Superfluous article of the month

Do we really need another article that telling us that evolution isn’t always “progressive”, going in a straight line towards traits that we consider “advanced”? (These are nearly always traits that humans have, like intelligence, high consciousness, and big brains.)

This form of evolution, often represented by the “straight line” diagram of human evolution shown in the new The Conversation article below, also called “orthogenesis,” is said to misrepresent evolution in several ways. It implies, for instance, that there’s an inherent directionality to evolution, which isn’t true (though in some cases, like arms races, it can approximate truth). It could be taken to imply that the directionality isn’t conferred by natural selection, but by some teleological force, like the “drive to consciousness” broached by computer scientist David Gelernter in a recent, dreadful, and grossly misleading critique of evolution. And it implies a scala naturae—a “scale of nature”—that could be (and was) taken as a ranking of how “evolved” something was. In the case of human races, the scale was used to imply that some races (invariably white ones) were more evolved than, and hence superior to, their pigmented brethren.

Click on the screenshot to read this short piece:

Perhaps I’m being too captious here. Perhaps misconceptions about evolution like this one need constant rebutting as each new generation becomes prey to scientific errors or the blandishments of creationists. Still, the three authors, all biologists, spend most of their time decrying the cartoon depiction of orthogenesis, like the one above, presenting lots of examples (easy to find), but neglecting some really interesting glosses on this idea. In fact, all they really say is that evolution doesn’t work this way, and pointing out three errors (an excerpt):

Originating with Plato and Aristotle, this view gets three main things wrong.

First, it holds that nature is organized hierarchically. It is not a random assortment of beings.

Secondly, it envisions two organizing criteria: things progress from simple to perfect and from primitive to modern.

And thirdly, it supposes there are no intermediary stages between levels in this hierarchy. Each level is a watertight compartment of similar complexity – a barnacle and a coral reef on the same rung are equally complex. No one is halfway between two steps.

Well, I’d argue that the first “error” is wrong, but is not necessarily implied by the figure, which shows straight-line evolution in a lineage, while the hierarchy comes from the branching of lineages, barely mentioned. And I’d argue as well that the progression doesn’t really imply that there are no intermediate stages. It just shows selected segments of an evolutionary lineage.

Had I written this, I would have added a few other points to flesh it out:

a). You can convert a branching bush into a straight line simply by following one line of ancestry. Here’s part of a slide I use to show that point in the evolution of the modern horse, which traces only the path to one twig on the luxuriant historical branching of equids:

The human “progression” above can be derived from picking out one lineage in the evolution from early australopithecines to modern H. sapiens, but hominin evolution was a branching bush, and many of the twigs went extinct. In fact, we are still ignorant of the exact lineage that took early hominins to modern ones.

b.) I would have added that sometimes evolution might take place in one direction, but it’s because natural selection, which could be reversed, drives it that way. No irreversible teleological forces are involved. I gave the example of predator-prey “arms races”, in which predators become ever faster, prompting the prey to also evolve fleetness. Or there might be an “open niche” in which mutations push evolution in a single direction. Brain size (and intelligence) in humans might be one example, although even here not all lineages got bigger and bigger brains: some died out and some, like H. floresiensis, might even have evolved reduced brain size as a consequence of smaller body size (the origin of this species is, of course, a mystery). Another example might be the ancestors of whales, which likely found an open niche in the sea, full of unexploited food. Ergo early whales became more and more amphibian and then fully marine. Natural selection made them that way: more marine whales presumably got more fish and experienced less competition.

c.) I would have pointed out examples in which evolution is regressive, losing features that evolved adaptively in other lineages. Fleas lost their wings, as did penguins. Tapeworms lost most of their sensory systems and their entire digestive system. Some Antarctic fish have lost their swim bladders, and the subgroup of icefish have also lost their hemoglobin, becoming the only vertebrates to lack that protein (dead hemoglobin genes still reside in their genomes, giving evidence of their ancestry). To compensate, they have also lost their scales, so that they can exchange oxygen through their skin. (By the way, I know of no good adaptive story for the loss of hemoglobin in this group).

