What is Irreducible Complexity?

I received an email from a fellow podcaster, Emery Wang, who wrote to ask me about the arguments from scientists who deny evolutionary theory to be scientific. To be blunt, there really aren’t that many. The best place to find them, to the best of my knowledge, is the Discovery Institute, which is a creationist organization that tries its very best to portray itself as scientific. You can find them online at www.discovery.org. They do actually have a few scientists in their ranks, but only a couple with the necessary biological credentials to speak authoritatively about evolution from a scientific standpoint. Their shining star, so to speak, is a man named Michael Behe, although most of the other well-known names in the Intelligent Design movement, such as William Dembski and Jonathan Wells, are also affiliated with this group. Behe is a legitimate scientist, a biochemist actually, and a professor at Lehigh University in Pennsylvania. If you know Behe at all, you know him primarily as the author of the book, “Darwin’s Black Box: The Biochemical Challenge to Evolution.” It’s the book that has the old man and the chimpanzee sitting next to each other, facing in different directions. It’s in this book that Behe first put forth the idea of “irreducible complexity.”

Irreducible complexity was an incredible success for the Intelligent Design movement, because at its core it’s very intuitive- unfortunately, however, it’s also unscientific. But since the scientific theory of evolution is counter-intuitive, it was widely accepted by the public, while scientists who knew better were grinding their teeth in frustration.

Irreducible complexity works like this: Suppose that you have a mechanism of some sort, perhaps a mousetrap. This mousetrap is composed of several different parts, each of which is essential to the operation of the mousetrap. You’ve got the flat wooden base, the spring, the horizontal bar, the catch bar, the catch, and the staples that keep all the metal parts attached to the wood base. Now, if you have all the parts together and assembled properly, the mousetrap works like it’s supposed to- pulling back on the horizontal bar causes the spring to wind back, and the catch bar holds the horizontal bar in place as long as it’s jammed in place by the catch. Once the catch is disturbed, the catch bar is free to swing out of the way, and the spring winds shut slamming the horizontal bar down hard on whatever disturbed the catch. Makes sense. But let’s say that you remove one part of the mousetrap- the catch. Well, in that case, you can never set the trap because you can’t keep the catch bar still. Or let’s say that you remove the spring. Well, in that case, the trap will never close because there’s no force to move the horizontal bar. Or if you remove the horizontal bar itself, there’s nothing for the spring to move. You get the idea, I’m sure- if you remove one part of the mechanism, the whole thing can’t work. Thus, the design of the mousetrap is described by Behe to be irreducibly complex- in other words, the complexity of the design requires that it can’t be reduced any farther without losing functionality.

Now, you’re thinking, “So what’s the problem with irreducible complexity? Obviously a mousetrap won’t work if you remove the spring, that’s just common sense.” And so it is. And I don’t think there’d be any problem if Behe had stuck to talking about mousetraps. But he doesn’t- he’s a biochemist, and so he applies this concept of irreducible complexity to something much smaller than a mousetrap, something so small it’s invisible to the naked eye- a bacterial flagellum. A flagellum is a long, whiplike structure that is used by cells to move around. Think of the tail on a sperm cell, and you’re basically there. Bacteria use flagella too, and the structure is of a long, hollow cord attached to the wall of the bacterium where it hooks into a molecular rotor that spins in response to an ion gradient, as much as 1000 rpm. When the rotor spins, the flagellum spins, and the bacterium moves forward. It’s a little bit like an outboard motor on a boat, and like a motor, it’s composed of a lot of different parts, in this case proteins, each of which is essential for the proper functioning on the flagellum. Well, you can probably see where I’m going with this: if the mousetrap is irreducibly complex since removing one part means that the whole thing doesn’t work, then a flagellum is irreducibly complex for the same reason, right?

