|Feature Article - June 2015|
|by Do-While Jones|
What do dino-chickens tell us about evolution?
Last month, it was reported (in both the popular press and real scientific journals) that,
With a little molecular tinkering, for the first time scientists have created chicken embryos with broad, Velociraptor-like muzzles in the place of their beaks.
The bizarrely developing chickens shed new light on how the bird beak evolved, scientists added. 1
Although they won’t admit it, the “new light” is that the DNA must have been manipulated on purpose by an intelligent being to achieve the desired result!
Seriously, there is some resemblance between the bones in a reptile’s nose and a bird’s beak, especially in the embryonic stage. Evolutionists believe that random changes to reptile DNA are what caused the nose bones to become a beak. Some scientists tried to figure out what these changes must have been by meddling with the DNA of a chicken to make a chicken with a dinosaur-like snout instead of a beak.
First, we are going to tell you how these experiments were reported in the popular press. Second, we will review the actual published study. Finally, we will tell you what the journal Science had to say about the research.
In addition to the quote above, LiveScience.com also said,
"The experimental animals did not have a beak, instead developing a broad, rounded snout," Bhullar said. However, "they still lacked teeth, and possessed a horny covering on the snout."
These embryos did not live to hatch, researchers stressed. "They could have," Bhullar said. "They actually probably wouldn't have done that badly if they did hatch. Mostly, though, we were interested in the evolution of the beak, and not in hatching a 'dino-chicken' just for the sake of it." 2
They didn’t have teeth—but they were still “Velociraptor-like muzzles” (just not so dangerous).
The genetically modified chickens could have hatched—but they didn’t. The scientists didn’t give them a chance to hatch. Why not? We don’t know. It could have been that they were afraid of the social backlash from the Monster Rights Activists. It would be immoral to murder the mutant chickens after they hatched; but it is socially acceptable to abort them before they hatched because monsters don’t have a “right to life” until they are actually born.
On the other hand, they might have been afraid of failure. Perhaps a dull, weak, toothless dinosaur snout would not have been able to break the shell the way a strong, sharp beak does. Failure to hatch would have proved them wrong.
Last summer, when I was in Colorado, I could have hiked up Pikes Peak—but I didn’t (because I couldn’t find anyone who wanted to hike with me, and I didn’t want to do it alone). But I could have hiked to the summit of Pikes Peak, just like those dino-chickens could have hatched. By today’s science standards, since I could have climbed Pikes Peak, I actually did it! Experimental proof is no longer necessary. If you say it could happen, then it did.
The point is, they did not actually create viable dino-chickens—they just claim they could have; and that’s good enough for lazy journalists.
The other point the lazy journalists missed is that things are not made by the same process that breaks them.
If you took a car with an 8-cylinder engine, and cut two of the spark plug wires, you would wind up with a car that has a poor 6-cylinder engine. It would not run smoothly because the spark plugs would not fire evenly—there would be gaps when the disconnected spark plugs should fire. But the engine would run on 6 cylinders. Learning how to turn a good 8-cylinder engine into a poor 6-cylinder engine tells nothing about how the 6-cylinder engine design evolved into the 8-cylinder design. You can’t turn a 6-cylinder engine into an 8-cylinder engine by cutting spark plug wires. You have to add wires, and spark plugs, and cylinders, and valves. You can’t add features using the same process that takes features away.
The question, “How can a dull, weak snout turn into a sharp, strong beak?” is not answered by learning how to prevent a beak from developing.
The actual research report can be found in the Wiley Online Library. It is very technical, so we won’t blame you if you just skim over the next three quotes. We will translate them into plain English; but some people want to get the information straight from the horse’s mouth, even if the horse has an accent which is hard to understand.
Anatomically, the internal skeleton of the upper beak is composed of fused, elongated premaxillary bones; these are paired, small and form the tip of the snout in ancestral reptiles (Fig. 1a, 3l). The remainder of the snout and much of the face in birds are truncated, a paedomorphic (Hanken and Wake 1993) condition with respect to ancestral archosaurs (Bhullar et al. 2012; Balanoff et al. 2013; Lee et al. 2014) (Fig. 1a). 3
Here we have shown that a relatively minor – though novel – additional region of gene expression at a sufficiently early stage can precipitate changes that result in a dramatic morphological transition of two distinct skeletal structures. 4
Two frontonasal signaling systems active at different times during embryonic development have been broadly hypothesized to be responsible for facial differences between the two distantly related and highly derived biomedical model amniotes, chickens and mice. The first is the frontonasal ectodermal zone (FEZ), which is present in 3-day-old chicken embryos (Hamburger-Hamilton stages 18-20) and is composed of dorsoventrally apposed expression domains of Fibroblast growth factor 8 (Fgf8) and Sonic hedgehog (Shh)(Hu et al. 2003). … The second signaling system implicated in bird-specific facial morphology is based on the WNT pathway, which is active in the frontonasal prominence for a period of time following the FEZ but preceding skeletogenesis (Brugmann et al. 2007). 5
Basically, they are saying that the relationship between DNA and bones is like the relationship between a blueprint and a building. Just as a blueprint tells the contractor how to make the building, DNA tells the embryo how to grow into the final form. Just as there is a sequence that has to be followed as the building is constructed, there is a developmental sequence that has to be followed as an embryo develops. DNA not only contains instruction for what proteins have to be manufactured, it also contains timing information so that things will be put together in the proper sequence.