At any rate, the misconceptions about orthogenesis give plenty of opportunity to impart lessons about and cool examples of evolution. What a pity that the three authors blew this chance (Conversation articles can be longer) to concentrate on example after example of straight-line evolution.

As I said, the article is not harmful to scientific education; in fact, it’s marginally useful. But it could have been much more useful.

h/t: Michael


  1. Mike Anderson
    Posted September 4, 2019 at 1:19 pm | Permalink

    Isn’t the “tree of life” (like the horse one above) also erroneous and outdated?

    (The new, more accurate metaphor being the “braided river”.)

    Having said that, I think that ubiquitous Ascent of Man image, for all it’s inaccuracies, is very useful for capturing the gist of evolution. It seems like it’s something 7 year old could understand.

    • Nicholas K.
      Posted September 4, 2019 at 3:55 pm | Permalink

      I agree. It can be an inspiring image that does not necessarily have to be completely accurate.

    • Torbjörn Larsson
      Posted September 4, 2019 at 3:59 pm | Permalink

      Anthropologist like the concept, the problem – it seems to me – is that despite some braiding the models insist on presenting us with trees. It is rarely that networks (braids) are useful vs having a couple of likely resolved trees as a result.

      • Torbjörn Larsson
        Posted September 4, 2019 at 4:00 pm | Permalink


      • Mike Anderson
        Posted September 4, 2019 at 4:08 pm | Permalink

        I have a curly willow tree whose branches will reconnect if they’re in tight contact (fairly uncommon event), so I guess “tree of life” is technically correct.

    • gravelinspector-Aidan
      Posted September 5, 2019 at 11:13 am | Permalink

      Isn’t the “tree of life” (like the horse one above)

      I think the point that PCC is getting at is that the simplistic linear tree Hyacotherium (previously Eohippus of the infamous “fox terrier” size) to Miohippus to Merychippus to Equus is an unrealistic pruning of a much “bushier” hierarchy depicted in geological time scale, and that the “select few” don’t themselves even lie on one lineage. It’s like Brenda The Constitutionally Powerless tracing her lineage to include Charlie 2, Edward 6 and Ælfwynn of Mercia – all of whom died without issue. The lineage “bush” depicted on the geological column is supported by the fossils, which means that it too drastically under-represents the true levels of diversity in mid-Cæozoic proto-Equuids.
      As for actual blood lines … I’m getting increasingly tempted to try to give a human-targetted genealogy programme a nervous breakdown by feeding it the genealogy of the Greek myths. Or Roman myths, or the thoroughbred bloodstock. That should let the magic smoke out, if nothing will.

  2. Ken Kukec
    Posted September 4, 2019 at 1:31 pm | Permalink

    I’m in no position to add to the academic analysis, but as to the excerpt, in listing the errors, why do the authors use “secondly” and “thirdly,” but not “firstly”? I mean, I think use of the adverbial form in such circumstances is clumsy, but if you’re gonna do it, at least be consistent, folks.

    • russellblackford
      Posted September 4, 2019 at 4:02 pm | Permalink

      It does seem illogical, but it’s what I was taught. It’s a pretty widely accepted convention, at least in some parts of the world. These days, I’d probably write “first”, “second”, “third”, etc., as the “first”, “secondly”, “thirdly”, etc., convention does seem a bit like an affectation (like going to elaborate lengths to avoid splitting an infinitive, or writing “It was she” instead of “It was her”). I checked my Oxford Dictionary for Writers and Editors just now, but I can’t find any relevant advice.

    • gravelinspector-Aidan
      Posted September 5, 2019 at 11:14 am | Permalink

      Quoth Martin Luther, “… and ninety fifthly …”

  3. Posted September 4, 2019 at 1:48 pm | Permalink

    “Perhaps misconceptions about evolution like this one need constant rebutting as each new generation becomes prey to scientific errors or the blandishments of creationists.”

    I think that’s true.

