A representation of our modern understanding of horse evolution, having some beginning diversity, a sort of “Oligocene Bottleneck,” and then a wide profusion of diversity throughout the New and Old World. From McFadden, Bruce. 2005. “Fossil Horses – Evidence of Evolution.” Science Vol. 307. no. 5716, pp. 1728 – 1730
As discussed previously in my summary of horse evolution, the development and radiation of various equids over the past 55 million years is one of the most celebrated examples of evolution in action. While we are fortunate to have such detailed examples of past evolutionary transitions, the presentation of the evolution of horses proceeding in a straight line from small, four-toed Eohippus to the extant Equus has sometimes done more harm than good. While the branching bush of horse evolution has been recognized in scientific circles since the middle of the 20th century (at the latest), a more orthogenic model has often still been presented in popular works and taught in schools, and David Godfrey has corroborated this in the comment thread of my previous essay. It is this weakness in using a “simple” illustration that has opened the door up to creationist complaints, and in this appendix to my original work I will attempt to review some of the more recent remarks made by the likes of Jonathan Wells (affiliated with the Discovery Institute) and Ken Ham (president of Answers in Genesis) on the evolution of horses.
Comparison of Eohippus to Equus. There’s a lot of evolution in that dashed line. From “The Dawn Horse or Eohippus” by Chester Stock (1947).
The book that introduced me (albeit painfully) to intelligent design and critics of evolution was the infamous Icons of Evolution by Jonathan Wells, and in it Wells spends an entire chapter attempting to discredit the idea that horses evolved. This is not surprising, especially given that horse evolution was so triumphantly heralded by none other than “Darwin’s Bulldog” Thomas Henry Huxley in 1876. Indeed, the rich amount of fossils uncovered, plus public interest and prestige allowed horses to take on an iconic status, caused the transitions among fossil horses to become one of the most widely-cited examples of evolution, the change from small, multi-toed ancestors to large, one-toed descendants making for a very compelling scientific narrative.
Despite the vast amount of fossil evidence available that proves, beyond doubt, the evolution of horses, Wells spends little time addressing the very topic that gives the chapter “Fossil Horses and Directed Evolution” it’s name. Wells quickly covers most of the history that I have myself summarized (and, at the risk of sounding conceited, I believe more aptly summarized), but he quickly turns to an attack on G.G. Simpson, Charles Darwin, and Richard Dawkins on tenuous philosophical ground rather than bring any closure to his chosen subject. In fact, it seems like the selection of horse evolution as one of his “Icons” was merely a set-up, and while it is not explicitly stated, the purpose of the chapter is to dust off the old idea of orthogenesis. Working primarily from the work of Matthew and Stirton (see the previous essay) from the first half of the 20th century, Wells states the following about the illustrations of horse evolution that appeared in the AMNH papers;
Despite having been revised, the picture of horse evolution still includes a line connecting Hyracotherium with its supposed descendants, all the way up to the modern horse. Ironically, this very Darwinian line of ancestor-descendant relationships still presents a problem for neo-Darwinists like Simpson, because it is as consistent with directed evolution as the linear series in the old icon. The mere existence of extinct side-branches doesn’t rule out the possibility that the evolution of modern horses was directed. A cattle drive has a planned destination, even though some steers might stray from a herd along the way. Or, to use another analogy, the branching pattern of arteries and veins in the human body has some randomness to it, but our very lives depend on the fact that the overall pattern is predetermined.
This doesn’t prove that directed evolution is true, but only that a branching-tree pattern in the fossil record doesn’t refute it. A straight line and a branching tree are equally consistent (or inconsistent) with the existence (or non-existence) of either a predetermined goal or an inherent directive mechanism. In other words, even if we knew for sure what the pattern was, that alone would not be sufficient to establish whether or not horse evolution was directed.
From Stirton, R. A. 1940. “Phylogeny of North American Equidae”. Bull. Dept. Geol. Sci., Univ. California 25(4): 165-198.
So there you have it, folks. Horse evolution appears to have a branching pattern because some lineages didn’t follow God’s plan during his 55-million-year-old evolutionary cattle drive. Wait, what? Either intentionally or as a result of lack of thought on the subject, Wells speaks out of both sides of his mouth in this passage, attempting to be a sort of Devil’s Advocate. In classic intelligent-design style, the identity of the force that Wells contends could have given direction to horse evolution is never mentioned, and it is only stated that such considerations cannot be ruled out. This sounds tentative, but the rest of the chapter is an attack on the concept that evolution does not have any sort of direction to it, diversity being a result of entirely natural processes (and not a divergence from some ill-defined bauplan ordained by a supernatural force). This sort of doubletalk is maddening and will appeal to those already inclined to agree with Wells, the gaping holes in his argument being obvious to anyone who is more familiar with the topic that the DI writer.
