Dogs Prove Evolution

Dogs provide an interesting proof of evolution. Consider the astonishing variety of different dog breeds. There is the tiny Chihuahua, about six inches tall and weighing under six pounds. And other dogs are enormous, with the Irish wolfhound rising above a person when on his hind legs, and the Saint Bernard weighing over two hundred pounds. Some dogs are extremely intelligent, including the border collie, retriever, poodle and German shepherd. These dogs learn new commands with ease, and can perform complicated tasks. Other dogs, however, seems very dimwitted, often requiring hundreds of repetitions to learn, and even then usually failing to obey a command. There is such an incredible assortment of different dogs that it is easy to forget that they are all the same species, Canis lupus familiaris. This means that even a Chihuahua and a Saint Bernard (assuming that the obvious physical challenges could be overcome) could mate and produce live and fertile offspring.

So where did dogs come from? Darwin thought they might come from multiple sources, including the wolf, jackal and coyote, thereby in part explaining their diversity. The DNA evidence, however, shows that they are all derived from the wolf. DNA from all dogs is over 99% identical to that of a wolf, while the wolf and coyote DNAs, for example, are over 4% different from each other. This means, surprisingly, that all of the diversity of dog types in the world today came from a single source, the wolf.

How did the wolf get transformed into a woof? The precise order of events is a matter of conjecture, but it probably began when an abandoned litter was taken in and nursed by people. The DNA evidence, which shows a strong similarity for all dogs, suggests that there might have only been only a few such domestication events. These early wolf dogs would be subjected to what is called artificial selection. In the wild natural selection is at work with the strongest, fastest and smartest wolves surviving better to make more wolves. But once under the care of people survival depends on a new set of rules. For example, animals that liked to bite people probably did not fare well. But dogs are natural hunters and could help in the search for food. They also could provide an early warning system, barking when unwelcome visitors approach. So people friendly watchdogs, with their heightened senses of hearing and smell, would be very useful to early humans.

People have selected dogs for a variety of features, including hunting ability, companionship, intelligence, herding ability, and looks. Interestingly, there are over four hundred dog breeds today, and most of them were developed in just the last 150 years. This shows a remarkably rapid evolution of a great number of different dog breeds. Most of these breeds were made by first taking two very different existing dog breeds and crossing them. This maximizes genetic diversity in the offspring. Then there is a systematic selection, choosing the pick of the litter, those animals with the desired characteristics, and interbreeding them to make the next generation. The continued brother-sister matings coupled with continued selection rapidly results in a new breed of dog with a new set of characteristics. The new breed is genetically pure, because the repeated inbreeding removes genetic diversity. And the new dog can have a very distinctive set of features because of the artificial systematic selection for those very features. The Doberman pinscher, the Australian cattle dog, and the whippet were all developed in this manner.

It is remarkable to consider that the wolf had enough genetic diversity in its DNA to give rise to all of the dog breeds we see today. Wolves all look pretty much alike, and you’d think that if you keep breeding wolves you’d just get more wolves. Yet there are actually millions of base differences in the DNAs of different wolves, among the billions of bases total. This is clearly sufficient diversity to produce progeny with quite distinct traits when the power of artificial selection is applied over many generations.

The dog story is an interesting demonstration of evolution at work. In an extremely short period of time, in evolutionary terms, the wolf evolved into the dog, including all of the great variety of dog types we have today. This is one evolutionary event that was not only watched by man, but indeed was driven by man. It is but one example of the many domestic animals and plants that illustrate the incredible power of artificial selection.

Darwin proposed that given enough time the forces of natural selection could change the traits of species. The neck of the giraffe would get longer, to reach more vegetation, the gazelle could get faster, to better escape, and the cheetah could get faster, to better catch the gazelle.

The artificial selection that drove the evolution of dogs is simply natural selection on steroids. It proves the principle, and shows without a doubt that evolution is true.

