponents of evolution, like Kent Hovind, say that macroevolution refers to one “type” or “kind” of organism evolving into another “kind”. Microevolution, they might say, is evolution within a “kind”. Evolution of one dog breed into another, they would say, is microevolution. Evolution of a “dog into a non-dog”, as Hovind puts it, would be “macroevolution.”’

One big problem with this argument is that “kind” is not clearly defined. It is a subjective term referring to organisms that seem similar to each other. Now, this is a definition that can easily be manipulated. And it doesn’t work very well when asking scientific questions. Because there is disagreement about what they actually mean, the terms micro and macroevolution aren’t often used in scientific literature. But when biologists do refer to “macroevolution”, most define it as “evolution above the species level”.

(Sources: http://ib.berkeley.edu/courses/ib200a/lect/ib200a_lect26_Lindberg_macroevolution.pdf, http://www.nescent.org/media/NABT/, http://evolution.berkeley.edu/evosite/evo101/VIADefinition.shtml, http://www.nhm.ac.uk/hosted_sites/paleonet/paleo21/mevolution.html)

In other words, at the smallest scale, macroevolution is the development of a new species. This definition is more useful because you can objectively determine whether two organisms are members the same species, but “kind” has no specific definition.

So what does “species” mean anyway? How is it different from “kind?” Well, the term species can be hard to define. Life is complex, and categorizing it into clear groups can be tricky. The currently accepted definition of species comes from what we call the “biological species concept.” Basically, the biological species concept says that a species is made of populations that actually or potentially interbreed in nature.

So, two populations that cannot mate to produce successful offspring are by definition separate species. Now, this definition doesn’t always work. For example, when you have a species that reproduces asexually, finding the boundaries between species can be a little tricky. But in most cases it does a pretty good job. It’s a good way to objectively determine where one species stops and another one begins.

The Biological Species Concept is especially useful when you have two species that look and act very similar. Eastern and Western Meadowlarks are a good example of this. They look almost exactly the same. But they cannot interbreed successfully. Therefore, they are separate species. This definition also helps when we study evolution. Where can we draw the line between microevolution and macroevolution? Well, it’s never easy, but having a working definition of this thing called a species helps out a lot. When enough genetic changes accumulate in a population, eventually it loses the ability to mate with others of its species. Then, by definition, it becomes a new species. In other words, macroevolution has occurred.

As we just discussed, many critics claim that macroevolution can never happen—one species can never cross over to become another one. This statement might sound valid, but a little bit of investigation shows that it is not well supported by evidence. For one thing, the only difference between micro and macroevolution is scope. When enough micro changes accumulate, a population will eventually lose its ability to interbreed with other members of its species. At this point, we say that macroevolution has occurred.

The same processes—random mutation and natural selection—cause both micro and macro evolution. There are no invisible boundaries that prevent organisms from evolving into new species. It just takes time. Usually, the amount time required for macroevolution to occur is significant—on the order of thousands or millions of years. That’s why you don’t normally see brand new forms of life appear every time you step out your front door. And that’s also why some people think that speciation never happens at all.

But sometimes macroevolution doesn’t take that much time. In fact, the evolution of new species sometimes happens so quickly that we can actually see it take place! Let’s look at a few recent examples.

Biologists Peter and Rosemary Grant had been studying finches since 1973. They lived on an island called Daphne Major in the Galapagos. It was here that they conducted their studies. When they first began their studies, only two species of Finch lived on Daphne Major: the medium ground finch and the cactus finch. But, in 1981, Peter and Rosemary noticed that an odd new finch had immigrated to the island. It was a hybrid, a mix between a cactus finch and a medium ground finch. It didn’t quite fit in with the other birds. The odd misfit had an extra large beak, an unusual hybrid genome, and a new kind of song. But somehow he was still able to find a mate. The female was also a bit of a misfit and had some hybrid chromosomes of her own. So their offspring were very different from the other birds on the island.