Wells also attempts to confuse the reader as to how evolution proceedings by taking certain ideas to extremes. By Wells’ logic, a branching pattern means that every genus must have a diversity of descendants, and if there seems to be any sort of anagenesis then that shows that evolution had direction. This view is certainly mistaken, but Wells seems to use it primarily as a rhetorical device to spark incredulity in the reader, and it might be all-too-easy for those unfamiliar with evolution to be taken in. The truth of the matter is that we can create a lineage of representative types showing the transition of horses from Eohippus to Equus to the exclusion of other genera, but such is a narrow view. This sort of representation, which persisted much longer than it should have in general or popular accounts, has done much to confuse the issue, even though the very people who have put forth the “simplified” model have recognized there was a greater diversity. It seems to be something of a fight between showing evolution as we know it to be and between trying to convince the reader that evolution has occurred, usually showing a phylogeny that is close to that of O.C. Marsh.
O.C. Marsh’s concept of “The Geneology of the Horse,” a decidedly straight-line progression. From Marsh, O.C. 1879. “Polydactyly Horses, Recent and Extinct.”
The bait-and-switch tactic of Wells in his book, as we have seen, is not very straightforward or even conclusive, but young earth creationists (YEC’s) tackle the problem in a different way, attributing the existence of horses to a definite intelligent agent: God. While generally silent about horses in their popular tracts The Lie and Refuting Evolution, the #1 creationist group in the United States (for the moment, anyway, as creationist ministries seem to have a bang-and-bust cycle) Answers in Genesis has a few articles on the subject available on their website. In an 1999 article, Jonathan Sarfati (now with Creation Ministries International,due to a schism within AiG) wrote “The non-evolution of the horse: Special creation or evolved rock badger?” in which he pontificates on why there are so many fossil horses with extra toes, low-crowned teeth, and of smaller stature;
An important part of the biblical creation model is that different kinds of creatures were created with lots of genetic information. Natural selection can sort out this pre-existing genetic information, by eliminating creatures not suited to a particular environment. Thus many different varieties can be produced in different environments. Note that this sorting process involves a loss of information, so is irrelevant to particles-to-people evolution, which requires non-intelligent processes to add new information.
Also, much of this (created) genetic information may have been latent (hidden, i.e. the features coded for are not expressed in the offspring) in the original created kinds. They also had other controlling or regulatory genes that switch other genes ‘on’ or ‘off.’ That is, they control whether or not the information in a gene will be decoded, so the trait will be expressed in the creature. This would enable very rapid and ‘jumpy’ changes, which are still changes involving already created information, not generation of new information.
Applying these principles to the horse, the genetic information coding for extra toes is present, but is switched off in most modern horses. Sometimes a horse is born today where the genes are switched on, and certainly many fossil horses also had the genes switched on. This would explain why there are no transitional forms showing gradually smaller toe size. [emphasis mine]
As can be easily seen, Sarfati attempts to escape into the realm of genetics, throwing around lots of scientific-sounding arguments in a feeble attempt to dazzle readers. One of the central philosophical doctrines of modern creationists is the necessity of the Fall (or the entrance of death and disease into the world as a result of Adam & Eve’s sin in Eden), and much of what creation ministries write circles around the degeneration or “devolution” of all life since the eviction from Eden. This is not the entire story, however, as the Noachian Deluge is of nearly equal importance, all animals alive today being (in the YEC view) descendants of survivors of the great flood. In order to make the vast diversity of fossil horse species consonant with such views, Sarfati even has to invoke a kind of punctuated equilibria (although I’m sure he’d never admit it), three-toed horses evolving at an exceptional rate within the last few thousand years, only to instantaneously go extinct. Sarfati could have said that horses like Pliohippus were alive before the Flood (their fossils being explained by the catastrophe), and while still horribly wrong it would at least make a little more sense. Sarfati decides to stick with saltational changes in horses in a post-flood world, however, pointing to the products of artificial selection in horses (especially in terms of size) as if they had occurred on their own in nature.
As is often the case with creationists, Sarfati’s thesis seems based on what was cutting-edge science during the end of the 19th century, and there is nary a mention of newer research by scientists like Bruce MacFadden (or even many of the paleontologists who worked on horses during the mid-20th century like Stirton and Matthew). Indeed, it seems as if he merely picked up some other creationist tracts, dumped them into a blender with some snippets from a basic genetics book, mixed it up, and wrote down whatever came out of the amalgamated bits and pieces. Sarfati must be given some credit in putting forth an idea as to the origins of the vast diversity of fossil horses (see the illustration at the beginning of this appendix); most other creationists have been content to signal the “death knell” of horse evolution and merely state it as an abandoned hypothesis that evolutionary scientists no longer want to discuss. In the book The Amazing Story of Creation From Science and the Bible, YEC-fave Duane Gish writes;
Even evolutionists acknowledge, however, that we cannot find transitional forms between these various kinds of horses. There are no fossil horses with part-browsing, part-grazing teeth. We cannot find fossils of a horse with three-and-a-half toes or two-and-a-half toes. The fossils show no progressive increase in size. In fact, some “later” horses were smaller than “earlier” horses. The number of ribs did not progressively increase. The number of ribs in fossil horses go up and down. Just as there are different kinds of primates today – lemurs, monkeys, apes, and humans – so there were different kinds of horses in the past, with no evidence that one kind of horse evolved from another kind of horse. Just as dinosaurs and many other kinds of creatures have died out since creation, so, also, many different kinds of horses died out. Evolutionists still search, and will continue to do so, without success, for the transitional forms which much exist, if evolution is true.