About the author. Steven Potter, PhD, is a Professor of Pediatrics, in the Division of Developmental Biology, at Children’s Hospital Medical Center in Cincinnati. He has authored Designer Genes: A New Era in the Evolution of Man, published by Random House He has also written over one hundred science papers and co-authored the third edition of the medical school textbook, Larsen’s Human Embryology.

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37 thoughts on “Dogs Prove Evolution

  1. i am an advocate of evolution, but before i show this to anyone there does need to be cited sources. i am mostly wondering where the “99% of dogs DNA comes from Wolves”

  2. Is this for real? How can variation within a kind be evidence of evolution? The fact that the DNA potential of a wolf can produce multiple types of dog, proves that the DNA potential of a wolf can produce multiple types of dog.
    No additional information is added to the genome, genes are merely selected from what is already there.
    Here is a slightly trickier point to consider. How did the wolf amass the dna potential to produce every breed of dog?
    I can’t believe that the author is serious about this considering his supposed credentials

    • Does a Chihuahua look like a wolf? How about a Saint Bernard? To some of us it is pretty interesting that Humans have been able to transform the wolf into these very different beasts by just applying the power of artificial selection over the course of a few thousand years. It shows how plastic a species can be. And it argues that the forces of natural selection could achieve similar changes, or even more profound ones, given enough time.

      • No a Chihuahua does not look like a wolf but it is a wolf genetically. They can breed together and according to DNA are the same. Your idea on selective breeding or environmental explains the needs for certain traits to be dominant for hunting or say survival. So since the thousands of years since dogs were domesticated they still have the ability to breed with wolves and Coyotes, yet not a single ape or monkey can breed with man?
        Evolutionists point to “Lucy” as evidence to the ‘missing link” yet that story has proven to be a fraud. No skull, no feet or hands and the proof of the hip bone being humanoid is actually a recreation made of ceramics…. lol. So is it just as possible that man and Neanderthal existed side by side for a few thousand years and that like wolves and Coyotes they could have interbred? That humans dominated the planet because of certain strengths or that Neanderthal died out because they had a weakness or that they had a poor immune system and contracted a virus from some mutated bacteria?

        I do believe that environment can force a particular species to adapt for survival. So during a time when food was scarce the neck of the giraffe would get longer to reach more vegetation but the Giraffe’s that were great swimmers did not return to the sea or become lake dwelling creatures did they? No because they were still Giraffe’s… they did not turn into another species. Darwin did a great job explaining in simple terms the effects of natural selection under certain circumstances. Now evolutionists have tried to use this theory to trace man’s origins all the way back to a puddle of water being struck with lightning to explain the origins of life…. that is a bit crazy don’t you think? Lets take Darwins theory for what it does try to explain and apply it your statement on dogs… yes, selective breeding programs in a confined population can develop certain traits and skills in a particular species but it does not prove that evolutionary process taught in our schools today. Selective breeding of dogs has also brought about many health problems. Over the last 150 years breeders have introduced many health issues into their breeding lines by trying to create animals with certain type of “look”. So the gene that provided a certain perceived benefit may also have carried the code for dwarfism, obesity or even blindness into their breeding lines. So instead of a “natural selection” method these planned breedings have not resulted in an evolutionary beneficial development but actually has hurt and nearly destroyed some breeds.

        Darwin’s theory is just a theory… it is not called Darwin’s Rule of Evolution….is it. Just because you were taught this in school it does not make it any more of a fact or a rule than any other theory. Our kids are taught that Columbus “discovered” America. Well we all know the Vikings were here before Columbus and they may have arrived after the Irish, the Chinese, the Polynesian’s and maybe even the ancient Japanese.

        • “So instead of a “natural selection” method these planned breedings have not resulted in an evolutionary beneficial development but actually has hurt and nearly destroyed some breeds. ”

          Quite the contrary, the bred cuteness of toy poodles makes them irresistible to rich, blue-haired old ladies, who nurture, feed, care for and breed them. On a human-dominated planet, that is a survival-oriented trait of signal value.

