The Monkey Gene Thing, Qualified for Once

Quick post with a word of thanks to National Geographic magazine. Though I smacked them around a little in the past about the whole “human embryo” vs “embryonic human” twist in a post long ago (which eventually became a commentary on the Tomorrow’s World website), I do enjoy the magazine when I have the time to read it.

The most recent edition (April 2008) has a fascinating article on some chimpanzees who seem to have learned how to use pointed sticks as spear-like tools for getting at yummy bushbabies (yummy from the chimp’s point of view, of course). It makes the usual stretches (which the title, “Almost Human,” foreshadows well), but it is still fascinating.

But one of the statements I liked most in the article had little to do with the substance of the article itself. The author, Mary Roach, reminds her readers of the “Monkey Gene Thing” — the often stated similarity in human and chimpanzee DNA — telling us that they are “around 95 to 98 percent the same.” But then she helpfully adds a parenthetical qualifier:

This is less meaningful than it sounds. Humans share more than 80 percent of their gene sequence with mice, and maybe 40 percent with lettuce.

Yes, indeed. For many of us this is not new news, but for many others it might be. Although the article makes it clear where Mrs. Roach stands concerning beliefs about human “ancestry” and though I clearly do not agree with that stand, I appreciate her qualifying that “95 to 98 percent” comment, as most evolutionists fail to put the comment in perspective in any way at all.

It is not that the genetic similarity is not meaningful at all — but it is “less meaningful than it sounds.” Yet when it shows up during evolutionist/creationist yelling matches (hard to call them debates), how it “sounds” is left unqualified, because how it “sounds” makes more of an impact when it is unqualified. Young Earth Creationists often make the same misstep, such as when they tout a scientific finding that is at odds with the understanding suggested by the vast majority of related findings and then fail to mention the rarity or uniqueness of the finding they are advertising. Why? Because the “sound” of what they are saying is more convincing if it is left unqualified.

Now, I don’t mean to call the kettle black while avoiding my own pottish nature. I make the same mistake, myself, however on guard against it I might be. (Troll around this blog for a while and you might see some examples, I am sure.) It is a part of human nature and a seemingly inherent tendency of our horribly human Jeremiah 17:9 heart.

All the more, then, it is nice for once to see the Monkey Gene Thing properly qualified in print.

15 thoughts on “The Monkey Gene Thing, Qualified for Once

  1. DNA is the chemical building block of physical life. Monkeys have arms and legs, toes and fingers. Lettuce doesn’t. And – sure enough – we have more DNA in common with monkeys than lettuce.

    Wow. What a surprise!

    But like you said, perception is more important than reality. Since we share more DNA with monkeys than lettuce, then we obviously evolved from monkeys instead of lettuce.

    Maybe the DNA research will lead the evolutionary crowd into a parochial shouting match over cladistics?

  2. I do not understand how it is “less meaningful than it sounds”. It is exactly as meaningful as it sounds. We share genetic similarity with all of life because all of life shares a common ancestor. That’s why we even have sequence similarity to bacteria and archaea. And this genetic similarity tracks with evolutionary relationship. It’s least for archaea and bacteria, greater for eukaryotes, and progressively greater with more closely related eukaryotes.

    Our sequence similarity with chimpanzees is extremely close. It varies depending on how you calculate it, but if you look at gene sequences only the similarity rises to 99%. Many of our genes have the exact same sequence as chimpanzee genes.

    Whoever Mary Roach is, she ought to know that chimpanzees are not monkeys.

  3. Howdy, Nimravid, and thanks for the comment!

    First, although I am not an evolutionist, let me defend Ms. Roach, who clearly is. Calling the chimp/human DNA comparison the “Monkey Gene Thing” uses my label, not hers. She says nothing of the sort. I didn’t think one would get an impression otherwise from my post, but I apologize if I came across that way.

    And if I may defend myself, also, I certainly know how to distinguish between a chimp and a monkey, and my use of “Monkey Gene Thing” is meant as a colloquialism as opposed to a strict taxonomic identification.