Rosemary and Peter continued to carefully watch the odd hybrid line. They wondered if the birds would become isolated from the other finch species on the island or if they would eventually re-assimilate. After four finch generations, a drought killed off many of the birds on Daphne Major. In fact, almost the entire hybrid line was exterminated. Only a brother and sister pair remained. The two family members mated with each other, producing offspring that were even more unique than their parent line. From that point on, as far as biologists Peter and Rosemary could tell, the odd population of finches mated only with each other. They were never seen to breed with the cactus finches or the medium ground finches on the island. The finches with the strange song had become a brand new species.

(Source: http://www.pnas.org/content/106/48/20141.full)

Another example of speciation, or macroevolution, also took place on an island—this time, on the beautiful Portuguese island of Madeira. According to history books, the Island of Madeira was colonized by the Portuguese about 600 years ago. The colonizers brought with them a few unassuming European House Mice, which they accidentally left on the island. It’s also possible that a group of Portuguese House Mice was dropped off later on.

Recently, Britton-Davidian, an evolutionary biologist at University Montpellier 2 in France, decided to collect samples of the Madeira mice and see how those original populations had changed over time. What she found was surprising. Rather than just one or two species of mouse, she found several. In only a few hundred years, the original populations of Mice had separated into six genetically unique species. The first mouse populations had 40 chromosomes altogether. But the new ones were quite different. Each new variety had its own unique combination of chromosomes, which ranged in number from 22 to 30.

What seems to have happened is that, over time, the mice spread out across the island and split into separate groups. Madeira is a rugged volcanic island with crags and cliffs. So it makes sense that this would have been easy to do. There were many isolated corners for the mice to occupy. Over time, random mutations occurred—some chromosomes became fused together.

Now, In order to reproduce successfully, both parents must have the same number of chromosomes. So when a population develops a chromosome fusion, suddenly that group cannot mate with the other members of its species. It becomes a brand new species. That’s exactly what happened on Madeira. And because of this phenomenon, 6 new species evolved from just 1 or 2 in an extremely short amount of time.

(Sources: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2009.04345.x/full, http://www.genomenewsnetwork.org/articles/04_00/island_mice.shtml, http://www.nature.com/hdy/journal/v99/n4/full/6801021a.html)

Another fascinating example of macroevolution was recently observed by researchers at Pennsylvania State University. This time, two species combined to make a single new one. In 1997, researchers at Penn State noticed a fruit maggot infestation on some recently introduced Asian Honeysuckle bushes. They decided to investigate the Honeysuckle fly population and determine how it was related to the other flies nearby. When they examined the honeysuckle fly’s genes, the researchers discovered something interesting. The fly appeared to be a hybrid of two native species—the blueberry fly and the snowberry fly.

But the honeysuckle fly’s genetic material was not an exact balance between that of the two parent species. The ratios of DNA varied from fly to fly. This showed the researchers that the honeysuckle flies had been breeding amongst themselves for many generations—probably at least 100. Also, they found that the Honeysuckle Flies were very unlikely to breed with any other species. They bred only on their host Honeysuckle plants. So they weren’t likely to mix with flies that lived on a different host.

According to Dr. Dietmar Schwarz, post-doctoral researcher in entomology, as far as the researchers can tell, “The new species is already reproductively isolated. They seem to be in a niche on the brushy honeysuckle where the parent species cannot compete."

(Source: http://www.psiee.psu.edu/news/2005_news/july_2005/hybrid_insects.asp)

While this kind of speciation—two species hybridizing to create a new one—seems odd, it is a significant mechanism of macroevolution. And it’s especially common in plants. In fact, a new species of weed recently arose this way in Great Britain. In 1991, Richard Abbot, a plant evolutionary biologist from St. Andrews University, noticed an unusual weed growing next to a car park in York. He discovered that the species, an unassuming scruffy weed, was a natural hybrid between the common groundsel and the Oxford ragwort, a plant that was introduced to Britain only 300 years ago. The York Groundsel lives in a different niche, or microenvironment, than either of its parent species. It is able to breed and reproduce, but only with other York Groundsel plants. It cannot successfully reproduce with any other species, including either of its parent plants. Thus, by definition, the York Groundsel is its own new species.

