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. 

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.

The tenth anniversary of the human genome has been marked by some striking new genetic insights into human evolution and diversity. Do these new discoveries have any significance for the dialogue between science and religion in general, or for our sense of human uniqueness in particular?

The publication of the Neanderthal genome sequence in May 2010 set the pace. Not surprisingly -- given that our last common ancestor with the chimpanzee was around 5 to 6 million years ago, compared to a mere half a million years for our last common ancestor with the Neanderthal -- it turns out that we are genetically far closer to the Neanderthals than to the apes. In all, only seventy-eight changes in the genetic letters ('nucleotides') that would change the amino acid sequence of particular proteins were found in the Neanderthal DNA that were the same as the chimpanzee sequence but different in the human. Amongst other differences, 111 duplications of small DNA segments were found in the Neanderthal but not human sequence. Genetically we are closely related twigs on the great evolutionary bush of life.

But we knew that already. More surprising for many was the provocative finding that non-African humans are genetically closer to Neanderthals than African humans. In fact, the European and Asian genomes that were sequenced appear to contain one to four percent DNA of Neanderthal origin, and the gene flow that occurred appears to have been almost entirely from Neanderthal to human, rather than vice versa. How come? The most likely scenario is that there were a few instances of sexual reproduction between Neanderthals and human individuals belonging to the population that is thought to have emigrated out of Africa to populate the world sometime after seventy thousand years ago, explaining why the Neanderthal DNA sequences are not found in African genomes. The contribution of the Neanderthal genome has remained in European and Asian populations ever since.

To put this in perspective, most of our genes are very similar anyway to those found in Neanderthals and chimpanzees, and to other mammals like mice. We all share a "how-to-build-a-mammal" instruction manual, and the relatively minor genetic differences between us (minor relative to those we share in common) are the icing on the cake, as it were, that make us a human rather than a mouse, a chimp or a Neanderthal.

The year 2010 saw yet another twig appear on the hominin branch of the evolutionary bush, this time one even closer to the Neanderthals than our own. This story begins with the discovery by a Russian team of a sliver of finger bone from a remote Siberian cave in the Altai Mountains, known as the Denisova Cave. The team stored it away, thinking it was from one of the Neanderthals that frequented the cave between thirty thousand and forty-eight thousand years ago. But when DNA extracted from the bone was eventually sequenced, the results -- published just before Christmas -- revealed a population distinct from both humans and Neanderthals.

The finger appears to belong to a novel hominin population that shared a last common ancestor with Neanderthals more recently than humans, and overall is genetically closer to Neanderthals than to humans. It is too early to say whether the so-called 'Denisovans' represent a separate species and fossil data will be required to clarify that question. But what the results do suggest is that Melanesians -- the inhabitants of Papua New Guinea and islands northeast of Australia -- have inherited as much as one-twentieth of their DNA from the 'Denisovans', indicating that some limited inter-breeding took place between these ancient populations. Most fascinating of all is the idea that multiple hominin lineages were coexisting in Europe and Asia, along with modern humans, as recently as twenty-thousand to forty-thousand years ago.

Do these findings have any particular theological significance? It is difficult to know why this should be the case. In the Judeo-Christian tradition humankind uniquely is made "in the image of God". The suite of capabilities that emerged during human evolution is necessary but not sufficient to do justice to this much discussed theological insight. Our particular genetic instruction manual generates large frontal lobes, advanced cognitive abilities, rationality, language, consciousness and the ability to choose between right and wrong. It is this suite that gives us the ability to pray, worship and engage in communal religious practices.

But the idea of being made "in the image of God" is not encompassed simply within a static list of such human qualities. Theologians have drawn attention to the dynamic, relational aspects of the concept. It is humanity-in-relation-to-God, together with God-given responsibilities to humans in relationship with each other, that are thought to be more central to the idea. When did such spiritual capabilities and responsibilities first come into being? It is really difficult to know, but the answer certainly seems more rooted in God's intentions and purposes for humankind than in genetic change per se. Students can spend a long time being trained in the finer points of drama, but the play only gets off the ground when the actors are finally given their lines.

It seems quite likely that more twigs will continue to appear on the hominin branch of the bush of life as genomics continues to extend its reach. Such discoveries as such do not appear to raise any new theological questions. But other 2010 discoveries did highlight two genomic insights that do have relevance for religious views of human identity. The first insight comes from further Genome Wide Association studies that continue to subvert any lingering commitments to genetic determinism, for example the idea that there are genes "for" a particular human trait. The second insight comes from the finding that we are all more genetically different from each other than we realized even a few years ago. Genetics is underlining the uniqueness of each human individual. By the end of 2011 it is estimated that more than 30,000 human genomes will have been sequenced. Watch this space. Theological reflections on these findings will be the topic for Part 2.

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

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 Part 1 of this essay I pointed out that metaphysical naturalism is not necessary nor inextricably tied to the practice of science, and that essentialism is only one of the historically-Christian ways to think about being human. As a case in point, we can identify the Patristic Fathers and Medieval Christian thinkers who discussed a relational alternative for understanding the nature or being of persons.¹ Roughly, the idea is that the three persons of the Trinity are what they are and who they are in virtue of their relationship with each other, not based on some intrinsic properties that ground their uniqueness as persons in the Godhead. That is to say that Father, Son and Spirit co-constitute each other, or are bound up together with enabling each other to be distinctly the persons that they are. Far from a static form of being and relationship, there is a dynamic interrelatedness in the Trinity. Father, Son and Spirit mutually constitute each other while enabling each other to be particularly who they are and engage creation and salvation in particular ways suited to who they are as persons. Father, Son and Spirit are being in community.

By analogy of relationship, humans are what we distinctly are in our being and personality in virtue of our relationship to God, creation and each other. Our involvements with others necessarily shape who we are as particular persons. The personal realm, then, is characterized by a dynamic relationality, as persons have ongoing mutually constituting influence on each other. This is part of the “dynamic order” of creation “that is summoned into being and directed towards its perfection by the free creativity of Father, Son and Holy Spirit. That orientation of being is, of course, distorted and delayed by sin and evil, and returns to its directedness only through the incarnation and the redeeming agency of the Spirit. But evil distorts the dynamic of being, does not take it away.”² Like the relationality of the persons of the Trinity, we are being in community.