    As for the statement being “less meaningful than it sounds,” I can’t explain with certainty what Ms. Roach meant (again, she clearly seems to be a supporter in evolution as popularly understood), but I can recommend that you read her article (really, very interesting) to see the comment in context.

    I can, however, explain what I took it to mean, and it really does seem clear from even the small amount of context I provided. The “95%-98%” similarity is usually stated to imply a close and unique commonality between chimps and humans, and it is stated quite often. “95%? Wow, that’s really high!” But when you add in the fact that we share 80% of our sequence with mice, the aura of “close and unique commonality between chimps and men” begins to feel not so special. And to share 40% with lettuce? I don’t know about you, but suddenly 95%-98% actually seems like it should be higher.

    Of course, if one is stressing a theme of “all life shares more in common than you would think” then, yes, the meaning is not diluted at all. But the point is that those who stress (over and over and over) the similarity currently believed to exist between chimp and human DNA are usually not trying to stress such a broad theme — rather, they are usually trying to stress a special genetic “bond” between humans and chimps.

    When it comes to impressions made (which is what Ms. Roach was parenthetically commenting on), the question really isn’t whether or not “our sequence similarity with chimpanzees is extremely close.” Rather, the question is whether or not it is surprisingly close. When one does not know about the 80% & 40% figures for mice and lettuce, it might be (though I don’t think it should be). But when one knows beforehand that he shares a full 40% similarity with the leafy green vegetable on his Big Mac, the 95% figure (or even the 99% you provide) becomes much less startling — even not startling at all. And that is exactly what Ms. Roach seems to be saying.

    Although I disagree that the genetic similarities present in various pairings of living organisms is due to a universal “common ancestor”, if you don’t mind I will not comment on that here, as such a discussion would be well outside of the scope of this post. 🙂

    Thanks, again, Nimravid, for your comment, and I hope my explanation helps to clarify what I meant, both for you and for others who might read.

    Best regards,
    Wallace Smith

  4. So you want to exchange the misapprehension “ZOMG, we’re 95%+ similar to chimps, and like no similar to other organisms, so we must be related to chimps!” for “ZOMG, we’re 95%+ similar to chimps and share significant sequence similarity with all other life, so that similarity is really meaningless!” ?? Those both are wrong. How about we go with reality–we are extremely closely related to chimpanzees, they are our closest living relatives since we share a common ancestor about 7 million years ago. We share sequence similarity with all of life because we all descended from a common ancestor. Since the pattern of life is a nested hierarchy, genetic similarity maps with evolutionary relationships.

    Common ancestry is indubitably true. Even ID icon Behe acknowledges common ancestry for all life. Some try to say that genetic similarities are due to a common blueprint, but these genetic similarities include meaningless changes and plagiarized errors. They also include changes that we can track to known causes that modified the genome in a single event in a common ancestor. You can see some examples of these mutations in the second and third entries here at my blog, although the first and last entries are interesting too.

    Please don’t call chimpanzees monkeys, even colloquially. It’s just wrong, and is a common error that it is easy to correct.

  5. Thanks for writing again, Nimravid. I hope you will read the post again and notice the explicit statement: “It is not that the genetic similarity is not meaningful at all…” So where you get the idea that I am saying that the “similarity is meaningless,” I am not sure. Perhaps you were having a bad day when you read the post.

    I’m not sure how you are missing the point, but I will try to explain it again. However, I admit that won’t be interested in doing it a third time, as I would guess that you would be just as uninterested in hearing it a third time. 🙂

    The statement about genetic similarity should make an impression, but not the impression that those who tout it are often trying to make. In most instances in which I have heard or read the 95% figure offered, the goal seemed to be to get the audience to look beyond the apparent phenotypical similarities/differences between humans and chimps and to admit a deeper connection than simple observation of the phenotype would suggest: in other words, to influence them to conclude specifically that we are much more similar to chimps than they had previously thought and that the phenotypical differences should be considered less significant.