Wrong. And hopefully once I explain why, you’ll understand that it’s necessary to assume design in order to come up with a concept like irreducible complexity in the first place. Let’s go back to the mousetrap. Let’s say that I remove the catch- mousetrap doesn’t work, right? Well, not exactly. It may not work the way that the manufacturer intended for it to work, that’s true, but is it absolutely good for nothing? I would say no- I can set the trap by pulling the horizontal bar into place, setting the catch bar over it, and then carefully laying the trap upside down so that its own weight holds the catch bar in place. I can still bait the trap, and the jostling of the upside-down trap by an eager mouse can still move the catch bar out of position and cause the trap to release. It’s not the best way for the trap to function, of course. But even though it’s not as effective, it still does function to some extent. And even if you removed the spring, you could still use it as a paperweight- it’s still good for something.

Likewise, the incomplete flagellum is also good for something. Recent research on bacterial flagella have shown that very similar proteins functioning in a very similar way, but without the flagellar whip structure, have another kind of function in bacteria- they form the basis of a secretory apparatus- a mechanism that allows bacteria to inject toxins into other cells. So half a flagellum is still useful to the bacteria, even if it’s not functioning in the same way that the full flagellum does. Thus, the flagellum is not irreducibly complex. You see, evolutionary theory doesn’t have a particular goal in mind- that’s why Behe’s analogy of the mousetrap doesn’t make any sense. Someone who sets out to build a mousetrap has an idea in mind of what he wants that trap to be capable of, but this is not the case for evolution. Structures and systems are only useful to an organism if they confer some kind of selective advantage- it doesn’t matter how that advantage operates.

Think of a fighter jet- that’s a pretty complex system, right? Every component in that fighter jet is absolutely essential for its operation, otherwise it wouldn’t be built into it. If you were looking at the jet from Behe’s point of view, you would say, wow, this jet is incredibly complex. This must have been engineered from a blank diagram specifically to work this way. But we know better. Airplanes themselves have been constantly evolving, since even before the Wright brothers flew their machine in North Carolina. Before that, there were all sorts of variations on gliders. Each component was added gradually, but each airplane that was built started with the blueprint of the one that went before it, and then added new things. If those additions made a better airplane, then everyone copied it. If those additions made it worse, then it was scrapped. This is how evolution works- variations are made on existing organisms, and if they confer an advantage, they are selected for. Just as we know that an airplane motor evolved from a more simple model, we can also show that a bacterial motor, a flagellum, evolved from a more simple structure.

And in fact, after looking at it in both simple mechanical and biomechanical examples, what does the concept of irreducible complexity really give us? Not really anything useful at all. Because the critical component here is complexity- this is something which is dependent on the proposed function. A mousetrap is a reasonably complex way to kill a mouse, but it’s a simple enough paperweight at the same time. And a bacterial flagellum is a reasonably complex way to move a cell around in a fluid medium, but it’s also a reasonably good way to inject proteins into other cells, if you take a few parts away. And complexity is also dependent on the point in time which you examine a system. If you look at a stone arch, it seems irreducibly complex- if you remove a single stone from the archway the whole thing comes tumbling down. But we know that a common architectural technique is called scaffolding- that is, the archway is built under support from a wooden scaffold that allows the stones to be put in place without falling apart- and it’s only after all the stones are secure that the scaffold isn’t needed anymore. Biological systems can evolve using scaffolds also- with less selective pressure, new proteins and enzymes can evolve unique functions which may become essential if other scaffolding enzymes are lost to the dustbin of evolutionary change.

So, in the end, we’ve seen that irreducible complexity is neither- biological structures are, in fact, reducible to states which give rise to other functions, and these functions are only as complex as their context requires of them. It’s an attractive concept to people that aren’t familiar with evolutionary theory, but it’s just not born out by science.

How Did Humans Evolve?

You’ve no doubt noticed the opening music that I’ve added. It’s the “Sunrise” piece by Richard Strauss, of the work, “Thus Sprach Zarathustra.” It’s more popularly known as the theme to the movie, “2001: A Space Odyssey,” and it’s from that usage that I take my inspiration. The opening scenes of the movie are subtitled, “The Evolution of Man,” and show a group of ape-like creatures learning how to use tools, and thus, become human. This aspect of evolutionary theory- the treatment of humans by evolution- is one of the central interests of the theory, because let’s face it- we humans are continuously preoccupied with ourselves. You’ve also seen this in the logo for the podcast- a variation of the classic, “March of Progress” imagery that shows hominids walking in a line at side profile, beginning with an ape-like creature and ending with a modern human.

