Giving Rise to Skeletons with Darwin’s Magic Wand

Mistakes in a fish embryo gave rise
to pole vaulters, thinks a Darwinist

Yesterday’s post (21 Aug 2023) explored the word “origination” as a Darwinian poof spoof (i.e., miracle story). Another kind of poof spoof uses the phrase “give rise to”—as if one object gives rise to a more complex object. It’s like a hat giving rise to a rabbit.

The human skeleton has 206 exquisitely crafted bones, each shaped and fit together with tendons, ligaments and muscles. Watch Illustra Media’s fun demonstration of what this skeleton allows people to do. Consider athletes using their skeletons to do pole vaulting, gymnastics, parkour, skiing, ballet, high hurdles, and so much more. Then we’ll see how a Darwinian evolutionist explains it.

Background Information

Learn about osteoblasts and how bones grow and remodel themselves automatically at this Medical Net page. Watch the simplified video of the homeostasis between bone-growing cells and bone-recycling cells. Clearly this dynamic process is under fine control so that bones maintain their shapes and relationships to other tissues—especially in the embryo and infant when all body parts are growing rapidly.

Enter the Darwin Storyteller

Scales, scutes, and embryonic origins of the vertebrate dermal skeleton (Andrew Gillis, PNAS, 2 Aug 2023). According to Dr Gillis from the Marine Biology Institute at Woods Hole, Massachusetts, all of the above wonders of the human skeleton (and of every other vertebrate skeleton, from naked mole rat to sauropod), began in the ocean long ago. A stem cell in the neural crest in an ancient invertebrate “gave rise to” the osteoblast: the specialized cell that builds bone. Presto: vertebrates were born!

Note: “Give rise to” is appropriate wording in embryology, where scientists can observe cells differentiating and developing into tissues and organs in the adult. Gillis uses the phrase a few times in that way. Most of the time, though, he is telling an evolutionary story about what happened in some marine ancestor’s neural crest that “gave rise to” the skulls and skeletons of vertebrates.

Referencing research by Stundl et al., Gillis uses the phrase in two ways: observationally, and evolutionarily.

This study clearly demonstrates that trunk neural crest cells in a nonteleost bony fish give rise to osteoblasts—and this, alongside data from cartilaginous fishes, points to a jawed vertebrate neural crest that ancestrally gave rise to bone and dentine along its entire axis, with restriction of this skeletogenic fate to the cranial region in amniotes (Fig. 1).

In amniotes (reptiles, birds and mammals), the specific cells in the embryonic neural crest develop into skull bones. In non-amniotes, those cells give rise to body armor and internal skeletons. Either way, the cells develop into osteoblasts (bone-forming cells) in the mature animal in life today. If these observational facts were all Gillis were talking about, there would be no controversy. He spins this finding, though, into a Darwinian tale about how skeletons evolved millions of Darwin Years ago.

• It therefore follows that to understand the origin and early evolution of vertebrates, it is important to consider not only the origin of the neural crest itself but also the evolution of its fate along the embryonic axis.
• Stundl et al. now report evidence that trunk neural crest cells do, indeed, give rise to the postcranial dermal skeleton of a fish, the sterlet sturgeon (Acipenser ruthenus), cementing the ancestral skeletogenic fate of this embryonic tissue within jawed vertebrates and highlighting its role in shaping the early evolution of the vertebrate body plan.
• Although both scales and scutes are often regarded as derivatives of the basal bony layer of a once more extensive dermal armor, perhaps the distinct embryonic origins of these elements reflect their independent evolutionary histories.

Evolution from ancient unobserved ancestors is on Gillis’s mind. His first sentence says, “The story of vertebrate origins is one of novel cell types and shifting germ layer fates—and at the center of this story lies the neural crest.” (Emphasis on story.) By “skeletogenic fate” he doesn’t just mean what cells in the embryos of living fish and birds do today to generate their skeletons. He means what some “skeletogenic” change in the embryo of an mythical ancestor did. In his imagination, perhaps he thinks a mutation in the neural crest of an unobserved ancestor’s embryo “gave rise to” a type of cell—an osteoblast—that would “give rise to” the human skeleton.

Update 8/22/23: The Discovery Institute just released another episode in its “Secrets of the Cell” series with Dr Michael Behe of Lehigh University. This episode called “The Mystery of Biological Information” is pertinent, in that it explains the complexity of bone and how specific complex information guides the processes of bone development as the body grows from embryo to adult.

Gillis was not there to see how the first vertebrate came to be, but like a professor in the Hogwarts School of Wizardry, he wanders lustfully through the tomes of ancient magic incantations, seeking which random mutation would turn a neural crest cell into an osteoblast. Then he conjures up a vision in the crystal ball where Darwin’s bearded visage sets the osteoblasts loose, flying out like bats, proliferating and assembling into bones, skeletons and body plans. In a few more hundred million Darwin Years of development, those bones gave rise to rabbits, sauropods and pole vaulters, like hats give rise to rabbits. Ah! Science!

Gaze at nature until Darwin’s face appears to give you insight and understanding. Crystal ball mister (source CostumePub)

Nonsense gives rise to laughter. Why? Because the human mind can grasp logic. So let it rise. Laugh loud and long.