The creation/evolution controversy has a long history of loud debate. Young-earth creationists and atheists alike have recognized that origins positions entail sobering consequences for morality and eternity. For young-earth creationists, the integrity of Scripture is at stake. If Genesis falls, what basis for godly living exists? If Adam never lived, what basis does the gospel have? Unbelievers also recognize this fact. Some have even publicly announced their desire to see the Bible fall—in order to justify an immoral lifestyle. With such high stakes, the fever pitch to which the origins debate has risen should be no surprise.
The theistic evolution (a.k.a. “evolutionary creation”) organization BioLogos1 has explicitly sought to quell this tone. Styling themselves as a bridge between the worlds of science and faith, the members of BioLogos have positioned themselves as the moderate voice in a raucous dispute. For example, in their approach to dialogue, they emphasize having a conversation rather than having a debate.2 In addition, they list as one of their core commitments “humility and gracious dialogue with those who hold other views.”3 BioLogos presents itself as a calm alternative to agitated and polarized extremes.
Not surprisingly, Duff’s article explicitly and exclusively focuses on criticizing the YEC view of speciation, rather than on supporting the evolutionary view.
In light of this background, a recent essay titled “Did Modern Animals Evolve From the Inhabitants of the Ark?”4 is puzzling. The author of the essay, Ph.D. biologist Joel Duff, is a member of the BioLogos Voices, a group of speakers who “personify the BioLogos mission of presenting harmony between science and faith.”5 Independent of BioLogos, Duff has a long history of attacking young-earth creation (YEC) science on his personal blog.6 Not surprisingly, Duff’s article explicitly and exclusively focuses on criticizing the YEC view of speciation, rather than on supporting the evolutionary view. Duff’s answer to the question in the title of his post is a clear “no.”
Prior to Duff’s post, I published five technical papers and at least eleven lay-level articles on post-Flood speciation (see here for links to both types)—all freely accessible and not hidden behind a paywall. In total, on the Answers in Genesis website I have around 90,000 words in print on this topic alone. Duff’s critique of YEC science offers a unique window into how much listening BioLogos has done to their opponents, as well as how much they have tried to understand the YEC model.
Objections based on history
Duff’s objections to the YEC model of speciation fall into three categories—historical, biblical, and scientific. Historically, Duff sees the current young-earth model of speciation as a recent invention and, therefore, questionable. For example,
I had an opportunity to tour the large timber-framed model of Noah’s Ark [at the Ark Encounter] in July. The reconstruction of the Ark is truly an impressive structure. But is it really big enough to house representatives of every animal on Earth? That depends partly on the interpretation of one Hebrew word: min.
When modern young-earth creationism, then called deluge geology, was founded by Seventh Day Adventists, the term min was employed to solve the problem of too many species by equating the term to that of groups of species we categorize as genera. Today, Answers in Genesis continues that tradition but greatly expands the boundaries of a min by proposing that a min is equivalent to a much broader taxonomic category. Rather than species or even genera, a min is said to be roughly equivalent to what scientists recognize as a family (e.g., great apes, canines, bears) and possibly even an order (e.g. bats). Therefore, a single min could represent 10s, 100s or a thousand modern species of animals.
To Duff, this is suspicious:
Significantly, no one ever proposed rapid post-flood speciation in the 6-day creation model prior to Darwin. The Scriptures do not demand this modern interpretation of a biblical “kind”, nor has the church historically understood that hundreds of species evolved from common ancestors that God created and preserved on the Ark. Only when the Ark got too small – because of scientific discoveries – to hold all of God’s created animals did the alternative hypothesis become necessary. Ironically, this approach openly involves adjusting an interpretation of the Bible to respond to modern scientific discoveries, which is exactly what young-earth creationists routinely accuse non-YECs of doing.
Duff makes several claims in these paragraphs. From accusing YECs of hypocrisy to pitting YECs against church history to impugning the motives of YECs, Duff levies several strong criticisms. At Answers in Genesis, we recognize our own sinfulness and weakness, and we freely admit that we are in the process of sanctification. We take indictments of our character and practice very seriously. Duff’s claims are worth exploring in detail.
Let’s begin with his contrast between YEC practice and church history. Is the relative novelty of the detailed specifics of the YEC position on speciation a good reason for skepticism?
One way to test the logic of Duff’s argument is to apply it to a question on which we can all agree. Let’s apply it to a question of Christian morality to which the answer is obvious. On the question I’m about to raise, Duff and I would find no disagreement.
For example, Duff and I would both strongly denounce internet pornography. However, only in the last few decades have Christians objected to internet pornography. In other words, if you exhaustively search Church history, you won’t be able to find a single example of a church father denouncing internet porn. Therefore, the sinfulness of internet porn is a recently adopted Christian position.