We can also pursue the doctrine of creation as an alternative to essentialism, to see if it sheds any light on possibilities for what it means to be human in a non-reductionist sense.³ As other writers have been exploring in the Forum over the past few weeks, the biblical claim that humans are created in the image of God is important to the Christian of view of humankind. This may sound like jumping out of the frying pan into the fire, for there are both Christians and non-Christians who claim that if humans arose through evolutionary processes, then we cannot be made in God’s image. Nevertheless, it is worth exploring as a way of showing that there are strong alternatives to a strictly essentialist understanding of being human.

The Image of God

Over the centuries, the dominant view of humans as the imago Dei has been grounded in the idea that there is something distinctive about the creation of humans that both sets us apart from the rest of the animals and that marks us as unique kinds of creatures. Though we are clearly both distinctive and unique, does affirming the imago Dei require this kind of essentialism? On the one hand, Genesis 1:27 has often been interpreted as grounding humanity’s being in the divine image of God on Earth. On the other hand, recent discussions in human evolution have focused on several independent lines of evidence supporting the hypothesis of common ancestry among primates and humans: fossil evidence over the last 6 million years; homologies or anatomical similarities between humans and the primates; biogeographical distribution of supposed human ancestors; similarities in developmental biology between humans and primates; and several lines of genetic evidence favoring common ancestry. In addition, our current best understanding of the genetic diversity of humans is inconsistent with models that assume all humans descended from a single original pair of individuals. Instead, the current best data and models indicate the human ancestral population was never smaller than several thousand individuals.⁴

On the surface, then, what contemporary evolutionary science currently says on human origins appears to challenge cherished beliefs and understandings of many Christians. However, to understand what implications, if any, an evolutionary development of humans might have on the image of God, we first need to get clear on what it means to be the imago Dei, and that has to be settled theologically, not scientifically.

Historically, some of the most popular proposals for the imago Dei were rooted in human rationality, human freedom or human creativity because it was thought that humans alone among the animals possessed one or more of these qualities. There are two problems with this traditional line of thought. First, investigations since the early 18th century have progressively led to the conclusion that such qualities of humans mark a difference in degree rather than a difference in kind (e.g., brains of mammals and humans are anatomically homologous, dolphins, primates, and some species of birds exhibit degrees of rationality and creativity). The degree of difference may be significant, but a difference in kind is necessary for the traditional line of essentialist thought.

Second, if we look to the Incarnation for clues to the imago Dei we find that Jesus’s humanity is never depicted as exercising extraordinary powers of rationality, freedom, creativity, and so forth. Primarily, Jesus lived as an embodied person in relationship with the Father, other humans and creation as enabled by the work of the Holy Spirit. In other words, Jesus’ human life in Scripture indicates that the divine image is a special relationship, or form of relationality: to be in relationship with the Father as a created, embodied person; to be sustained or upheld in this relationship with the Father through the perfecting Spirit; and to be in relationship with other persons and all of creation.⁵ Moreover, this special relationship is also a vocation to mirror or reflect the glory, life and worship of God.⁶

If to be the image of God is to be sustained in a special relationship with the Father, each other and creation through the Spirit, then the imago Dei is not grounded in intrinsic qualities that particularly mark humans as distinct from the rest of the animals, as essentialism would have it. Christians can understand Genesis 1: 24-31 and 2: 4-5, as many of the Patristic Fathers did, as an account of our unity and connection with the rest of creation as well as of our special relationship with God and role in God’s kingdom. So if Father, Son and Spirit created human beings through evolutionary processes, we would have continuity and connection with all of creation while still being the imago Dei. Evolution does not threaten human specialness before God unless it is viewed as a replacement for divine creative activity (which, of course, is what Richard Dawkins, Jerry Coyne and Answers in Genesis all do repeatedly).

If evolution is broadly right as an account of the creation of all living things (an empirical matter), and if some form of essentialism is found to be consistent with such an account (a philosophical and biological matter), Christians would then have two options for how to understand what it means to be human. We can look for some stable, unique intrinsic features in virtue of which we are human; or we can look to the special Spirit-sustained relationship we have with God, creation and each other. Both are biblically consistent, though I judge understanding the imago Dei as special relationship to make better sense of the whole of the Bible, as well as our experience in the world.

Notes

1. See Gunton, The one, the three and the many and Gunton, The Promise of Trinitarian Theology, T&T Clark (2003).
2. Gunton, The one, the three, and the many, p. 166.
3. Gunton, The Triune Creation; Robert C. Bishop, “Recovering the Doctrine of Creation: A Theological View of Science,” 31 January 2011.
4. For example, see Dennis R. Venema,“Genesis and the Genome: Genomics Evidence for Human-Ape Common Ancestry and Ancestral Hominid Population Sizes,” Perspectives on Science and Christian Faith, vol. 62, No. 3 (2010): 166-178.
5. See Gunton, The three, the one, and the many.
6. As such, the imago Dei has an inextricable missionary focus towards extending the kingdom. See N. T. Wright, How God Became King: The Forgotten Story of the Gospels, HarperOne (2012).

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.

In a Nutshell

The meaning of the “image of God” has been debated for centuries in the church. A common view is that the image of God refers to the human abilities that separate us from the animals. However, scientists have found that abilities like communication and rationality are also present in animals on a basic level. Plus, theologians do not see the image of God as human abilities. Some theologians see the image of God as our capacity for a relationship with God. Other theologians see it as our commission to represent God’s kingdom on earth. Both of these theological positions are consistent with scientific evidence. Whether God created humanity through a miracle or through evolution, God gave us our spiritual capacities and calls us to bear his image.

In Detail

The “image of God” is a key concept in Christian theology, foundational to Christian thinking about human identity, human significance, bioethics, and other topics. Many Christians see evolution as incompatible with the image of God. How could God’s image bearers have evolved from simpler life forms? Doesn’t image-bearing require miraculous creation of humans rather than shared ancestry with chimpanzees? And when in the evolutionary process did humans attain this image? These questions are tied to many other issues concerning human origins, including the soul, the Fall, and the historicity of Adam and Eve (see sidebars), but in this article we will focus specifically on the image of God.

See “How does the Fall fit with evolutionary history?” and “Were Adam and Eve historical figures?”

The phrase “image of God” does not appear many times in the Bible, but the importance of the concept is emphasized by its repetition in the creation account:

Then God said, “Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.” So God created mankind in his own image, in the image of God he created them; male and female he created them. -- Genesis 1:26-27

From this text, it is clear that part of bearing God’s image is ruling over the animals. Genesis 9:5-6 reveals another aspect of image bearing: all human lifeblood is sacred because all humans are made in the image of God. The emphasis on Judeo-Christian thought on the sanctity of human life is derived in part from this passage. In the New Testament, the idea is expanded further as Christ is revealed as the true image of the invisible God (2 Corinthians 4:4, Colossians 1:15).