    There’s a somewhat different misconception that is reinforced by some illustrations of evolution; viz. videos that show an individual morphing over time from simple forms to fish to amphibian to reptile to mammal to human. This potentially reinforces the misconception (which some creationists seem vulnerable to) that evolution involves the change of individual organisms, rather than changes across populations over time.


    • Steve Gerrard
      Posted September 4, 2019 at 2:17 pm | Permalink

      Sometimes those making creationist arguments also seem to think that mutations happen to the whole population at once. “Most mutations are detrimental,” they point out. “Species are loosing information all the time,” they claim.

      They can’t seem to get the idea that when one individual shows up with a negative mutation, the population just loses that individual. It is only when a good mutation shows up that it spreads throughout the population over generations.

    • Posted September 5, 2019 at 5:11 pm | Permalink

      I agree that people need these reminders, and Jerry himself took the trouble to make a closely related point just a few days ago. When he pointed out that two species of the genus Homo could exist for overlapping times, and yet the one be descended from the other, I thought: huh? Why the need to mention that?

      Because straight-line diagrams of evolution! That’s why. A lot of people would need that reminder, at least among less-regular readers of WEIT.

  4. mikeb
    Posted September 4, 2019 at 2:01 pm | Permalink

    The “march of progress” continues to bug me: it is largely false. Most people just don’t get the nuances of evolution, and the diagram is simply a misrepresentation. I do think it needs continual debunking.

    Imagine if I posted a picture of myself, my father, his father, his grandfather… on up the patriarchal line, and said “This is where I come from.” It’s inane.

    • Posted September 6, 2019 at 12:02 pm | Permalink

      But of course, people *do* do that, for example lists of monarchs of a country.

  5. Posted September 4, 2019 at 2:04 pm | Permalink

    Re: icefish hemoglobin, perhaps it was a situation analogous to primates and vitamin C.

  6. Vita206
    Posted September 4, 2019 at 2:08 pm | Permalink

    I saw this article on the internet earlier today and was wondering whether you would have a posting responding to it. Thanks!!!

  7. rickflick
    Posted September 4, 2019 at 2:27 pm | Permalink

    I’ve been toying with the idea that evolution is a bit like the arrow of time, i.e. entropy. Entropy of the universe increases because there are many more ways for a system to be more disordered than more ordered. The first life forms were bacteria which were the only life for a billion years. Bacteria are rather simple. Once multi-cellular life got a start, diversity grew rapidly and life became more complex. It became more complex because there were many more ways for random mutation and selection to make new complex forms than less complex forms. So, built into evolution is a tendency to add complexity. I could be all wet.

    • gravelinspector-Aidan
      Posted September 5, 2019 at 11:22 am | Permalink

      Consider that one of the most important parts of any organism’s environment is the organisms that have closest needs to it – it’s siblings and cousins – then you rapidly start to see that every mutation introduced to an initially simple ecosystem rapidly increases the intensity of competition within that environment.
      The proverbial primordial ooze, where a self-replicating catalytic metabolic cycle started to mutually interact with an information storage and catalysis polymer (RNA-world, PNA-world, or something considerably simpler), then the different descendants of the first organisms would have started with a considerable diversity of chemical and thermal environments, and it would get more complex with very generation from then on.

      • rickflick
        Posted September 5, 2019 at 1:26 pm | Permalink

        Exactly so. The built in tendency to complexity does not deny that a population can simplify as well and so increased complexity is not necessary or constant.

    • Posted September 5, 2019 at 5:18 pm | Permalink

      Sean Carroll on the entropy-complexity relationship:

      Complexity requires moderate entropy, so at least, in the few tens of billion years after the Big Bang, you would expect complexity to increase along with entropy.

      You’re not all wet.

      • Posted September 6, 2019 at 12:04 pm | Permalink

        Complexity also requires *size*. Things that are smaller have fewer parts so can be permuted less.

  8. E.A. Blair
    Posted September 4, 2019 at 2:41 pm | Permalink

    Eliminate that “Ascent of Man” image and hundreds of cartoonists would lose one of their most popular clichés!

