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. 

Despite this usage, most of us know that randomness has something to do with probability, and that it often implies a lack of conscious intentionality. But what do mathematicians and scientists mean when they say something is random? Can a random process lead to an ordered, even predictable outcome? Is there evidence that God makes use of random processes to fulfill his creative purposes?

These are big questions, and we won’t address them all today. But I think randomness is an important topic to cover for two reasons: 1) it is integral to many processes in biology (and math, physics, chemistry, etc.), and 2) it is commonly misunderstood to be incompatible with Christianity.

As I said above, most of us know that randomness has something to do with probability. If you pick a card “at random” from a shuffled deck, you have a small probability of drawing an ace (4 out of 52, or a 7.7% chance). If you flip a coin, you have an equal probability of getting heads or tails.

Randomness also seems to imply a lack of intentionality or purposefulness. After all, you might hope for an ace when you draw a card, but you can’t choose one on purpose. You might call heads when you flip a coin, but you can’t know beforehand what the outcome will be. Thus the outcome is indeterminate, but is it purposeless? Not necessarily. Indeterminacy simply means the result cannot be predicted from the outset.

It should be noted that indeterminacy does not imply that God does not have foreknowledge of future events. Christians ought not to be uncomfortable with the idea of God interacting with his creation through chance. We often describe a seemingly-random (i.e. unplanned by us) sequence of events as being “providential,” or planned by God.

In biology, it is very hard or impossible to calculate precise probabilities for most processes, so when we say a process is random, we typically mean it is extremely unpredictable. Eventually we will discuss randomness within biological evolution, but first we must consider some simpler processes, like the self-assembly of a virus.

Viruses are remarkably efficient entities. Coiled tightly within a protein-based shell is a small amount of DNA needed for self-replication. The shell, called a capsid, is made of many repeating protein subunits and is therefore highly symmetrical (see figure). Important biomedical insights have certainly been gleaned from structural studies of viruses, but viruses also teach us about the emergence of order from non-order.

The virus life cycle has four main steps: 1) enter a host cell, 2) hijack the cell’s replication and translation machinery to make many copies of itself, 3) assemble into many virus particles, and 4) exit the cell to invade another host.

When I first learned about this process, I found it very hard to believe it just “happens.” The idea that a bunch of molecules bumping into each other inside a crowded cell could spontaneously assembly into a fully-functional virus seemed a bit far-fetched. Many viral capsids have over 100 protein subunits that must interact with each other in just the right way, or it won’t work. Surely there must be something driving this process, right?

There is! Random motion. I had to see it to believe it. I distinctly remember sitting in class during my first year of graduate school when the professor demonstrated self-assembly of a virus using a 3D model as shown in the following video. In less than 30 seconds, you can watch a jumbled heap of proteins become a beautifully ordered structure.

As the narrator explains, sub-assemblies form and break apart en route to the most stable structure, the full capsid. As the sub-assemblies begin to form, further associations with free subunits become more favorable and as a result occur rapidly, while the final steps may take considerably longer. While the subunits in the model are rigid, in reality the proteins take on multiple conformations, allowing the capsid to “breathe.”

Amazing as it is, the system we just considered—one virus capsid in a jar—is pretty simple. One wonders how self-assembly can happen in a crowded cell, where there are countless other molecules diffusing around, potentially getting in the way. We can’t directly see how it happens in a cell, but we can reconstitute the process in a test tube using different combinations of constituent molecules.

Consider two viruses, where each protein subunit in one virus is the mirror image of the corresponding subunit in the other. Putting the two viruses together by hand would be pretty tricky, because the constituent parts look so similar. But random motion can do the job in short order:

From this model, we can see clearly, in real-time, how distinct complex structures can arise from their parts randomly interacting with one another. Many large viruses also use special scaffolding proteins to assist in the assembly process, and some even use their own genomes as a scaffold. In addition, two closely-related viruses that happen to infect the same cell can exchange parts to create a new virus. This is one way viruses can evolve quickly to evade the host’s immune system.