(Sources: http://www.nerc.ac.uk/publications/planetearth/2003/summer/sum03-evolution.pdf, http://www.nature.com/hdy/journal/v69/n5/abs/hdy1992147a.html)

So, as we have seen, macroevolution is an established process. Usually it takes thousands of years to occur, but sometimes we get lucky and catch it in the act. When Kent Hovind said that, “no one has ever seen a dog produce a non-dog” he was technically quite correct. But this statement infers that macroevolution means a drastic and obvious change from one type of organism into another. Those who think this way believe that macroevolution is something like two dogs breeding to suddenly produce a cat, or two guinea pigs mating to produce a mouse.

But this is not how evolution works at all. Over millions of years, a dog-like animal may indeed evolve into a something that looks completely unlike a dog. However, this is not something that we would expect to be able to observe. It just takes too much time. To put the scale of evolution into perspective, consider this. If the average lifespan of a United Stated citizen, 78 years, were a single minute, then single-celled life has been around for nearly 100 years. On this scale, all we get to see is one minute. And even in that time frame we sometimes see new species forming. God’s time is not our time and we tend to forget this. What we do expect to observe is a very slow step-by-step accumulation of tiny genetic changes that eventually result in speciation. And indeed, as we discussed today, this is exactly the sort of evidence revealed in nature.

So, macroevolution is not a “myth” by any means. It is supported by a vast amount of evidence. That evidence includes the fossil record and genetics, as discussed in previous BioLogos podcasts, and, when we get lucky, direct observation of speciation. God, being who God is, could conceivably have created species out of thin air in a single instant. But what if instead if God created and sustained the process by which new species are created? Does that make him less powerful or less "god-like"? Is it somehow more God’s process if it happened in an instant, than it is if it happened over a long period of time? Presumably even if it happened in an instant, it would still happen by some sort of process—only faster.

God’s time is not our time, and perhaps it’s a good idea for all of us to simply stand back in amazement while God does God’s work in God’s time through God’s process.

The beauty of the scientific process is its inherent scepticism. (See "What Scientists Do" by Steven Benner). If there is only one way of reaching a conclusion, the scientific process requires the scientist to remain highly sceptical. The only conclusions in science which are widely accepted are those which are supported by multiple, reinforcing lines of evidence – “all roads must lead to Rome”. If there is even one scientific trajectory that seems to clearly lead off to Peoria instead of Rome (to use a recent analogy of Francisco Ayala), the scientific process demands that the scientist find out why. The scientist who does not retain an attitude of scepticism when there is only a single line of evidence, and particularly one who ignores other, conflicting lines of evidence, is on a stubborn trajectory of his own—a trajectory to failure. If the only reason for following the directions which “lead away from Rome” is a particular view of Scripture, then it is important to consider the possibility of human error. Biblical hermeneutics, after all, is a human enterprise just as science itself is. For example, John MacArthur in his current series on Genesis is human and is interpreting Genesis in his way just like the rest of us. He, wonderful pastor and shepherd that he is, interprets Scripture too. There is good reason to be quite certain that the interpretation he subscribes to is mistaken.

As Christians, we are called to follow Jesus. In so doing, Jesus said we are to love the Lord our God with all our heart, soul and mind—not just our heart and soul. Indeed if we close our mind, we are actually disobeying what Jesus said was the greatest commandment of all. So let’s not be shy about using those minds. Are there multiple independent ways of keeping track of time since the creation of the earth? If so, do each of those ways point to the same conclusion?

