- Part 1: Introduction and the Introduction
- Part 2: Darwin Didn’t Know About Chromosomes!
- Part 3: Darwin 1, Old-Timey Creationists 0
- Part 4: All Your Evidence Are Belong To Us
- Part 5: An Admittedly Weak Chapter
- Part 6: Jeanson’s Fulcrum Fails
- Part 7: TBA
- Part 8: TBA
- Part 9: TBA
- Part 10: TBA
In this chapter, Jeanson is going to tackle the subject of common ancestry. Let’s dive right in.
Chapter 5 – The Riddle of Ancestry
Jeanson begins by describing the Linnean taxonomy system: kingdom, phylum, class, order, family, genus, and species, arranged in a nested hierarchy with numerous species in each genus, numerous genera (the plural of genus) in each family, etc.
Unfortunately, I don’t think I can paste several pages verbatim from the book here, because Jeanson takes the time to note the parallels between this hierarchical categorisation of life on Earth with the tree-like nature of the relationships in a family tree. He notes that one difference is the fact that a family tree has a time element to it while the Linnaean taxonomy system doesn’t, but is quick to point out that fossils can also be classified using the Linnaean taxonomy system, and these can provide relative timestamps due to the law of superposition. Older strata are generally found below younger strata, and younger strata contain fossils more similar to extant species while older rocks contain long-extinct species:
This patterns holds true for other families.5 For example, species from the other two families within the order Perissodactyla are also present in the fossil record. Living rhino species are found in the shallowest layers; deeper layers contain extinct species. Living tapir species exist in the uppermost layers; lower layers contain extinct species.
This arrangement implies a time sequence.
Another parallel that Jeanson points out is that if you were to test the resemblance of yourself to your great-great-great-grandfather, it would probably be pretty low, but if you compared your great-great-great-grandfather to his son (your great-great-grandfather), the resemblance would be more apparent, and this trend would hold true through the series of intervening links between you and and your great-great-great-grandfather. In other words, you can be connected to your distant ancestors through a series of “transitional forms”:
Today, when you stand a zebra next to a rhino, the resemblance between these species is much less striking than the differences. However, zebras can be connected back to a less equid-like ancestor via a series of extinct species (Figure 5.1). Rhinos can be connected back to a less rhino-like species in the same way. The same holds true for tapirs. In the deeper fossil layers, you can even find creatures like Cambaytherium that seem to blend the features of primitive rhinos, tapirs, and equids. To be sure, the visible differences between species might be bigger than the visible differences between generations on a family tree. But the resemblance is still present.
Later, he acknowledges that these “blended” forms even exist deeper in the fossil record to connect much broader groups of organisms:
This fact is true even deep in the fossil record. For example, in 2006, the discovery of Tiktaalik (Figure 5.5) was published.8 With scales like a fish, a head like a land-dweller, and limbs that looked like intermediates between fins and legs, Tiktaalik blended the features of fish and land-dwelling species. Blended species exist even deeper in the fossil record.
It’s hard to understate my reaction to all this. For how many years, for how many decades, have creationists been insincerely begging “evolutionists” to “just show us the transitional forms!”? Now here we have one of AIG’s top guys, in a book being promoted by AIG more intensely than I’ve ever seen them do before, blithely admitting that transitional forms exist! Not only that, he specifically says that they are consistent with the expectations of evolution and universal common ancestry!
But don’t get too excited. Jeanson says that all these parallels with a family tree can actually be drawn equally well to… drumroll please… human transportation systems. That’s right, a similar hierarchy can be constructed between different cars, trucks, and planes etc. They didn’t evolve, they were created, so hierarchy can just as equally point to design! Take that, evolutionists!
He claims that this easily explains morphological relationships like the classic tetrapod forelimb diagram, similar to Figure 1. Evolution explains this by homology: descent from a common ancestor with the same basic forelimb structure, while Jeanson explains it by saying that God designed them in an organised manner, re-using good designs such that they fit a nice nested hierarchy.
