May 4, 2016 | David F. Coppedge

Just-So Stories for the Birds

Any evidence can be forced into an evolutionary story if your imagination is strong enough.

Not WAIR again: Old Montana chukar hunter Ken Dial hasn’t reformed since we exposed his silly partridge family story 12 years ago (12/22/03). How could he? There’s no better alternative story if you’re a Darwinist. Most of his evolutionary comrades have problems with the tree-down (arboreal) or ground-up (cursorial) theories on the origin of flight, so his story (not theory) of wing-assisted incline running (WAIR; must have a scientific-sounding acronym) fills up a falsifying gap. His trainee Ashley Heers keeps the tradition going. Science Daily describes her latest science-y experiments with X-rays that observe, legitimately, that “young birds acquire a mature flight stroke early in their development, initially relying heavily on their legs and wings to work in tandem to power the strenuous movement.” How that supports evolution is quizzical, but she finds a way. Here’s Heers’s rationalization for looking busy:

The transition from ground-living dinosaurs to flight-capable birds is one of the major evolutionary transitions in vertebrate history, because flight is the most physically demanding form of locomotion,” said lead author Ashley Heers, a postdoctoral researcher in the American Museum of Natural History’s Division of Paleontology [so far so good]. “The kind of flight that we normally think of in living birds–for example, what you might see in a pigeon or a robin–involved a huge evolutionary overhaul of the animal’s basic body plan over time. And although scientists have been studying flight for more a century, there’s actually a surprising amount that we don’t know about how birds fly.

That deficiency could be solved quickly with a single viewing of Flight: The Genius of Birds. But since that knowledge doesn’t need Darwin, she plugs on, running her little baby chukars up the ramp against their will, hoping to channel the ghost of Haeckel’s dead recapitulation theory:

Baby birds anatomically look a lot like some of the dinosaur fossils that we see,” Heers said. “And so, by studying baby birds and looking at how they actually use these dinosaur-like anatomies, we can get a better sense of how these long-extinct animals might have been using their wings.”

Dial keeps running this meme in the PLoS ONE paper as co-author. Note to science historians: Dial & Heers actually reference Haeckel favorably in an earlier paper on Current Biology. Taxpayers can thank the National Science Foundation for keeping these two storytellers employed and Haeckel undead.

From lizard to gizzard: The Chinese found another bird skeleton in their exceptional fossil deposits. The report in Current Biology, however, is not particularly helpful to Darwin. This enantiornithine bird ate fish and produced gastric pellets like modern birds, who digest food with grinding rocks (gastroliths) in their gizzards, a process that involves storage of gastroliths, strong muscles to grind the food and push it on to the intestine, and the software to run all the equipment. It’s the earliest known evidence for gastric pellets in birds, and looks just like modern ones. For evolutionists, this means that 120 million years ago, “Two-chambered stomach and antiperistalsis were present in Early Cretaceous birds.”

Darwin finch re-interpretation: Remember the 157 years of claims that Darwin’s finches represent a classic example of natural selection? New evidence published in PNAS is calling for a revision of the story that food availability caused beak sizes to change. The new paper says, “The shapes of bird beaks are highly controlled by nondietary factors.” Whoops; this implies that beak shape and skull size are not driven by food availability, but by other factors like genetic and developmental histories. How will this affect the iconic Darwin finch story?

We show that beak and skull shapes in birds of prey (“raptors”) are strongly coupled and largely controlled by size. This relationship means that, rather than being able to respond independently to natural selection, beak shapes are highly constrained to evolve in a particular way. The main aspects of shape variation seem to correspond with specific genes active during development. Because raptors are not each other’s closest relatives, similar shape constraints may therefore have been present in the ancestors of all modern songbirds, including Darwin’s finches, the classic example of explosive evolution in birds. If this hypothesis is true, then such classic examples may be unusual, needing first to break a genetic lock before their beaks could evolve new shapes.

The paper was edited by Neil “your inner fish” Shubin, famous for his discovery of Tiktaalik.

The storytelling never ends, but the observations tell a different story. Have you watched Flight yet? You owe it to yourself to hear the non-evolutionary alternative for bird origins.

 

 

 

 

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