The best known method of calculating the age of material on earth depends on the well-established fact that certain elements in the earth’s crust are unstable and decay at a fixed rate that can be measured. (For an introduction to this topic see this BioLogos FAQ.) This instability functions sort of like a set of clocks that have been ticking through the eons of time. Indeed there are many types of unstable elements; there are many ticking clocks. Each of the various clocks tick at a different rate. The rate of each can be calibrated, and, with an amazing degree of consistency, all “clocks” point back to the same starting point: an ancient earth with rocks that are hundreds of millions and even billions of years old. This “ticking clock” technique is known as radiometric dating.^1,2

There are other totally independent ways of estimating the age of material on earth. To appreciate how these work, perhaps we should start with shorter spans of time, which for human beings are much more readily comprehensible. Some of the fondest boyhood memories of one of us (DK) come from visits to the majestic California redwood forests. He especially remembers an exhibit of a section from a giant tree which showed the pattern of growth rings within it. It turns out that these rings accumulate in response to seasonal differences in rainfall and temperature, which in turn produces differences in growth rate. Fastened within this huge slab of wood was a series of tags, proceeding from the surface inward, demonstrating the dates of major historical events: the landing of the Pilgrims on Plymouth Rock; Columbus’ discovery of the New World; the Norman conquest of England, and so forth. It was possible to see in the yearly growth rings a history of what seemed then to be the very distant past!³

Growth layering processes are not restricted to trees. Many species of marine invertebrates accumulate calcium carbonate from their watery environment and incorporate it into some form of shell. Examples would be clams and corals. In fact, for these species, the variation in shell deposition occurs on a both a daily and a yearly basis, so an even finer counting of time periods is possible.⁴

Just as it is possible to count the rings in trees and correlate their age to known historical events in the past, it is also possible to count the banding patterns preserved in the fossils of marine organisms, and use this as a method to estimate their ages. Let’s see how it works.

Astronomical data, developed and analyzed over the past couple of centuries, has revealed that the rotation of the earth is gradually slowing down. This is due to the friction created daily by the moving tides on the earth’s surface, produced by the gravitational pull of the moon and sun. Furthermore, as the earth slows down slightly, some rotational energy is transferred to the moon, which alters its orbit slightly (its orbit is moving slowly away from the earth). The data leading to these conclusions range from analysis of ancient solar eclipses (whose dating allows the precise position of the earth, sun and moon to be determined) to bouncing laser beams off mirrors placed on the surface of the moon by the Apollo astronauts. For our purposes, what will be important is the slowing of the earth’s rotation. This predicts that the length of each day has been slowly increasing since the formation of the earth/moon system. The average increase in the day length is estimated at 2.3 milliseconds (.0023 seconds) per century.^5,6 Hence as we examine events in the past, day length was shorter, by an amount that can be calculated. Ten thousand years ago, a day would have been .23 seconds shorter than it is today. If direct experimental estimates of day length can be obtained, they allow an estimate of the age of the material.

One way that such experimental estimates of day length can be obtained is through the periodic growth rings deposited in the shells of marine invertebrate organisms. Take for example a clam living in an intertidal environment. If the tide is in and the shell is open, it can readily absorb oxygen from water, use aerobic metabolism, and incorporate calcium carbonate into its shells. When the tide is out and the shells are closed, however, little oxygen can be absorbed, anaerobic metabolism is used, shell decalcification occurs, and organic rich material accumulates in the shell. This alternating pattern of shell deposition occurs on a daily basis, and is clearly visible in both shells from living and fossil clam species by microscopic examination. Furthermore, shells contain an identifiable mark resulting from the first freezing day of winter, and from the first really hot day of summer. Hence a yearly growth interval can be readily determined.⁷

When such data are analyzed for a number of fossil species, it is clear that the number of days these organisms experienced each year was higher than today. Given that, we have another clock - a totally independent way of measuring the age of certain fossils. So how well do clocks based upon radiometric dating agree with those based on measuring rings in certain sea shells?

As already mentioned, organisms living 10,000 years ago would have experienced shorter days, but they would only have been shorter by 0.2 seconds. Organisms living 1 million years ago would have experienced a day length that was 20 seconds shorter. If the earth really is very, very old, organisms living 465 million years ago, for example, would have experienced approximately 416 days per year, each day being about 21 hours long.⁷ Amazingly, shelled fossils in formations dated by radiometric clocks to be about 465 million years old show, by their banding patterns, that the days really were three hours shorter. In fact the two sets of clocks agree within 1 percent!

