Haeckel Again: This Time with Plants - Evolution News & Views

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Haeckel Again: This Time with Plants

Haeckel_Muscinae.jpg

Some 56 miles from where Haeckel propounded his defunct "biogenetic law" or recapitulation theory, six German evolutionists claim to have found a "developmental hourglass" for plants. But there are many problems with their ideas and claimed evidences.

"Ontogeny recapitulates phylogeny," Haeckel's faked embryo drawings that remain in some evolution textbooks -- how long must we endure this persistent fraud? The tortured history of this "law" of nature was revealed 12 years ago by Jonathan Wells in Chapter 5 of his book Icons of Evolution. Wells is not the only one critical of the notion that an embryo repeats its evolutionary stages; prominent evolutionists have also rejected it. The late evolutionist Stephen Jay Gould called it "the academic equivalent of murder." Yet the myth lives on, reappearing from time to time in more subtle guises.

A new incarnation appeared in Nature on October 4,1 proposed by six German scientists from Halle (Saale), about 90 kilometers down the road from the University of Jena, where Haeckel spent 50 years advocating Darwinism. To a casual reader, the paper by Quint et al. seems detached enough; they never mention Haeckel; they deal with plant embryos, not animals; and most important, they look for (and find) a "developmental hourglass" in embryogenesis -- one of the phenomena that undermined Haeckel's Law. What's the problem?

The problem is that the paper is saturated with evolutionary assumptions that color their observations, just like Haeckel's work. The problem is that their findings are a deduction from their prior commitment to evolutionary theory, not an induction from the evidence. The problem is that they still credit Haeckel, though indirectly.

Jonathan Wells pointed out that "biology textbooks continue to teach it [Haeckel's recapitulation theory] -- though they usually attach von Baer's name to it" (p. 101). Here they go again, right in the abstract:

Comparative anatomy of vertebrate development--based on the Meckel-Serrès law and von Baer's laws of embryology from the early nineteenth century--shows that embryos from various taxa appear different in early stages, converge to a similar form during mid-embryogenesis, and again diverge in later stages. This morphogenetic series is known as the embryonic 'hourglass', and its bottleneck of high conservation in mid-embryogenesis is referred to as the phylotypic stage. (Emphasis added.)
The favorable reference to the "Meckel-Serrès law" is a giveaway. As Wells explained, in the 1820s Johann Friedrich Meckel and Etienne Serrès proposed a link between embryos and their evolutionary past that Haeckel later incorporated into his cause célèbre, deceiving even Darwin himself with the notion that animal embryos retrace their evolutionary ancestry. Darwin considered "the leading facts in embryology" (as filtered by Haeckel) to be "second to none in importance" as evidence for his theory. Haeckel's theory is the direct descendent of Meckel and Serrès's false notion. Wikipedia states, "The Haeckelian form of recapitulation theory is now considered defunct," yet these German scientists are still referring to it, albeit indirectly, as a "law."

You also see their reference to "von Baer's laws of embryology." What they don't say is that von Baer (1792-1876) was an opponent of Darwinism. In the 1830s, he had published four generalizations from his observations of animal embryos to argue against (1) preformationism, the idea that embryos are mere immature adults, and (2) the "law of parallelism" advocated by Meckel and Serrès. Von Baer proposed that "the more general characters of a large group of animals appear earlier in their embryos than the more special characters." But in opposition to Darwin and Haeckel, he also maintained that "the embryo of a higher form never resembles any other form, but only its embryo." According to Darwin biographer Janet Browne,2 "Karl von Baer rejected transmutation outright" (p. 258).

Calling von Baer's principles "laws" is a bit of a stretch; for one thing, they only refer to the later stages of development. Wells considers them "summaries of empirical observations." As with most ideas from the 1830s, his "laws" have been swallowed up by later, better observations, including photographs. Even in his own century, Adam Sedgwick disputed the extent of the similarities von Baer alleged (Wells, p. 97).

But there Quint and team go, citing von Baer as if a supporter of Darwin. Browne describes how Darwin pleaded with Huxley to get a good review of the Origin from the famous embryologist: "If you write to von Baer, for heaven's sake tell him that we should think one nod of approbation on our side, of greatest value" (p. 86). Yet Wells describes how von Baer remained a "strong critic of Darwinian evolution until his death in 1876" (p. 86), especially after he found out Darwin had quoted him as if in favor of Haeckel's recapitulation theory. "But Darwin persisted in citing him anyway, making him look like a supporter of the very doctrine of evolutionary parallelism he explicitly rejected" (Ibid.) -- another egregious example in the long history of evolutionary frauds.