So I thought that this week I would talk about the evolution of humans. I think we’ve tackled enough relevant topics so far to begin investigating the subject. The molecular evidence showed very clearly that chimpanzees are our closest living relatives, and so, logically, we must share an ancestor in common at some point in the past. This common ancestor, or concestor, wasn’t necessarily identical to modern chimpanzees- remember, all populations are in a state of evolutionary flux, it’s just that some are required by their environments to evolve faster than others. So although the human-chimpanzee concestor wasn’t a chimpanzee, we’d probably recognize it as being more chimpanzee than human if it were alive today.

So, humans and chimpanzees are both descended from an ape-like concestor. When did the lines split into human-only and chimpanzee-only lines? The answer may not be as cut and dry as you might think. The best theories based on the fossil evidence indicate that our concestor lived between 5 to 7 million years ago, at which point evolutionary forces caused one population to evolve human-like characteristics while the other line evolved more chimpanzee-like characteristics. However, new evidence has just been made available that shows by examining the human and chimpanzee genomes that human and chimpanzee ancestors diverged and then converged, before diverging for a final time less than 5 million years ago. Genetic analysis suggests that humans and chimpanzees evolved into separate species which then interbred, forming a hybrid species which then bred back into one of the parent populations. It’s not clear whether this human-chimpanzee hybrid returned to the human or the chimpanzee population, but the molecular evidence is clear that the hybridization did happen- the X chromosome has a particularly recent connection to the chimpanzee genome. This means that human-chimpanzee hybrid males would have been infertile, but the females were not, and thus returned back to the parental population, mixing chimpanzee and human genes each time. This new study by the Broad Institute in Massachusetts is scheduled to be published in Nature later this year, but the results have been made available on the Internet, so I’m sharing the scientific cutting edge with all of you.

But regardless of the human-chimpanzee hybrids, eventually the two lines did split for good. And gradually, our ancestors changed from being something that was willing to mate with a chimpanzee, into something that would rather hunt them for food, train them for entertainment, or sequence their DNA. What was the first step? The first step, as it seems, is literally a step. A bipedal step, to be precise- the first thing to distinguish our ancestors from chimpanzee ancestors is the ability to walk upright. But being able to walk upright doesn’t earn the scientific, phylogenetic designation of human- we designate all human species by the genus “Homo” as in our binomial, “Homo sapiens.” But these first human ancestors weren’t human enough to be considered part of our genus, and instead are called, “Australopithecus.” One species of this genus in particular is thought to have been ancestral to humans- Australopithecus afarensis, one specimen of which has been nicknamed, “Lucy.” Like most of the Australopithecines, Lucy lived in Africa.
Lucy, and the rest of her species, resembled chimpanzees in a lot of ways, but one difference is obvious- she walked upright, like a human. And not just sometimes, the bone structure of her pelvis indicates that she was upright most of the time.

The next big change in human evolution was the expansion of the brain. This was different than a lot of scientists had expected- they had assumed that a larger brain would have been the first change in the human-chimpanzee divergence, followed by other human traits such as bipedalism and tool use. This turned out not to be the case- walking upright evolved first. But the expanding brain followed soon after, and in fact it’s how we classify human species- that is, species that belong to the genus “Homo.” The first human, or at least the first recognizable human species to which we’re willing to give the designation, is the Handyman, Homo habilis. The Handyman lived between 1.5 and 2.5 million years ago, and he gets his name because rudimentary tools have been found with fossils of this species. These tools weren’t anything spectacular- just flakes of stone used as rudimentary knives, for the cutting of meat off dead animals. It’s unlikely that the Handyman was a hunter- more likely, he would have taken meat from already dead animals like a scavenger.