Another way such estimates of ancient day length can be derived is to look at the periodic patterns formed in fine silts in ancient river estuaries. The daily tides produce shifts in the mud, leaving a fine layering pattern, which is recorded in rock as these sediments transform into materials such as sandstone (such deposits are called “rhythmites”). Other shifts in the mud are produced over longer time intervals, including seasonal and yearly shifts. By counting the number of daily depositional layers per year, in a similar fashion to work with marine organism shells cited above, an estimate of ancient day length can be derived. One advantage of the rhythmite analysis method is that it can be applied to more ancient materials, in eras of the earth’s history when organisms suitable for shell analysis were scarce or non-existent. For example, radiometric analysis of certain rock formations in South Australia dated them at 620 million years of age. On this basis one would predict that the day/night cycles should have been about 20 hours long in these formations. Actual measurements of day length from the preserved mud banding patterns, although off from the expected by ten percent (estimated day length is 22 hours) is again consistent with the formation being hundreds of millions of years old just as the radiometric dating has predicted.⁸

In conclusion, there is data derived from three independent sources: the decay of radioisotopes, the growth patterns recorded in fossilized shells of marine organisms, and rocks containing tidal depositional material from river estuaries, which all agree on an ancient age for the earth. Furthermore, by a totally independent method it is also possible to measure the age of the universe as a whole and again it is billions, not thousands of years.

All of the roads in God’s book of Nature “lead to Rome” (i.e an ancient earth) - it is only mistaken human interpretation of Scripture that causes some of our precious brothers and sisters in Christ to end up in Peoria.

The next blog in this series can be found here.

Editor's Note: Dr. Kerk offers a further discussion of the age of the earth in the comment section of this post, beginning here. Dr. Kerk has also included the following graph:

References

1: Elementary principles of radiometric dating are discussed by Richard Dawkins. Dawkins, R. 2009. The Greatest Show on Earth: The Evidence for Evolution. Free Press, New York Pgs. 91-98.

2: Wiens, R.C. 2002. Radiometric Dating: A Christian Perspective. This is a more detailed but still highly readable account of radiometric dating, written by a well-qualified physicist who is also a professing Christian. It can be obtained from the web site of the American Scientific Affiliation: http://www.asa3.org/ASA/resources/Wiens.html

3: Tree ring dating (“dendrochronology”) is discussed by Dawkins, pgs. 88-91.

4: Dating using coral skeletal deposition is discussed by Jerry Coyne: Coyne, J.A. 2009. Why Evolution is True. Viking Penguin, New York. Pgs. 24-25.

5: “Tidal Acceleration”, Wikipedia: http://en.wikipedia.org/wiki/Tidal_acceleration

6: Stephenson, F.R. 2003. Historical Eclipses and Earth’s Rotation. Astronomy and Geophysics 44:2.22-2.27.

7: Zhenyu, Z., Yaoqi Z., Guosheng J. 2007. The periodic growth increments of biological shells and the orbital parameters of Earth-Moon system. Environmental Geology 51: 1271–1277.

8: Williams, G.E. 2000. Geological constraints on the Precambrian history of Earth's rotation and the Moon's orbit. Reviews of Geophysics 38(1):37-59.

Misconceptions about Evolution and the Nature of Science

“Evolution is not science because it is not observable or testable.”

This misconception encompasses two incorrect ideas: (1) that all science depends on controlled laboratory experiments, and (2) that evolution cannot be studied with such experiments. First, many scientific investigations do not involve experiments or direct observation. Astronomers cannot hold stars in their hands and geologists cannot go back in time, but both scientists can learn a great deal about the universe through observation and comparison. In the same way, evolutionary biologists can test their ideas about the history of life on Earth by making observations in the real world. Second, though we can't run an experiment that will tell us how the dinosaur lineage radiated, we can study many aspects of evolution with controlled experiments in a laboratory setting. In organisms with short generation times (e.g., bacteria or fruit flies), we can actually observe evolution in action over the course of an experiment. And in some cases, biologists have observed evolution occurring in the wild.

"Evolution is 'just' a theory."