Here we have seen how viruses demonstrate a principle inherent in God’s world—that order can emerge out of chaos from random processes. In my next post, we will look at some other biological processes that make use of—rather, depend on—randomness. This will set the stage for us to see that such processes can not only assemble a structure within seconds or minutes, but also generate complex, information-bearing molecules over billions of years. Even though the freedom inherent in nature sometimes produces unintelligently-designed structures (like viruses, which can kill us), we see that God has made, and continues to oversee by his providence, a good creation that, at least in part, is capable of creating itself.

Next weekend, we’ll continue this series about randomness and God’s divine will. Up next: how God created the body to heal itself, and how can random mutations can be both harmful and benign.

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.

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

Suppose a man falls among thieves, or wild beasts; is shipwrecked at sea by a sudden gale; is killed by a falling house or tree. Suppose another man wandering through the desert finds help in his straits; having been tossed by the waves, reaches harbor; miraculously escapes death by a finger’s breadth. Carnal reason ascribes all such happenings, whether prosperous or adverse, to fortune. But anyone who has been taught by Christ’s lips that all the hairs if his head are numbered [Matt. 10:30] will look further afield for a cause, and will consider that all events are governed by God’s secret plan.

In this passage, Calvin presents belief in “fortune” as evidence of carnal reasoning, and statements like this one have contributed to a widely-held notion that modern scientific understandings of the role that randomness plays in nature is inconsistent with belief in divine providence. In other words, if “randomness” equals blind and capricious “fortune,” then how can God be said to be working all things to his ends?

But Calvin could not have known of the very different understanding of randomness held by today’s scholars. Physical scientists, mathematicians, and statisticians have not yet agreed on a single unambiguous definition of the term “randomness,” but among these scientists, the term consistently refers to a family of related concepts focusing on unpredictability of the outcomes of single events and the absence of pattern in sequences of outcomes. I like this statement by John Polkinghorne, “Chance doesn't mean meaningless randomness, but historical contingency. This happens rather than that, and that's the way that novelty, new things, come about.” In Polkinghorne’s view, chance is an agent of creativity and can be perceived as being purposeful.

In fact, there are abundant examples of phenomena in nature in which randomness plays a role one could understand as being purposeful. For example, osmosis is a marvelous mechanism that enables all 10 trillion cells in our bodies to be nourished – it depends on the random motion of molecules. The human immune system is able to defend the body against attacks from millions of different microorganisms using a relatively small number of building blocks and random combinations of these to fashion defenses specific to each adversary. We never take a breath and find it to be all nitrogen or carbon dioxide – random motion of molecules keeps oxygen close to uniformly distributed throughout the atmosphere.

In 2007, a British statistician, David Bartholomew published God, Chance, and Purpose in which he argues that God “can have it both ways”—that he can use low level randomness to accomplish divine purposes while simultaneously maintaining order at a higher level. Of course, we cannot prove that God ordained these random processes to achieve divine purposes in the world. But to a person of faith, such an interpretation in both consistent with the observations we make in science and with the Scriptural notion of God’s providential care for the world.

Considerations like these led the John Templeton Foundation to provide a generous grant of $1.69 million to support a new research initiative on the theme of Randomness and Divine providence. Beginning this past summer, the program has the purpose of providing support for solid theoretical exploration of the kinds of ideas and possibilities expressed above—involving theology, philosophy, natural science, mathematics, and statistics. The grant will support individual scholars and teams of scholars who are willing to devote a significant amount of time between March of 2013 and June of 2015 to such work, and the project’s request for proposals suggests the following as questions researchers might pursue:

• How might God work providentially through indeterminate processes? Can recent advances in understanding the nature of randomness offered by algorithmic information theory, physics, biology, and other sciences provide insight into this question?
• Can we bring clarity to the concept of "randomness"? Philosophers and scientists have tried on occasion to give precise definitions of when a process is random, but more work needs to be done on the question. How do (or should) conceptions of randomness vary across academic disciplines?
• What are some possible implications of randomness for hiding or unfolding divine creativity and purpose in the world? Could God use randomness to (1) generate creativity, (2) hide divine actions, or (3) unfold information? Why might God do so?
• How might we identify and come to understand a significant collection of nondeterministic processes in which agents could intentionally employ randomness to bring about purposeful results?
• How might we mathematically and physically model random processes in ways that help us understand how divine providence could be exercised in a "chance-governed" world?
• How do "laws and orders" in nature interplay with "chance and randomness" in bringing about results that can be interpreted as aspects of divine providence?
• Might randomness be evidence of limitations in human knowledge but nothing more? Or might it be evidence of ontological indeterminism? Might this be tested?
• What implications does randomness have for aspects of God’s relationship with the physical world such as God’s relationship to time and God’s role in causation? How might randomness be reconciled with God’s foreknowledge?
• How might an understanding of providence based on an extended Molinism and/or open theology incorporate randomness? For example, could an extended Molinism provide a plausible account of the relationship between quantum mechanics and divine providence?
• What are some theodical implications of randomness, particularly for the issue of natural evil?
• How have the theological traditions of Augustine, Maimonides, Aquinas, Luther, and Calvin addressed chance and fortune? In what ways might they incorporate ontological randomness?
• How do or could religions other than the Judeo/Christian tradition understand and incorporate randomness?
• How is the concept of randomness understood by advocates of secularism, naturalism, and new atheism? What are the strengths and weaknesses of these usages?
• How might an understanding of randomness in the world alter our conceptions of divinity, especially our understanding of divine providence?

Despite the range of issues mentioned above, research is by no means restricted only to these topics. In fact, the structure of the program is designed to foster collaboration and build community between scholars, with the end of expanding the range and integration of their work: two conferences will be held to bring scholars together with each other and then with members of the public—one at Calvin College in 2013 and the other at Fuller Theological Seminary in 2015. To get more information and to learn how to submit a proposal, see the project website; then join us in exploring the truth that all creation glorifies God—even randomness!

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.

For more, be sure to read Randall Pruim's recent series Randomness and God’s Governance, Kathryn Applegate's post That's Random: A Look at Viral Self-Assembly, and our FAQ How Do Randomness and Chance Align with Belief in God's Sovereignty and Purpose?.

Author's Note

I am so thankful that I grew up in a Christian environment, which both kindled and nurtured my relationship with Jesus Christ. The Biblical instruction I received from my parents, pastors, and teachers has been invaluable as I walk out my love for the Lord from day to day. However, there was one specific topic growing up which was not fully addressed, namely evolutionary theory.

Coming from a conservative Christian background, evolution was given little or no thought because of its seeming contradiction to the creation story in Genesis. To me, evolution meant a monkey became a human, and as far as I knew, I had never seen that happen! So, of course, it appeared too improbable to hold any truth. When it was discussed, an inadequate picture of its ideas was often painted, which caused immediate suspicion and rejection of the theory. I don’t think this was intentional, but most Christians have never learned an unbiased, in-depth theory of evolution that is completely detached from societal agendas and philosophical conclusions. Therefore, their explanations of the theory are often misinformed.

My senior year of high school, I took AP Biology, and finally learned the scientific reasoning supporting this theory. I was surprised by how logical and obvious the mechanisms of change (such as mutations, natural selection, genetic drift, and so on) were that gave rise to new species. My subsequent response was, “No wonder people believe evolution occurred.” At that point, I was convinced that microevolution (evolution within a species) existed, but I was still questioning macroevolution.

Now, being at Point Loma Nazarene University as an undergrad in the Biology-Chemistry major and a year-round, student intern at BioLogos, my understanding of evolution has expanded enormously. I have enjoyed critically thinking through the evidence for evolution and reading articles that tackle difficult issues at the interface of science and Christian faith. Ultimately, I know that God has created all things, but the processes he used surpass my small understanding.

My personal wrestling with evolution and quest for truth has led to times of prayer and studying God’s Word, which has deepened my love for him in ways I cannot express. The first chapters of Genesis, in particular, have come alive. My whole life, the creation story was a straightforward list of facts about the creation of the world; I never searched further. I didn’t even perceive the truths Genesis declared over my very identity and God’s character. The more I study his Word and handiwork, I glimpse the awesomeness and majesty of the Creator, who loves me much more than I know. There is still so much to learn, but I am confident that he will lead me into all truth as I seek him out.

I desire to give others the opportunity to see evolution accurately and to distinguish it from the traditional, philosophical, and personal conclusions that too often cloud the scientific theory. I believe these conclusions alienate Christians from evolution more than the scientific theory itself. Ultimately, I do not mean to convince someone about evolution, but simply to give them the freedom to understand it.

