In Search of the Equine Common Ancestor: Horse Series Part III

In our last installment of this series, When is a Horse a Horse? we recognized that the living species of equines (horses, zebras, donkeys etc..) represent groups of genetically divergent individuals that naturally do not interbreed on a regular basis.  Each of these lineages of equines is behaving as a species as defined by the biological species concept.  This raises the obvious question for those interested in exploring the origins of equine diversity: are each of these distinguishable equine species based on morphology (the way they look) and their genetic differences the product of special fiat creation or the product of a process of speciation from a common ancestor?   It  may surprise you to learn that secular evolutionists, evolutionary creationists, some intelligent design advocates, and most young earth creationists and whatever combination that I have left out, have the same answer: all equine “species” today are the descents from a common ancestor that lived sometime in the past.

To be more blunt, all parties agree that if we went back in time we would eventually come to a point where there were no clear differences between horses, donkey’s and zebras but rather any observer living at that time would have recognized the existence of a single species.  What origins models (evolution, intelligent design, young-earth creationism etc…) do not share are common views of what that common ancestor may have looked like, how far back in time we would have to travel to find that ancestral species and the mechanisms of evolution required to generate the present-day groups of species.

To illustrate, let us look at what young earth creationists have in mind when they say that all of today’s horse species are derived from a common ancestral stock.   A few years ago several young earth creationists including Todd Wood, a leading figure in framing the creationist concept of “baramins,” (Thoughts on Baraminology) attempted to apply a set of criteria for understanding the limits of the horse baramin, which is a way of saying finding the limits of how far the originally created horse kind could be stretched (see references below).   For our purposes we can say that they were asking the question: when is a horse a horse?

After studying modern equine species and the fossil record Dr. Wood and his co-authors came to the conclusion that undoubtedly all living equines originated from a single common ancestor.  Even more interesting and controversial, at least among those in the creation science community, they suggested that that ancestor of all modern equines may have been a much smaller multiple-toed horse known only from the fossil record.  They suggested that this was the representative over the equine kind that Noah took on the ark and from which all fossil and living horse species have since “evolved.”   In effect what they are suggesting is that the “horse series” observed in the fossil record does, in fact, represent a real set of ancestral horse species. Wood writes about their results in a blog entry entitled The Horse Series and Creationism: “The evolutionists got that one right, and we creationists appear to have gotten it wrong.”

Before you scold me for quote mining to make my point, let me clarify what I believe that Wood intended by this conclusion.  Dr. Wood is only referring to the actual existence of horse-like fossils, their relative order and that all these fossils and living horse species have a common ancestor.  Dr. Wood very much believes in the special creation of the original horse kind and is not convinced that secular evolutionary theories (natural selection, genetic drift and mutation) can fully explain how these horses evolved from that original horse kind to the many species and fossil species we know of today.

I don’t have time here to explore his idea of altruistic genetic elements (the AGEing process) at this time but will explore his and other creationists’ views of how evolution happened within kinds in a later post.  However, I must give Wood credit for recognizing the veracity of the fossil record, realizing that is must represent a post-flood series within the young earth creationists worldviews, and seeing the implications for the question of the origins of horses.

You will not be surprised to hear that not everyone within the creationist community are ready to accept that this standard example of macro-evolutionary evidence might be correct given it has been labeled as being an outright fabrication for so long.  At least two articles have been penned by creationists (see references below) about horses.  In one, Mats Molen, responds to Wood’s assessment of horse evolution and takes the position that there are at least two “evolutionary gaps” in the series and therefore rather than a single horse “kind” God must have made at least three created kinds rather than all having evolved from one to another.  However, with respect to seven living species of horses he believes they are all one kind and therefore derived from a common ancestral pair of horses on Noah’s Ark.

Let’s not lose sight of Molan’s conclusion that there are “gaps” between the living horses and most fossils species and even gaps between some fossils species.  He believes those gaps exclude any possible common ancestry among the fossils that evolutionary biologists have concluded are part of the common ancestry of modern horses.  Dr. Wood and colleagues think differently which brings us right back to our original question:  what makes a horse a horse?

These “gaps” sound really interesting because presumably they define one group from another and thus could tell us what is a horse and what isn’t. Alas, the author gives us virtually no criteria for determining what a “gap” is between kinds or how we would recognize it leaving us to guess which is rather unhelpful.