This misconception stems from a mix-up between casual and scientific use of the word theory. In everyday language, theory is often used to mean a hunch with little evidential support. Scientific theories, on the other hand, are broad explanations for a wide range of phenomena. In order to be accepted by the scientific community, a theory must be strongly supported by many different lines of evidence. Evolution is a well-supported and broadly accepted scientific theory; it is not ‘just' a hunch.

For more, see the question "What is evolution?"

"Evolutionary theory is invalid because it is incomplete and cannot give a total explanation for the biodiversity we see around us."

This misconception stems from a misunderstanding of the nature of scientific theories. All scientific theories (from evolutionary theory to atomic theory) are works in progress. As new evidence is discovered and new ideas are developed, our understanding of how the world works changes and so too do scientific theories. While we don't know everything there is to know about evolution (or any other scientific discipline, for that matter), we do know a great deal about the history of life, the pattern of lineage-splitting through time, and the mechanisms that have caused these changes. And more will be learned in the future. Evolutionary theory, like any scientific theory, does not yet explain everything we observe in the natural world. However, evolutionary theory does help us understand a wide range of observations (from the rise of antibiotic-resistant bacteria to the physical match between pollinators and their preferred flowers), does make accurate predictions in new situations (e.g., that treating AIDS patients with a cocktail of medications should slow the evolution of the virus), and has proven itself time and time again in thousands of experiments and observational studies.

For more, see the questions "How can evolution account for the complexity of life on earth today?" and "How can evolution account for the complexity of life on earth today?"

"Gaps in the fossil record disprove evolution."

While it's true that there are gaps in the fossil record, this does not constitute evidence against evolutionary theory. Scientists evaluate hypotheses and theories by figuring out what we would expect to observe if a particular idea were true and then seeing if those expectations are borne out. If evolutionary theory were true, then we'd expect there to have been transitional forms connecting ancient species with their ancestors and descendents. This expectation has been borne out. Paleontologists have found many fossils with transitional features, and new fossils are discovered all the time. However, if evolutionary theory were true, we would not expect all of these forms to be preserved in the fossil record. Many organisms don't have any body parts that fossilize well, the environmental conditions for forming good fossils are rare, and of course, we've only discovered a small percentage of the fossils that might be preserved somewhere on Earth. So scientists expect that for many evolutionary transitions, there will be gaps in the fossil record.

For more see out question "What does the fossil record show?"

Misconceptions about the Acceptance and Implications of Evolution

“Evolution is a theory in crisis and is collapsing as scientists lose confidence in it.”

Evolutionary theory is not in crisis; scientists accept evolution as the best explanation for life's diversity because of the multiple lines of evidence supporting it, its broad power to explain biological phenomena, and its ability to make accurate predictions in a wide variety of situations. The vast majority of scientists do not debate whether evolution took place, but they do debate many details of how evolution occurred and occurs in different circumstances. Antievolutionists may hear the debates about how evolution occurs and misinterpret them as debates about whether evolution occurs. Evolution is sound science and is treated accordingly by scientists and scholars worldwide.

For more see the questions "Does thermodynamics disprove evolution?", "How can evolution account for the complexity of life on earth today?" and "How can evolution account for the complexity of life on earth today?"

"Evolution supports the idea that 'might makes right' and rationalizes the oppression of some people by others."

In the nineteenth and early twentieth centuries, a philosophy called Social Darwinism arose from a misguided effort to apply lessons from biological evolution to society. Social Darwinism suggests that society should allow the weak and less fit to fail and die and that this is good policy and morally right. Supposedly, evolution by natural selection provided support for these ideas. Pre-existing prejudices were rationalized by the notion that colonized nations, poor people, or disadvantaged minorities must have deserved their situations because they were "less fit" than those who were better off. In this case, science was misapplied to promote a social and political agenda. While Social Darwinism as a political and social orientation has been broadly rejected, the scientific idea of biological evolution has stood the test of time.

"Evolution and religion are incompatible."