So now, along come Quint, Drost, Gabel, Ullrich, Bönn and Grosse, ready to apply a 21st-century coat of whitewash to this fallen, faded icon. It's odd, isn't it, that nobody ever tried to apply recapitulation theory to plant embryos. This oversight was their challenge:

Although extensively explored in animals, an embryonic hourglass has not been reported in plants, which represent the second major kingdom in the tree of life that evolved embryogenesis. Here we provide phylotranscriptomic evidence for a molecular embryonic hourglass in Arabidopsis thaliana, using two complementary approaches. This is particularly significant because the possible absence of an hourglass based on morphological features in plants suggests that morphological and molecular patterns might be uncoupled. Together with the reported developmental hourglass patterns in animals, these findings indicate convergent evolution of the molecular hourglass and a conserved logic of embryogenesis across kingdoms.
Keep track of that phrase, "conserved logic of embryogenesis." More on that later. For now, we notice the "possible absence of an hourglass based on morphological features in plants." Have they no microscopes? Has no one ever done a Haeckel-like drawing of embryos from a moss, a fern, a horsetail, a pine tree and a petunia? Watch for the phrase "historical relevance" in the next quote, and picture the line-up of characters in that history, from Meckel to Haeckel:
One notable difference between embryogenesis in animals and plants concerns the establishment of morphological variation between taxa. For example, vertebrates develop morphological variation in late embryogenesis, whereas differences between flowering plant taxa are only established during post-embryonic development. Inspired by the historical relevance of the embryonic hourglass model in animals, by recent transcriptional support from studies in zebrafish and Drosophila, and by the absence of any reported anatomical evidence for such a pattern during plant embryogenesis, we assess the possible existence of a transcriptional hourglass during embryogenesis of the plant reference species A. thaliana.
Knowing they are looking for "convergent evolution" and a "conserved logic" in their data, let's see if they find it. If they do, it won't be in the "morphological features" they can see by observation. They will have to conjure it up out of molecules. We don't need to go into a lot of detail; all you need to know is that their methods are soaked, basted, and roasted in evolutionary assumptions. And that goes for both of their "two complementary approaches."

Approach one they call "transcriptome age index" (TAI). This is "based on evolutionary age." The other one they call "transcriptome divergence index (TDI). This is one is "based on sequence divergence." In other words, both methods depend on the assumption of evolutionary common ancestry. What do you get when you convolve evolutionary assumptions with evolutionary procedures? Know what GIGO stands for?

Even so, the two methods did not quite agree: "Interestingly, evolutionary age and sequence divergence as quantified above show only weak correlations," they said. That this was "interesting" hints that they were surprised. But right away, their assumptions came to the rescue: "indicating that both measures of evolutionary distance can be regarded as complementary." They don't really disagree; they help each other. They "can be" regarded that way. Whether they "should be" is another question.

Massaging their data appropriately, they found their hourglass. (Note: they only examined gene activity for one plant, A. thaliana; nothing about pine trees or petunias). The hourglass apparition appeared when they graphed transcription activity in the TAI for "ancient genes" vs. "young genes" (assuming evolution) as the embryo progressed, and for "conserved genes" vs. "divergent genes" (assuming evolution) in the TDI. According to their interpretation, the embryos begin life by expressing the "young, divergent" genes as the plant embryo goes through its seven stages. Those are shut off as the embryo approaches the neck of the hourglass, when the "old, conserved" genes take a moment to reflect on their ancient, evolutionary roots. Then, the embryo diverges again with the young, divergent genes expressing themselves according to the "now" generation.

Is it too harsh to describe it this way, as if the scientists ascribe to the plant a kind of wistful remembrance of its ancestry? Doesn't the evidence support this "hourglass" as a physical reality? Perhaps, but remember, they only looked at one species of plant. It's a little premature to consider what they found a law or principle, let alone a generalization. What does the "developmental hourglass" signify, even if it's real?

Wells cautions that the developmental hourglass (which he pictures on page 100, Fig. 5-4) is a bit misleading. If animal embryos did really converge to a similar shape at the mid-stage of their growth, it might signify something interesting. Whether helpful to evolutionary theory, though, would be debatable, because one of the criticisms of Haeckel's biogenetic law is that there would be no functional purpose for an organism to retain or relive its ancestry. Does a contractor relive the wood-burning stove stage when installing a modern furnace? Does a car manufacturer install a buggy whip before the gas pedal?

