March 29, 2023 | David F. Coppedge

Batty Hypothesis Supposes Powered Flight Is Glorified Gliding

What good is an unpowered wing? Will it start flapping?
Evolution makes it happen, say 13 Darwinists.

 

Whenever Darwinian biologists offer a detailed presentation of how something evolved, we like to give them an honest hearing. In this instance, consider the observable fact that there are six kinds of mammals that glide, and one kind (bats) capable of powered flight—not just the ability to flap wings and lift a body against gravity, but magnificent flight! Bats are masters of aerobatics, turning on a dime, flipping and somersaulting and catching bugs at the same time. Plus, they have sophisticated echolocation for doing all this in the dark!

Compare that with a flying squirrel. It can leap from branch to branch, stretching out skin between its fore- and hindlimbs to use as a kind of parachute. The stretched-out skin is called a patagium, and like in bats, the patagium is connected to the limbs. But the flying squirrel cannot flap or ascend. Its patagium only slows down the effect of gravity.

Is there not a phenomenal difference between a bat and a flying squirrel? It’s like the difference between a fighter jet and a parachute. But to Darwinists, Stuff Happens, so both are examples of “flight” that evolved.

Once Upon a Time, Storytelling Began

Charles Feigin, postdoc in genomics and evolution at University of Melbourne, led 12 other team members to explain the evolution of “flight” (both powered and unpowered) in mammals. Look at how dismissive he is of the vast difference between flapping flight and gliding, as he waves the magic wand of “convergent evolution” to explain the observations. At The Conversation on March 24, he writes,

While birds are the undisputed champions of the sky, having mastered flight during the Jurassic, mammals have actually evolved flight more often than birds. In fact, as many as seven different groups of mammals living today have taken to the air independently of each other.

These evolutionary experiments happened in animals scattered all across the mammalian family tree – including flying squirrels, marsupial possums and the colugo (cousin of the primates). But they all have something in common. It’s a special skin structure between their limbs called a patagium, or flight membrane.

Evolutionary experiments happened. They just happened. Flight happens. Stuff happens. Feigin waves the magic wand of “convergent evolution” and stretches his imagination further, to encompass all mammals, including us!

The fact these similar structures have arisen so many times (a process called convergent evolution) hints that the genetic underpinnings of patagia might predate flight. Indeed, they could be shared by all mammals, even those living on the ground.

Humans, start your engines. Flap your arms. You have the genes for a patagium, maybe even for powered flight! What are you waiting for? Forget your hang glider; Darwin has given you the “genetic toolkit” to join the Flying Squirrel Brigade. And if really lucky stuff happens, you might be selected for the Bat Battalion!

Ahem, Dr Feigin. Convergent evolution is not a process. It is an after-the-fact rationalization at best, a question-begging theory escape at worst. Are bicycles and helicopters examples of convergent evolution because they both have wheels, or is their common design instead?

Seriously, Darwin

Surely we should expect better scholarship from Feigin et al., so let’s try to keep a straight face and look at their research as seriously as it deserves. In the article and in their open-access paper in Science Advances,1 they clearly worked hard. They studied marsupial “sugar gliders” in detail, isolating hundreds of genes related to the patagium. They found some genes common to both the marsupials and the bats, particularly one called Wnt5a, which is expressed during the thickening of epithelial tissue in development when the sugar glider’s patagium is forming.

1. Feigin et al., Convergent deployment of ancestral functions during the evolution of mammalian flight membranes, Science Advances, 24 Mar 2023 Vol 9, Issue 12, DOI: 10.1126/sciadv.ade751.

Then they noticed that Wnt5a is also associated in bats when their wing membranes are developing. And then (aha!) they found Wnt5a at work in the external ears of mice. What can this mean? To a Darwinist, only an evolutionary hypothesis is allowed.

Together, these results suggest something profound. Wnt5a’s role in ushering in the skin changes needed for a patagium likely evolved long before the first mammal ever took to the air.

Originally, the gene had nothing to do with flight, instead contributing to the development of seemingly unrelated traits. But because of shared ancestry, most living mammals today inherited this Wnt5a-driven program. When species like gliders and bats started on their separate journeys into the air, they did so with a common “molecular toolkit”.