Does that mean we should rush to view X-rated material, titillate our senses, and gorge our sexual appetites with images of people other than our spouse? Should we impugn the motives of those who oppose internet pornography? If we logically extend Duff’s reasoning on speciation to questions on pornography, we might embrace internet porn and criticize those who oppose it. Obviously, this would be erroneous and sinful. Undoubtedly, in response to the questions at this beginning of this paragraph, Duff would vigorously answer in the negative.
Then where did Duff go wrong in his speciation argument? The analogy to pornography illuminates the answer. The recent origin of objections to internet porn do not stem from a sudden discovery of a new interpretation of an obscure Scriptural passage. It’s not that science has now discovered harmful effects of porn and the church is backtracking to reinterpret the Scriptures to fit modern scientific claims. Rather, internet porn itself is a recent invention. Objections to it arise from an ancient text—Jesus’ teaching on lust in Matthew 5:27–30. Only the application of Jesus’ words is new, not the interpretation.
The YEC speciation model is a recent invention because species themselves are recent inventions.
Similarly, the YEC speciation model is a recent invention because species themselves are recent inventions. I don’t mean that the creatures are recent. The species concept as we understand and use it—and as Duff uses it—is a recent invention. Modern taxonomy didn’t begin until Carl Linnaeus published his Systema Naturae in the 1700s. Furthermore, Linnaeus’ understanding of species was a far cry from what we understand today. For example, in 1758 only 154 of the modern mammal species were recognized.7,8 In 1859, the year in which Charles Darwin first published On the Origin of Species, only 1,780 modern mammal species were documented.9 Today, over 5,400 living mammal species have been documented.10
Actually, what I’ve just described is overly generous. Just because a scientist documents a new species somewhere doesn’t mean that the scientific community as a whole is aware of it. The process of communicating new discoveries takes time. As an example, consider standard mammalian reference texts as a surrogate for the general understanding of the scientific community. In 1993, one such text11 listed only 4,629 mammal species—even though 5,186 species were technically documented.12 Just 12 years later, the same text was updated to include over 780 additional mammal species, bringing the total to 5,416.13 When we count species and seek to explore their origins, we are doing so with a recently invented concept.
Therefore, it would have been impossible to apply the interpretation of min to “species” before Linnaeus. Before the 18th century, theologians would not have been able to apply min to a certain number of species, genera, or families because such classification categories didn’t exist in the biology of that day. Only when hundreds and thousands of creatures were brought into the public consciousness could the application of min begin.
This recent history of “species” delayed the application of min for a second reason. As my published literature (e.g., see here) demonstrates, we can infer from the plain statements of Genesis 6 and 7 that interbreeding is a good first-step test for identifying what min are. Imagine trying to apply this test in the 18th century. You couldn’t even ask if two species could interbreed because most “species” didn’t exist. Only when they entered the modern scientific consciousness could rational scientific tests—fertility experiments—be conducted to answer the question of whether more than one species constitute a min.
Furthermore, breeding tests take time and effort. It has taken many years to organize a large enough group of YEC scientists to systematically document the full extent of breeding compatibility among species. The application of min has followed as the data have been collected.
Duff has confused biblical interpretation with biblical application—a fundamental hermeneutical and logical oversight. Sadly, Duff should know better. In his own article, he tacitly acknowledges the facts I’ve just described:
In the 18th century, the known number of land animal species was much smaller than today.
Not only is Duff’s historical objection to young-earth speciation logically deficient, it’s undermined by Duff’s own statements.
Consequently, Answers in Genesis did not engage in “adjusting an interpretation of the Bible to respond to modern scientific discoveries.” Instead, we maintained a consistent interpretation of the Scripture (see below), and the applications of this position changed as the scientific community made discoveries. Christians have done the same thing with lust. The interpretation of Matthew 5:27–30 has been consistent for 2,000 years; the applications of this passage have changed as technology has advanced. Interpretation and application of Scripture are two very different processes, and Duff confuses the two.
Interpretation and application of Scripture are two very different processes, and Duff confuses the two.
Duff’s error points to something bigger than a simple hermeneutical slip. Since biblical hermeneutics has been a flash point in the origins debate for decades, YEC proponents have volumes of literature on this topic. It’s difficult to sit through a YEC conference or to digest several YEC books without coming away with a clear understanding of good hermeneutical practice. Duff’s error raises the question of his familiarity with the literature of his opponents.
What could Duff have done differently? Good scholarship demands fluency in an opponent’s views—such that one side of a controversy can accurately derive and describe the position of the other. This level of engagement would have prevented the elementary mistakes that Duff makes.
Finally, Duff’s errors reflect on BioLogos as an organization. Again, Duff is a member of the BioLogos Voices, and the BioLogos website prominently featured his blog. Were BioLogos more familiar with our literature, they would not have endorsed Duff’s logical faux pas.