After Homo habilis, we find the next major step in human evolution. Homo erectus, or the Upright Man arose in Africa about 1.5 to 1.8 million years ago. Homo erectus had a larger brain than Homo habilis, and its anatomy was more similar to modern humans. But the most interesting thing about Homo erectus was its incredible success- it was the first human species to engage in actual hunting, and this had the effect of expanding its territory. Because its diet became more reliant on animals than plants, Homo erectus began to migrate- and thus spread out of Africa, and colonized southeast Asia, even going up farther north into Eurasia. There is also evidence that Homo erectus was able to control fire. There is some controversy about whether Homo erectus evolved into a separate species once it migrated out of Africa and into Asia, but even if this happened, the two species are so similar to make it almost impossible to tell today.

Homo erectus is the last major evolutionary transition before we get to modern humans, Homo sapiens. But how did this transition take place? There are a couple hypotheses- the “Out of Africa” hypothesis suggests that Homo sapiens evolved from the Homo erectus population back in Africa, and migrated out again, following the path that Homo erectus had taken earlier. The multiregional hypothesis suggests that Homo sapiens evolved in different geographical locations independently from different Homo erectus populations. This would suggest that European Homo sapiens evolved from a European population of Homo erectus, and the same is true of Asians, Africans, and Indonesians. This latter hypothesis is looking weaker and weaker as the genetic evidence piles up- any given human isn’t that significantly different from another, whatever the geographical origin. Richard Dawkins has come out in support of an “Out of Africa again and again” hypothesis, which suggests that Homo sapiens migrated out of and back into Africa several times before finally spreading out over all the continents. This hypothesis is backed up by genetic evidence tracing the genetic similarity of various genes among different human populations, and it looks the most promising. One of the major differences setting Homo sapiens aside from the other homonids is our use of language. This development is likely what allowed modern human society to expand and become as complex as it is now.

But what about the Neandethals? I haven’t forgotten them. Homo neandethalensis doesn’t figure in human ancestry- they aren’t direct ancestors. Analysis of mitochondrial DNA found in Neandethal fossils has confirmed this. What is most likely is that Neanderthals evolved from European populations of Homo erectus, and were either hunted or out-competed by the our ancestors, the Homo sapiens that had migrated into Europe from Africa. So you can think of them as our evolutionary cousins, if you like.

So that’s the basics of human evolution. The transitions aren’t really as simple as I’ve made them seem, and there are several subspecies that are transitional between the major species, but by and large, this is what you should know. After diverging with the other great apes, bipedalism evolved in the Australopithecines, but they weren’t human quite yet. Once a large enough brain evolved, rudimentary tools began to be used, as seen in Homo habilis, the Handyman. These then became migratory hunter/gatherers, as seen in Homo erectus. Modern humans evolved the use of language, and migrated out of Africa and all over the world, to where we are today.

What are Transitional Species?

This week I’d like to take a look at an important concept to evolutionary theory- that of the transitional species. This concept is also often referred to by a less-meaningful term, “missing link.” This concept is packed with mistaken assumptions and used unscientifically far too often, which is partially the fault of uninformed journalists and partially the fault of creationists.

The problem is that there is really no such thing as a transitional species. The reason for this is that all species are transitional species. Now, obviously that sounds like I just contradicted myself, but let me explain. Dedicated listeners will remember from the episode about species that I never really defined what a species is. I gave a number of different methods that can be used to describe a species, but I also said that there’s no clear-cut definition, because every system has exceptions. So, if there’s no way to absolutely define species, then there’s no way to absolutely define transitional species. However, our brains don’t like ambiguity. Humans like to classify things, and so we come up with systems of organization and classification, such as the Linnean taxonomy that I’ve mentioned already. And usually classification makes sense- dogs are different species from cats, for example, by any objective measurement. But what about the ring species that I mentioned before, like the salamanders of which all subspecies but two can interbreed? There, the concept of species is not so clear.

In the same way that the concept of species can be provisionally meaningful to describe organisms at a single point in time, the concept of transitional species can be provisionally meaningful to describe organisms over a length of time, usually quite a long time, like hundreds of thousands or millions of years.