Because of some individuals and groups stridently declaring their beliefs, it's easy to get the impression that science (which includes evolution) and religion are at war; however, the idea that one always has to choose between science and religion is incorrect. People of many different faiths and levels of scientific expertise see no contradiction at all between science and religion.

In fact, science and religion can have a constructive relationship. The majority of scientists during the emergence of modern science in medieval Europe, for example, were devout or conventionally religious. Religious belief, then, can function as a framework within which scientific progress flourishes. Religious belief can also be influenced by science. In the Galileo Affair, scientific evidence of a heliocentric universe caused the church to revisit its interpretation of a part of Scripture.

Oddly enough, some people argue that God’s existence is actually a scientific claim and should be tested like any other. However, God’s existence is not something that can be tested by the scientific method in the same way the existence of postulated new elementary particles are tested in supercolliders. Because science provides knowledge about the natural world, no amount of testing or theorizing could prove or disprove the existence of a supernatural creator. Rather than an empirical claim about nature or its laws, the claim that God exists is a metaphysical one, a statement about what there is, whether it be natural or supernatural.

For more see the questions "What is the proper relationship between science and religion?", "Can scientific and scriptural truth be reconciled?", "What were the initial Christian responses to Darwin?", and "What role could God have in evolution?"

Misconceptions about Evolutionary Theory and Process

"Evolution is a theory about the origin of life."

Evolutionary theory does encompass ideas and evidence regarding life's origins (e.g., whether or not it happened near a deep-sea vent, which organic molecules came first, etc.), but this is not the central focus of evolutionary theory. Most of evolutionary biology deals with how life changed after its origin. Regardless of how life started, afterwards it branched and diversified, and most studies of evolution are focused on those processes.

For more, see our questions on "What is Evolution?" and "Isn't the Origin of Life Highly Improbable?".

"Evolution is like a climb up a ladder of progress; organisms are always getting better."

One important mechanism of evolution, natural selection, does result in the evolution of improved abilities to survive and reproduce; however, this does not mean that evolution is progressive — for several reasons. First, natural selection does not produce organisms perfectly suited to their environments. It often allows the survival of individuals with a range of traits — individuals that are "good enough" to survive. Hence, evolutionary change is not always necessary for species to persist. Many taxa (like some mosses, fungi, sharks, opossums, and crayfish) have changed little physically over great expanses of time. Second, there are other mechanisms of evolution that don't cause adaptive change. Mutation, migration and genetic drift may cause populations to evolve in ways that are actually harmful overall or make them less suitable for their environments. For example, the Afrikaner population of South Africa has an unusually high frequency of the gene responsible for Huntington's disease because the gene version drifted to high frequency as the population grew from a small starting population. Finally, the whole idea of "progress" doesn't make sense when it comes to evolution. Climates change, rivers shift course, new competitors invade — and an organism with traits that are beneficial in one situation may be poorly equipped for survival when the environment changes. And even if we focus on a single environment and habitat, the idea of how to measure "progress" is skewed by the perspective of the observer. From a plant's perspective, the best measure of progress might be photosynthetic ability; from a spider's it might be the efficiency of a venom delivery system; from a human's, cognitive ability. It is tempting to see evolution as a grand progressive ladder with Homo sapiens emerging at the top. But evolution produces a tree, not a ladder — and we are just one of many twigs on the tree.

For more, see our questions "What is Evolution?" and "Did Evolution Have to Result in Human Beings?".

"Evolution means that life changed 'by chance.'"

Chance and randomness do factor into evolution and the history of life in many different ways; however, some important mechanisms of evolution are non-random and these make the overall process non-random. For example, consider the process of natural selection, which results in adaptations — features of organisms that appear to suit the environment in which the organisms live (e.g., the fit between a flower and its pollinator, the coordinated response of the immune system to pathogens, and the ability of bats to echolocate). Such amazing adaptations clearly did not come about "by chance." They evolved via a combination of random and non-random processes. The process of mutation, which generates genetic variation, is random, but selection is non-random. Selection favored variants that were better able to survive and reproduce (e.g., to be pollinated, to fend off pathogens, or to navigate in the dark). Over many generations of random mutation and non-random selection, complex adaptations evolved. To say that evolution happens "by chance" ignores half of the picture.