Long ago, when a “species” was equal to a “kind” in most creationists’ minds, gaps where a bit easier to define.  Every species was specially created, preserved on the Ark and then was represented in the fauna today with only minor micro-evolutionary changes.  But today, most creation scientists are more apt to see species as just pools of genetically similar individuals that are actually part of a much larger unit called a kind which may include hundreds of species.  These “kinds” are more difficult to define than species which we have seen is not easy task itself.  Boundaries between kinds can be fuzzy and they get much fuzzier when the fossil record is included.  In the case of horses, the fossil record appears to contain a gradation of animals from small canine-sized multi-toed broad-leaved plant herbivores to the large grass-grazing zebras and horses of today.

Let’s look at a second paper about horses written by a creationist.  This one is by Jonathan Sarfati who is rather famous for his creative reinterpretations of evolution and the fossil record. His article written in 1999 predates Wood’s assessment but I see no evidence in his recent writings that he has changed his mind.  He does not claim outright that the 25 or more genera (and 150+ species) of living and fossil “horses” are not one created kind but he blasts the traditional evolutionary view of modern horses as having evolved from a small multi-toed ancestor.  Rather, he believes that all the fossils species were all contemporaries of each other and thus could not represent a series of evolutionary steps.  He appears to accept that all fossil horses (all those shown in the figure above) are actually just natural variants within a horse kind but for him this doesn’t constitute any form of evolution.  How does he do that?

From Sarfati’s article The non-evolution of the horse we find this explanation:

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…   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….  These mechanisms would explain the alleged horse evolutionary series as variation within the equine (horse) kind. The amount of variety within living horses, undoubtedly one kind, supports this.

What Sarfati appears to be saying is that all this variation in the entire horse “series” which includes at least 150 different recognized species are all just variations within a single kind and that this variation was produced by genes being switched on and off to cause “jumpy” changes that would make the transitions to new species appear suddenly.

He is promoting a form of what he and other YECs like to call de-evolution. He believes the horse kind was created with many regulatory genes and some have been turned off over time resulting in loss of information. As a result Sarfati argues that we find many forms of horses that evolutionists have simply tried to put into some sort of order of progressive evolution.   As best as I can tell, he seems to be open then to a four-toed ancestral horse that had genes turned off resulting in the loss of toes so that all the living horses today have one toe but he is not going to call this evolution but rather a loss of information resulting in large morphological changes.  Rather than a series of steps from one horse to another I think he rather sees the evolution of horses as a tangled bush rather than a tree with one created “kind” of horse in the middle and then all the species being formed directly from that ancestral population.  We will examine this in more detail in future installments of this series but for now I would say that Sarfati’s de-evolution claims are little more than hand-wavy explanations that have little bearing in the reality of our knowledge of genetics or the fossil record.  He doesn’t account for the sequence of fossils in successive layers of rock nor does he really define the boundaries of where a horse kind ends and other kinds in the fossils record begin.  For example, are fossils from Macrauchenia (pictured above) of South America remains of a different kind of ungulate or should we also lump them in with the equine kind and how would we tell?

A Note on Missing Links in the Horse Series

I can’t help but point out the irony of Sarfati’s use of “jumpy” changes in organisms. He is trying to use quick changes due to regulatory genes being turned on and off to explain how there can be such big differences between members of the horse kind including fossils of horses that have different numbers of toes, different shaped teeth, and even different chromosome numbers.  The result of such fast jumpy changes should be that intermediate or so-called “missing links” would not be expected to exist.  So here we have Sarfati providing a legitimate reason why missing links are not to be expected between all species genera or even families of organisms and yet he is one of the first to make fun of evolutionists for not providing those missing links to prove that organisms have evolved from common ancestors.

The Ark Encounter and horse evolution

When Ken Ham opened his Ark Encounter theme park he included on the ark representatives of what the Answers in Genesis science advisers believed might be the ancestors of the various “kinds” of animals that Noah preserved. These animals are said to have stored all the genetic information for allowing them to evolved into the thousands of species that exist today and all the fossil species that were preserved in post-Flood catastrophes.

They have a pair of “horses” on display. These horses are about the size of a Great Dane and have three toes.  So it appears they also believe some of the oldest fossils of horses represent the original horse ancestors which was much smaller and had different feet than today’s horses.

In Part IV I will explore the problem that each of these explanations for the origin of horses today have in common.

References:

The Non-evolution of the Horse.  by Jonathan Sarfation on the CME website.

 Baraminology: Creationists re-examine the horse series. by Tony Breeden on his blog “Defending Genesis”

Cavanaugh, D.P., Wood, T. and Wise, K.P., Fossil equidae: a monobaraminic, stratomorphic series; in: Walsh, R.E. (Ed.), Proceedings of the Fifth International Conference on Creationism, Creation Science Fellowship, Pittsburgh, PA, p. 143–149, 2003

The Evolution of the Horse by Mats Molen.  Journal of Creation 23(2):59–63  August 2009