    • Kahlil Jabroni
      Posted September 5, 2019 at 2:52 am | Permalink

      S.J.Gould sometimes went overboard in exhausting every possible wrinkle of a notion; in ‘Wonderful Life’ he included a number of examples of those satirical versions of ‘The Ascent of Man’ & also insisted on describing the ones that he couldn’t get permission to publish.

      • gravelinspector-Aidan
        Posted September 5, 2019 at 11:25 am | Permalink

        Was that “Wonderful Life”, or one of his diatribes in … “Natural History” magazine?
        Of course, there was nothing to stop him re-using one essay as a chapter in another book. And my memory may be faulty – I don’t have my book collection in the same country any more.

  9. Ronald Jenner
    Posted September 4, 2019 at 2:51 pm | Permalink

    There is nothing wrong with linear evolutionary imagery. As long as you don’t line up collateral descendants (members of different evolutionary lineages). The most basic topology of evolution is the linear descent of descendants from ancestors. Such lineages can fuse, and lineages can diverge, but these fusions and divergences involve linear lineages of ancestors and descendants. The late Stephen Jay Gould completely failed to understand this, and I penned a rebuttal of his view last year in the journal BioEssays titled “Evolution Is Linear: Debunking Life’s Little Joke”. I’d be more than happy to send you a pdf if you email me.

    • W.Benson
      Posted September 7, 2019 at 6:28 pm | Permalink

      I agree with Jenner. I never really understood why people find objectionable the “March of Progress” ape to man imagery when it is used, as it usually is, to represent spaced points along an ancestral lineage.

  10. Posted September 4, 2019 at 3:14 pm | Permalink

    Alongside the numerous misconceptions about evolution are the equally numerous ones about creationism. Problem is, we tend to blithely accept the concept of creationism foisted on us by fundamentalist Christians, who in fact know zip about how anything gets created. We should be looking to people who actually create things—namely, artists (painters, composers, poets, etc.)

    If we did this, we would immediately see that a key component of any true creative act is improvisation. And all improvisation is a microcosm of—you guessed it—evolution. It grows from seemingly nothing, from what appear to be random elements of the environment, and self-organizes into a distinctive event with its own shape, with feeling and relevance. As Shakespeare put it:

    . . .as imagination bodies forth
    The forms of things unknown, the poet’s pen
    Turns them to shapes and gives to airy nothing
    A local habitation and a name.

    So while science may not be compatible with religion, I see no reason why evolution should not be compatible with creationism. True creation is evolution.

    • Posted September 4, 2019 at 4:21 pm | Permalink

      This is all confused because you’re conflating biological creationism with artistic creation. And when you do that, you have produced what looks to me like an extended Deepity.

      • Posted September 4, 2019 at 6:06 pm | Permalink

        “. . . you’re conflating biological creationism with artistic creation. And when you do that, you have produced what looks to me like an extended Deepity.”

        With due respect to Daniel Dennett, one definition of a “Deepity” is something that would be very important if it were true. So what I’m suggesting is that we might learn something by conflating biological and artistic creation and seeing what we come up with.

        After all, this is how many scientific discoveries have been made. As Thomas Kuhn observed, “Metaphors [in essence, conflations] play an essential role in establishing links between scientific language and the world.” Think of Maxwell’s Demon or Schrödinger’s Cat.

        That said, I know of know one who has even considered thinking of biological evolution in terms of artistic creation, or vice versa, which strikes me as shortsighted.

        • Murali
          Posted September 5, 2019 at 8:24 am | Permalink

          ‘…thinking of biological evolution in terms of artistic creation…’

          So let’s make a start.

          Maxwell’s Demon and Schrödinger’s Cat are thought experiments. Are you proposing a thought experiment?

          • Posted September 5, 2019 at 11:32 am | Permalink

            It isn’t hard to think of life as somebody’s artistic creation. I don’t think it is but I totally get the attraction of the idea. When I think about what I know that convinces me that life arose without the hand of a creator, it doesn’t surprise me that Creationism has a hold on so many people.