For centuries, theologians have discussed these and other passages, debating the meaning of the image of God (“imago Dei” in Latin). Being made in God’s likeness is not a matter of our physical appearance, because humans don’t all look the same. But to what does the image of God actually refer? Many ideas have been suggested over the centuries, producing a huge body of theological writing. While hard to summarize, we give a brief overview below of three common themes for the image of God. After developing this theological context, we’ll consider how these ideas intersect with evolution.

Image of God as our abilities

A common view is that the image of God refers to human abilities. When people talk of the things “that make us human,” they refer to abilities like reason and rationality, mathematics and language, laughter and emotions, caring and empathy, and cultural products like music and art. Often the motive is to distinguish humans from animals by showing that humans have unique abilities that make us special and superior to animals. Saint Augustine (354-430 A.D.) wrote something like this when he said “Man's excellence consists in the fact that God made him to His own image by giving him an intellectual soul, which raises him above the beasts of the field.”¹ Saint Thomas Aquinas (1225-1274 AD) also emphasized intellect and rationality in his discussion of image bearing.² But Augustine and Aquinas were not speaking of intellect as an aptitude for math or music; Aquinas instead writes of an “aptitude for understanding and loving God.” In fact, the modern emphasis on reason comes more from secular Enlightenment ideas than from Christian theology. During the Enlightenment, the image of God was connected to ideas like the natural dignity and majesty of humankind that separates us from the brute beasts of the animal world.

Scientific evidence is piling up that humans have more in common with animals than was once thought. Genetic evidence shows that humans and chimpanzees share much of their DNA. Studies of animal behavior (particularly of chimps and other apes) show that animals not only laugh and cry and care for each other, but can learn sign language and even have basic reasoning ability. In fact, Christian neuroscientist Malcolm Jeeves writes that “any attempt to set down a clear demarcation between the reasoning abilities of nonhuman primates and humans is found to have become blurred.”³ Obviously, humans have a much larger capacity to reason than animals, but reasoning is not a uniquely human ability. As neuroscientists and animal behaviorists learn more about animals, they see how traits appear in a rudimentary form at a level similar to human children.⁴ Whether or not one accepts evolution, evidence from living humans and animals does not show a distinct difference in kinds of abilities (only degree).

See “Made in the Image of God: The Theological Implications of Genomics” a 2-part blog by Denis Alexander.

Another challenge for this picture of the image of God is the place of people with mental disabilities. If a person is impaired in reasoning or language, are they bearing less of God’s image? Are they not showing his true likeness? The Christian answer to these questions is No! The Bible repeatedly teaches that God values all people, particularly those who are rejected by society or unable to care for themselves.⁵ In fact, Genesis 9:5-6 points to image bearing as the reason that all human life is valuable. This is a major motivator for Christians who seek to protect the unborn, the poor, and the aged. Surely bearing God’s image must mean something other than using our abilities.

PLEASE READ THE REST OF THE ANSWER HERE.

Notes

1. Saint Augustine The literal meaning of Genesis, Book 6, Chapter 12 (Google books, p. 193)
2. Thomas Aquinas, Summa Theologica, First Part, Question 93 (html)
3. Malcolm Jeeves, “Neuroscience, Evolutionary Psychology, and the Image of God” Perspectives on Science and Christian Faith (2005) 57.3, p. 178 (PDF)
4. Similarly, many human traits have been replicated in artificial intelligence, particularly logic and math but also conversational language and computer-generated art.
5. For more see, Kathy McReynolds “More Than Skin Deep” BioLogos Forum June 2010

As we’ve seen in recent essays (and comments) touching on Biblical scholarship, philosophy, theology, and anthropology, the imago Dei is a complicated idea, linked to the question of whether what makes humans unique among the creatures on earth is physical, cultural, spiritual, or some combination of all three. As Christians who seek to frame what the natural sciences tell us about our physical humanity with what the Bible suggests are our defining human qualities, we tend to focus on what Genesis means when it says Adam was “made in the likeness of God”; but it is helpful to remember that the first mention of God’s image in human form looked forward to the full revelation that would come in Christ. Thus, we ought also seek to understand Jesus as the model towards which Adam always pointed, and by which we should understand both Adam and ourselves.

Going one step further, we should also look forward from Jesus to the life of the Church. For if Jesus was the true image of God, then at Pentecost, the new community of believers took on the role of imaging the continuing presence of God in and for the world. The Church was constituted as the very Body of Christ, charged with making him known in their lives as well as their words. Thus in the structure and life of the Church we also see something important about the imago Dei.

Perhaps one way to hold in tension the various interpretations of the image—that is, to affirm the incomplete truths available through the relational, functional, substantial, and elective models—is to look at a literal image of the way the social aspect of imaging God via the Church interacts with the intensely individual and personal aspect of imaging God in individuals. Picking up on Kathy McReyolds’ sketch of personal transformation through encounters with those with disabilities (More than Skin Deep), I’d like to turn our attention towards the work of Chicago artist Tim Lowly, whose monumental portrait of his disabled daughter (Temma on Earth, 1999), is pictured above. Lowly’s work compels us to recognize the image of God even in one who lacks markers of those other roles, capacities, and relationships, and highlights two linked characteristics common to Jesus and Church: brokenness that does not merely equate with imperfection, and a social picture of our essential identity in Christ. By allowing Lowly to place Temma’s identity and humanity at the center of our attention, we can reframe our sense of what it means to bear the image of God and reflect the crucified Christ as his Body.

Profoundly Other

Born in North Carolina but spending his youth in South Korea (where his parents were Presbyterian missionaries), Tim Lowly attended Calvin College and began work as an artist in Michigan. But his life and work took an unexpected turn in 1985, when Tim and his wife Sherrie’s daughter was born and suffered a medical emergency during her first two days home from the hospital. In 2002, journalist Fred Camper’s incredibly sensitive article treated the Lowlys’ physical, emotional and spiritual journey with Temma at length, and I encourage readers to turn to that essay for the full narrative background to Tim’s approach to his daughter and his art. But the central facts are that for all of her now 27 years, Temma’s host of physical and mental disabilities have made her completely dependent on others, and have meant that the relationship she has with her parents (and they with her) is a radical departure from ‘normal.’ Temma’s “profound otherness” challenges most of our expectations about the human capacity to image God. Speaking to Camper, Lowly describes Temma:

It's unlikely that she thinks in a way that we would call thinking," he says, "because our ways of thinking are based so much on learning, experience, sight, socialization, and history, and I doubt any of those things have any bearing on Temma. I don't even think comparing her to animals makes sense. There's a certain wholeness to the way animals think that I don't think Temma is capable of. I'm pretty sure she does have an inner life, but I don't think she has the mental mechanisms that would make it correspond in an understandable way to the way we think.