        • False. It is time to get your news from reality and not fantasy land. Lucy is real, the hip bone is not ceramic.

          If you really believe those things and yet they are false, doesn’t that raise a few questions? Why are your teachers/religious leaders lying to you about evolution? If they really could prove it false wouldn’t they be able to use the truth to do so? The fact that they need to consistently misrepresent the facts to people like you should be a clue.

        • “Darwin’s theory is just a theory…”

          And so ends any credibility you have to speak about science.

          JUST a theory? Theories are the end goal of science. They are the explanatory frameworks which account for the facts. You, as most laymen who don’t understand scientific terminology, speak as if “theory” means “guess” or “something we’re not very sure about”. It doesn’t. Theories must be supported by watertight evidence and have passed round after round of destructive testing and attempts at falsification intact.

          You appear to think that a “Theory” is a step below a Law. It isn’t. Laws are interesting. Theories win Nobels.

          Theory of gravity.
          Relativity Theory.
          Atomic Theory.

          Get the picture?


        • Eric, thanks for your conemmt on Furr. I think you’re right, wolves have gone from predators to underdogs and in the process we root for them. I also think you are right that they are easy to anthropomophize (sp?) because they are social, agressive, and nurturing – just like us. It is a good song – I found a video of Blizen Trapper playing Furr one of the late night shows – can’t remember which. Its probably easy enough to find on YouTube. Are you carrying any of these themes forward in your dissertation?

    • What the hell is a “kind”? I always see creationists use that term and every time I ask them to define it all I get is hand waving.

      Is it a species? Apparently not, because poodles and wolves are emphatically different species.

      Is it broader than a species? It must be if it includes wolves and dogs… but then the question “how is variation within a kind evolution” is rather obvious, isn’t it?

      All that aside, since even variation WITHIN a species is evolution the question doesn’t make any sense anyway.

    • Variation within a kind is the basic requirement for all evolution. These variations come from many sources–they are DNA mutations that occur naturally. Usually, these mutations are “masked,” because individuals have 2 copies of every gene. So, a new mutation won’t be seen right away (most of the time). When you inbreed individuals, you can unmask the mutations. Also, when you combine different mutations you can get different outcomes.

      In nature, most mutations are bad, so they are “selected against” (meaning wolves with the bad mutations would probably die). But, humans can play the part of nature and select for mutations they like, regardless of whether they would be good in the wild.

      This process of selecting different mutations, either by nature or by humans, is evolution.

  3. Dogs show how selective breeding can bring about certain traits to be dominant… it does not prove evolution. Look for recent studies in Hungary where research teams raised both dogs and wolves side by side…. the wolves never adopted domestic dog traits. It is believed that dogs have the ability to communicate and anticipate human emotions where wolves could care less and rarely even make eye contact with humans.

    If you want the best study on wild animal domestication the Russians have an ongoing study using silver foxes. The study shows that foxes, through selective breeding, can be made docile and human friendly in roughly three generations. They also started to adopt different colored coats and markings from the breeding done with aggressive animals in the controlled study.

    What does this tell us…. that man can manipulate canines through breeding patterns…. it does not explain evolution. For you to prove evolution you will have to explain how the most complex cells known evolved from a single organism in to a mammal. Darwin’s theory is just that… a theory. It has no more validity that what creationists or intelligent design theorists believe. If you want to prove evolution show me one concrete fossil showing a transitional animal.. say an fish growing arms and legs and walking out of the water. There is zero proof that any animal ever turned into any other animal. Like you said…. though dogs look different and have developed certain traits…. they are still a wolf. When you can show me a wolf turning into some other species through natural selection I will agree with you… until then it is just a theory. I also think Darwin was a bit of a crackpot.

    • The Russian study, where foxes were subjected to artificial selection for dog like features is indeed extremely interesting. In a very brief period of about 50 years they were able to generate friendly foxes, with wagging tails and floppy ears. It further shows how selection can dramatically change traits, in this case in a mere blink of an eye in evolutionary time. It is, once again, very strong evidence in support of evolution.