Objections Based on Scripture
Duff also finds fault with the biblical derivation of the concept of kinds. As the quotes above show, Duff thinks the rough equivalence of kind (Hebrew = min) with the classification rank of family (or maybe even order) is an after-the-fact fitting of Scripture to science. Since this is the very practice for which Answers in Genesis criticizes evolutionists, Duff’s accusation carries even more weight.
The problem with his assertion is that it’s factually in error. For example, in the lay-level article series on speciation that I published prior to Duff’s post, one of the articles explicitly derived the concept of kinds. From the Scriptural text alone, I derived a test by which kinds could be recognized. Applying this test to species (something we can do in the 21st century, thanks to Linnaeus’ work) leads to the modern concept of kinds. It’s impossible to read my article and walk away thinking that young-earth creationists fit Scripture to science, rather than starting with Scripture and interpreting the world through it. Either Duff is being dishonest, or, more likely, he’s ignorant of young-earth creationist literature.
Again, this pattern is troubling. Good scholarship prevents factual errors like the one that Duff makes. If BioLogos had engaged our literature before publishing a critique, they could have saved themselves from this misstep.
Again, at Answers in Genesis, we welcome the process of iron sharpening iron. We desire to uphold the integrity of the Scriptures in all that we do, and we zealously wish to conform our practices to the explicit teachings of the Bible. The types of charges that Duff levies represent claims that we take very seriously. Unfortunately, on two counts, Duff’s criticisms appear to reflect more on BioLogos’ standards of engagement rather than on our character and practice.
Objections Based on Science
Speciation in the Recent Past?
The scientific problems that Duff finds with the YEC view of speciation all revolve around the concept of min. While none of his claims rise to the level of impugning character, motives, or Scriptural fidelity, we seek truth in our scientific practice, and we desire factually honest presentations of scientific findings. Furthermore, as I mentioned earlier, I have a massive body of published scientific claims on speciation. If I’ve made mistakes, I earnestly would like to correct them.
To his credit, Duff maintains an elementary understanding of the most central concept within the YEC speciation model:
A necessary consequence of this modern young-earth interpretation [note Duff’s erroneous word choice] of min was that the species you and I recognize today are not what God created and preserved on Noah’s Ark. Rather a representative pair of ancestors to all species of each min are said to have been on the Ark. Thus, those ancestors must have given rise to many distinct descendant lineages that we call species today.
Thus, despite his missteps on hermeneutics, Duff grasps the scientific significance of the YEC teaching on the meaning of min. The significance is what Duff finds so objectionable.
If there were only 1400 or fewer “kinds” on the Ark, as claimed on the Ark Encounter, and today there are more than 34,000 land-animal species and countless additional extinct species, is there evidence for this sudden appearance of thousands of new species over just hundreds of years? Absolutely none. [Emphasis his] Scientists and natural philosophers in the 17th and 18th centuries (long before Darwin) did not document new species forming before their eyes, nor have the tens of thousands of species they described changed into new species since then.
Again, Duff lumps several criticisms into a single paragraph. Let’s carefully explore each in turn.
First, are there “countless additional extinct species” as Duff claims? Public databases of fossils exist14 and are searchable. If you search for mammals (one of the best fossilized classes of vertebrates—animals with backbones), you get less than 16,000 unique species entries.15 Some of these species overlap with modern species. But even if they didn’t, all the documented mammal species that ever existed would amount to less than 25,000 (i.e., 16,000 + 5,416 = 21,416, which is less than 25,000). Furthermore, reptiles, amphibians, and birds together contain less than 30,000 living species,16 and less than 10,000 fossil species.17 Even if we assume that the number of fossil amphibian, reptile, and bird species will increase by around 350% (i.e., bringing the number of fossil species in each class closer to the mammalian number of 16,000), all the documented mammal, reptile, amphibian, and bird species that have ever existed amount to less than 100,000.18 This number is a far cry from the millions of total species (animal, plant, fungal, and microbial) alive today. In short, generous overestimates of fossil numbers predict a modest number of post-Flood speciation events.
Second, what about Duff’s claim that “scientists and natural philosophers in the 17th and 18th centuries (long before Darwin) did not document new species forming before their eyes”? We should first ask how these 17th and 18th century scientists and natural philosophers could have done this experiment. Again, mammals provide an excellent test case.19 With 5,415 mammal species alive today20 and a post-Flood time period of around 4,500 years,21 an average of 1.2 new mammal species would be predicted to form per year (5,415 / 4,500 = 1.2). In 1758, 154 of these mammal species were recognized.22 By 1799 (the end of the 18th century), 468 mammal species were documented. In 42 years encompassing these two dates, according to the predictions of the YEC model, 50 mammal species should have formed (42 * 1.2 = 50.4). Yet, in 1799, over 91% (5,415 – 468 = 4,947) of today’s mammal species were unknown to science. It’s rather difficult to document the formation of a new species, when you aren’t even aware of the existence of >85% of their ancestors.23
Again, Duff’s own statement earlier in his article implicitly acknowledges this fact. Yet he ignores or forgets it by the time he criticizes the YEC model on scientific grounds.