            • Posted September 6, 2019 at 12:12 pm | Permalink

              This idea has a very long history – from Plato to Leibniz to Goethe and beyond. Unfortunately, it is wrong – it runs into the aesthetic equivalent of the argument from evil. I do find the natural world lovely, but not necessarily all of it (death can be horrific). So which aesthetic values are being “created”? It seems that they are, like with the evil/good thing, they are at odds, and then at odds with our own notions of aesthetics. So just as “good in a way we cannot understand” is just an equivocation, “beautiful in a way we cannot understand” (or whatever aesthetic value) is *also one.

              Incidentally, Aristotle only in one place seems to address the *global* question that Plato dealt (and the others were to deal) with. This is interesting and shows how unChristian his philosophy really is. Not only does he confess that he does not know what the universe as a whole is for the sake of, this shows that under the influence of Christianizations, he is portrayed as a teleologist in a *wrong* way. The wings of a bird, he says, are *for its sake* (which is wrong) but at least he does not say they (or the bird) is thereby for the universe (he may say that it is for us, to eat, etc., however).

              Why do I mention Aristotle in light of this? Because he’s aware of the competitive and messy nature of existence, and *tentatively* suggest the universe as a whole is for the sake maximizing beauty. Reading this was a real WTF moment on my part, but there you go.

  11. KD
    Posted September 4, 2019 at 3:16 pm | Permalink

    It would be interesting to see someone address the mathematical problem of deriving a biologically useful protein from random mutations.

    Also, if we submit as a hypothesis that living organisms may have some means of employing recursive optimization algorithms, I would presume you would have a way of addressing the improbability arguments while remaining in a philosophical naturalism.

    Obviously, such processes would manifest a microteleology (organism optimizing toward some end), and I presume the organisms with favorable optimization features would out-compete the random organisms.

    • KD
      Posted September 5, 2019 at 9:37 am | Permalink

      The reason for discussing optimization algorithms is, of course, because you could mathematically formalize a system for optimizing organisms versus random organisms, you could make some mathematical predictions about adaptation rates, and you could run a variety of yeast experiments to see whether rates of adaptation were slow (consistent with chance) or fast (consistent with optimization).

    • gravelinspector-Aidan
      Posted September 5, 2019 at 11:29 am | Permalink

      It would be interesting to see someone address the mathematical problem of deriving a biologically useful protein from random mutations.

      Yet again?
      But, does anyone in the Origins of Life community think that proteins were anything but a late addition to the original chemistry of life? Oh, sorry, have you missed the last 30 years of work?

      • KD
        Posted September 5, 2019 at 2:06 pm | Permalink

        I think the argument in the piece addressed the creation of new proteins. Are you contending that the emergence of a complete set of proteins occurred at the very beginning of the emergence of life, and no new proteins emerged after the beginning? But even if all the proteins are emerge ex nihilo at the beginning, that makes the problem worse because you compress the time frame for random mutations to occur.

        If there are new proteins, ever, since the “lightning strike”, then it seems on the surface a cogent argument that requires rebuttal, not hand-waving.

        The problem I have is that non-responsive responses like yours actually cause me to give the argument more credence. I’d like to see someone systematically treat it somewhere.

        If some coincidence like a monkey randomly typing Shakespeare is necessary to swallow in order to preserve the theory, it is in trouble.

        • Posted September 6, 2019 at 12:05 pm | Permalink

          Have you read Andreas Wagner? 🐜

          • gravelinspector-Aidan
            Posted September 7, 2019 at 3:51 pm | Permalink

            Or for that matter Manfred Eigen or Gûnther Wächterhäuser (I always get the umlauts in the wrong place – my own mutation process)?

            Oh dear, Eigen died a few months ago. Sad to hear that. By the Saucy Balls of the FSM, his works gave me headaches to understand.

