|Evolution in the News - February 2013|
|by Do-While Jones|
The 2013 Society for Integrative and Comparative Biology Annual Meeting revealed that eating was tough for early tetrapods, and the nervous system may have evolved twice.
Science sent Elizabeth Pennisi to the 2013 Society for Integrative and Comparative Biology Annual Meeting. She learned two remarkable things there.
First, she learned that eating was tough for early tetrapods. Tetrapods are creatures with four limbs, including amphibians, reptiles, birds, and mammals. The first (unknown) tetrapod supposedly evolved from an unknown fish.
While a fin-to-limb transition made possible the first steps on land for vertebrates 390 million years ago, it took a long time for ancient tetrapods to leave behind their aquatic ways and become true landlubbers. After that initial landfall, another 80 million years went by before tetrapods developed jaws adapted for terrestrial feeding, according to Philip Anderson, an evolutionary paleobiologist at the University of Massachusetts, Amherst, who presented a survey of fossils from this time period at the meeting. 1
Fish don’t eat the same way we do. Watch what happens when you drop some fish food in your aquarium. The fish swim up to the food, and then open their mouths quickly. The vacuum created causes water (and food) to rush into their mouths. But air isn’t as thick as water, so creatures on land (except teenage boys) can’t inhale their food like that.
With fishlike mouths, early tetrapods would have faced a difficult task eating on land. Underwater, fish usually rely on suction to draw food into their mouths and swallow. To generate enough inward force in less dense air, a fish—or early tetrapod—would have to expand its mouth 28 times faster, Sam Van Wassenbergh, a biomechanist at the University of Ghent in Belgium, reported at the meeting. And even then, because air is so much less viscous, the air flow might not be enough to draw in prey. Moreover, most fish mouths face forward to grab food items suspended straight ahead in water, not food laying below on the ground.
Many modern terrestrial tetrapods have solved their swallowing problem by having tongues do the job. 2
Of course, the first tetrapods were supposedly amphibious, so they could have gone back into the water to eat—but wait! Isn’t the reason they evolved because the ponds they lived in were drying up, or short on food?
Those early tetrapods must have had a hard time figuring out how to swallow terrestrial food, if another study presented at the meeting is any guide. That work described the great lengths that some modern fish must go to catch and eat prey out of water. "That's something that paleontologists have not thought about too much," says Alice Gibb, a functional morphologist at Northern Arizona University in Flagstaff. The combination of paleontology and functional morphology evidence shows "that the switch [to eating on land] was awfully hard," concludes Richard Blob, an evolutionary biomechanist at Clemson University in South Carolina. 3
There are many things paleontologists have not thought about too much. They like to gloss over the glitches in their theories.
That’s the main difference between a paleontologist and an engineer. An engineer can’t gloss over the fact that a bridge made out of straw won’t be strong enough to bear the load because he actually has to build the bridge. It isn’t enough for an engineer to come up with a story good enough to convince his investors that the bridge will be strong enough. If the bridge isn’t strong enough, it will fall down, no matter how good the engineer’s rhetorical skills are.
On the other hand, a paleontologist just needs to be a good enough story teller to get his story published and his research funding renewed. He never has to prove he is right.
Evolutionists believe that the central nervous system developed by chance. Fortunate mutations just happened to cause sensors (for vision, hearing, touch, and smell) to somehow get connected to an accidental brain that just happened to be programmed to process that sensory data and send signals to muscles (or other cells) to respond accordingly to the perceived data. It was such an incredibly good stroke of luck that it could be called “miraculous,” if one weren’t afraid of the word. It is hard to believe that it happened once; it is even harder to believe it happened twice! But, in order to reconcile DNA data with reality, evolutionists now have to believe that stars aligned perfectly twice!
Biologists have long assumed that the neuron—with its axon, synapses, long processes called dendrites, and a suite of nerve-specific proteins—is the epitome of a specialized cell and thus likely to have evolved only once in the history of life. But a newly sequenced genome of a comb jelly, an ocean-going predator sometimes confused with traditional jellyfish, threatens to upend this view.
The DNA data put these invertebrates, also known as ctenophores, on a different, older branch of the tree of life from that of other organisms with complex nervous systems. This new placement will be controversial, but it suggests to some researchers that nervous systems arose twice. Indeed, the ctenophore's nervous system does appear to be different from those of other animals because its genome lacks genes for proteins that are considered essential to nervous system development and function. "All the things that are fundamental to [a nervous system] are missing in ctenophores," says Casey Dunn, an evolutionary biologist at Brown University. 4
The more scientists discover, the less plausible the theory of evolution is. The dating of tetrapod fossils isn’t consistent with the evolutionary fairy tale because tetrapods would have had to have gone on an 80-million-year diet before evolving a mouth that could eat on land. DNA analysis shows that two creatures, similar enough that some people call them both “jellyfish,” have fundamentally different nervous systems, so they could not have evolved from a close common ancestor.
When will enough scientific evidence against evolution accumulate to cause the theory to be abandoned? That’s a silly, naïve question. Scientific evidence has nothing to do with it. Every contradiction in the theory is merely an opportunity for another research grant to come up with another story that can’t be proved. The theory won’t be abandoned until the funding dries up.
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Elizabeth Pennisi, Science, 25 January 2013, “Eating Was Tough For Early Tetrapods”, pp. 390-391, http://www.sciencemag.org/content/339/6118/390.full
5 Elizabeth Pennisi, Science, 25 January 2013, “Nervous System May Have Evolved Twice”, p. 391, http://www.sciencemag.org/content/339/6118/391.1.full