      The business you mention about housing dogs and wolves together, and the wolves not turning into dogs, makes very little sense. Of course not.

      And the final comments about there being no transitional organisms is also nonsense. Look at the fossil record. Evidence abounds.

        • All species are to some degree in transition as natural selection suggests all of them will eventually become extinct as forms more suited to the environment advance. However, the suggestion that there are no transitional fossils is a typical creationist argument, completely ignoring the vast number of fossils that show lineages. If you are expecting a crocoduck, this would never exist but there are plenty of fossils showing intermediate characteristics, such as the poster children of evolution, Archaeopteryx and Tiktaalik. Don’t tell me that a bird with teeth/lizard with feather wings or a fish with wrist bones is not transitional. For a longer list, a quick look at “Transitional Fossils” in Wikipedia will begin the search. More valuable, if you really want to learn something, is to read Donald Prothero’s “Evolution: What the Fossils Say and Why It Matters.”

    • Another creationist who can’t understand the scale of time or the meaning of words like “Theory”.

      After *only* 30,000 years of breeding a Chihuahua in the wild would have extreme difficulty breeding with a mature wolf (or a great dane or any other larger breed) and be able to produce viable offspring.

      Now, expand that 30,000 years of divergent paths to 1,000,000 years (throw a group of chihuahuas on an island for example) and enough mutations would occur that their DNA would likely be more than 99% similar. After 1,000,000 years it is predicted by the theory that a chihuahuhuahua would not be able to breed with the wolf.

      This theory has been proven by ring species; salamanders in California for example. Different groups of salamanders can breed with their neighbors as they spread in different directions around a mountain range. At the other end of the mountain range, the two separate species of salamanders who are known to have descended from the original group cannot interbreed, but they can breed with their neighbors from their own side of the mountain all the way back to the original group. A1 can breed with 2 and B. 2 and B can breed with 3 and C… When you get to Z and 26, they cannot breed with each other (No Z26), but they can still breed with Y (YZ) and 25 (25-26). That is modern, observable speciation.

      If you want to see a transition species, look in a mirror. Everything around you is a transition species.

    • A showcase of intelligent design? Perhaps, if you think of Man as the intelligence driving the design, using the genetic tools of artificial selection.

    • Of course you have solid evidence for intelligent design or is this just another God of the gaps argument where when you don’t know the answer you insert a god?

  4. Of course artificial selection was important in terms of the development of all the different varieties of dogs. However, artificial selection would have gotten nowhere if there hadn’t been the variation from which to select. Turns out that nearly all of the morphological variation can be traced back to just a little over a dozen regulatory proteins.

    Please see for repeats in protein coding regions:

    Mutations in cis-regulatory sequences have been implicated as being the predominant source of variation in morphological evolution. We offer a hypothesis that gene-associated tandem repeat expansions and contractions are a major source of phenotypic variation in evolution. Here, we describe a comparative genomic study of repetitive elements in developmental genes of 92 breeds of dogs. We find evidence for selection for divergence at coding repeat loci in the form of both elevated purity and extensive length polymorphism among different breeds. Variations in the number of repeats in the coding regions of the Alx-4 (aristaless-like 4) and Runx-2 (runt-related transcription factor 2) genes were quantitatively associated with significant differences in limb and skull morphology.

    John W. Fondon III and Harold R. Garner (December 28, 2004) Molecular origins of rapid and continuous morphological evolution, PNAS, vol. 101, no. 52, pp. 18058-63

    Tandem repeats and simple sequence repeats are far more common in the genome than one would expect due to pure chance. It turns out that they are left behind by the retrotransposition of retroelements. Largely Long Interspersed Nuclear Elements (LINEs) and SINEs. SINEs appear to be formed by LINEs due to template switching — where the LINE begins by using its own template then that of the neighboring region as a primer for retrotransposition.