And yet Lowly has produced hundreds of paintings and other works that feature Temma, some of them monumental in scale, none of them shying away from questions of the purpose, value, and meaning of her life for their family, and for ever-widening circles of community. Certainly there is a political component to Lowly’s work that addresses inequity in culture and church. Generally, he says, the church has been compassionate, but “nearly always from perspective of the able-bodied and the ‘whole’ vs. the disabled, never mind that none of us measure up to complete wholeness.” Yet his work also reflects the way Temma, in her “otherness,” creates community. Artist-in-residence and gallery director at Northpark University since the mid-1990s, Lowly has often made Temma a physical presence in the studio and classroom. Carry Me, 2002 (drawing on panel, 108" x 48," at left) depicts students from an advanced class holding Temma, but they were also involved completing the project. Another large work, Culture of Adoration, 2008, shows Temma as the model in a drawing class, with Lowly drawing the parallel between that scene and the adoration of the Magi at Jesus’ birth. That comparison pictures the way a community forms around loving attention and worship, but subverts artistic and cultural expectations that only what is beautiful should be valued. Lowly notes that while Temma is often alone, in some ways she’s never alone: “She’s cared for by her parents, but that relationship extends out to a much broader church outside her family.” Both paintings, then, are images of Christ’s corporate body as much as they are of Temma or the painting students who carry and draw her.

What bearing, then, does Lowly’s particular way of seeing and depicting his daughter have on us, on our sense of the imago Dei? Part of his ongoing artistic project is to understand and interrogate the way the traditions of perspective in Western art and culture presuppose and privilege the individual, solitary and unified point of view as the most important, the most true. In the wake of modernist emphases on self-expression in art, Lowly also sees value in pursuing ways of working that bring out the meditative (and even prayerful) craft aspect of painting, and that at least partially de-emphasize his and other artists’ subjective positions. He increasingly works from photographs (and collages of many individual pictures), and has more and more sought to bring collaboration into the making of his work. When Lowly takes Temma as his subject, these features of his practice emphasize the way that, in the Church, our individual identity is experienced as a tension between brokenness and wholeness in the Body.

Broken Together

There is a sense in which we look at Temma and we want to affirm that she is made in the image of God by denying that the image of God has anything to do with her physical, material body. Indeed, one way to approach the problem made visible through Lowly’s painting is to imagine the soul as imparted to (or trapped in) the physical frame. This certainly fits with saying that the image-bearing role of humanity in general is an act of the grace of God, not something dependent on our abilities. But in the election model, we are reminded that God didn’t call Abraham just to a “spiritual” identity, but also to physically constitute a people sent into the very concrete physical world.

Likewise, if we recognize Jesus as our model for the image of God, we will not deny the physicality of the human experience, nor the incarnation, nor even Christ's suffering on our account. Indeed, we must affirm the goodness of creation and our physicality, even—especially—in its brokenness because Jesus, himself, was broken. Even after the resurrection, his wounds were not abolished or erased, but remained tangible marks by which the Lord revealed himself every bit as much as he did in his creative and healing power. And in the Revelation image of the victorious Christ, we have another picture of that essential and persistent sacrificial brokenness in the Lamb who appeared “as if slain.”

What of the Church? Similarly, the Church remains a fragmented whole when it is at its best—broken open to be dispersed into the world. And though it is also all-too-often broken by own individual and corporate sin, even that finds its meaning and redemption in the image of bread broken in the Lord’s Supper—the way that sharing brokenness together unites the individuals in a congregation with each other and with Christ. As a reminder of Jesus’ own individual body, communion addresses both of those senses; it is the means of both healing and sending.

Christ’s commission to the Church, then, presents a profoundly social model of being the continuing revelation of God for the world. We bear the image of God together, and the image of God is only fully realized when we are members of a community, in relation to other human beings (even if that relationship is one of complete dependence), as opposed to seeking independence. This does not and ought not compromise the absolute worth of each individual, but should remind us that part of our worth is tied up in our integration with the whole body of Christ.

One last example of Lowly’s work gives iconic form to this inter-relation between image-bearing, self, identity, and the community of the Church. Made to commemorate Temma’s 25th birthday in 2010, At 25(right, and below), is a collaborative piece constructed of 25 individual, two-sided panel blocks that fit together something like a puzzle. On one side is a black and white portrait of Temma, while on the reverse, the individual blocks have been painted and gilded in different patterns and techniques. Lowly constructed the piece, but sent each block out to be completed by 30 different artists, either working alone or in pairs. In requesting them to do their sections of the composite portrait in an “artistically neutral” style, he was asking them to subjugate their artistic personae and self-expression to the depiction of Temma. Not every artist was able to do that to the same extent, so the final object is an image of the imperfection of our self-giving—or our inability to see others without looking through our own particular lenses of self—even while being a testament to the compassion and care of Lowly’s dispersed community.

Most importantly for this discussion, At 25 suggests that our image-bearing of God does not rest on our individual “fitness,” much less how well we “fit in.” Rather, it is carried by the whole human community, most fully in the broken Body of Christ. In this respect, brokenness is not something to be corrected; it is something that makes the particular community of the Church possible. Individuals may not be able to fulfill or even recognize the functional aspects of the imago Dei, they may not even be capable of the relational aspects—or of returning expressions of love or kindness or thanks, or even awareness. But the whole body, the beloved community, the nation God set apart for himself and the world, is called to be the image of God for each of us—precisely when we can’t.

Tim Lowly is Assistant Professor of Art at Northpark University. An inter-disciplinary artist, he works with painting, drawing, installation, digital media, photography and music: both individually and collaboratively. His work has a lyrical realism and quiet spirituality that have contributed over the last thirty years to the development of a international reputation. While Tim’s art and music address a variety of subjects, the central pillar of his work has been his daughter Temma who is, in his words, “profoundly other”. The clinical diagnoses of “multiple impairment” or “spastic quadriplegia” do little to address the compelling presence of this young woman and the way her being and essence have shaped her father’s work.