    However, were one to begin with the fact that using similar measures of genetic similarity, we are 40% similar to lettuce, then the impact of the 95% comment [Note: when it comes specifically to the desired conclusion stated in the previous paragraph, NOT concerning other possibly very meaningful conclusions] is clearly weakened for most readers. In fact, a more natural reaction might be an increased significance in the mind of readers about the phenotypical differences, as well as a sense of diminished significance about the phenotypical similarities. Personally, when I read that we are 40% similar to lettuce, the phenotypical differences between lettuce and humans are so jarring, that by comparison I would expect a similarity much greater than 95% (or even 98% or 99%) between us and relatively phenotypically similar simians. (I have checked this with others, and after hearing about the lettuce, they were, indeed, surprised at the comparatively “low” figures for chimp similarity — again, this post was about intended impressions, nothing more.)

    Mentioning that there is such amazing genetic similarity between creatures of such radically different phenotypes, dilutes the normally intended objective behind mentioning the chimp/human genetic similarities. It does not make it a statement of no significance. It simply means that the intended impact for which the statement is often used (not always used) is diluted by the additional information. This is not to say that the impact of other statements might be all the stronger.

    That seems to me the most obvious purpose of Ms. Roach’s parenthetical comment, and that is how I take it. As a public speaker and someone for whom the art and science of influence is something I have to take into account in my regular work, I believe that she makes a good point — a point that is helpful and one not nearly as controversial as our current conversation makes it seem.

    As for your assertion of the supposedly indubitable status of common ancestry, I will only say that I do not agree, and that the interesting facts and studies to which you refer on your blog, as well as similar studies and information I have read before, haven’t convinced me otherwise. Behe is certainly free to come to his own conclusions, as are you. And all three of us in this happy little group are equally free to change those conclusions as more facts come to light and as the task of hypothesizing about the world continues in its merry way. It is not the purpose of this post to get into a common ancestry debate, and I don’t intend to start here, so I will simply state my disagreement move along.

    And finally, I’m sorry that my colloquialism offends you. In matters of taxonomy, it may be an error, but as far as simple sentiment I see nothing wrong with it at all. And should I ever be on the Jay Leno show appearing with a baby chimp and the animal’s handler playfully places the little tyke on my shoulders, please forgive me if I jokingly say that I have a monkey on my back. If you feel such a statement is too ripe with the potential to accelerate the perpetuation of a dangerous taxonomical error, I would suggest that you switch to Letterman for that segment.

    Actually, the Bible does encourage us to go two miles with one who compels us to go one, so perhaps I can avoid using the phrase “Monkey Gene Thing” during those moments when I know you will be reading. And, rest assured, if I get any e-mails from offended chimpanzees — or even orangutans — I will be happy to throw it completely out! 🙂

    More seriously, thanks again for your comment, and I hope this succeeds in clarifying the intent of the post better than my previous comment did. If it does not, then I will have to admit my inability to do so, and it would probably be fruitless to continue our conversation about it.

    Best regards,
    Wallace Smith

  6. Ryan G.

    Perhaps as a point of irony, is this the same Mary Roach who is a humor columnist for Readers Digest? Her writing style certainly sounds the same.

    We could also say that we have protein similarities with all sorts of creatures, that is really what this DNA business boils down to. Wouldn’t one expect that, when considering the function and purpose of the proteins and tissues that compose living bodies whether they be human or animal? I am being overly simplistic here, but the DNA similarities argument seems very moot to me.

    Have you read Behe’s latest book The Edge of Evolution? Would be curious on your thoughts about it.


  7. “Perhaps you were having a bad day when you read the post.”

    Apparently not as bad as you were when writing this one! 😀

    “In most instances in which I have heard or read the 95% figure offered, the goal seemed to be to get the audience to look beyond the apparent phenotypical similarities/differences between humans and chimps and to admit a deeper connection than simple observation of the phenotype would suggest: in other words, to influence them to conclude specifically that we are much more similar to chimps than they had previously thought and that the phenotypical differences should be considered less significant.”

    This may be one of those things where once you’re familiar with something you think about it differently than those not familiar with it, and so do not perceive something in the same way. When I look at chimpanzees I see 99% identity in their genes (the decrease to 95% or so happens when you consider noncoding DNA). That does make me ask why we are so different if our proteins are almost exactly the same. The answer is our gene expression patterns are different. The conclusion I draw is that while your genes do have something to do with your phenotype (for instance, humans suck at fixing nitrogen because we don’t have that gene, while some bacteria do), when you turn on or off those genes during development often has the greater impact. The second conclusion I draw is that this means you can evolve a very different phenotype than the one you start out with without having to interject much genetic novelty at all–evolution is easier than we sometimes think!

