The Most Popular Textbook Example of Punctuated Evolution Has Been Debunked by Researchers

Seven Species of Bryozoans

The picture shows the seven species of bryozoans that were used in the debunking.The white line is only 500 micrometers in lenght. Copyright: JoAnn Sanner, The University of Chicago
The most popular textbook example of

Researchers at the University of Oslo have debunked a textbook example about how evolution proceeds during speciation. Renowned paleontologist Stephen Jay Gould fronted the old theory.

Evolutionary biologists have for a long time disagreed on the rate of evolution when new species emerge. Are new species the result of gradual changes – as Charles Darwin suggested – or is evolution speeding up for short periods of time when new species evolve?

World renowned paleontologist Stephen Jay Gould (1941-2002) formulated the theory of punctuated equilibrium together with Niles Eldredge (1943-) in 1972. The theory states that species remain more or less unaltered during their existence, with major evolutionary change happening during rapid events of speciation. As evidence for this view, Gould pointed to the fossil record.

Marine Fossils New Zealand

Fossils can tell scientists about what life on Earth looked like in the past. The picture shows two million year old fossils of marine organisms found on an expedition to New Zealand. Credit: Kjetil Lysne Voje/UiO

According to Gould, the fossil record typically show that species do not change significantly after they emerge, and that major changes occurred when new species appeared.

Stephen Jay Gould was one of the twentieth century’s most famous evolutionary biologists and a bestselling popular science writer. Some even claimed that Gould was the foremost biologist of his time – perhaps the greatest since Charles Darwin himself – so his words have carried a lot of weight to this day.

In a new paper from researchers at the University of Oslo, the authors claim to have found several methodological problems in the most famous and well-trusted example supporting the theory of punctuated equilibrium.

“We find no evidence for punctuated evolution in our reanalysis of the most recognized dataset that Gould used to support his theory,” says Kjetil Lysne Voje at UiO’s Center for Ecological and Evolutionary Synthesis (CEES) at the Department of Biosciences.

Textbook example is rejected

Fossils of the bryozoan genus Metrarabdotos – a group of aquatic invertebrates thoroughly investigated by the excellent paleobiologist Alan Cheetham – have been the prime example of punctuated evolution.

Gould called Metrarabdotos “the most brilliantly persuasive, and most meticulously documented, example ever presented for predominant (in this case, exclusive) punctuated equilibrium in a full lineage” (Gould 2002, page 827).

Kjetil Lysne Voje

Researcher Kjetil Lysne Voje led the new study on evolution of species within the bryozoan genus Metrarabdotos. Credit: Unni Vik/UiO

“We detected some critical methodological issues in the original work on Metrarabdotos. When we take the methodological issues into account, we do not find any evidence of punctuated evolution in our reanalysis of the Metrarabdotos data,” says Kjetil Lysne Voje.

Bryozoans are so small that scientists have to use an electron microscope to study them in detail, but they form colonies that can be quite large (up to 1 meter). Most bryozoans live in the sea, but there are also many species in fresh water. The bryozoan genus Metrarabdotos has been used as a textbook example in evolutionary biology and paleontology, showing how evolution speeds up  when new species form compared to a much slower evolution of already established species.

“But our new results show nothing else than a gradual evolution of the bryozoan species both before, during and after the formation of new species,” emphasizes Voje.

Why is this important?

The idea of ​​fast-track evolution during speciation has been controversial. Critics of the theory of punctuated equilibrium found it difficult to believe that the evolutionary processes leading to new species should be markedly different from the processes that cause already existing species to change.

“Species are continuously evolving and our results support the hypothesis that evolution does not “behave” differently when new species emerge,” says Voje.

The paper with the new results was published in the May issue of The American Naturalist. The authors of the study are Kjetil Lysne Voje, Emanuela Di Martino and Arthur Porto.

Reference: “Revisiting a Landmark Study System: No Evidence for a Punctuated Mode of Evolution in Metrarabdotos” by Kjetil Lysne Voje, Emanuela Di Martino and Arthur Porto, 17 March 2020, The American Naturalist.
DOI: 10.1086/707664

45 Comments on "The Most Popular Textbook Example of Punctuated Evolution Has Been Debunked by Researchers"

  1. VladimirJosephStephanOrlovsky | June 27, 2020 at 1:53 pm | Reply

    Sorry, but both are wrong!
    For INDIVIDUAL organism, change is someone the same (as a average for all organisms of that species).
    Then a ‘new species emerged’, total number of individual/organisms are relatively small, and changes/deviations are more dynamic (averages ‘drifted left-and right’).
    Than species established and number of individual get much-much larger, deviation of averages/changes are get much-much smaller)
    /* Mother Nature do not have specific plan (‘from human point of view’) */

  2. Gotta be one of the worst designed outcomes. They are taking a single species and because they can’t see evidence for the theory, this everything out? Def need to stop reporting on things that can’t pass peer review or stop drawing your own conclusions (you science writer) that aren’t supported by the evidence.