The concept, in essence, is fairly straightforward. Let’s say that you have a Species A that existed some time in the past, say, 10 million years ago. Currently, we observe Species C that exists now and shares a lot of the anatomical characters that are seen in fossils of Species A, but which also has several characters that are not seen in Species A. Evolutionary theory predicts that if Species C is descended from Species A, then there is likely a Species B which has more characteristics in common with Species C than Species A. We refer to Species B as a transitional species, but this is only in the context of the difference between Species A and C. These transitional species are often referred to as “missing links” because they are hypothesized to exist, given the fact that fossils are not found one after the other in a continuous line into the past, but are found corresponding to various points in prehistory, which is the reason that gaps exist in the fossil record.

The fact that these gaps exist is not a failing of evolutionary theory, however- it is a limitation of human investigation. We have no way of knowing where fossils are going to be exactly (although we can make some pretty good guesses), and we don’t know what specific fossils are going to be found (although we have some pretty good guesses on those too).

I also want to point out again that the concept of a species being “transitional” is only relative to the species that existed before and after it. And the concept of “species” is a classification that is made by humans strictly for organizational purposes. So a “transitional species” is a contextual classification, nothing more. This is what I meant when I said that there’s really no such thing as a transitional species. But since, given evolutionary theory, all species are in the process of evolutionary change (assuming they don’t become extinct), all species are themselves giving rise to new species eventually, and thus we can say equally that all species are “transitional.”

Now, since I’ve just gone to the trouble of confusing you at length by telling you that transitional species don’t really exist, let me confuse you further by giving you some examples of some. What I mean here is that, since the concept of a transitional species is contextual and relative to a specific classification, it can be meaningful if we view it in that restricted way- that is, if we assume a specific context relative to specific classifications.

For example, if you assume the classifications Fish and Amphibians, there are a number of excellent transitional species, including one amazing species discovered in the past year, called Tiktaalik. Tiktaalik lived about 375 million years ago, and belonged to the group of fish called “lobe-finned,” which are ancestral to all tetrapods, that is, all animals with four limbs. Tiktaalik had characteristics of both fish and tetrapods, including the scales and gills of a fish, limbs that are intermediate between fish and tetrapods, and the mobile neck and lungs of a tetrapod. That’s right- it had both gills and lungs. You can learn more about Tiktaalik at its very own website, http://tiktaalik.uchicago.edu/.

If, however, you assume the classifications Reptiles and Birds, there are also a number of transitional species, most notably Archaeopteryx. Archaeopteryx lived about 150 million years ago, and would technically be classified among dinosaurs, which are a subset of the reptile group. Archaeopteryx had characteristics of both reptiles and birds, including a long bony tail, and a bones structure that is very similar to a reptile. It also had fully-formed, flight-capable feathers, which makes it distinctly similar to birds. It’s unknown whether Archaeopteryx was able to fly the same way that modern birds do- it may have only been able to glide, or perhaps to take wing-powered hops, but the feathers are there, and they show it to be distinctly transitional between reptiles and birds.

There are also a couple well-characterized transitional species in the mammal lineage, especially in the evolution of the whale and the evolution of the horse. Ambulocetus was an amphibious mammal and ancestral to modern whales- it lived about 50 million years ago and has many characteristics of modern whales and many characteristics of the artiodactyla family, the cloven-hoofed mammals, which it is transitional between. In the evolution of the horse, clear transitions can be seen between Eohippus, which is recognized as the first horse, and all the later species such as Mesohippus, Parahippus, Merychippus, all of which used fewer and fewer digits on the foot until our modern horses, which use only one.

More recently, and of more personal interest, is the evolution of humans. Although the specific relationships between fossil species are still somewhat controversial, it is clear that transitional species exist between Australopithecus and modern Homo sapiens, including Homo habilis, and Homo erectus. Homo neanderthalensis, also known as Neandethal Man, is not our direct ancestor, as has been shown by mitochondrial DNA analysis, but is a related ancestral human species, sort of like an uncle.