Third, what about his claim “nor have the tens of thousands of species they described changed into new species since then”? Using mammals as a representative dataset, what would the formation of new species look like? Again, using the predicted rate of 1.2 new species per year from 1800 to 2016, about 260 new species should have formed (217 years * 1.2 species per year = 260.4 new species). Yet, in this same time period, 4,947 new mammal species were described. The rate of species documentation far exceeds the predicted rate of species formation.
How can we distinguish speciation events from discovery of pre-existing species? Since Duff is the one asserting that absence of evidence for species formation, he should supply the criteria. He has to separate—without ambiguity—the formation of 260 new species from the documentation of nearly 5,000. The signal-to-noise ratio confronting this task is not encouraging.
His article contains no proposed methodology.
At least six different definitions of species exist.
Another potential reason that his article lacks such tests might be the nebulous concept of species. At least six different definitions of species exist. By the way, this isn’t an obscure claim buried in an isolated journal; it’s textbook evolutionary science.24 How can you unambiguously document the formation of a new species if the concept itself is fluid?
To practically illustrate this challenge with a singular example, take a look at the pairs of individuals below. One pair represents two subspecies within a single species. Another pair represents two species within the same genus. (I’ll let you look up these images yourself to find out which is which.) If the two individuals currently identified as subspecies are eventually reclassified as separate species, will we have witnessed the kind of evidence that Duff requires? Will he acknowledge that speciation is happening before our eyes? Or will he insist that only a bookkeeping change has occurred?
The example I chose is significant for another reason. When a population of individuals moves from subspecies status to species status, it’s not just classification nerds who should care. I’ve published a model of speciation previously, and this type of classification change exactly fits the mechanism I’ve proposed.25 In other words, the movement of populations from subspecies status to species status represents exactly the type evidence I’d predict to see as a result of the operation of this mechanism.
What makes Duff’s assertion even more problematic is the fact that subspecies aren’t rare phenomena. To appreciate how pervasive subspecies are, consider the number of extant mammal species—5,415. The number of mammal subspecies? 6,348.26 In other words, more subspecies exist than actual species. These subspecies are also fairly well distributed among mammal species; nearly one fourth (24%) of all mammal species have subspecies.27 (You might ask: How can over 6,300 subspecies exist, and yet belong to just 1,310 (24%) species? Many species have several subspecies.) Separating discovery of preexisting species from bona fide speciation events is much harder than Duff’s strong assertion implies.
Yet another challenge confronting Duff’s criticism is the taxonomic distribution of species within families (i.e., kinds). As I’ve published previously,28 the rate of speciation within a family is predictable from the current number of living species within a family. In other words, the most speciose families alive today also speciate at the highest rates.
Since 1799, which mammal families would have participated in predicted formation of 260 new species? At a minimum, a family would have to have enough species to form at least one every 217 years (2016 – 1799 = 217 years). Conversely, the predicted rate of speciation is the current number of species divided by the post-Flood time period. Using this equation, how many species must a family possess in order to produce at least one new species every 217 years? At least 21 species (1 species per 217 years * 4,500 years = 21 species). Of the 153 documented mammal families, only 44 (i.e., 29%) have 21 or more species.
To produce just 3 new species in 217 years, a mammal family would have to possess at least 62 species (3 species per 217 years * 4,500 years = 62 species). Only 16 mammal families (i.e., 10%) contain 62 or more species.
In short, the most speciose families would contribute the most new species in the 217 years since 1799. Of the predicted 260 species formed since 1799, the seven most speciose mammal families would be responsible for over half (i.e., 136 species).29 These seven families consistent of four rodent families (2 mouse families, a shrew family, and a squirrel family) and three bat families. In other words, the majority of predicted speciation events would come from creatures of small size.
To unambiguously separate speciation events from species discovery, the complete tallies of the genetic and morphological varieties in each of these families would have to be tracked consistently on a global scale. Why? The published YEC speciation model30 that we’ve been exploring shows that the rate of speciation per species is declining. As more species form within a family, the chance that any one particular species will form another goes down. Thus, global tracking rather than regional tracking is a must.
As a practical example, consider the most speciose mammal family of all, Muridae (a mouse family). It contains 730 total living species.31 Over the last 217 years, the YEC model predicts that 35 new species formed.32 In other words, in 1799 only 695 murid species would have existed, and since then 35 new species would have been added to this total.33 Since new species come from preexisting species, within the last 217 years a maximum of 35 of these 695 species would have formed a new species. In other words, a maximum of only 5% of the total murid species would have undergone a speciation event—at least 95% would not. To put it in statistical terms, if all you did over the last 217 years was track a single species of mouse with a regional geographic distribution, there’s a 95% chance you would see no speciation occur—and this is what the YEC model predicts, not Duff.
