June 28, 2016 | David F. Coppedge

How the Dragon Got Its Beard

Scales are not feathers are not hair, but evolutionary tales get hairy sometimes.

It’s evolutionary storytelling time in Geneva, where Darwinians conjure up bearded dragons evolving into bearded men. It all started when two researchers from Switzerland found thickenings in crocodile skin, then had visions of birds taking off into the trees, with mammals scampering in the underbrush. The tale is told on Science Daily, “Hairs, feathers and scales have a lot in common.” More recondite jargon is supplied in Science Advances to satisfy the academics.

But of course hairs, feathers and scales have some things in common, being composed of keratin, but don’t the differences swamp the similarities? Not to these evolutionists. To understand their thinking, we have to learn a new word: placode. Wikipedia defines it as: “A neurogenic placode is an area of thickening of the epithelium in the embryonic head ectoderm layer that gives rise to neurons and other structures of the sensory nervous system. Placodes are embryonic structures that give rise to structures such as hair follicles, feathers and teeth.

Mammalian hairs and avian feathers develop from a similar primordial structure called a ‘placode’: a local thickening of the epidermis with columnar cells that reduce their rate of proliferation and express very specific genes. This observation has puzzled evolutionary and developmental biologists for many years because birds and mammals are not sister groups: they evolved from different reptilian lineages. According to previous studies, reptiles’ scales however do not develop from an anatomical placode. This would imply that birds and mammals have independently ‘invented’ placodes during their evolution.

The story ramps up the tension, heading toward the resolution: lo and behold, the Swiss researchers find evidence for placodes in reptiles. They examine eggs of crocodiles, corn snakes and bearded dragons (a kind of lizard) and found local thickenings of the epidermis—at least briefly during development. Common ancestry is saved!

Jump to the Methods section in the paper. One notices that they did not do any work on birds or mammals: just on 3 species of reptiles, and there, only on their eggs. Environmentalists will be relieved to hear that no animals were harmed in the process: “Maintenance of and experiments on reptilians were approved by the Geneva Canton ethical regulation authority (authorization GE/82/14) and performed according to Swiss law.”

The researchers scraped some scale protein, took photos, and studied DNA sequences from these reptile eggs. That’s about it. No feathers or hairs were found on the reptiles, but they found a gene that disrupts scale formation in bearded dragons, just like it disrupts beards in humans. If disrupting a gene can’t allow a placode to form for a dragon beard scale, or a placode for a hairy human beard, that must prove Darwin right. “These data all coherently indicate the common ancestry between scales, feathers and hairs.

Here’s how the story came out for the press: “The single evolutionary origin of placodes revealed.

Today, Nicolas Di-Poï and Michel C. Milinkovitch at the Department of Genetics and Evolution of the UNIGE Faculty of Science and at the SIB put this long controversy to rest by demonstrating that scales in reptiles develop from a placode with all the anatomical and molecular signatures of avian and mammalian placodes. The two scientists finely observed and analysed the skin morphological and molecular characteristics during embryonic development in crocodiles, snakes and lizards. ‘Our study not only provides new molecular data that complement the work of the American team but also reveals key microanatomical facts, explains Michel Milinkovitch. Indeed, we have identified in reptiles new molecular signatures that are identical to those observed during the development of hairs and feathers, as well as the presence of the same anatomical placode as in mammals and birds. This indicates that the three types of skin appendages are homologous: the reptilian scales, the avian feathers and the mammalian hairs, despite their very different final shapes, evolved from the scales of their reptilian common ancestor.’

They need to fine-tune the story a little; just a little mop-up work, that’s about it. All in a day’s work for Darwin storytellers.

The next challenge for the Swiss team, and many other researchers around the world, is to decipher the fine mechanisms explaining the diversity of forms of skin appendages. How has the ancestral scaly skin given rise to the very different morphologies of scales, feathers and hairs, as well as the astonishing variety of forms that these appendages can take? These future studies will hopefully fine-tune our understanding of the physical and molecular mechanisms generating the complexity and the diversity of life during evolution.

A bird-of-paradise’s plumage or a fashion model’s coiffure couldn’t be far behind. Just give those epidermal thickenings a few million years.

The evolutionists in Geneva might want to see how the evolutionists in Australia are doing. They’re trying to figure out if snakes evolved in the sea or on the land. PhysOrg shows a fossil Tetrapodophis, a very long slender lizard with tiny limbs that appears adapted for aquatic life. But the provenance of this fossil is “highly problematic.” Scientists are concerned that the “reproducibility crisis” will taint the reputation of this fossil and claims built on it.

Meanwhile, snake enthusiasts (or snake-o-phobes) may wish to learn a little more about rattlesnakes from Simon Worrall of National Geographic, who intereviewed herpetologist Ted Levin about them; “far from being scary monsters, these elusive predators are surprisingly social,” he says. The venomous beasts may actually reduce Lyme Disease in humans by cutting down on their mammal vectors—chipmunks and mice. As for the snakes themselves, “They are fascinating and gorgeous to look at,” Levin says. From a distance, of course. “They can see colors we can’t see and read the world with the tips of their tongues. They communicate through pheromones, in a language we don’t really understand. The more you look into them, the more fascinating they are.”

Update 6/28/16: Remains of bird wing feathers have been found in Burmese amber. National Geographic has a picture; says the feathers look just like modern feathers, even though they are claimed to be 100 million years old.

Levin takes a swipe at Genesis when asked about why we fear snakes:

It’s not just rattlesnakes. I think we fear all snakes. Until I began to research this book in earnest, I thought it all went back to the Book of Genesis, the Judeo-Christian story of Adam and Eve in the Garden of Eden. But now I realize that that story goes way back to the dawn of primates, when venomous snakes were their principle predators. I think we carry that with us, like the fear of the dark.

Thus he trades one miracle story for another. He can’t accept a talking snake in Genesis, which neither Adam or Eve feared at the time, and if they learned to fear snakes later, could not have invented a mutation to pass on that fear. So instead, he believes that some mutation in a mouse in the Jurassic keeps modern humans afraid of snakes, like a fear of the dark, that we haven’t been able to shake in 200 million years while growing larger and smarter than snakes. Go figure.

The Swiss evolutionists think they are doing their job by weaving stories from “physical and molecular mechanisms.” They think that tiny, evanescent thickenings in the epidermis of a crocodile egg led to the luscious locks of the Breck Girl. They think that switching off one gene in a bearded dragon proves the evolution of Grizzly Adams’s beard. See? Everyone believes in miracles. And the evolutionists believe in the supernatural, too. They believe that logical and moral truths emerge from physical and molecular mechanisms. That’s the only way they could write scientific papers purporting to express truth. Unless truth is supernatural, eternal and changeless (i.e., it doesn’t evolve), they could never know that—or anything.

 

 

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