    LINEs appear to be descended from Group II Introns found in bacteria and organelles. Unlike our spliceosomal introns, Group II are mobile retroelements that employ reverse transcriptase. However, our spliceosomal introns appear to be derived from them as well.

    Please see:

    Here we discuss the experimental basis for our current understanding of group II intron mobility mechanisms, beginning with genetic observations in yeast mitochondria, and culminating with a detailed understanding of molecular mechanisms shared by organellar and bacterial group II introns. We also discuss recently discovered links between group II intron mobility and DNA replication, new insights into group II intron evolution arising from bacterial genome sequencing, and the evolutionary relationship between group II introns and both eukaryotic spliceosomal introns and non-LTR retrotransposons

    Alan M. Lambowitz and Steven Zimmerly (2004) Mobile Group II Introns,
    Annu. Rev. Genet. 2004. 38:1–3

    At some point a LINE appears to have captured a DNA transposon, giving rise to a chimeric fusion known as a LTR-retrotransposon and at some point a LTR-retrotransposon acquired an ENV(elope) gene responsible for the capsid that protects the RNA — making possible lateral transmission as the first exogenous retrovirus. Retroviruses replicate through reverse transcription into DNA that is then integrated into the genome as a provirus which once there remains there but then is transcribed into RNA that consists of copies of the viral RNA. When exogenous retroviruses enter the germline they become endogenized, vertically transmitted as proviruses in the genome from fertilized egg to somatic cells and from parent to child. The envelope gene decays and natural selection eventually brings about a mutualism that appears to include three endogenous retroviruses creating a barrier to the mother’s immune system in the placenta that is required for implantation and embryonic development — without which the developing embryo would be treated as an organ transplant (since it is genetically distinct from the mother) without the presence of an immunosuppressant.

    Please see:

    When Villarreal inserted a virus known to suppress endogenous retroviral genes into cells that form the placenta in mice, the placentas did not become implanted into the uterus.8 Important contributions were made by Leyden and Rote in Ohio and Johnson in Liverpool.19 These workers characterized and defined HERVs in normal human placentas, while O’Connell and colleagues went on to identify and characterize a particular virus now known as ERV-3, whose envelope gene was expressed in the syncytiotrophoblast.

    Frank P Ryan (2004) Human endogenous retroviruses in health and disease: a symbiotic perspective, J R Soc Med.; 97(12): 560–565

    From the abstract: The human placenta, unique in its active expression of retroviral sequences that are not expressed in other tissues, may hold the key to an improved understanding of the functional significance of HERVs. In this review, we discuss the contribution of retroelements, particularly HERVs, to placental function and dysfunction. We describe fusogenic and immunosuppressive HERV activities and emphasize epigenetic regulation of retroelement expression.

    Jun Sugimoto and Danny J. Schust (November 2009) Review: Human Endogenous Retroviruses and the Placenta, Reproductive Sciences, vol. 16 no. 11 1023-1033

    … and:

    Jonathan P. Stoye (July 21, 2009) Proviral protein provides placental function, PNAS, vol. 106 no. 29 11827-11828

    It turns out that the design of mammalian placenta often differ rather remarkably among mammals. A function of the endogenous retroviruses that are responsible for protecting the developing embryo.

    However, more broadly, in leaving behind repeats, retroelements facilitate hypermutation where the longer a repeat sequence is the more likely it is to mutate. They promote recombination and both intrachromosomal and interchromosomal rearrangements. And they promote gene duplication — whether it is the result of retrotransposition or simply chromosomal rearrangements — and thus Copy Number Variation.

    Hypermutation makes it possible for proteins to rapidly evolve — then upon finding an optimal variant the nucleotide repeats are broken up by synonymous mutations forming cryptic, amino acid repeats that are no longer subject to slippage. Similar processes apply to repeats in promoters and introns.

    Anyway, my apologies for this not being better written but I am in a bit of a rush tonight.