Thus, to rigorously demonstrate that, within the seven most speciose families, no new species formed within the last 217 years, an investigator must simultaneously track all species within these families on a global scale. Obviously, given the small size and fast reproductive rates in these types of creatures, this type of global tracking represents an extremely difficult task. For Duff to assert that no speciation events have occurred in these families within the last 200 years, he has to claim nearly supernatural abilities for the scientific community as a whole.
Of the remaining speciation events, most would be fairly rare on a per-family basis. Aside from bovids (seven predicted speciation events), Old-World monkeys (six predicted speciation events), and another bat family (five predicted speciation events), the remaining speciating mammal families would each contribute four new species or less. This small number of speciation events would be all the more difficult to distinguish from the massive amount of new species documentation.34 Separating new species formation from documentation of existing species is a tall order.
Rather than engage what I’ve published and constrain his criticisms by what we actually believe, Duff acts as if my published literature doesn’t exist.
Unfortunately, Duff gives no evidence of having wrestled with any of these challenges. Instead, he made blanket statements without any scientific data to support his claim. Furthermore rather than engage what I’ve published and constrain his criticisms by what we actually believe, Duff acts as if my published literature doesn’t exist.
This sad discussion reflects very poorly on BioLogos’ standards of scholarship. The challenges I’ve identified are not obscure, hard-to-derive problems with Duff’s assertions. Rather, they represent minimal next-step investigations from publicly available data—data in both my published literature and the evolutionary literature. To strive for dialogue, BioLogos needs to do much more than publish knee-jerk broadsides at their opponents.
Biblical constraints on speciation?
Duff’s scientific criticisms extend to biblical data as well:
Importantly, the Bible also paints a picture of species living thousands of years ago that display characteristics that we observe today. Old Testament passages refer to foxes in Israel and describe their behavior in ways that are strikingly similar to the red fox species that live there today (see Song of Songs 2:15; Ezekiel 13:4; Matthew 8:20). Wolves and domestic dogs are also referred to in the Bible and ancient Near-Eastern literature in terms familiar enough to identify them. And this is only a sampling of the familiar animals mentioned by the Bible whose descriptions correspond well with modern species. This is a strong biblical testimony to the consistency of species boundaries over long periods of time.
In this objection, Duff acts as if the appearance of one species in a min implies that all descendants of the min must have, therefore, formed as well. Instead, as I detailed in a technical paper, new species form in a temporal order, implying that some modern species split off early from the min ancestor while others split off late. In other words, the early appearance of some modern species is exactly what my model predicts.
Furthermore, in this same technical paper as well as in the lay literature, I have already rebutted his points explicitly and in much more detail than I’ve given here. Again, since he fails to interact with either of these sources of YEC information, he supplies no evidence that he’s even aware that these bodies of written material exist.
As a side note, Duff sees a pattern in the YEC speciation model that sounds (to him) very suspiciously like evolution:
This origin of species from a common ancestor [on board the Ark] occurred by evolutionary processes. This is made clear by an exhibit on the Ark Encounter where we learn that, “species give rise to new species, modified characteristics develop over time, and the fittest animals survive.” This is a reasonable description of Darwin’s explanation for the origin of species by means of natural selection. Many visitors to the Ark Encounter may be surprised to discover exhibits which embrace Darwin’s mechanism – natural selection – for producing new species albeit with some strict limits. Along with other natural mechanisms of change the Ark Encounter has proposed what I call a “post-flood rapid speciation model” of modern biological diversity to solve the problem of the limited dimensions and manpower of Noah’s Ark.
In reality, creationists have embraced natural selection—and its profound limits—for decades. “Natural selection is not evolution” has been a textbook teaching point for Answers in Genesis and YEC scientists for years. The only people who will be surprised are those who have paid little attention to YEC.
Furthermore, Duff’s blanket statement above reveals his unfamiliarity with the YEC technical literature. “This origin of species from a common ancestor [on board the Ark]” did not occur “by evolutionary processes.” Do we invoke natural selection? Sure we do—the placards right next to the one that Duff photographed and included in his article explain our position clearly. So what is Duff missing? A gigantic difference between YEC and evolution traces to the source of genetic variety we see today. As I published previously and discussed in great depth,35 Darwinists think all genetic differences are due to mutation; I have argued that most differences between species are due to shifts from heterozygosity to homozygosity—a technical term implying that God created kinds with built-in genetic diversity (see here and here for lay-level explanations of this concept). This singular difference in the source of genetic variety has massive consequences for how new species can form and for the limits to speciation. Duff doesn’t appear to have read this paper. If he has, he’s deliberately clouding the clear and enormous distinctions between YEC and evolution by his shallow descriptions.
Returning to Duff’s overall point, is there really no evidence for rapid speciation, as Duff asserts? The lay-level summaries of the technical papers that I’ve written (see here for links) on this topic discuss multiple lines of evidence that support the YEC model—everything from Darwin’s own writings to modern genetics. Since Duff makes no attempt to interact with this literature, we have no evidence that he’s aware of it.