What is truly odd about Gish’s statement is that he expects modern scientists to believe in an orthogenic progression (similar to the rhetorical attempts of Wells, as mentioned above), anything that runs counter to that decimating Gish’s straw man. Just like Wells, he also attempts to spark some amount of incredulity in the reader, suggesting that toes disappear piecemeal, bone by bone, rather than overall reductions and changes that have left vestiges in Equus today. Gish’s comment about teeth is also strange, as if he expected horses to think “Hmmm, I want to be a grazer, not a browser; better start changing my teeth!” It is the changes in ecology in which a population exists in and the branching out into new niches that puts pressure on existing characters to shape the organisms, and there is no cosmic force that decides that in 10 million years time the teeth of the animal should look a certain way and push it towards that goal. In fact, Gish’s creationist views are far closer to the straw man that he mocks than the scientific truth of the matter, but it seems that such a philosophical relationship is often lost on YEC’s.
Even stranger and false than Gish & Sarfati’s works, however, is Lawrence Richards’ It Couldn’t Just Happen. Rather than suggesting that scientists are merely misguided or that they have abandoned horses as an example of evolution, Richards attributes to them some amount of dishonesty (or at least fanciful thinking);
But why did evolutionists ever think fossils from different parts of the world should be linked together in the first place? Part of the reason is that they were tricked by their own theory. The Theory of Evolution said that modern animals should develop from similar but different animals of the past. It said that hooves should be an adaptation and have developed from several toes to one. Size would help a horse survive by enabling it to run faster, so animals should gradually become larger. Simply put, evolutionists fit the fossil bones of different animals into a series and said they were horses, because the bones fit their Theory of Evolution!
It’s almost as if you were outside one day and found a tennis ball, a soccer ball, and a basketball in a weedy field. You noticed that each ball is hollow, and each has an increasingly thicker skin. You’re really excited, and figure that each evolved from some common ancestor! Then you spend the rest of your life trying to figure out how that could possibly have happened. You invent story after story to explain that evolution, and even though the evidence is against each suggestion you make, many people believe you. They don’t seem to realize that finding the balls lined up in a particular order doesn’t prove descent at all.
If you’re spending all your time stealing equipment from PE class and trying to tell people that basketballs evolved from a tennis ball, I’d say you’ve got some rather important mental health problems. That aside, Richards’ example is yet another poor YEC analogy (I swear, half of creationist literature is bad analogy) that intimates that scientists are deluded fools that have essentially created a hypothesis and constructed a lineage to prove the ideas they already possessed. As can be seen from my earlier essay, that is most certainly not the case, and Richards’ passage is at best grossly misinformed and at worst malicious.
To be entirely honest, I was rather surprised by the overall paucity of creationist literature as pertaining to horse evolution. Given it’s prominence in textbooks and museums (and even though many books and institutions still present such evolution incorrectly) I would have expected at least a semi-rigorous creationist explanation for horses, but they seem content to merely criticize the work of Marsh and Huxley, praising Richard Owen for not associating the European Hyrcaotherium with living horses. Even in the one book (Icons of Evolution) that specifically targets horse evolution, the phylogeny is only a set up in order to allow Wells to attack Darwin and Dawkins, hinting that orthogenesis should still be considered as being a good hypothesis for evolution. If such attempts are the best that creationists can muster, I really must wonder how they have gained so much influence with such weak arguments. My question is a rhetorical one, being that pre-existing religious leanings often dictating what will be swallowed and what will be spat out when it comes to science, but perhaps the influence of creationist talking heads like Wells and Gish show just how intellectually lazy Americans have become, citizens being willing to agree with anything that won’t upset anyone during Sunday dinner after church.
As mentioned here and in my previous work, however, museums and those who write books (be they popular or for students) mentioning horse evolution are far from blameless. The “branching bush” of horse evolution is often ignored so that a general type of anagenesis from one type to another can be put forward, and this sort of technique does not serve anyone well. It will only cause confusion if presented alone, and over and over again it is apparent that evolutionary images are far more powerful than the text of any given book. While those who wish to bring about scientific understanding to the public should not let up in terms of accuracy within their writings, we must be mindful of what images we use to illustrate evolution, an inaccurate image being able to haunt educators for far longer than an obscure reference in a book. Often unintentionally, writers of popular science books and museum curators/designers have created “monstrous memes” that reproduce at an astonishing rate, persisting long after their original source material is forgotten, and if we are to be successful in getting the public to understand science, we must supplant and replace the illustrative errors of those who have come before.