    To me the 95% similarity value is pretty meaningless because it considers noncoding DNA such as transposons, and those can vary widely. For instance, the Animal Genome Size Database lists fish genomes as ranging from 0.35 to 133 picograms. Wow! Does this mean the pufferfish has a max of 0.3% similarity to the lungfish? Nope, if you examine the gene sequences they will be extremely similar. The noncoding portion of the genome can expand or contract significantly. That’s why I think the 99% value for expressed genes is more informative.

    The range from 87% (or thereabouts) for mice to 99% for chimpanzees may seem like a tiny difference, but if we then consider that all humans are 99.9% identical, we can see with a tiny change of 0.1% we can encompass a wide range of phenotypes. This may re-intensify the significance of the similarity that you believe to be reduced when we compare ourselves to other organisms with high sequence identity but low phenotypic resemblance.

    I’m not even sure if the 40% value for a plant is accurate, just taking Roach’s word for it. It’s hard to figure how to calculate that. Plants have genes that we don’t have, and we have some genes that they don’t have. We have non-coding DNA they don’t have, they have non-coding DNA that we don’t have. Some of our genes are going to vary widely in sequence, while others that are more foundational will keep an extremely similar sequence, probably much greater than 40% sequence identical.

    The upshot:

    1. Comparing total genome sequences is often uninformative.
    2. Sequence identity for genes can vary widely, with some genes conserved surprisingly well across more than one domain of life (across bacteria and eukaryotes, for instance), and others only possessed by a limited subset of one domain.
    3. Tiny changes in sequence can produce notable phenotypic differences.
    4. Most of the change in phenotype across closely related species is due to changes in gene regulation, not changes in gene sequence.

    “In matters of taxonomy, it may be an error, but as far as simple sentiment I see nothing wrong with it at all.”

    It’s like calling a dog a seal. Or a snake a lizard. I guess you find it amusing that I think that this is a significant enough error to object to it, but I find it distasteful that you know it’s an error and don’t care.

    “More seriously, thanks again for your comment, and I hope this succeeds in clarifying the intent of the post better than my previous comment did. If it does not, then I will have to admit my inability to do so, and it would probably be fruitless to continue our conversation about it.”

    Perhaps. I’m afraid I may be more concerned with Big Picture and in-depth meaning of similarity, while you are more interested in the impression stating it in certain ways leaves upon the reader.

  8. “Apparently not as bad as you when you were writing this one!”

    Ha! OK — that’s funny. 😀

    I think your point about familiarity with unspoken context altering perception is a valid one, but it still doesn’t change the validity of Ms. Roach’s comment or my observation about it. In fact, it highlights that validity, as those who tend to use the statistic to make their point should know their audience well enough to know whether they are familiar with the context of their comment to properly interpret and understand it. one of the cardinal rules of speaking to a crowd is to know your audience — have an idea of what they know, what they don’t know, and how their knowledge or backgrounds may influence them to understand what you are saying in ways that differ from what you want them to understand.

    The fact (and based on my own experience with others it does seem to be a fact) that “Average Joe” audiences respond very differently when they year the “Chimp Gene Thing” (I hope you will appreciate my concession!) as a “stand alone” comment versus when they hear it alongside the “Mice & Lettuce Gene Thing” is a powerful sign that Ms. Roach makes a excellent point. And it is a point that agrees well with your point about the effect of familiarity with the context. Actually, your point makes me all the more pleased that Ms. Roach qualified her comment as she did. An educated reader is much more likely to put comments in their proper context and draw more accurate conclusions. [It really is clear from what I have read in the article that, unlike me, she is a strong supported of evolutionary theory, and in this sense she is simply educating her readers to understand a point in a proper context.]

    The cynical would believe that those who use the “Chimp Gene Thing” do know their audiences and prefer their comment to stand without context for that reason. But I am not that cynical. Generally.