Therefore, my goal for this podcast is two-fold:

• First, to offer a new perspective on randomness within natural processes that removes its negative connotations (especially as it relates to evolution).
• Second, to expose why evolution is powerless to support conclusions beyond the physical realm.

This will hopefully encourage others to study evolutionary theory and draw their own conclusions about its meaning in the framework of their faith.

Many of the games I enjoyed playing involve a combination of strategy and randomness: card games of various sorts, backgammon, and board games like Monopoly and Parcheesi. Some games that rely exclusively on chance (like War and Candy Land) or too heavily on chance (like Sorry) quickly became uninteresting to me. In fact, for Sorry, War, and several other games, I introduced additional rules to change the balance of strategy and luck—for example, by allowing each player to hold a hand of cards rather than merely flip a card and follow its bidding.

When my children were young, I played many games with them, especially those involving some amount of chance. I always play to win, so games of pure strategy like chess gave me too great an advantage—at least when they were still young. I still remember the first time I played the German game Mitternachtspartie with my children and some of their cousins. The game uses a die on which the number 5 has been replaced with the image of Hugo the ghost. Each player rolls the die and moves one of his figures the specified number of squares, unless Hugo is rolled, in which case Hugo moves instead.

I quickly worked out the expected distance Hugo would move for each of my turns and the expected number of squares I would get to move my own figures each turn. Using that information, I could strategically place my figures in the opening portion of the game. I fully expected to win this first game, since my young children were going to have to learn from experience what I already knew by the mathematics of probability. I lost—badly. As it turned out, the die had two Hugos on it. So compared to my expectations, Hugo moved twice as often, and my figures moved slightly less far. That combination turned the carefully calculated positioning of my figures into a disaster.

From Fun and Games to Science

I still enjoy playing games, including games that involve chance. But these days I encounter randomness even more often in my profession. I was trained as a mathematician and now work at the intersection of mathematics, statistics, and computer science. Like many scientists, I use randomness on a daily basis as part of our toolkit for modeling and investigating all sorts of phenomena. Models known as stochastic models, which explicitly incorporate random components, often via simulation in computer software, are used to model everything from diffusion to genetics to quantum mechanics. Insurance companies and financial institutions use stochastic models to manage risk. If we include all the applications of statistics, then almost no area of science is untouched by the use of randomness.

Most of the time, scientists and game players alike don’t devote much thought to just what makes randomness tick. But they both know that the better they understand the probabilities, the more successful they are. Nevertheless, if you ask many of them what it means for something to be random, they may struggle to put it into words. I won’t try to give a precise definition either, but it is important that we have some idea what we are talking about, so let’s consider one of the prototypical examples of randomness: the tossing of a fair coin.

If I flip a coin, the result could be heads or tails. Until I flip the coin, I don’t know which it will be. In this sense, the coin toss is unpredictable. If the coin is fair, each result is equally likely, so while I cannot say in advance whether a particular result will be heads or tails, I can say something about a large number of flips: approximately half should be heads and the other half tails.

A little mathematics even allows me to determine a range around 50% in which the percentage will almost surely lie. For example, if I flip a fair coin 1,000 times, the percentage of heads will most likely be between 45% and 55% (where “most likely” means a 99% chance). If the percentage of heads lies outside this range—especially if it is quite far outside this range—I am going to be suspicious that the coin flipping process is not fair. That’s one of the key ideas in statistics: not only can we calculate the frequency with which an event occurs, but we can compare data to a stochastic model to see if they are compatible or incompatible.

There are several interesting things we can learn by considering a coin toss. First, probability calculations rely on assumptions. If the assumptions are incorrect, then the probability calculations will also be incorrect. For example, if the coin is biased (such as one that is heads 60% of the time), but we assume it is fair, then the probability calculations given above will be wrong. Of course, if the assumptions are not too far from correct, the results may still be sufficiently accurate for scientific conclusions. If we have an appropriate way to collect data, then we can test our assumptions by comparing data to projections made based on the assumptions.