To review- a transitional species is a classification based on a specific context- a species that exhibits characteristics of species that existed prior to and following it. Gaps in our knowledge of specific transitional species is a function of limited detection, not a failing of evolutionary theory. And many excellent examples of transitional species exist between any number of biological classifications, and more are being discovered every year.

Molecular Evidence 6: Objections to Molecular Evidence

All right, this is the final podcast in a series of six that I’ve planned on the molecular evidence for evolution. I’ve been using Dr. Douglas Theobald’s resource on Talk.Origins.org pretty heavily, so you can use that to follow along with the previous five episodes if you like.

To get to this point, I’ve introduced you to the basics of molecular biology, I’ve explained why function follows from structure, why structure follows from sequence, and why sequences are functionally redundant, both with amino acids and with nucleic acids. I’ve shown you sequence homology between different species, verifying the evolutionary hypothesis. I’ve also taken you through noncoding DNA sequences, analyzing three different kinds of molecular artifacts which also verify the evolutionary hypothesis. Every last bit of genetic information that’s contained in your genome indicates that you share a common ancestor with chimpanzees and other primates, by any conceivable measurement.

Genetic information has an advantage over other kinds of evidence, such as fossils. Fossils are the result of genes that existed in the past, but the genetic information we analyze in living organisms is very much a part of the here and now. It’s a living, breathing (literally) piece of evidence. We can measure it, find out how it works. If you compare the fossils of two different kinds of dinosaurs, for example, which both have the same kinds of foot structure, we can hypothesize that they were related phylogenetically, but that’s all we can do. If we were to take two different kinds of organisms today, we can do the same thing, but we can go one step further- we can compare their DNA. Every physical structure that exists as a part of their body is the result of their particular genes- their genotype. The physical manifestation of that genotype is called a phenotype. So, a gene which codes for a protein which regulates beak shape in a bird is part of its genotype, and the shape of the beak is the phenotype. For living organisms, we can correlate genotype with phenotype, and since heredity is the only known mechanism for shared genotype, it’s so much more powerful than just comparing the way animals look.

Despite the power of genetic evidence, there are still detractors, people who don’t accept the conclusion that the molecular evidence supports the evolutionary hypothesis. This is just one of those things that happens in Science- not everybody is going to accept your conclusions. That’s okay, and it happens with just about everything. There are people who don’t accept the HIV hypothesis of AIDS- they don’t believe that the Human Immunodeficiency virus is what causes AIDS. There are also people that don’t accept the cholesterol hypothesis of cardiovascular disease- they think that you can eat as much cholesterol as you want and you won’t get a heart attack. Some of these criticisms come from scientists- the scientific community in general isn’t monolithic and dogmatic, at least it’s not supposed to be. There are always conflicting hypotheses in Science, and it often takes a long time before there’s sufficient experimental evidence to show that one hypothesis is right and the other is wrong. Whatever the case, when the evidence piles up, scientists generally all get behind the hypothesis that the evidence supports, and the conclusion is, for all practical purposes, a closed issue.

This is the case for evolution. The evidence supporting evolutionary theory has been piling up for a couple centuries now, and it’s basically a closed issue in the scientific community. It’s like the HIV hypothesis of AIDS or the cholesterol hypothesis of cardiovascular disease- there’s just no debate among scientists; the evidence is overwhelming.

The reason why I’m making this point is because I want to make it clear that the objections raised against evolutionary theory don’t come from scientists. They come from people with an ideological and theological presupposition that demands a rejection of evolution- of course, I’m talking about creationists. If you have noticed, there’s a critique of Dr. Theobald’s reference at Talk.Origins that is written not by another scientist, but by a lawyer, named Ashby Camp. Why would a lawyer be interested in critiquing scientific evidence for evolution? Well, it just so happens that Mr. Camp is not just a lawyer, he’s a Church of Christ minister and avowed creationist who wrote his critique for the website TrueOrigin.org, which is subtitled, “exposing the myth of evolution.” Clearly, Mr. Camp has a theological interest in portraying evolution as false- he views evolutionary theory as incompatible with his own theology, and therefore must choose one or the other. Obviously, he’s chosen to assert his theology- but this is not always the case. Dr. Kenneth Miller is an evolutionary biologist who finds the science of evolutionary theory compatible with theology, and he writes about this in his book, “Finding Darwin’s God,” which I can recommend highly as a popular introduction to evolutionary theory, especially for those who are under the same assumptions as Mr. Camp.