The problem is that this explanation doesn’t explain why, for example, Cetaceans (whales and dolphins) have fins with the classic tetrapod arrangement of bones, while animals that are otherwise very similar like sharks have a completely different bone/cartilage structure in their forelimbs. Why are they not the same, since they perform the same function? As an added bonus, their tail fins, while functionally very similar (used for propelling them in the water) are completely different too: sharks and other fish have vertical tail fins, while Cetaceans have horizontal tails. Evolution can easily explain these facts: whales more closely resemble terrestrial tetrapods than they do sharks and other fish because they’re actually more closely related to the former. The reason whales have tail fins that are oriented horizontally and swim by moving their tails up and down, and the reason for this is because they’re descended from 4-legged terrestrial mammals which had a spine that only flexes in that dorso-ventral direction. Humans are no different: we can bend our spine to touch our toes, but we can’t do the same by bending to the side. There are so many other traits that obviously point to Cetaceans being descended from terrestrial mammals, e.g. their lungs instead of gills, and terrestrial olfactory features. So many, in fact, that one leading creationist has suggested that whales really did evolve from terrestrial mammals, after they got off the ark of course. Meanwhile, creationists can only shrug in the face of this kind of data and say “well, I guess God wanted some animals in the sea to pair lungs with horizontal tails, and all the rest to pair gills with vertical tails, because reasons.”
His argument with regard to transitional forms is even more limp: they can be designed – just look at human-designed amphibious assault vehicles, for example… Were you expecting more? If so, you’re out of luck – that’s literally all his argument is. Creators are capable of creating things that blend the features of other things, and sometimes do, therefore transitional forms are just as good evidence for creation. It kind of makes you wonder why creationists spent so much time and energy banging on about transitional forms if they can be subsumed into “creation theory” so easily, doesn’t it?
At this point I think it’s worth briefly discussing a point I’ve mentioned before on this blog, in an unrelated post about human chromosome 2 fusion (a subject which actually features later in the book, so look forward to that!): a bit of the philosophy of science regarding the weighing of competing hypotheses. Jeanson has only presented a very simplistic view of this so far: models are pitted against competing ones until one gets eliminated. The problem that things are rarely this clear-cut, and Jeanson is ignoring all the shades of grey in-between. Two competing models might well be able to explain the same set of observations, but this does not necessarily make them equal. An observation that is explained by both models can still favour one model over the other. This is the case when one model specifically predicts the observation, while the other is ambivalent. This fact is readily apparent in the case of transitional forms from the way creationists argue, saying things like: “if evolution is true, where are the transitional forms?” This common mantra refers to the fact that if evolution is true, we should expect to see transitional forms, and if we don’t see transitional forms, the theory of evolution has a problem. The same cannot be said for creationism: they don’t predict to see transitional forms, they can only come along after the fact and say “oh, well they look like that because that’s how God wanted them to look”. Technically, this is still an explanation, but it’s infinitely weaker than evolution’s explanation because it has zero predictive power. That’s not even touching on the the theory of evolution’s ability to predict with some precision where in the fossil record a particular transitional form should be found, a reality totally at odds with both creationism and a global flood forming the geological column (which Jeanson holds to). Creationism can make no analogous predictions. But I’m getting ahead of myself. Long and obvious story short, transitional forms support evolution over creationism, not both equally.
I should also say that there’s nothing special about being able to classify a collection of things into a hierarchical taxonomy. It can be done with life, regardless of whether it was created or evolved, it can be done with designed objects like vehicles, and it can be done with natural objects like rocks, clouds, and elements. Any set of non-identical objects can be arranged into some kind of hierarchical pattern based on their properties. Try it yourself. Think of 10 random objects, as diverse as you like, and you’ll find that by asking a series of questions you can classify them in some kind of hierarchy. It isn’t the mere observation of hierarchy that supports evolution over the other models, it’s that it fits the branching pattern you’d expect from descent with modification so neatly and that it makes specific predictions about future observations (e.g. finding transitional fossils). Combined with the clear evidence of common ancestry between species on a small scale through descent with modification that came from biogeography in the last Chapter, it’s clear that the hierarchical pattern is best explained by the process of evolution, not design. It’s just like I said in the last paragraph: 2 competing models might well be able to explain the same set of observations, but this does not necessarily make them equal.
The fact that the diversity of life so vividly resembled the branching pattern of common ancestry was what allowed Willi Hennig and his successors to formalise classification in the 20th Century into what is now known as “cladistics”, or, more broadly, “phylogenetics”. This change turned classification from a field of arbitrary categories into a rigorous scientific discipline of defining evolutionary relationships on a mathematical basis. Only an evolutionary process would predict highly parsimonious, objective, hierarchical patterns to emerge from the huge character matrices that are used in (especially molecular) cladistic analyses. And they do emerge.
The last thing I’ll mention on this subject is that during his discussion of the parallels between the hierarchy of life and designed vehicles, Jeanson says:
In fact, you’d probably even find shared elements in the blueprints for each of these cars. Why? Since the end products have similarities, the blueprints will, of necessity, have them as well.