Lowly was born in Hendersonville, North Carolina in 1958. The son of medical missionaries, he spent most of his youth in South Korea. He attended Calvin College and received a BFA degree in 1981. His wife Sherrie Lowly is a United Methodist Pastor. They reside in Chicago, Illinois. Since 1994 Tim has been affiliated with North Park University in Chicago as professor, gallery director, and artist-in-residence. Tim is represented by Koplin Del Rio Gallery in Los Angeles.

For additional information (including exhibitions and collections) see Tim’s personal website.

All images © Tim Lowly.

For the past twelve years, I have had the privilege to teach in the Bible Department at a prestigious Christian university. Most of my students have been raised in Christian homes and have attended conservative, Bible-believing churches all of their lives. These students believe that they have a pretty solid understanding of what the image of God entails; at least they think they do until they encounter the world of disability. Disability creates a dissonance in their worldview that they are not expecting. All of a sudden, what they thought they understood about the image of God comes crashing down like a house of cards. The image of God and disability just do not seem to go together.

The following quotes from some of my student’s papers are representative of many and their experience with the disabled “strange other.” What is communicated loud and clear is the challenges disabilities raise for their conception of the image of God:¹

I believe that those with disabilities are equal to us … but I discovered a hidden evil in my heart. Deep in my heart, hidden from the world, I believed that children born with disabilities that would normally not survive its first few days should be allowed to die.

I think I could have intellectually acknowledged that all men and women are created in the image of God … In this class I was challenged to see the realities of disability and ask if I really did believe that God created these individuals in his image and salvation was for them too.

Though I have always known that these individuals are created in His own image, I often found myself secretly thinking that they were miserable and often a burden on others.

Sometimes I feel pity for disabled individuals because they are not “normal”. I feel that their disability is hindering them from experiencing the best life possible. I think disabled people experience a lesser quality of life because they cannot physically and/or mentally do as many things as a “normal” person could.

Now, these young people are not more spiritually or morally bankrupt than others in contemporary society. In fact, to the contrary, these Christian students are considerably more spiritually and morally sensitive in general because of their commitment as Christ- followers. Still, these views have been nurtured and influenced by two factors, one that is cultural and one that is religious: 1) the pervasiveness of a reductionist view of human being fostered by scientism; 2) a wooden, literal interpretation of Genesis 2:7 which says that “the Lord God formed the man from the dust of the ground and breathed into his nostrils the breath of life and the man became a living being.”

Taken together, these two factors present a skewed view of human being, one that focuses on the physical and material rather than on the spiritual and essential. This is one of the reasons why my students twinge and recoil a bit at the thought that persons with disabilities can be made in God’s image. “They just don’t look like it,” they say, zeroing in on what is physically seen. This view has had enormous consequences for people with disabilities. In fact, Adolf Hitler, as part of developing his approach to the weaker members of society in his book Mein Kampf, identifies the stronger (better looking and functioning) members of society as “images of the Lord” in contrast to the weaker members who are mere “deformities” of that image, and who ought to be cleansed from society. Many have argued that Hitler’s ideas concerning those with disabilities were inspired solely by Darwinian evolution. However, these quotes from Mein Kampf reveal a horrific misuse of Scripture, not evolutionary ideas.

Furthermore, with regard to evolution, a face value exegesis of Genesis 1 & 2 does not dictate that the physical stuff God used to create human beings was special or unique or that the image itself resides in it. It shows, rather, that all matter was formless and void until God, who acted and willed out of his good pleasure and sovereign choice, brought order and harmony to it. This applies as well to the creation of human beings who are uniquely created in God’s image. If this image is not merely physical stuff, what is it? What does the literary and historical context of Genesis 1 & 2 reveal?

There are three views on the image of God: 1) Substantial; 2) Relational; and 3) Functional. The functional view sees the imago Dei as a function or role that humans fulfill--such as being priests or having dominion. The relational view has to do with humans imaging God in their ability to have spiritual relationships—primarily with God, but also expressed in terms of our male and femaleness and other nuances. The substantial view essentially says that God’s image is imprinted on the person’s soul as an image is impressed on a coin, and has much to do with human capacities like our free will and ability to reason. It has been predominant in Christian theology in the West since about 600 AD.

But though we do have specific capacities that bear on our responses to God, as the substantial view says, the human being is an embodied soul who has both relational and functional capacities, as well. The relational implications include the biblical truth that among all God’s creatures, only human beings can know Him and be consciously aware of Him. Most importantly, he knows us and can be in relationship with us even when we do not acknowledge him out of rebellion, or cannot respond to him because of disability. If we consider the Substantial view’s emphasis on conscious awareness, ability to exercise freedom, and decision-making capacities alone, however, some human beings may not qualify as persons, whereas some non-human animals might.

Against this, a more holistic view affirms that all human beings bear God’s image, regardless of capacities. The image of God cannot be lost or compromised in anyway. Even the poorest functioning human being profoundly reflects God’s image.

In an unexpected and peculiar way, my students discovered this truth about the image of God when they began to interact with people with disabilities in my classroom. This truth about the image utterly transformed and they began to see people with disabilities quite differently. The following quotes come from the same students quoted at the beginning:

What I came to realize is that since the disabled are people, they deserve life. As humans made in the image of God, we are to try to preserve our fellow disabled brothers and sisters who are also made in the image of God.

When I went to the day group home, it was an amazing experience. I really enjoyed interacting with everyone there. I was able to paint with them, and one of them sang to me and taught me to dance; it was so much fun. It was great to see how each and every one of them was so unique and made in the image of God.

In this class I was challenged to see the realities of disability and ask if I really did believe that God created these individuals in his image and salvation was for them, too. As a result of what I have learned from this class my answer to these two questions is a resounding yes! God loves individuals with disabilities and knows the depths of their hearts and minds on a level I could never comprehend. Who am I to doubt who God knows, who He loves, and to whom He offers the gift of His Son.

At the beginning of the semester, disability was a foreign world for me. That world was new and uncomfortable. I had no idea how to interact with anyone with a profound disability and had little desire to learn how. Throughout this course, the walls of misconceptions, fears, and insecurities that I have built up to distance myself from disability have slowly been chipped away. As I learned more about disability, my fears and discomfort were replaced with compassion and joy. Exposure to individuals and families with disabilities was the most effective way to break down those walls. Having the opportunity to observe and interact with individuals with disabilities was invaluable. Participating in disability ministry is not burdensome, as I had initially worried, but freeing. I left the night feeling uplifted, loved, and so aware of God’s mysterious presence within broken humanity.