Second, “random” does not imply “equally likely.” A fair coin should have equal probabilities of heads or tails, but a biased coin is no less random. It’s just different. It is not as simple to handle arithmetically as a situation in which all outcomes are equally likely, but it is not otherwise special. It is a common mistake to assume random events are equally likely when they are not (or when that assumption is not justified).

Third, randomness is about the process. It is a fun experiment to flip a penny 100 times, then spin a penny 100 times and record the side that is showing when it finally tips over, then to stand the penny on end (this takes a steady hand and a little practice) and record which side is showing after pounding the table. These are three different processes, and they do not yield the same results.

Fourth, random processes produce patterns. I sometimes ask my students to mentally flip a coin and record the results as a sequence of letters (e.g., “HTTHHTHT”). Then I have them actually flip a coin and record the results. If the sequences are long enough, I can almost always tell them which is which. The sequences imagined by the students tend to have too few runs of consecutive heads or tails. The sequences based on real coin flips usually include several heads in a row. People not familiar with randomness are often surprised at the patterns that result and assume that the process must not have been random when they perceive a pattern. Our eyes and minds are drawn to similarities and patterns—even those that are produced purely randomly. This can lead us to draw false conclusions from coincidences of all sorts.

Consider the image in Figure 1. It was constructed using a computer to randomly throw 300 darts at a square board. Every position on the board was equally likely to be hit by a dart. This does not, however, mean that the dots are evenly spaced. There are 100 smaller squares. The average is three dots per square. But your eye is likely drawn to some clusters and voids. My eye also catches a graceful downward swoop in the lower part of the upper left quarter. All of this is exactly what we should expect from this random process. If we repeated this experiment, we should expect similar results. Several of the smaller squares would be empty and some others would have two or three times the average number of dots, but these clusters and voids would appear in different places.

Finally, randomness can be used to produce patterns intentionally. Consider the two pictures in Figure 2. You may think the two pictures are identical, but they are not. However, they were each constructed using the same random process:

1. Start at the lower left corner of the big triangle.
2. Randomly choose one of the three corners of the big triangle.
3. Move half way to that corner, placing a dot at the new location.
4. Repeat steps 2 and 3, 50,000 times.

The first few steps of this process for each image are illustrated in Figure 3. Although the final images look very similar, the route taken to get there is very different. In fact, the only point the two images have in common is the starting point. As the creator of the program that generated these images, I knew full well that the result would resemble a fractal image known to mathematicians as Sierpinski’s Triangle, even though I did not know or exercise any control over how the individual points would be selected.

Despite our familiarity with children’s games and the importance of stochastic models throughout the sciences, many Christians have a reaction to randomness that falls somewhere between uneasy and antagonistic. And yet, those same Christians may well watch the evening news to learn about public opinion polls forecasting upcoming elections, take prescription drugs approved by the FDA based on statistics found in clinical trials, obtain electrical power from a nuclear power plant that uses random fission reactions, and insure their cars with companies that rely on stochastic models to set the rates. The foundation of each of these activities is a thorough understanding of randomness that begins with the simple description above.

So where does the uneasiness come from? Likely it comes from the feeling that taking randomness seriously means not taking God seriously. Or put more strongly, it comes from a fear that believing in randomness means not believing in God. Next week we’ll address that problem by asking the question, “Could God use randomness to achieve his purposes?”

In the 1950s, Cage began using various methods of “casting lots” to determine how elements of his music would be chosen and arranged—principally the Chinese system of I Ching. His controversial program was to distance himself from his own creative process, and he explored many additional strategies to transform the role of “creator” into one of “observer.” Most famous of these was his musical composition, “4.33,” which consisted of a pianist sitting at the instrument doing nothing at all for four minutes and thirty-three seconds, while musician and audience listened to the ambient sounds of the concert hall. Yet contrary to that main thrust of Cage’s work, a description of the activities during the week-long residency at the Mountain Lake Workshop where the New River Watercolor Series were made suggests that choice, constraint, and intention were integral and inescapable tools in putting randomness to work for creative ends.