Given the context, I’m pretty sure “blueprints” refers to DNA, so the claim is that DNA should be similar because the end products (the final organisms) are similar, even if they were separately created. This is only true to a certain point. Not every difference in the DNA corresponds to a phenotypic difference, so you can’t chalk all the similarities up to shared functions and all the differences to different functions. A very basic principle in phylogenetics is that neutral DNA sites are often the best to construct phylogenies with because they don’t have functional reasons to group organisms with convergent traits together. They’re the least biased, the most likely to record an accurate record of phylogeny. Under creationism, on the other hand, there’s no reason to expect these neutral sites to tell any kind of consistent story. Without getting into the details, the reason phylogenetics is such a standard tool in evolutionary biology is because these sites do tend to tell a very consistent story of common descent. Jeanson obviously knows this, since he talks about neutral sites later in the book. In later chapters, he reveals that he circumvents this problem by postulating that there are almost no such things as “neutral sites” in genomes that contain differences – virtually all sites that are different between “kinds” are functional. More on that ridiculous idea later.
In short, the creation and design model predicts with equal force each of the biological evidences we examined. Thus, by the standards of the scientific method, the evidences that Darwin used to argue for universal common ancestry fail — because Darwin’s evidences fail to eliminate competing explanations.
Again, there’s a difference between “eliminating” competing explanations and providing a far superior explanation, with more explanatory and predictive power (contrary to what Jeanson claims). A model as nebulous as special creation can essentially never be “eliminated” – every new observation can be explained by “god did it that way”, but by explaining everything, a model really explains nothing: it’s utterly useless. It’s unfalsifiable.
To be fair, both Darwin and his scientific descendants have attempted to eliminate the design explanation.
For example, evolutionists have frequently cited organs in the human body as “vestigial” — purposeless leftovers of evolution.
Jeanson gives this definition of “vestigial” here (my emphasis) even though in the Glossary he says:
In evolutionary thought, vestigial structures are leftovers of past evolutionary processes. While they may have performed a function in the ancestors of the species in which they exist, they often no longer do so.
These 2 definitions are not synonymous. In the main text Jeanson says vestigial means “purposeless”, AKA non-functional, while hidden away in the Glossary (which most people won’t read in detail), he gives a more correct (but still not very good) definition that mentions they don’t actually have to be non-functional after all. A more correct definition can be found in any good Evolutionary Biology textbook, such as this one in Evolutionary Analysis (Fifth Edition) by Herron and Freeman (my emphasis):
A vestigial structure is a useless or rudimentary version of a body part that has an important function in other, closely allied, species.
In fact, “rudimentary organs” was the term that Darwin used in On the Origin of Species, to mean “quite useless” or “almost useless”. Darwin also noted that:
Again, an organ may become rudimentary for its proper purpose, and be used for a distinct one: in certain fishes the swim-bladder seems to be rudimentary for its proper function of giving buoyancy, but has become converted into a nascent breathing organ or lung. Many similar instances could be given.
The reason for using the incorrect definition of “vestigial” soon becomes clear, as Jeanson brings up some classic examples of vestigial structures: the appendix, the human coccyx, and whale pelvic bones. He argues that because these all have some kind of associated function (in the immune system, the attachment of pelvic floor muscles, and in mating, respectively), they’re not vestigial so can’t be evidence against special creation. This misses the point. It’s true that if the structures were truly non-functional, they would be better evidence against design (although no doubt creationists would then just argue that they lost their function due the fall or something), but even if they serve a function, it doesn’t change the fact that they can be used to support evolution over design. I’ll try to illustrate the principal with a different example: the wings of flightless birds. Creationism (especially 19th-century creationism) might say “they’re there because they’re functional in X, Y, and Z small way” (e.g. ostrich wings stabilising the body while running). This gives an explanation for why it has wing structures, but evolution is able to one-up that explanation by taking into account both that functionality but also the evolutionary history of the species. I think even Jeanson would accept that the presence of wings in flightless birds suggests they are descended from flying ancestors, regardless of what how functional those wings are today. Equally, just because something like the whale pelvic bones are found to have a function in mating today, that doesn’t mean that their original primary function as a true pelvis and legs can’t be inferred and used as evidence for structures changing throughout the course of evolution. Jeanson acknowledges this point, and devotes all of a paragraph to it, but dismisses it with one example (the appendix) where recent evidence has shown its evolutionary history to be more complex than initially thought. Unfortunately, we’ll have to wait until Chapter 8 for any discussion of pseudogenes, the molecular equivalent “vestigial organs”.