During Jesus’ ministry on earth, often the best way to find him was to seek out those society considered strange, unclean, or undesirable; Jesus often sought them out, himself, in order to show that God’s love for us does not depend on our merits or abilities, much less our outward appearance. Similarly, my students today meet the Lord anew—and discover that same message of God’s unmerited grace and love—when they seek out relationships with those our society finds strange and broken, with those who they could easily avoid seeing at all. Rather than judging with the eyes alone, my students learn to recognize their cultural and theological blind-spots, and see both the disabled and themselves in the light of Christ’s love. Relationships are transforming; and relationships with people with disabilities can transform not only our image of them, but of the God who made in His image, and dwells with us in places deeper than the skin.

Notes

1. All student quotes used by permission. Names are left out to protect student privacy.

Left: "Abrahamic Covenant" by Christoph Weigel, 1695.
Courtesy Pitts Theological Seminary, Emory University.

The people of your culture cling with fanatical tenacity to the specialness of man. They want desperately to perceive a vast gulf between man and the rest of creation. - Ishmael ¹

For the destiny of humans and the destiny of animals is the same: As one dies, so dies the other; Both have the same breath of life. And humans have no preeminence over the animals…All go to the same place; All come from dust, And to dust all shall return. - Ecclesiastes 3:19-20

What is humankind’s place among the animals? Should we even count human beings among the animals at all? Perhaps we—as men and women—are something else entirely? Such questions are not new. Indeed, they are as old as writing itself and similar ponderings about human identity occupy the most ancient of texts. While many of these primeval writings have crumbled in the winds of time and have come to us only in fragments, the Genesis account of human and animal origins remains a living document that occupies a vital place in the life of Christian practice and thought. In the first chapter of the Genesis narrative we read that humans—male and female—were created in the image (tselem) and likeness (demuth) of God. But what does this mean? There is certainly no shortage of proposed answers, and over two thousand years of theological tradition bears witness to this fact. Here, however, we are not primarily interested in tradition—as valuable and insightful as it may be—but we are concerned with what the Bible itself has to say.

Taking the authority of Scripture seriously demands that we engage with Scripture in light of both its original languages and its original cultural context. If we are to avoid—as much as it is possible—projecting our own personal, modern and post-modern cultural presuppositions onto Scripture, then we must be willing to do some of the hermeneutical (or interpretive) hard work. In other words, if we want to allow Scripture to speak for itself, we must be hyper-aware of the cultural lenses we are wearing when we read it. Interpreting the Bible through five hundred years of Protestant tradition, fifteen hundred years of Roman Catholic tradition, or one hundred years of Seventh-Day Adventist tradition won’t do.² Rather we must venture to take off the thick hermeneutical lenses of tradition and boldly attempt to go into the world of the sacred text itself so that we can allow the ancient inspired words to shape the lenses or our reading.

With this approach to Scripture in mind, I believe it is useful to address the matter of the image and likeness of God (or imago Dei) by first asking what the imago Dei is not. Throughout the centuries, theologians, philosophers, and others have posed a number of answers to the question of what the imago Dei is. The vast majority of these answers have focused on one or a few characteristics that humans alone have and that non-human animals lack. For example, Evangelical Christian author Kay Warren explains: “Animals and people are two different classes of created beings and they will never be equal in their worth. As precious as animals are to our daily existence, they operate from instinct, not volition. Only people have a spiritual dimension. We are the ones created in the image of the Creator, the only ones with a soul.”³ In a similar manner, political commentator Ann Coulter, citing “the story of Genesis”, maintains: “It’s not merely opposable thumbs and a bipedal gait that make us distinct from the other beasts. It is consciousness of our mortality, a moral sense, language, mathematics, art, beauty, music, love, longings for immortality, a sense of symmetry, the soul’s ascent, the ability to accessorize, and our fascination with Branson, Missouri…We are in God’s image, and we’re the only ones in God’s image, which is why we eat escargot rather than worship them.”⁴ While these are two popular contemporary voices, similar views are espoused by numerous academics as well. In this way the imago Dei has, for many, become synonymous with one central characteristic or several key traits that make humans unique among and/or superior to animals.⁵

As intriguing as such perceived indicators of human uniqueness are, and regardless of the scientific status of claims for such distinguishing human traits, the idea that there are particular physical features and/or behavioral characteristics that make men—and not beasts—in the image and likeness of God is not one that is found anywhere in the pages of Holy Scripture. With regard to humans as “the image and likeness of God,” a literal and consistent reading of the Genesis narratives discloses that the imago Dei designation does not refer to unique characteristics or capacities which humans posses in a way that excludes other non-human animals.

Hebrew scholar Phyllis Bird informs us that the scriptural context of the phrase “image and likeness of God” makes it plain that “its theological significance is in the place it gives to humans within the created order, not in any physical or moral attribute of the species, in either its present or ‘original’ state.”⁶ In the Bible the imago Dei is not about exceptional human capacities or characteristics that automatically qualify humans as being included in the imago Dei category. There is no reason, explains Bible scholar James Barr, to believe that the author of Genesis chapter one “had in his mind any definite idea about the content or location of the image of God.”⁷ The terms “‘image’ and ‘likeness’…make no statements about the nature of human beings.”⁸ When we read of “the creation of human beings in God’s image (Gen 1:26)…the biblical narrative remains silent…about any qualities of human nature that might account for their special standing.”⁹

If we are to properly understand the meaning of the texts, then, says Old Testament scholar Claus Westermann, we must confidently resist “the tendency to see the image and likeness of God as a something, a quality.”¹⁰ Consequently, a literal reading of the early Genesis accounts demands that no specific anthropological content or characteristics may be directly equated with the imago Dei. If one is to take the findings of biblical exegesis seriously, then—apart from theological tradition—the image of God cannot be defined on the basis of particular physical traits or behavioral characteristics. This means that—according to a straightforward reading of Genesis and the rest of Scripture—humans are not said to be biologically or behaviorally unique in a way that is related to their being named the “image of God.”