  3. This does not surprise me. Gould was never that good a scientist-his PhD work on snails was very pedestrian. What he was good at was language-he told wonderful science stories to the world. The punctuated equilibrium shtick comes out of Raup’s computer simulations, which had little basis in fact.

  4. Douglas axe has disproven evolution

  5. jason roberts | June 27, 2020 at 3:23 pm | Reply

    My assumption was, a new species would be created as individuals evolved so far apart that they could no longer reproduce with each other.

    Occam’s razor- the simplest explanation usually turns out to be so…

    I don’t think there’s anything specific to debunk in ‘punctuated equilibrium’. It’s just a theory using a sledge hammer to crack a nut… It’s over-engineering, as it were.

    • Occam’s Razor is not always right. For example the earth appears flat and stationary to most people. In fact, the earth is neither flat nor stationary (except for Flat Earthers and literal Bible believers).

  6. a few years ago they found 350 genes unique to humans disproving universal common descent

    • Tna: We get it: you are poorly educated in science. Thank you for letting us know.

    • Scruffy Cookie | June 28, 2020 at 11:34 am | Reply

      Your ridiculous assertion noted and dismissed. Provide actual evidence and peer-reviewed papers and we might listen to you. Otherwise, you should probably get out of the basement and go help your mommy upstairs.

  7. Punctuated equilibrium doesn’t negate slow processes, just states that species don’t change drastically unless they HAVE to from some outside effect, like environmental change, volcanic eruptions, or a chunk of space debris slamming into the Yucatan. When the environment changes species either die out or adapt – just like Darwin said. It explains why one normally doesn’t find a lot of those pesky transitional species that so vexed Darwin. They occur in the transitions. Unless the study was concentrated on one of those transition periods, you wouldn’t find a lot of transitional species. Punctuated Equilibrium doesn’t negate evolution, or anything Darwin said about it. It DOES explain the fossil record better, because Gould and Eldridge had more of it to work with. One bunch of critters from a single lineage isn’t GOING to demonstrate it. New analysis of a bad example is just that. Nothing more.

  8. Jurek Kolasa | June 27, 2020 at 4:43 pm | Reply

    The debate of punctualism vs gradualism does not reflect the facts or logic. Species may change gradually over long periods of time, extremely slowly, or first rapidly and then slowly. There is nothing inherent in ‘species’ to postulate one mode over or another. Darwin knew it and we, I hope, still do that species change in response to selection. Selection changes in response to environment biological, abiotic, or both RELATIVE to species traits that define its ability to cope. Fish of Tanganyika (explosive radiation), dogs, crops (accelerate on demand), sturgeon and horseshoe crab (change little over millions of years) illustrate the diversity of change. Size of the population and chance, as someone mentioned earlier, matter, too. And perhaps many other factors that need to be related to each other in a broader model.

    • As i understand it neither side denies that the other happens, it’s mostly a debate over which is more impactful overall to speciation events.

  9. random mutations cannot invent this has been proven but let’s just pretend for a minute that it’s possible by accidental events why are not all primates human?

    • Timothy Smith | June 28, 2020 at 12:53 am | Reply

      Why the hell would they be? Every speciated population having the exact same mutations is ridiculously unlikely.

      • Timothy what you just said is one of the most insanely idiotic things I’ve ever heard at no point in your rambling incoherent response we’re you close to anything which could be considered a rational thought

        • marcus taber | June 28, 2020 at 5:16 am | Reply

          Is that a cut and paste response used on actually large statements and since he used two sentences it shows the cat is out of the bag. You are just a bronze age goat herder mythologist who is upset that your fairy tale has no standing amongst the intellectually non troglodytic population.

        • Jurek Kolasa | June 28, 2020 at 5:50 am | Reply

          Thank you. TNA’s knowledge is insufficient to express any opinions here. J

        • How so? Please enlighten us as to where your understanding breaks down, we’d be happy to elucidate.

    • Evolution does not say that the goal of all living things is to eventually become human. Evolution shows that each creature develops features that help it best to survive in the environment it finds itself in. Being human is not the ultimate goal of evolution. It’s just one of many results that have happened so far along the way.

  10. Valentin Herrera | June 27, 2020 at 6:44 pm | Reply

    Evolution is just a Theory. Even Darwin couldn’t find any transitional species. Mutations by default follow the 2nd law of thermodynamics never create new species. Adaptation is possible but it will never make a fish come out and lose its “fishness”

    • Timothy Smith | June 28, 2020 at 12:51 am | Reply

      Well that would explain why us tetrapods share so may traits with fish, wouldn’t it.

    • marcus taber | June 28, 2020 at 5:27 am | Reply

      Gravity is just a theory, you should not be ignorant on the difference between hypothesis and theory. 2nd law of thermodynamics has nothing to do speciation. Ever notice how human embryos resemble fish embryos during that transitional stage in their development? I could go on but I am sure evidence means nothing to you unless it proves what you want to be true. At this point all of science supports all of science and science self corrects. So your god has lost the battle and war. That is why less and less people are falling for your god’s lies.

    • Right on Valentine, Never mind the other two, they dont seem to understand engineering.