For more see our questions on "What is Evolution?" and "How do randomness and chance align with belief in God’s sovereignty and purpose?".

“Humans are not currently evolving”

Humans are now able to modify our environments with technology. We have invented medical treatments, agricultural practices, and economic structures that significantly alter the challenges to reproduction and survival faced by modern humans. So, for example, because we can now treat diabetes with insulin, the gene versions that contribute to juvenile diabetes are no longer strongly selected against in developed countries. Some have argued that such technological advances mean that we've opted out of the evolutionary game and set ourselves beyond the reach of natural selection — essentially, that we've stopped evolving. However, this is not the case. Humans still face challenges to survival and reproduction, just not the same ones that we did 20,000 years ago. The direction, but not the fact of our evolution has changed. For example, modern humans living in densely populated areas face greater risks of epidemic diseases than did our hunter-gatherer ancestors (who did not come into close contact with so many people on a daily basis) — and this situation favors the spread of gene versions that protect against these diseases.

For more see our question "Did evolution have to result in human beings?".

"Species are distinct natural entities, with a clear definition, that can be easily recognized by anyone."

Many of us are familiar with the biological species concept, which defines a species as a group of individuals that actually or potentially interbreed in nature. That definition of a species might seem cut and dried — and for many organisms (e.g., mammals), it works well — but in many other cases, this definition is difficult to apply. For example, many bacteria reproduce mainly asexually. How can the biological species concept be applied to them? Many plants and some animals form hybrids in nature, even if they largely mate within their own groups. Should groups that occasionally hybridize in selected areas be considered the same species or separate species? The concept of a species is a fuzzy one because humans invented the concept to help get a grasp on the diversity of the natural world. It is difficult to apply because the term species reflects our attempts to give discrete names to different parts of the tree of life — which is not discrete at all, but a continuous web of life, connected from its roots to its leaves.

Misconceptions about Natural Selection and Adaptation

“Natural selection involves organisms trying to adapt”.

Natural selection leads to the adaptation of species over time, but the process does not involve effort, trying, or wanting. Natural selection naturally results from genetic variation in a population and the fact that some of those variants may be able to leave more offspring in the next generation than other variants. That genetic variation is generated by random mutation — a process that is unaffected by what organisms in the population want or what they are "trying" to do. Either an individual has genes that are good enough to survive and reproduce, or it does not; it can't get the right genes by "trying." For example bacteria do not evolve resistance to our antibiotics because they "try" so hard. Instead, resistance evolves because random mutation happens to generate some individuals that are better able to survive the antibiotic, and these individuals can reproduce more than other, leaving behind more resistant bacteria.

“The fittest organisms in a population are those that are strongest, healthiest, fastest, and/or largest.”

In evolutionary terms, fitness has a very different meaning than the everyday meaning of the word. An organism's evolutionary fitness does not indicate its health, but rather its ability to get its genes into the next generation. The more fertile offspring an organism leaves in the next generation, the fitter it is. This doesn't always correlate with strength, speed, or size. For example, a puny male bird with bright tail feathers might leave behind more offspring than a stronger, duller male, and a spindly plant with big seed pods may leave behind more offspring than a larger specimen — meaning that the puny bird and the spindly plant have higher evolutionary fitness than their stronger, larger counterparts.

“Natural selection produces organisms perfectly suited to their environments.”

Natural selection is not all-powerful. There are many reasons that natural selection cannot produce "perfectly-engineered" traits. For example, living things are made up of traits resulting from a complicated set of trade-offs — changing one feature for the better may mean changing another for the worse (e.g., a bird with the "perfect" tail plumage to attract mates maybe be particularly vulnerable to predators because of its long tail). And of course, because organisms have arisen through complex evolutionary histories (not a design process), their future evolution is often constrained by traits they have already evolved. For example, even if it were advantageous for an insect to grow in some way other than molting, this switch simply could not happen because molting is embedded in the genetic makeup of insects at many levels.