A final objection that Duff raises to the YEC speciation model comes from the way in which we use breeds as an analogy for the speciation process.
For the non-scientist, domestic dogs provide powerful imagery for the potential of natural selection to produce many different forms in a short period of time. However, like so many other young-earth arguments, it is a case of describing apples and then suggesting that oranges are the same thing.
The origin of dog breeds from a single species of canine isn’t comparable, temporally or mechanistically, to the origin of multiple canine species.
Before we explore the reasons Duff gives to justify his claim, let’s first consider the danger of his sentence. It’s dangerous because breed-species analogies didn’t originate with modern YEC scientists. Darwin himself used breed-species analogies to argue for common ancestry of species and for the ability of natural selection to play a role in the speciation process.36 To this day, prominent evolutionists like Richard Dawkins use the process of artificial selection in breeds to argue for the plausibility of natural selection in the wild.37 If all Duff did was dismiss breed-species comparisons with unqualified blanket statements, Duff would be contradicting his fellow evolutionists.
As an example, consider the following paragraph from Duff:
Equating dog diversification and canine speciation also fails in one other important way: dogs breeds have been “created” not by natural selection but by artificial selection. Domesticated animals have been derived through an intensive process of selection that frequently results in the opposite of what “nature” might do. Artificial selection is an unnaturally strong force that results when a few individual traits are chosen to the exclusion, and sometimes detriment, of hundreds of other characters. For example, spots are selected to make a Dalmatian without considering other characters like deafness that might be linked to the character of interest. Selection, operating in nature, would not exclusively select a character like spot shape or color over a more important character for its overall survival—the ability to hear.
Now go and read Darwin’s analogies between artificial selection and natural selection. Read Dawkins’ attempts to illustrate one with the other. Then read Duff’s paragraph above every time you run across these analogies. Duff is dangerously close to undermining his own evolutionary model.
The recent origin of breeds shows the sufficiency of the YEC timescale for speciation within families.
How does Duff avoid the contradiction? What specific evidence would Duff need to find in order to reject the creationist use of the breed-species analogy? Let’s consider the limited options Duff has at his disposal. As I’ve published previously (both at the lay level and technical level), the recent temporal origin of breeds argues for the plausibility of rapid speciation. Specifically, breeds have tremendous morphological variety (e.g., the 344 dog breeds recognized today38), yet they originated very recently. In contrast, species have less variety than breeds (i.e., only 35 living species of canids exist39)—surely they could form in a short amount of time as well! In other words, since lots of variety can happen quickly, then of course a little bit of variety can happen in the same amount of time (longer periods of time for speciation make the task even easier). In technical terms, the recent origin of breeds shows the sufficiency of the YEC timescale for speciation within families. To contradict this analogy, Duff would have to show that species took less time to form than breeds did.
Here’s his first justification:
Nor is there biblical or other historical eye-witness reports to support this speculative inference of rapid speciation. To the contrary, the fossil record of canine and vulpine species we see today reveals that most modern species – e.g. coyotes, wolves, foxes, jackals, Dholes, etc. – have existed much as they appear today for many thousands of years. Likewise, Answers in Genesis appeals to gross visual differences between organisms to make their case that the external appearance of a species is but a small part of its biology. Vast quantities of genome/DNA data are available for many canine species. Even a cursory examination of this data reveals that domestic dogs are remarkably similar to one another genetically – far more similar than humans are to one another—confirming their wolf subspecies status. On the other hand, wolves are much more genetically diverse than domestic dogs, even though they appear—superficially—to look rather similar to one another. When other species of canines are compared, genetic differences become far more pronounced. So pronounced, in fact, that the differences between chimpanzees and humans look small in comparison.
You could say the difference we see in domesticated dogs are only skin deep, and thus it would be foolish to use those differences to build an argument for recent common ancestry of hundreds of species.
With respect to Duff’s claims about the biblical and historical eyewitness evidence, we have already dealt with them above, and we observed that Duff didn’t do his homework on either.
What about the fossil evidence? Duff doesn’t seem to be trying to argue that species formed more quickly than breeds. Instead, he seems to be arguing that many species have been around longer than breeds. Since no creationist disputes this, this is irrelevant to his attempts to dismiss the breed-species analogies.
Duff then takes his argument a different direction. He compares genetic differences among canid breeds and species to the visible differences among breeds and species. Duff claims the former far outstrips the latter.
Unfortunately, Duff doesn’t specify at which level he’s performing a genetic comparison. DNA sequences exist in two compartments in the cell, the nucleus and mitochondria (see here for lay-level explanation), and these sequences can be compared between populations or within individuals (i.e., because two different copies of nuclear DNA exist in the cell; see here for lay-level explanation). Nevertheless, we can evaluate each potential comparison in turn and evaluate the ramifications of each for Duff’s claims.