    • It is indeed interesting that many of the trait differences, like size, can be attributed to a relatively small number of genes. And I could go on for pages concerning repeats, transposable elements and such. When I was a Postdoc at Harvard I did some of the key experiments showing that the moderately repetitive fraction of DNA actually consists of jumping genes, or bits of DNA that can move around the genome. The scarring patterns left behind by these movements in DNA represent some of the best molecular evidence of evolution. See my book Designer Genes: A new era in the evolution of man, for more details.

  5. I am utterly convinced by the evidence for organic evolution (and a dog-lover as well). But I am concerned that all you’ve done here is reassert Darwin’s metaphor as proof. No one has ever denied that what Darwin did was say nature acts over long spans of time the way humans act on domestic breeds. Animal- and plant-breeding explain but logically cannot prove natural selection. By overstating the power of Darwin’s metaphor you risk exposing the anti-creationist camp further to charges of being unscientific.

    Bacteria are better evidence for evolution. They evolve all by themselves, with no human selection, with a fast generation time that acts like time-lapse photography, allowing us to see the natural processes of evolution in months or years, rather than millennia.

    • I agree that bacteria provide an excellent proof of evolution. Look at the evolution of antibiotic resistance, which has taken place in just the past few decades. I’ve actually published a paper on this topic (BMC Evol Biol 2008 Feb 18:8:52), showing how epigenetic inheritance can play a role in this process.

      In my view there are many proofs of evolution. The fossil record. DNA sequence comparisons, including the ancestral scarring patterns generated by retroviral infections and the movements of transposable elements, or jumping genes. And dogs. If the forces of Human selection can evolve the wolf into a Chihuahua over the course of a few thousand years, then it seems a perfectly logical extension to conclude that the forces of natural selection, given hundreds of millions of years, could create the diversity of species that we see today.

  6. It’s nice to see this so eloquently written. I’ve been telling people this for years, with one big difference, inspired by a wolfdog I once had, namely, that we make the distinction between wolves and dogs but that nature does not. The idea of breeds and the standards we apply are simply human hubris– all dogs are wolves. All the traits you find in all 400 breeds of dogs were originally in the wolf– we have no more bred anything like loyalty into the dog any more than we could breed in the ability to fly. All the dogs who don’t pass the standards for their “breed” are showing the hallmark of lupine genetic diversity and highlighting the shortsightedness of people who’d like to take responsibility for what nature wrought. Speaking of shortsightedness, it amazes me that people are willing to say of breeds of one species that some are smarter than others– they’d never apply that reasoning to the human species.

  7. The presumption is that all mammals are related and rightly so, by definition. But is is a puzzle that almost 25% of 5676 species are bats.

  8. It’s as much about Genetic expression as it is about genetic diversity. Belyaev demonstrated that simply breeding out stress hormones caused numerous unrelated changes to appearance and behavior.

    Henty, Bats have been around much longer than most other Mammals, resulting in far greater diversity.

  9. The fundamental premise of a separation of species is that the two distinct species are no longer able to produce viable offspring. A great example is the mule (cross between horse and donkey where all male offspring are infertile and so are most females).

    In this framework, the dog and the wolf are not separate species. All kinds of dogs can mate with wolves, and produce viable offspring. The example of dogs being bred from wolves does provide a nice example of (un)natural selection of traits (no different from Mendel’s original experiments with breeding peas, but it does not provide evidence of the evolution of one species from another.

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  11. How does a non-flying animal turn into a flying animal? l don’t care how many millions of years elapse l just don’t see how this can happen from mutations and natural selection.

    • The flying squirrel would seem an interesting intermediate, that can coast but not fly. There would be a huge selective advantage to being able to take to the air to escape predators. Animals that could jump from trees, for example, and glide through the air would do better than those that could not. Go from glide to fly and that would be better still.

  12. Bats. If you can turn a wolf into a Chihuahua in a few thousand years, it sounds very plausible to turn a rodent into a bat in a few million years. Why is that so hard to believe. I guess in the end you just believe what you want to believe, despite how much evidence flies in your face.

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