Even so, the similarities in the hourglass stage are not that striking. At every stage in development, animal embryos look far more diverse than Haeckel portrayed in his faked drawings. Photographs show that. Furthermore, different organisms reach that hourglass stage ("phylotypic stage") at different rates and at different times. Michael Richardson, whose embryo photographs in 1995 exposed the extent of Haeckel's fraud, said, "the phylotypic stage is a misleading concept concept that needs to be reassessed," because "in vertebrates, body plan characters develop over a long range of different stages, not just at one stage" (Wells, p. 98). How much more so for plants that do not even exhibit an unambiguous phylotypic stage (that is, without assuming evolution).

Furthermore, the "developmental hourglass" was contrary to Darwin's expectations in the first place. As Wells described, Darwin and Haeckel expected the earliest stages of the embryo to be the most similar. This was not an observation; it was a logical deduction. "The actual pattern -- early differences followed by similarities, then differences again -- is quite unexpected in the context of Darwinian evolution," Wells said. Instead of providing support for Darwin's theory, the embryological evidence presents it with a paradox" (p. 99). Wells then described various attempts by modern evolutionists having to "re-interpret it to fit the theory" (p. 101).

Having pulled the rug out from the empirical claims by Quint et al. that occupy the central bulk of their paper, we can revisit their opening premise and final conclusion.

We see from the outset that the authors were not willing to consider anything other than Darwinian evolution. "Animal and plant development starts with a constituting phase called embryogenesis, which evolved independently in both lineages," they began. There's no reason for such complex sequences of coordinated events to "evolve independently" on two separate branches of life that supposedly evolved from microbes.

Then they claimed, "Together with the reported developmental hourglass patterns in animals," [hold it; those patterns are not as strong as indicated], "these findings" [assumptions, not findings] "indicate" [to whom? only to some Darwinian evolutionists] "convergent evolution" [a rescue device when Darwinists are confronted with similarities not due to common ancestry] "of the molecular hourglass and a conserved logic of embryogenesis across kingdoms."

"Conserved logic of embryogenesis": what on earth could that be? There's no logic in Darwinism, at least at the time when embryogenesis supposedly evolved, long before philosophers turned up. That is a bizarre phrase for a materialist. One might picture some kind of Platonic form being impressed on the nature of the universal plant and universal animal. This notion is reinforced in the final paragraph, after the charts and graphs have had their say:

Using a phylotranscriptomic approach based on two complementary measures of evolutionary distance and two independent datasets, we have observed a molecular embryonic hourglass in plants, which seems to be predominantly caused by down-regulation of young and divergent genes towards the torpedo stage (Fig. 4). This observation is surprising for two reasons. First, morphological diversity during embryogenesis of flowering plants is negligible, so the increase of both transcriptome indices in late embryogenesis precedes the morphological differences established only during post-embryonic development. Second, convergent evolution of a molecular hourglass pattern in animals and plants suggests operation of a fundamental developmental profile controlling the expression of evolutionarily young or rapidly evolving genes across kingdoms. We speculate that such a mechanism may be required for enabling spatio-temporal organization and differentiation of complex multicellular life.
Aha! So while they claim they found Darwinian evolution, what they really found was a "fundamental developmental profile," and a "mechanism" that is a requirement "for enabling spatio-temporal organization". What's another name for that, class? Intelligent design!

Nevertheless, the Haeckel myth lives on, partly because it is still taught uncritically with a flawed knowledge of history. One example can be seen in an interview with Arkhat Abzhanov on Live Science. Abzhanov, a Harvard biologist, was responsible for the study of Darwin's finches included in Nature's "15 Evolutionary Gems" discussed previously here at ENV. What he shared about Darwin as his model for scientific inspiration reveals what many continue to be taught:

Charles Darwin himself was very curious about the breakthroughs in embryology and often referred in his important works to the internal "laws of growth" that helped explain the observed patterns of evolutionary changes along with natural selection and other forces.
Well, we know what Darwin often referred to in his important works, and it was Haeckel's fraud-supported myth.

References

1. Quint, Drost et al., "A transcriptomic hourglass in plant embryogenesis," Nature 490, 98-101, (04 October 2012), doi:10.1038/nature11394.

2. Janet Browne. Charles Darwin: The Power of Place. Princeton, 2002.


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