Here’s art historian and theorist Howard Risatti’s description of Cage’s plan of action for the New River Watercolors, from the website of artist Ray Kass, who runs the Mountain Lake program and was Cage’s collaborator for his work there:

Following upon [a previous (1983) Mountain Lake workshop] “painting experiment,” stones collected from the New River were sorted into three groups according to size, which were separately numbered; numerous and varied brushes were divided into two separately numbered groups; likewise, feathers to paint with, colors and washes, and papers were also divided and numbered. In this way, chance procedures using pages of random numbers that were now generated by a computer program could be used to determine the specific materials utilized for each painting (e.g., which painting instruments, what type of paper and which colors, how many washes, which stones to paint around, where to locate the stones on the paper).

While this list enumerates all the specific variables that Cage and his team submitted to chance, there was an incredible level of personal engagement with the materials: Cage didn’t just show us drawings of where the I Ching said the rocks ought to be, he (or his assistants) placed them on the paper and used them as guides to paint around. Large custom brushes were constructed to lay on washes of color, and even the paints were hand mixed, combined, and diluted according to his desires.

Cage’s use of chance, then, was not a “hands off” process, but neither was it a matter of total control: Cage selected processes to create a space of play between himself and the materials he used: the feather between himself and the paper, for instance, introduced variability of resistance and spring, its ability to hold paint, the width of the line. All of these things were elements of material ‘freedom,’ areas in which Cage asked the stuff he used to make the paintings to take part in the process—to contribute its own identity to the intentional, purposeful, and determined work of creating “based on chance.” This should not be surprising, as all art, all creation that we can observe, happens as a dialectic between materials and the creator, and such engagement and interaction in no way lessons the purpose of making, the end in sight.

Kass’ book The Sight of Silence: John Cage’s Complete Watercolors, gives a much more complete account of the tools, processes, and interpersonal reactions between Cage, Kass, and the team of student assistants who helped at almost every stage of the creation of the works. The book goes to great length to honor Cage’s ideal of being present in but not controlling the outcomes (not least by nearly always putting words like “choice” in quotation marks), but the description of his process makes the centrality of Cage’s personal aesthetic and artistic motives inescapable, even more than his physical engagement. What comes through perhaps even more than the way Cage intended to allow chance to ‘guide the creative process’ is that way Cage, himself, not only set the parameters of the chance he allowed into the system, not only engaged directly with the materials during the process, but also exercised judgment over the results, both in process and at the end:

“Cage decided he didn’t want the images of the stones to overlap or go off the sides of the paper. To guarantee this restriction, he created conditions and rules to limit their possible placements.” (p. 51)

“For this single painting [Series IV, #1, pictured above] Cage chose to confine the images of the rocks to a lower area of the paper that represented the proportion of the “golden rectangle. . .” (p. 57)

“While “choice” established much of the work’s nature, “chance” highlighted the intrinsic nature of the materials to reveal a refreshing presence.” (p. 59)

“[H]e initially decided to remove [the first painting of Series III] from the group, and then, liking it more, changed his mind and returned it to the group that would be signed.” (p. 56)

This last note is particularly interesting in that it highlights the fact that Cage was claiming these paintings, naming himself as their author, and was attentive to which ones he approved of enough to call his own. There is no way around the fact that Cage was subjectively as well as objectively the maker of these works: the author of the procedures by which they came to be, but well as the judge (and sometimes redeemer) of the results. For Cage, randomness was a tool, no different than the brushes or rocks or paints is that its specific parameters were chosen at the outset, and always used within the context of his over-arching vision. Perhaps we may likewise think of God’s use of chance—constrained by and tuned to the material conditions he established at the birth of the cosmos—as a way to both engage with and allow freedom for the creation itself.

With any work of art it is reasonable to ask, “Is it beautiful?” or more tellingly, “Would I hang this on my wall?” Seeing Cage’s watercolors for first time without any knowledge of the process or the relative fame of Cage himself, some might be intrigued by the structure of the work (the proportions of the golden rectangle, the overlapping stone shapes, the colors of the paint) while others would be completely uninterested, perhaps even after hearing about how they were made and seeing them in the context of the rest of the New River Watercolor series. But if you had been there in the shop as an assistant, or even observer, if you had been party to the relationships that developed even over the few days Cage spent at the Mountain Lake Workshop, your sense of the beauty of these paintings (and perhaps even scraps of paper Cage used to try out brushes or washes), would take on a different meaning, in much the way we treasure the crayon drawings of our children not because they are spectacular art, but because they are tokens of our relationship.