Since arguments against scientific theories from theology can’t offer competing scientific evidence, they almost always employ a type of argument commonly referred to as an “argument from ignorance.” These are very attractive, but are also logically fallacious. They’re easy to spot, too- all you have to do is listen or watch for someone to start talking about something that Science “doesn’t know,” or talk about something which “may be possible,” even though there’s no evidence to support the conclusion now. The implication is that since something is not known to be the case, it is not the case, or vice versa. Since these arguments against Science often come from a theological perspective, they’re also known as “God of the Gaps” arguments, because the idea is that there is some gap in scientific knowledge that is explained only by assuming that a deity is responsible for that phenomenon. Coming from a theological perspective makes these kinds of arguments no less fallacious, however, and if you run across any kind of criticism of this sort, be sure to pay attention for the arguments from ignorance, or the “God of the Gaps.”

This kind of argument is precisely what we see from Ashby Camp. When confronted with the evidence from protein functional redundancy, he says, “how could one be sure that God would not conserve amino acid sequences (or the underlying codons) when creating cytochrome c in separate species? After creating cytochrome c in the first organism, it certainly is conceivable that he would make changes to that blueprint only when necessary for his purpose. In other words, the default in this instance may be similarity rather than dissimilarity. There is no basis for demanding that God introduce novelty for novelty’s sake.” In other words, since we don’t know that God did not create cytochrome c functionally redundant in different species, he must have done so. Did you catch the argument from ignorance? When confronting the evidence from DNA functional redundancy, he says basically the same thing, “how could one be sure that God would not conserve codon sequences when creating cytochrome c gene in separate species? After creating the cytochrome c gene in the first organism, it certainly is conceivable that he would make changes to that blueprint only when necessary for his purpose. In other words, the default in this instance may be similarity rather than dissimilarity. Again, there is no basis for demanding that God introduce novelty for novelty’s sake.” Same argument from ignorance, and it’s just as fallacious the second time around.

The same mistake is repeated for the rest of the evidences. Regarding transposon, he says, “God may have had a functional reason for initially placing them at the same chromosomal location in separately created species. He also may have had a functional reason for designing certain transposons with an insertion bias for certain loci.” Regarding redundant pseudogenes, he says, “maybe lateral gene transfers occurred in the past through a mechanism that targeted a specific location in recipient cell DNA and that did not leave viral sequences near the inserted pseudogenes. Perhaps this mechanism is no longer operating, as a result progressive degeneration, and the viral action we see today is a distorted remnant of that originally designed process.” Regarding endogenous retroviruses, he says, “God may have had a functional reason for initially placing them at the same chromosomal location in separately created species. He also may have had a functional reason for designing a system to favor the insertion of certain ERV sequences at certain loci.” Did you catch all those “maybes” and “perhaps?” That’s right, obvious giveaways that he’s arguing from ignorance.

And it’s also the special case of the argument from ignorance, the God of the Gaps. For every piece of evidence, Mr. Camp makes the statement, “God may have a purpose for doing so that is beyond our present understanding.” In other words, Mr. Camp is making the claim that there is some kind of gap in our scientific knowledge about molecular biology in which some yet unknown purpose may have been intended by God.

This should be pretty easy for you now. When it comes to criticisms of the evidence for evolution, keep your ears open for arguments from ignorance, and that special case, the God of the Gaps. If you do that, it should be pretty easy for you to shut down critics who use logical fallacies as their only weapons. Well, this is it for the Molecular Evidence for Evolution. I hope this has been interesting and instructive, and more than that, I hope I’ve motivated some of you to check out the evidence for yourselves. Next week, I’ll be back to answering questions. Take care.