Let’s say that Duff meant that the DNA differences in the mitochondrial DNA among breeds are smaller than the mitochondrial DNA differences among species (a true statement). Since mitochondrial DNA acts like a clock (see here for multiple links), this would imply that species have been around longer than breeds. Since no creationist disputes this, this is, again, irrelevant to his attempts to dismiss the breed-species analogies. Conversely, the rate at which the mitochondrial DNA clock ticks is powerful evidence that confirms the YEC timescale of speciation and rejects the evolutionary timescale. Duff doesn’t have much evidence to support him here.
If Duff did indeed mean mitochondrial DNA differences, this might explain why he referenced human and chimpanzee genetic comparisons in his argument. On his personal blog, he’s tried to argue that mitochondrial DNA differences among members of an Answers-in-Genesis-accepted min exceed the genetic differences between humans and chimpanzees. Since YEC scientists claim that species within a min have a common ancestor but that humans and chimpanzees have separate ancestors, Duff sees an inconsistency in the YEC model. Duff thinks this fact undermines the evidence for the YEC post-Flood speciation model.
Not surprisingly, this claim is yet another example of Duff’s ignorance of the literature. In the few species in which the mutation rate has been measured (nuclear or mitochondrial, it makes no difference), various species have contrasting rates of mutation. Naturally, this would lead to a disparity in genetic differences among diverse groups of creatures. With respect to mitochondrial DNA mutation rates in particular, as compared to other species, humans mutate rather slowly on a per-year basis. Hence, it would be no surprise to find that intra-min mitochondrial DNA differences exceed human-chimpanzee mitochondrial DNA differences. Furthermore, these mutation rate facts are published in the secular literature—Duff should know better. Even if he didn’t, all he had to do was read my technical papers, in which I fastidiously referenced these secular studies. In other words, different mutation rates in different species is not a YEC-specific, anti-uniformitarianism argument. It’s an empirical observation from secular studies.
One last curiosity about mitochondrial DNA: If Duff is attempting to discredit the YEC model of speciation, why focus on mitochondrial DNA? After all, I haven’t proposed that changes in mitochondrial DNA drive speciation. I’ve proposed that changes in nuclear DNA drive rapid speciation.
What if Duff meant that the DNA differences in the nuclear DNA among breeds are smaller than the differences among species? First, the differences aren’t as big as he implies later in his article (see below). Second, if Duff were familiar with my technical paper, he would know that nuclear DNA differences are not a straightforward marker of time in the YEC model. So if his point is about the temporal order of appearance of species, he has picked a complicated tool. Even if the tool were straightforward, YEC scientists agree with him that species have been around longer than breeds.
Third, with nuclear DNA, Duff has really only one way in which he can try to undermine the breed-species analogy that YEC scientists use. As I detailed in my technical paper, the primary mechanism by which speciation occurs under the YEC model is not mutation and natural selection. It is shifts from heterozygosity to homozygosity (see here and here for lay-level explanations of this concept). If Duff wants to argue that breeds are a poor analogy for species, then he needs to compare heterozygosity levels in breeds and species. If he wants to show “skin deep” differences, he needs to make his comparison at the level of heterozygosity for it to be relevant to the YEC speciation model. Furthermore, since breeds have more morphological variety than species, he needs to show that species have less heterozygosity—less potential for morphological variety—than breeds do.
In fact, dog breeds and canid species have overlapping levels of heterozygosity—with slightly higher levels of heterozygosity in species.40 Consider the implications of this fact: Humans have produced tremendous morphological variety among domestic breeds—much more variety than exists among species in the wild—and they did so by starting with genetic variety that is comparable to that in the wild. In other words, species still have the potential—today!—to produce as much morphological variety as exists among domestic breeds. All that is needed is a shift from heterozygosity to homozygosity in a few individuals, followed by the isolation of these individuals from the remaining heterozygous individuals to form new populations (a process I explained in lay-level terms here). In other words, breeds are the near-perfect analogy for the speciation process. To adopt Duff’s terms, the breed-species analogy is about as close as one can get to an apples-to-apples comparison.
Is there anything else that Duff could cite to contradict this YEC conclusion? In subsequent paragraphs, Duff tries to make an indirect argument from the differences between natural selection and artificial selection:
Natural selection rarely, if ever, selects for single or even a few traits to the exclusion of all other traits. Natural selection takes into account the entire organism, and individuals with the best combination of hundreds of genes that contribute to overall fitness are selected. In nature, then, selection on a single gene variant is rarely very strong. As a result, significant changes in allele frequencies (different traits) of multiple traits in nature usually require thousands of generations to be observed. The upshot of this is that natural selection usually takes a long time to shape populations.
Has Duff found a problem that we’ve overlooked? Had he read my technical paper, he would have found an entire section devoted to population growth calculations, models of natural selection in specific mammal families, and extensive mathematical arguments for a very limited role for natural selection in the post-Flood speciation process. In other words, he would have found that I concluded something similar to him.