Inebriated on Darwine, Feigin sees visions of flying humans on his imagination screen. “Not only that,” he leaps with arms flapping, “but this same toolkit is likely present in humans and working in ways we don’t fully understand yet.” In his final sentence, he says,

For now though, our study presents an exciting new view of flight in mammals. We may not be the strongest fliers, but trying is in our DNA.

It’s hard to keep serious, but we’ll try harder. To his credit, Feigin acknowledges some limitations of the research.

There are definite limits to our recent work. First, we haven’t made a flying mouse. This may sound like a joke, but demonstrates we still don’t fully understand how a region of dense, thick skin becomes a thin and wide flight membrane. Many more genes with unknown roles are bound to be involved.

Second, while we’ve shown a cause-and-effect relationship between Wnt5a and patagium skin differentiation, we don’t know precisely how Wnt5a does it. Moving forward, we hope to fill in these gaps by broadening the horizons of our cross-species comparisons and by conducting more in-depth molecular studies on patagium formation in sugar gliders.

What’s Left After Fallacy Washing?

OK, those are honest confessions of ignorance and legitimate questions to investigate. It’s fine to compare the anatomies of different mammals, and even to compare the genes and physiology of bats with non-mammalian flyers like insects and birds. One doesn’t have to say they are related by Darwinian common ancestry. Engineers could compare paper airplanes with jets and spacecraft without invoking “convergent evolution” or saying “stuff happens” such that the paper airplane evolved into an F-16 (by itself, that is, without engineers).

But even when trying to stay serious, we see the paper committing several logical fallacies that beg the question of Darwinian evolution. See our Baloney Detector for definitions and examples of these fallacies.

  • Faulty analogy: They assume that gliding is analogous to powered flight.
  • Personification: “Genetic toolkit” embeds the notion of purposeful action into a blind, aimless chance process. Tools are for tool users.
  • Non-sequitur: If multiple species use a gene like Wnt5a, it is not necessarily true that they are related by a Darwinian process. This is like thinking that a trombone and a pot are related because they contain brass. Maybe they were designed for different purposes using the same substance.
  • Post-hoc: If a species appeared after another species, it did not necessarily evolve from it on a branch of a phylogenetic tree.
  • Circumstantial evidence: If two species share 6 genes out of 21, they do not establish “convergent evolution.”
  • Reductionism: The idea that species are genetically determined. What about epigenetics?
  • Extrapolation: Thinking that the Wnt5a gene found in a non-flying animal suggests that it could evolve to fly.
  • Sidestepping: Dodging the complications of getting powered flight by the Stuff Happens Law.
  • Equivocation: Thinking that “convergent evolution” is like Darwinian evolution, and that gliding is like powered flight.
  • Card stacking: Focusing on the similarities and downplaying the differences.
  • Subjectivity: Treating evolution as a causal force like physical laws.

If impartial judges called foul on begging the question of evolution, these Darwinists would have a serious challenge to explain bat flight.

Does the existence of multiple gliders in mammals require Darwinian evolution? How would creationists explain this? Consider that the Wnt5 gene family is widely used by animals for numerous roles, such as building external ears. A patagium is just an extension of the same kind of skin and fur that non-flying squirrels have. Creationists allow for modifications of existing tissues within the same genus or species. Flowers can change color; butterfly patterns can shift to avoid predators; a molecule or process in one environment can become toxic in another. “Phenotypic plasticity” (changes in outward appearance) clearly occur within the same species or the same genus. No two humans look alike, and human traits show quite a bit of plasticity. These involve modifications of existing traits without the addition of genetic information. That is not Darwinian evolution.

Squirrels or sugar gliders have the innate potential to vary and adapt because those abilities were designed into them, enabling them to fill various ecological niches. Powered flight, though is another story. That requires an irreducibly complex set of hardware and software traits that defy unguided natural processes. A hubcap in a car accident might fly like a frisbee for a small distance, but it’s not going to fly itself across the Atlantic or equip itself with echolocation. This is a serious flaw in the paper. The authors assume that evolution is like a genie that can call up whatever miracle is needed to give an organism powered wings.

Exercise: Take the list of fallacies above and locate them in the scientific paper or article. Use our Baloney Detector for definitions and examples.

 

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