In addition to the broad consensus among biblical scholars that the image of God in humans, when understood within its original Hebrew linguistic and Ancient Near Eastern context, has nothing whatsoever to do with an appeal to the human possession of particular characteristics which non-human animals lack, research in biblical exegesis has similarly revealed that there is no essential or substantial super-natural divide between humans and other animals. Scripture, when read in the original languages, clearly describes both “man and beast” as possessing “the breath of life” and refers to both equally as “souls.” In this way Scripture makes no ontological or metaphysical distinctions between humans and non-human animals. Instead, the scriptural “emphasis lies on the commonality that exists between the humans and the rest of the animal creation.”¹¹

While the use of the Hebrew word nephesh, often translated as “soul”, to describe humans has been taken by some as an indication that humans are substantially set apart from the animals, the nephesh is not an exclusive possession of humans. Indeed, the Hebrew text describes both humans (Gen 2:7) and animals (Gen 1:21, 24) equally as nephesh hayyah or “living souls.”¹² Thus, Bible Scholar Gordon Wenham explains that in Genesis 2:7, which describes the human being as a nephesh, “it is not man’s possession of the ‘breath of life’ or his status as a ‘living creature’ that differentiates him from the animals—animals are described in exactly the same terms.”¹³ In Genesis, “human beings…are only one subset of God’s ‘living beings,’ into whom God has breathed the breath of life” and established as “living souls.”¹⁴

According to the biblical understanding, then, “what is distinctive about human beings is not that they have a ‘soul’ which animals do not possess, nor that they have a ‘spirit’ which other creatures do not possess.”¹⁵ It is clear, then, that “the possession of nepheš is not a unique characteristic of the human person.” Indeed, “unless one is ready to grant that animals have ‘souls’ in the same way that humans are alleged to have, then we might better conclude that the Genesis account is referring to the divine gift of life: ‘the human being became a living person.’”¹⁶ Consequently, “claims for a ‘special creation’ of humanity in comparison with animals and the material world conflict with the strong assertion in Genesis 2 that, physically (organically), Adam does not differ from the ‘beasts of the field.’”¹⁷ The theological language of anthropology in Genesis 1 and 2 “underscores Adam’s linkage with the animal creation, not his difference from it.”¹⁸

Whatever else the imago Dei might be, then, a clear and consistent reading of Scripture does not permit us to equate it with either a non-material soul which animals lack or some unique physical characteristic or behavior which animals lack. These conclusions regarding what the image and likeness of God in humans IS NOT lead us directly to our discussion of what the imago Dei IS.

In Part 2 of this series, Dr. Moritz examines how the phrase "image and likeness of God" is used within Scripture itself.

Notes

1. Daniel Quinn, Ishmael: An Adventure of the Mind and Spirit (New York: Bantam, 1992), 146.
2. I mention SDA because the prophecies of Ellen White and her interpretations of Genesis have played a significant role in shaping contemporary Evangelical understandings of the text. See Ronald L. Numbers, The Creationists: The Evolution of Scientific Creationism (Berkeley, CA: University of California Press, 1992), 74. For an online lecture on this topic see http://vimeo.com/38687776
3. Kay Warren, “Puppies Aren’t People: When compassion for animals goes too far,” (Accessed May 22, 2012) http://blog.christianitytoday.com/women/2009/04/kay_warren_puppies_arent_peopl.html. In this essay Kay Warren cites the theological views of her husband Rick Warren.
4. Ann Coulter, Godless: The Church of Liberalism (New York: Crown Forum, 2006), 266.
5. For example a recent group of Genesis interpreters concludes, “Evidence points to the fact that man is a unique creation, made in the image of God.” David N. Menton, “Did humans really evolve from ape-like creatures?” in War of the Worldviews: Powerful Answers for an Evolutionized Culture, ed. Ken Ham, Bodie Hodge, Carl Kerby, et al. (Green Forest, Arkansas: New Leaf Press, 2006), 43-59.
6. Phyllis A. Bird, “Theological Anthropology in the Hebrew Bible,” in The Blackwell Companion to the Hebrew Bible, ed. Leo G. Perdue (Malden, MA: Blackwell 2001), 262.
7. James Barr, “The Image of God in the Book of Genesis: A Study of Terminology, ” Bulletin of the John. Rylands Library 51 (1968-69), 13.
8. Horst Dietrich Preuss, Old Testament Theology, vol 2, trans. Leo G. Perdue (Edinburgh: T & T Clark, 1996), 115
9. Kathryn Tanner, “The Difference Theological Anthropology Makes,” Theology Today 50:4 (Jan 1994), 573.
10. Claus Westermann, Creation, trans. John H. Scullion, S.J. (Philadelphia: Fortress Press, 1974), 57-58.
11. Iain Provan, “The Land Is Mine and You Are Only Tenants (Leviticus 25:23): Earth-keeping and People-keeping in the Old Testament,” CRUX 42:2 (Summer 2006): 5.
12. Claus Westermann, Genesis 1-11: A Continental Commentary, 1st ed. trans. John J. Scullion (Minneapolis, MN: Fortress Press, 1994), 136.
13. Gordon Wenham, Word Biblical Commentary: Genesis 1-15 (Waco: Word, 1987), 61.
14. Provan, “The Land Is Mine and You Are Only Tenants,” 5.
15. Ray Anderson, “Theological Anthropology” in The Blackwell Companion to Modern Theology, ed. Gareth Jones (Oxford: Blackwell, 2004), 85 (emphasis added).
16. Joel B. Green, “Restoring The Human Person: New Testament Voices For A Holistic and Social Anthropology,” in Neuroscience and the Person: Scientific Perspectives on Divine Action, ed. Robert John Russell, Nancey Murphy, Theo C. Meyering, and Michael Arbib (Vatican City State and Berkeley, CA: Vatican Observatory and CTNS, 1999), 5.
17. Lawson G. Stone, “The Soul: Possession, Part, or Person? The Genesis of Human Nature in Genesis 2:7” in What About the Soul?: Neuroscience and Christian Anthropology, ed. Joel B. Green (Nashville: Abingdon, 2004), 50.
18. Ibid., 57.

I want to express my gratitude to those associated with BioLogos for the chance to dialogue with them. I have found their material to be challenging and thought provoking, and look forward to continuing the conversation. In the area of science, to call me a novice would be a kindness, and so to question their evaluation of the scientific evidence for the evolutionary process would be inappropriate for me. However, I do want to raise some questions about their evaluation of theological issues, especially concerning the image of God in humanity. I refer especially to their response to the question, “At what point in the evolutionary process did humans attain the ‘Image of God?’”¹

The BioLogos response begins by correctly noting that the precise meaning of the image of God has been the subject of debate throughout Christian history, but they believe the majority view sees the image of God as “characteristics of the mind and soul,” such as “the ability to love selflessly; engage in meaningful relationships; exercise rationality; maintain dominion over the Earth; and embrace moral responsibility.” They see these characteristics as being acquired through the evolutionary process, though they also state, “We do not know if humanity received the image of God by the immediate onset of a relationship with God or by a slower evolutionary process.” Further, since they identify the image with characteristics of the soul, they add in a discussion of the soul, “We also cannot know whether God directly intervened in the evolutionary process at this point [referencing Gen. 2:7], or whether the unfolding evolutionary process produced the human soul.” It is at this point I wish to question whether or not it is possible for the image of God to be produced through the evolutionary process apart from the special intervention of God. BioLogos seems to lean toward the image being produced through evolution, but is ultimately non-committal on the possibility of divine intervention. I want to argue that there is good reason to argue for the necessity of divine intervention in giving to humans the image of God.