The abilities of these processes are so strong that the plausibility of post-Flood speciation isn’t even a valid question anymore.
If natural selection takes a long time to lead to speciation, what are creationists left with? I detailed an answer in my technical paper. In short, the population genetic processes of inbreeding, small population sizes, and migration/geographic isolation—in technical terms, shifts from Hardy-Weinberg equilibrium—could produce enormous species diversity in 4,500 years or less. (For a lay-level explanation of this, see this previously published article—appropriately titled, “Did Natural Selection Play a Role in Speciation?”) In fact, the abilities of these processes are so strong that the plausibility of post-Flood speciation isn’t even a valid question anymore. Instead of trying to ask if any species could have arisen in a few thousand years, we may as well ask why more species haven’t done so!
Duff then finishes his objections with a very unusual paragraph:
Canine species such as coyotes, wolves, and dholes and vulpines such as red foxes differ not just in a few places in their genomes (like domesticated dogs) but at hundreds of thousands of locations throughout their genome. Hence, foxes and coyotes are most certainly separate species by any definition. They have achieved complete genetic separation since their origins from a common ancestor. Domestic dog breeds are not different species. Collectively, they aren’t even a distinct species from wolves, despite more than 10,000 years of intensive selection! This explains why descriptions of animals and plants of the Old Testament match those of animals and plants alive today. The space of 4000 years is simply not enough time for significant changes to have taken place in most species.
It appears that Duff is trying to make a genetic argument for the length of time that speciation required. He seems to suggest that speciation has taken enormous amounts of time and, therefore, cannot be compared to the process of forming breeds. However, he does so by assuming that nuclear genome differences are a straightforward, simple marker of time. In effect, he assumes away the model that I’ve proposed before then trying to scientifically criticize it. This is circular reasoning.
By the way, all Duff had to do was read the subtitle of my article to be tipped off to my position. “Created heterozygosity” is a technical term that means that God created many min with preexisting nuclear genome differences. If he had read the paper, he would have discovered that I have proposed that the vast majority of nuclear genome differences stem from creation, not mutation. Therefore, raw genome differences are not a marker of time under the YEC model. By assuming that raw genome differences are a marker of time, Duff has assumed evolution before trying to scientifically reject YEC.
In addition, Duff assumes a domestication timescale—10,000 years—that is based on the assumption of the evolutionary timescale. In other words, he assumes the evolutionary timescale, before then turning around and trying to use this “fact” as a scientific argument against the YEC timescale. Two circular arguments do not make a logical whole.
Finally, Duff appears to make his argument without fully checking his facts. He claims that canid species “differ not just in a few places in their genomes (like domesticated dogs) but at hundreds of thousands of locations throughout their genome.” In fact, domestic dogs differ from one another at hundreds of thousands—millions—of locations throughout their genomes.41 Thus, Duff’s arguments fall flat on several counts.
Summary and Future Directions
Duff has written a strong denunciation of the YEC speciation model—and, specifically, of the Answers in Genesis’ speciation claims. Upon careful examination, all of Duff’s criticisms manifest a troubling pattern. They possess internal contradictions, hermeneutical errors, incorrect facts, or logical deficiencies—or some combination of these.
More importantly, Duff shows no evidence of grappling with a single technical or lay-level article that I’ve written. In his article, Duff never cites a single paper or article that I’ve penned, despite the freely accessible nature of my literature. Furthermore, most of his claims show obvious evidence of ignorance of this literature. In short, Duff lambasts an idea that he doesn’t know.
This conclusion raises disquieting questions about BioLogos’ stated commitment to “strive for humility and gracious dialogue with those who hold other views.” Clearly, BioLogos has endorsed Duff’s article. Yet, for dialogue to occur, BioLogos must listen to their opponents—especially before publicly attacking them. Based on the size of the YEC literature that Duff has ignored (i.e., >90,000 words), BioLogos has a very significant listening task to complete.
In the meantime, BioLogos could take steps to pursue their stated goal by publicly retracting Duff’s article. They could also refrain from further criticism of the YEC speciation model until they have thoroughly read and understood all that we’ve written on this topic—especially my technical papers. I would encourage BioLogos to do so.
Furthermore, I would encourage BioLogos to repudiate Duff’s claims, if not for reasons of dialogue, then for the purpose of maintaining their own scientific credibility. BioLogos has placed great emphasis on the “harmony between science and biblical faith,”42 but they do so by insisting on acceptance of the scientific consensus of the day. I have pointed out that the scientific consensus of our day is misguided. Because the vast majority of professional scientists are ignorant of the YEC speciation model, they are unqualified to scientifically reject it. Duff’s article makes BioLogos a participant in this ignorance. Their credibility in rejecting YEC scientific models could be bolstered by repudiating what Duff has published and by familiarizing themselves with our technical literature before attempting to dismiss it.