I make that observation to emphasize one other aspect of Cage’s creative process: that Cage was the instigator first and foremost of relationships of creation. His process created not only paintings but the fellowship that developed as the work was being done. That social, interpersonal dimension is what gives the objects a depth of meaning beyond their material composition, and suggests the particular roles humanity has been given by God. One role is to join into the creative process as lesser, but not unimportant co-creators with him; the other is to observe, recognize and celebrate his activity in the world. Where some will see randomness as evidence of an absent God, our knowledge of this most personal and participatory aspect of creation points us to the God who is with us.

With God’s creation as with human art, we may (or may not) marvel at any one particular “work,” or even think the specifics of how it was made are interesting or attractive; but knowledge of and fellowship with the artist transforms our appreciation of the process as well as its results. When we know the maker, we come to recognize and treasure even the most “random” bits of his handiwork, and name them as his, nonetheless.

For Further Reading:

Ray Kass. The Sight of Silence: John Cage’s Complete Watercolors, 2011.

Website for John Cage Centennial Festival, Washington, DC. September 2012.



]]> Sun, 13 May 12 12:53:04 -0700 Mark Sprinkle http://biologos.org/blog/understanding-evolution-theory-prediction-and-evidence-1?utm_source=RSS_Feed&utm_medium=RSS&utm_campaign=RSS_Syndication http://biologos.org/blog/understanding-evolution-theory-prediction-and-evidence-1?utm_source=RSS_Feed&utm_medium=RSS&utm_campaign=RSS_Syndication In science, we don’t really know the true way things actually work. What we have are theories—broad explanatory frameworks supported by experimentation, which we can use to make testable predictions about the natural world. One of the challenges for discussing evolution within evangelical Christian circles is that there is widespread confusion about how evolution actually works. In this (intermittent) series, I discuss aspects of evolution that are commonly misunderstood in the Christian community. In this post, we explore how evolution is a theory in the scientific sense, how it is supported by converging lines of evidence, and how it can make accurate predictions about the natural world, using whale evolution as an example.

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.

Perusing the writings of atheistic scientists and philosophers like Daniel Dennett, one could easily get the impression that arriving at a simpler explanation for something equates to a revelation that things are “lower, cruder, and more trivial.” But at the heart of Barr’s critique is the observation that in fundamental physics and advanced mathematics, “simpler” does not mean more chaotic and inchoate, but rather more elegant and beautiful. Those who hold to a philosophical reductionism “overlook the hidden forces and principles” that govern the processes of cosmic evolution.

Barr’s article lays out the way that the work of scientists and mathematicians exploring the fundamental principles of physics (from Kepler to Einstein to those currently running the Large Hadron Collider in Switzerland) actually suggests “that order does not really emerge from chaos, as we might naively assume; it always emerges from greater and more impressive order already present at a deeper level.” This excerpt gives his first example, the starting point from which he guides us into strangely beautiful world of particle physics, and towards the discovery that “matter, although mindless itself, is the product of a Mind of infinite profundity and infinite simplicity.”

Fearful Symmetries

“Let’s start with a simple but instructive example of how order can appear to emerge spontaneously from mere chaos through the operation of natural forces. Imagine a large number of identical marbles rolling around randomly in a shoe box. If the box is tilted, all the marbles will roll down into a corner and arrange themselves into what is called the “hexagonal closest packing” pattern. (This is the same pattern one sees in oranges stacked on a fruit stand or in cells in a beehive.) This orderly structure emerges as the result of blind physical forces and mathematical laws. There is no hand arranging it. Physics requires the marbles to lower their gravitational potential energy as much as possible by squeezing down into the corner, which leads to the geometry of hexagonal packing.

At this point it seems as though order has indeed sprung from mere chaos. To see why this is wrong, however, consider a genuinely chaotic situation: a typical teenager’s bedroom. Imagine a huge jack tilting the bedroom so that everything in it slides into a corner. The result would not be an orderly pattern but instead a jumbled heap of lamps, furniture, books, clothing, and what have you.