  11. Marcus you have a blinding ignorance there’s a book out by Douglas that will open your eyes

  12. Why any sane human being would dream up he was a fish is beyond me

  13. I don’t think this is a very good article all told. The primary point is that an example commonly held aa an example of punctuated equilibrium isn’t a good example anymore. It doesn’t dismiss punctuated equilibrium outright. This article phrases it like it does. The debate is far from over and is far more complicated than is let on here.
    I myself like to think that it’s somewhere inbetween, that gradual change is constant but it isn’t expressed dramatically until a major adaptive radiation occurs, such as an extinction event.
    The fact that there are so many creationists in the comments section trotting out the usual drivel with such confidence illustrates the danger of such oversimplified and alluring headlines/subjects. It gives the idiots false-confidence.

  14. I believe in God, but I’m pretty sure he does not sign off on creationist bullshit.

  15. Ngf why do monkeys and apes exist if we evolved from them for some absurd reason we got smarter they stayed dumber explain why this happened?

    • Monkeys and apes are better suited to live in their environment than human beings. Different types of creatures diverged along the evolutionary tree. Are you able to live high up in trees and swing from your tail? I don’t think so. But some creatures are able to do this. That helps them to survive. Being human is not considered the pinnacle of evolutionary development. If you were at the south pole, being a penguin would be a much better evolutionary result than being human. The small group of humans would probably perish. A Group of penguins would flourish. Why aren’t all plants roses? Why aren’t all birds eagles? Evolution explains diversity.

  16. AmericanMuse | June 29, 2020 at 12:39 am | Reply

    In what way was Metrarabdotos claimed as an example of Gould’s punctuated equilibrium? Nary a word about that by the writer of this article. And how did that young Swedish researcher disprove the theory?

  17. Craig K Dillon | June 29, 2020 at 1:42 am | Reply

    That is NOT how I understand punctuated evolution. I do not see a conflict between the two…
    1. DNA changes do occur at a statistically constant rate — given, agreed.
    2. Species stay constant over a long period of time — despite changes in DNA — why? the Environment does not allow the changes to survive. The environment acts like guide rails, keeping a species from changing too much in any direction.
    3. THEN the environment changes — like when South American finches found themselves in Galapagos. In their home in South America, they were stable, not changing for countless thousands of years.
    4. In the Galapagos, no competitors. No other species eating seeds newly available to them.
    Now, changes in DNA that caused a deformation of their bills, made them better able to eat some of the new seeds. The result? Within a few hundred years or so, the finch had radiated into a series of new species with different beak shapes to eat different seeds.
    An example of Punctuated Evolution — and it DOES NOT violate the idea of a steady rate of DNA changes.

  18. Punctuated equilibrium was a stab at explaining why Darwin’s tree of life does not show in the fossil record. The actual data show species appearing abruptly and remaning unchanged. Other species, perhaps similar to them also appear abruptly and also remain unchanged. Not finding any diagonal lines linking these appearances. Those who examine the actual record decided that if evolution really happens, it must occur in short bursts that are invisible in the record.
    Textbooks are still full of fish embryos and eohippus even though those stories were fabricated.
    Forget origin of species (the lowest taxanomic division). What about the origin of phyla? All the phyla appeared at one time in the Cambrian and no new phylum has appeared since then. Darwin owes his acceptance not on science but on the concept of “favoured races.”

  19. Paul what you’ve just said is one of the most insanely idiotic things I have ever heard at no point in your rambling incoherent response we’re you close to anything which could be considered a rational thought every person who reads it is now dumber

    • I don’t know what you find incoherent. I’d like to add that We didn’t evolve from apes and chimps. Humans, apes and chimps all have common ancestors from which we have all evolved. You can look at the bones that have been discovered. Not too long ago the found remains called homo neledi. The bones had definite characteristics that seemed human-like. Yet they found other characteristics that we’re definitely ape-like. They seem to be somewhere in between. Scientists don’t use the term “missing link”, but these remains seem to be very early human-ish remains that we are much different than humans today. The bones exist. You can deny it.

    • Your question of why are there still apes and monkeys, and why have they not also evolved into humans by now, is a very common question posed by people who have a very limited knowledge of the theory of evolution. Your question just exposes your lack of understanding.

  20. paul because you think that everything has to be explained naturally doesn’t make you right have they found a missing link no not even close

  21. Have they found a ape to man transition only in the minds of an atheist is this even possible naturally scientifically it’s impossible it’s been proven there’s no debate

  22. Good science is non-theistic. It isn’t atheist, it isn’t theistic either. It makes no judgment about God. Science uses factual evidence that can be measured and observed and weighed. Evolution isn’t just a story that someone made up to make religious people angry. It’s based on mountains of evidence. If there is a God he apparently used evolution to create life on earth. Evolution is just a fact of nature.

  23. Animals cannot evolve from one species into another, but there is a huge capacity for variation within each species. This type of evolution has been observed and it is true. The type of evolution that has never been observed and is not true is the production of a completely different animal with a different genome from an existing animal and genome.

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