Jeanson recognises the fact that the hierarchy of life combined with the evidence for (at least limited) common ancestry among species can be extrapolated to suggest that all life shares a common ancestor, not just similar species, especially when we see things like transitional fossils that seem to plug the gaps between distinct groups of organisms. Since breeds came from a common ancestor, maybe their parent species did too? But then what about their parent genera? What about their parent families? At what level do creationists draw the line between common ancestry and “created kinds”?
However, these same rules of inductive reasoning prevent over-application of this logic. In other words, the elimination of the hypothesis of species fixity does not automatically require the acceptance of the hypothesis of universal common ancestry. Since 1859, creationists have approached the question of the origin of species with a keener eye on the biblical text.
That’s right, it’s time to turn to the Bible again!
From a few phrases in Genesis, such as “after their kind” and the fact that the story of Noah’s ark describes a male and female representative of each kind for the purpose of reproduction after the flood, Jeanson infers, as most YECs do, that if 2 species can hybridise and produce viable offspring, they’re probably the same “kind”. He doesn’t require this offspring to be fertile, apparently, so he doesn’t equate “kind” with the biological species concept, but instead up to around the “family” or “order” levels of classification.
In addition, modern creationist views differ from the creationist views of 1859 on the question of geography. Again, modern creationists have approached science with a keener eye on the biblical text. In Genesis 8, the narrative describes the fate of Noah’s Ark — it lands on the mountains of Ararat. From this location, the min [RM: “min” = kinds] disembarked. Scholars still debate the exact location of the Ararat of Genesis 8, but they agree that it is likely somewhere in the Middle East. From the Middle East, the min spread out over the earth. In other words, they migrated — just as Darwin argued. Modern creationists would have no qualms with the conclusions of chapter 4.
So they migrated, just like Darwin said, therefore the 2 hypotheses are indistinguishable? The radiation of all land animals from the middle east is certainly quite different than what Darwin proposed! Embracing the concept of migration is great, but then you need to engage the evidence which doesn’t at all agree with the idea of a recent mass populating of the planet originating in the Middle East.
With respect to Darwin’s evidences for universal common ancestry, all fail to eliminate modern creationist views. His evidences do not distinguish between the hypothesis of common ancestry and the hypothesis of common design. Furthermore, though his breed-species comparison successfully eliminated the hypothesis that each and every species has been independently designed, his comparisons failed to eliminate the hypothesis that original ancestors of each family were designed. In other words, all of Darwin’s evidences fail to eliminate modern creationist views.
I’ll say it for the fourth and final time, just in case it wasn’t already clear: one model doesn’t have to utterly eliminate a competing one, it just has to provide a more compelling explanation with greater predictive power. It’s always possible to come up with some kind of alternative explanation of the facts, but that doesn’t mean all competing hypotheses are created equal. I can come up with an ad hoc model which explains any topic of your choosing, especially when answers like “that was done supernaturally” and “because that’s how the designer chose to do it” are allowed, but I can already tell you that it won’t be as cohesive as any existing scientific theories.
Just to clarify, Jeanson isn’t simply arguing that because Darwin (or anyone else, apparently) wasn’t able to completely eliminate creationist models, creationists at least have their foot in the door and should be worthy of some consideration. No, he’s explicitly arguing that up until studies of DNA were possible, evolution and creationism were on precisely equal footing, fighting for pole position (my emphasis):
Similarly, Darwin’s clues initially seemed to plausibly connect all species together. However, these same pieces worked equally well in positions that connected species within a family, while simultaneously rejecting connections between different families.
In light of the history of genetics, this uncertainty was natural. The only direct scientific record of a species’ ancestry is found in DNA. Since the DNA sequences of various species (i.e., the edge pieces to the puzzle) weren’t available until recently, it’s no surprise that the debate over ancestry would persist to this day.
Until genetics came along, it was apparently impossible to distinguish between evolution with universal common ancestry and creationism with created “kinds”. That’s Jeanson’s take-home point, which will shortly lead into Part III of the book where he lays out his genetic “evidence” in favour of creationism. Throughout this post, I’ve laid out several reasons why this claim is ridiculous, and I could lay out many more, but this post is long enough as it is already, so I’ll leave it there for now.
Comments and queries are welcome.