        • gravelinspector-Aidan
          Posted September 7, 2019 at 4:12 pm | Permalink

          When talking about the origin(s) of life, you’re generally not talking about the massive complexity of information transmission, information translation ad protein construction of modern life, but far, far simpler metabolic cycles onto which catalysis by various chemicals (today proteins, in the early stages maybe RNAs, maybe mineral surfaces (my mineralogy lecturer had a thing for several decades about corrosion pits in feldspar surfaces, which have dozens of degrees of freedom but with repetition and critically variation, on a molecular scale comparable with metabolic molecules), or something else) had an influence. Once you’ve got a catalytic cycle going, if the elements of that cycle interact with your environment then you are going to migrate to the most efficient cycle – as Eigen’s work demonstrated and why he got his gong. If a new cycle element arrives in the environment, then that would get incorporated. If fragments of the environment get moved (as Russell demonstrated for hydrothermal venting while I was a student, and AGC Smith also showed for clay minerals) then the cycle can show both reproduction and variation. Those are the elements on which evolution can act.
          How a genetic system got grafted onto that – well people are still arguing. Evidently one did – we see it today, and possibly the echoes of some of the previous genetic systems – but also quite likely the original system (clay, iron sulphide minerals, feldspars, whatever) was only moderately effective. But it doesn’t need to be terribly effective as long as it metabolised to fix carbon and increase the amount of material in the system. We can see some of those systems operating in the test tube today, and we probably see see their remains in the catalytic cores of important biochemistry today, once you strip away the last 3 or 4 billion year of refinement that has been bolted onto the core reactions.

          If some coincidence like a monkey randomly typing Shakespeare is necessary to swallow in order to preserve the theory, it is in trouble.

          No less concerning to you than a god. Oh well, that’s your pipe to smoke.

  12. Posted September 4, 2019 at 3:50 pm | Permalink

    “And thirdly, it supposes there are no intermediary stages between levels in this hierarchy.”

    I don’t get that from the picture. Sure, it shows only specific species and not intermediates but how could such a diagram show otherwise? Our knowledge also consists of a small number of species with gaps between them.

    I find the biggest falsehood of this kind of diagram is its portrayal as a single progression leading to modern humans rather than a tree with many dead-end branches. It the opposite of the truth that most species that ever existed are extinct.

    • mikeb
      Posted September 4, 2019 at 4:03 pm | Permalink

      “I find the biggest falsehood of this kind of diagram is its portrayal as a single progression leading to modern humans rather than a tree with many dead-end branches.”

      Another huge falsehood is that it also renders the impression that individuals “evolve” into other individuals, when we all learned that evolution occurs to populations, not individuals.

  13. Torbjörn Larsson
    Posted September 4, 2019 at 3:52 pm | Permalink

    Whoops! I just – like Ronald Jenner here – commented on that article. (I trolled actually, by the measure of this site, placed 3 comments with the previous 8. But the topic was interesting.) This article responded so much better!

  14. Raskos
    Posted September 4, 2019 at 5:58 pm | Permalink

    Dr. CC – could I copy and use your slide for my own introductory biology course? I’d like to be able to post it on the course’s online site but require your permission before doing so.

  15. Diana MacPherson
    Posted September 4, 2019 at 8:02 pm | Permalink

    I dunno. As I caution when I build a process map, “the map is not the terrain”. We make conscious decisions to leave out certain details for simplicity sake. That’s why there needs to be some narrative around images and maps.

  16. Hrafn
    Posted September 4, 2019 at 10:31 pm | Permalink

    I saw this, or something very similar to it, a few days ago. My knee-jerk reaction was that it is not ‘wrong’, just a necessary simplification for the format. It would be quite difficult to present a full ‘tree’ of morphological changes without it becoming much larger, and more complex and confusing.

    Of course, as with any simplification, it is subject to misinterpretation. But that happens any time complex scientific information is simplified for a lay audience.

    • Posted September 6, 2019 at 12:15 pm | Permalink

      Both W. Wimsatt (who is right in Jerry’s part of the world, last I checked) and M. Bunge have pointed out that deliberately false theories, classifications or non-referential ideas, etc. if *done appropriately* not only allow us to think, but also allow us to know their own limitations, *and* to point the way to the truer ones.

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