    On a side note: For the record I personally believe that telomeres, cytogenic differences, etc. should be considered in such comparisons and that the 95% figure is a more accurate picture, but I recognize that there is legitimate debate, both about whether or not they should be included in calculations and also how to properly quantify them if they were included — facts your example highlights well. (I hold my tongue concerning questions I may have concerning the sample size of bases used and the methodology used to analyze them, that peace may reign in the land…)

    Also, as for evolution being “easier than we sometimes think,” I will for the moment merely smile and say that this is not the conclusion I would draw. 🙂

    I do apologize if I have offended you by using the word “monkey” more loosely than your sensibilities allow. As a mathematician, I used to have the same issue with people using the word “proof” loosely until I realized that I was the one who had the problem, not them. (You may come to a similar conclusion, perhaps? Someday? Maybe?) I will admit that I did find your concern as expressed in your second comment amusing, but I was hoping to laugh with you instead of at you — my apologies if that came across poorly.

    As you may have noticed above, I have renamed the phenomenon the “Chimp Gene Thing” in your honor. Though I must say that I think your dog/seal comparison is way off… Your snake/lizard suggestion is a little closer, but tomato/vegetable would be a much better (almost spot on) analogy I think — not scientifically accurate, but reasonably and properly acceptable in many if not most other contexts. I hope you appreciate the sacrifice I have made and will think of me fondly.

    Finally, you really do hit the nail on the head in your last paragraph, which encourages me to believe that we actually have successfully communicated! You said:

    “I’m afraid I may be more concerned with Big Picture and in-depth meaning of similarity, while you are more interested in the impression stating it in certain ways leaves upon the reader.”

    While I, too, am concerned with a Big Picture, you are absolutely correct: the point of my post was completely about the impression that is made when facts are communicated in certain ways, and not at all about the actual, debated implications of similarity. That is exactly right! (I feel like doing a touchdown dance, here.)

    Thanks, again, for contributing, Nimravid. It was good to meet you, and I hope that you and all 100% of your DNA base pairs have a good day. Perhaps in the future or in another post we can discuss the other side of things (that is, the meaning of similarity), if I can take off a week or so. 🙂

    Best regards,
    Wallace Smith

  9. It continually amazes me how some use DNA or morphological similarities between species to prove evolution as fact. It doesn’t prove anything.

    Physical life is little more than bunch of atomic sequences. That we share certain chemical building blocks with other species shouldn’t come as a big surprise.

    Noting the objective fact doesn’t prove the subjective conclusion that life “evolved.” What, God was suppose to use some other substance to create physical human beings?

    Give me a break.

  10. Howdy, Ryan G., and I apologize — I did not mean to ignore you!

    First, I doubt that Mary Roach is the same as the Readers Digest author, though I suppose I cannot say so with 100% confidence. Ms. Roach, in the parenthetical comment in the NG article, really wasn’t trying to be humorous (as far as I can tell)–simply making a helpful, clarifying point.

    As for Behe’s The Edge of Evolution, I have not read it, though I might some time in the future. As one might expect, I have read good and bad reviews of the book, though it is hard to get reliable reviews from an unbiased source when the topic is one so heated.

    The Evolution/Creation debate is a favorite subject of mine (as you might have guessed!), but my discretionary reading time is so limited these days that I have difficulty finding the time to read anything in addition to the “must read” stuff. And recently when I have found the time, I have been focused on some topics that are more broadly apologetic as opposed to focused on this particular subject.

    Thanks for writing in, and sorry for the delay!

  11. I worry that, once they discover they are related to lettuce, creationists will take that as license to act as lettuce.

    We’re also related to sea cucumbers, who eat their own brains. The possibilities for bad analogies for human behavior are endless, from nature.

  12. Ah, Mr. Darrell. It seems you can always be counted on to say something unnecessarily insulting when folks are trying to be pleasant. And I wouldn’t say that creationists would have a corner on that market of behavior. There’s enough “monkey see, monkey do” (or “monkey hear, monkey repeat”) in the realm of Darwinists and evolutionists to keep up.

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