The growth sequences are called “pathways.” Genetic engineers have learned a lot about these pathways by making small changes in the DNA which inhibit the proper operation of these pathways. They know that if they break a particular gene, then some physical feature does not develop properly. This tells them what that gene does.
They have discovered two pathways that are associated with the development of a beak or nose. By making small changes to the DNA, they can affect the timing or result of these pathways. In other words, they have discovered how to mess with the DNA to affect the shape of whatever grows on the front of the face to make it more like a snout or a beak.
This is important research because it has medical applications. The more we know about how DNA affects physical functionality, the better we will be able to develop ways to cure diseases through genetic repair. Our complaint is that, instead of devoting all of their efforts to making practical use of this knowledge, many scientists are wasting their time trying to figure out how all these genetic pathways developed by accident. If these pathways didn’t develop by accident, their search is doomed to failure. If they did develop by accident, what does it matter? Either way, it is a waste of valuable scientific resources.
The scientists who did this study were trying to replicate the steps by which a dinosaur’s snout turned into a bird’s beak. This is hard to do because,
A large gap between the birdlike and non-birdlike clusters presumably represents missing transitional forms among early avialans. The experimental embryos bridged this gap and overlapped the non-bird snouted archosaur cluster (Fig. 5b). Thus, we propose that the experimental embryonic phenotypes actually predict the morphology of yet-undiscovered early avialan palatines and that new fossils will eventually be found that will show a gradual morphological transition toward modern birds. 6
They can’t be sure they have replicated the steps found in the fossil record because the steps can’t be found in the fossil record! But they know that new fossils will eventually be found, so the actual discovery of those fossils is scientifically unnecessary.
We acknowledge, however, that the transition to the avian rostrum was undoubtedly complex – as shown by multiple transitions to a premaxilla with some bird-beak-like features in the fossil record. The results reported here represent one part of a manifold transition. Additionally, the characterization of the beak as a key evolutionary innovation is made more complex because its components were assembled over a longer period of time than that represented by the proximal stem of Aves – a caveat that applies to many such transformations or putative innovations (Donoghue 2005). However, the abrupt geometric gap between non-beaked archosaurs and birds and stem-birds with beaks may suggest a rapid, comparatively saltational transformation. The difference in ontogenetic trajectories of shape change between non-beaked forms, in which the premaxilla becomes shorter and broader with time, and beaked forms, in which it becomes longer and narrower, also suggests a discontinuous distinctiveness to the beak. 7
There are two important admissions in this paragraph. First, the genetic changes they discovered don’t fully explain the differences. They claim to have found just one piece of the puzzle. Of course, without the rest of the puzzle pieces, one can’t be sure the piece really fits.
Second, the Punctuated Equilibrium problem has reared its head again. Darwin predicted slow, gradual change. Since this isn’t found in the fossil record, Stephen Jay Gould (and others) suggested Punctuated Equilibrium as an explanation. He believed that long periods of time went by with no evolution. These periods of time were separated by brief intervals during which evolution happened so rapidly that there wasn’t time for the transitional forms to be captured in the fossil record. In other words, he believed evolution proceeded by “saltations” (jumps), contrary to the widely accepted scientific axiom, Natura non facit saltus. (Nature doesn’t make jumps.) 8
The precise selective pressures that operated on the beak after its initial appearance are unknowable with certainty, but a series of careful, broadly comparative behavioral and functional morphological studies on the use of the avian feeding apparatus in paleognaths and conservative neognaths would make inroads toward inferring the set of functions associated with the ancestral beak and therefore, indirectly, perhaps what environmental pressures led to the selection which resulted in its persistence and continued elaboration. 9
In other words, “We don’t know for sure how natural selection caused the beak to evolve; but we are sure something in the environment did it.”
Although other scientists admire this study’s approach (that is, attempting to relate DNA to fossils), they don’t necessarily agree with the conclusions.
Their conclusions are at odds with an earlier study. But even those who disagree with the result say Abzhanov and his student Bhart-Anjan Bhullar, now a postdoctoral fellow at the University of Chicago in Illinois, have demonstrated a powerful new approach: pinning down how anatomy changes using fossils, then trying to recapitulate the changes in the lab by tinkering with genetic signals. “The value of this paper is their ability to blend paleontology with evolutionary developmental biology,” says Richard Schneider of the University of California, San Francisco (UCSF), who has linked beak evolution to different genes. 10
At least one developmental biologist might share our concern about the viability of the modified chickens.
Marcucio, a developmental biologist, also worries that the changes in facial structure observed by the Harvard team may stem from unintended cell death caused by the inhibitors they used. 11
We aren’t sure, but Marcucio might be saying that messing with the DNA might cause fatal unintended consequences.
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Charles Q. Choi, LiveScience.com, May 12, 2015, “Chicken Embryos With Dinosaur Snouts Created in Lab”, https://www.yahoo.com/news/chicken-embryos-dinosaur-snouts-created-lab-131834500.html
3 Bhullar, et al., Wiley Online Library, 12 May 2015, “A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history”, http://onlinelibrary.wiley.com/doi/10.1111/evo.12684/pdf
9 Bhullar, et al., Wiley Online Library, 12 May 2015, “A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history”, http://onlinelibrary.wiley.com/doi/10.1111/evo.12684/pdf
10 Elizabeth Pennisi, Science/I>, 15 May 2015, “How birds got their beaks”, http://www.sciencemag.org/content/348/6236/744.full