I have no strong objection to the list of characteristics given in the BioLogos response, though I would see most of them as underlying the capacity for relationship with God, which I see as central to the image. Nor do I have any necessary objection to the idea that God used the evolutionary process in developing the brain and other physical abilities of human beings necessary for exercising some of the characteristics involved in the image. Nor do I think that Gen. 2:7 requires the direct intervention of God in implanting the soul (though it certainly allows it). The problem, rather, is in not recognizing that the image of God in Scripture seems rather clearly linked with something immaterial in the human constitution (whether it is called soul or spirit) that could not have come into being by evolutionary processes. My argument for affirming the necessity of direct intervention of God in the creation of humanity in the image of God rests on three assertions. Let me try to state and defend them.

First is the assertion that central to the image of God is the capacity for relationship with God. I do not think this would be rejected by those in the BioLogos community. Within the BioLogos response the phrase “relationship with God” is found numerous times in association with the image of God. They may not like the part about such a capacity being central to the image of God, but the fact that the image of God is what distinguishes humans from other animals in Genesis 1, coupled with the fact that it is humans, and not other animals, who engage in personal relationship with God throughout Scripture, makes a fairly strong case for linking “image of God” to “capacity for relationship with God.”

The second assertion is that this capacity for relationship with God is something that continues after the death of the body, and is associated with something in human beings that continues to exist after the death of the body. Here I recognize that there has been a growing chorus of voices advocating monistic views of the human constitution,² but they all seem to fail to account for the strong biblical evidence for human existence in the intermediate state.³ That which survives death is called the soul in some places (Gen. 35:18; Rev. 6:9-10) and the spirit in others (Eccles. 12:7; Heb. 12:23), but it is identified with the person himself in II Cor. 5:8 and Phil. 1:23. Jesus says to the thief on the cross, “Today, you will be with me in paradise” (Luke 23:43). Both of their bodies would soon be in graves, but the words “you” and “me” seem to affirm an existence apart from their bodies.

The third assertion is that whatever it is in human nature that survives the death of the body (soul or spirit) must be non-material, and could not be produced by the evolutionary process.⁴ Alvin Plantinga, in an argument against materialism, asks, “How could an immaterial soul have come to be by way of evolutionary processes?”⁵ He quotes Richard Dawkins,

Catholic morality demands the presence of a great gulf between Homo Sapiens and the rest of the animal kingdom. Such a gulf is fundamentally anti-evolutionary [and hence wholly heretical?]. The sudden injection of an immortal soul in the timeline is an anti-evolutionary intrusion into the domain of science.⁶

I would change Dawkins’ wording from “Catholic morality” to “The image of God in humans” but the conclusion is the same. I cannot imagine how an immaterial reality, which survives the death of the body, could be produced by natural processes, such as evolution, even God-guided evolution. I do not think this is a God-of-the-gaps argument that could eventually fall to advances in science, but a logical argument, based on the intrinsic difficulty of seeing how the natural and mortal could produce something immaterial and capable of surviving the death of the body. Even if someone were to question my association of the image of God with the spirit or soul (assertion 1), I would argue that the mere existence of an immaterial spirit/soul that survives death (assertion 2) yields the same necessity of divine involvement in the creation of the immaterial aspect of human nature (assertion 3), which is my chief contention.

Notes

1. Subsequent references are taken from the response given at http://biologos.org/questions/image-of-god, accessed 10/14/2011.
2. Joel Green has been perhaps the most prominent voice advocating monism (see Joel Green, Body, Soul, and Human Life: The Nature of Humanity in the Bible [Grand Rapids: Baker Academic, 2008] and Joel Green, ed., What About the Soul? Neuroscience and Christian Anthropology [Nashville: Abingdon, 2004]), though a similar view has been affirmed by a number of his Fuller Seminary colleagues who advocate a “non-reductive physicalism” (see Warren S. Brown, Nancey Murphy, and H. Newton Malony, eds., Whatever Happened to the Soul? Scientific and Theological Portraits of Human Nature [Minneapolis: Fortress Press, 1998). For a more complete presentation of views, see Joel Green, In Search of the Soul: Four Views of the Mind-Body Problem (Downers Grove, IL: InterVarsity Press, 2005).
3. John W. Cooper, Body, Soul & Life Everlasting: Biblical Anthropology and the Monism-Dualism Debate (Grand Rapids: Eerdmans, 1989) gives a strong defense for dualism primarily from the evidence in Scripture for the intermediate state.
4. I recognize the objection here of William Hasker and the idea of emergentism, or emergent dualism, in which a distinct soul or self emerges from the complex configurations of the biological organism, similar to magnetic fields generated by physical objects but distinct from them. See Hasker, The Emergent Self (Ithaca, NY: Cornell University Press, 1999), for the fullest presentation of his view. The difficulty of his view lies in attributing to material stuff the power to generate a non-material reality. This difficulty is raised by Alvin Plantinga (see n. 5 below) and others and emergent dualism is as of today still a minority view in philosophical circles.
5. Alvin Plantinga, “A New Argument Against Materialism” (plenary address for the Evangelical Philosophical Society, Atlanta, GA, 18 November 2010).
6. Ibid. No source for Dawkins is given.

Evolution: just a theory

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

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

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

Whale evolution: an example of converging lines of evidence

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

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

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

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

Going out on a limb

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

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

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

… and passing the test

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

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

For further reading

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

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

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

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

Transcript

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Today's video features biologist Kerry Fulcher and is courtesy of filmmaker Ryan Pettey, director/editor of Satellite Pictures.

In today's video, Kerry Fulcher discusses the idea of viewing creation as a constant, evolving process in which God is intricately involved, rather than a single explosion of creation a long time ago. When we get stuck on the idea of having biological ancestors, Fulcher says, we can miss the point that being made in the image of God is a relational quality, not a biological trait. It means that we can communicate and have a special relationship with God, and we can reflect his character and represent him to the rest of creation.

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.