Why the difference? Part of the answer is that, unlike the objects in the bedroom, the marbles in the box all have the same size and shape. But there’s more to it. Put a number of spoons of the same size and shape into a box and tilt it, and the result will be a jumbled heap. Marbles differ from spoons because their shape is spherical. When spoons tumble into a corner, they end up pointing every which way, but marbles don’t point every which way, because no matter which way a sphere is turned it looks exactly the same.

These two crucial features of the marbles—having the same shape and having a spherical shape—should be understood as principles of order that are already present in the supposedly chaotic situation before the box was tilted. In fact, the more we reduce to deeper explanations, the higher we go. This is because, in a sense that can be made mathematically precise, the preexisting order inherent in the marbles is greater than the order that emerges after the marbles arrange themselves. This requires some explanation.

Both the preexisting order and the order that emerges involve symmetry, a concept of central importance in modern physics, as we’ll see. Mathematicians and physicists have a peculiar way of thinking about symmetry: A symmetry is something that is done. For example, if one rotates a square by 90 degrees, it looks the same, so rotating by 90 degrees is said to be a symmetry of the square. So is rotating by 180 degrees, 270 degrees, or a full 360 degrees. A square thus has exactly four symmetries.

Not surprisingly, the hexagonal pattern the marbles form has six symmetries (rotating by any multiple of 60 degrees: 60, 120, 180, 240, 300, and 360 degrees). A sphere, on the other hand, has an infinite number of symmetries—doubly infinite, in fact, since rotating a sphere by any angle about any axis leaves it looking the same. And, what’s more, the symmetries of a sphere include all the symmetries of a hexagon.

If we think this way about symmetry, careful analysis shows that, when marbles arrange themselves into the hexagonal pattern, just six of the infinite number of symmetries in the shape of the marbles are ex-pressed or manifested in their final arrangement. The rest of the symmetries are said, in the jargon of physics, to be spontaneously broken. So, in the simple example of marbles in a tilted box, we can see that symmetry isn’t popping out of nowhere. It is being distilled out of a greater symmetry already present within the spherical shape of the marbles.”

In the full essay, Barr gives a richer description of how this most basic kind of symmetry is just one sort of order, and how even this form points to other much more complex kinds of symmetry whose properties may be described only through the tools of complex mathematics. As he says, “the symmetries that characterize the deepest laws of physics are mathematically richer and stranger than the ones we encounter in everyday life.” But even more important than the fact that such mathematical concepts exist and are beautiful, more important even than the way such esoteric mathematical symmetries have suggested imminently practical experimental projects, is the way they point to a universe that is anything but brutish and trivial, though its elegance may be hard to see:

“It is true that the cosmos was at one point a swirling mass of gas and dust out of which has come the extraordinary complexity of life as we experience it. Yet, at every moment in this process of development, a greater and more impressive order operates within—an order that did not develop but was there from the beginning. In the upper world, mind, thought, and ideas make their appearance as fruit on the topmost branches of an evolutionary tree. Below the surface, we see the taproots of reality, the fundamental laws of physics that shimmer with ideas of profound simplicity.”

This essay appears with the permission of First Things. To read Barr’s complete essay, please click here.

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.

Today's video is courtesy of filmmaker Ryan Pettey, director/editor of Satellite Pictures and features physicist Ard Louis.

In today's video, Oxford physicist Ard Louis discusses the famous debate between renowned evolutionary biologists Stephen Jay Gould and Simon Conway Morris. Gould believed (and wrote in his book Wonderful Life) that if the "tape" of evolution were rerun, the chance that anything like human intelligence would emerge is essentially zero. In other words, humanity is here through random accident. Gould pointed to the work of Morris and fellow scientists in their research of the Burgess Shale as evidence for this view.

However, Morris himself disagrees, pointing to what is called evolutionary convergence. As Morris notes, there are numerous examples of identical features evolving multiple times throughout the history of life independently. Morris believes that if the tape of life were replayed, we would see something like humans emerge. A Christian might say, it looks like we were planned.

Some Christians might find Simon Conway Morris' viewpoint, with its implicit teleology, more attractive. Others, perhaps motivated by a high view of providence, may find Gould's emphasis on contingency equally congenial to their faith. What do you think?

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.