October 10, 2016 | David F. Coppedge

Evolution: A Theory in Constant Revision

Darwinian evolution survives by constant patching of weaknesses in its web of belief.

Permian extinction revised (PNAS): In “Estimates of the magnitudes of major marine mass extinctions in earth history,” Steven M. Stanley argues that we’ve been told a bit of a fib all our lives: “the great terminal Permian crisis eliminated only about 81% of marine species, not the frequently quoted 90–96%,” he says. That’s still a lot, but “Life did not almost disappear at the end of the Permian, as has often been asserted.” Extinctions were going on in the background, he argues, and didn’t disappear in a single event. Evolutionists will undoubtedly be able to absorb this revision in their web of belief.

Population genetics revision (PNAS): In “Theory of prokaryotic genome evolution,” Eugene Koonin and two colleagues upset an applecart in population genetics regarding microbe evolution. Out with the old, in with the new – but once again, Darwinians will probably just patch up this contradiction.

Bacteria and archaea have small genomes with tightly packed protein-coding genes. Typically, this genome architecture is explained by “genome streamlining” (minimization) under selection for high replication rate. We developed a mathematical model of microbial evolution and tested it against extensive data from multiple genome comparisons to identify the key evolutionary forces. The results indicate that genome evolution is not governed by streamlining but rather, reflects the balance between the benefit of additional genes that diminishes with the genome size and the intrinsic preference for DNA deletion over acquisition. These results explain the observation that, in an apparent contradiction with the population genetic theory, microbes with large genomes reach higher abundance and are subject to stronger selection than small “streamlined” genomes.

Revised fish story (Science Daily): “Today’s most successful fish weren’t always evolutionary standouts,” this article announces in its headline. The evolutionary story of teleost fishes—the most diverse vertebrate group on earth—is in need of revision. Teleosts weren’t winners in the competition. They weren’t necessarily the best innovators, either, compared to the holostean fish team. Some revisionists at U Penn want to rearrange some strands in the web of belief:

But this view of the teleost success story may be based on the false premise that teleosts dominate today because they have always been more evolutionarily innovative than other groups. A new analysis of more than a thousand fossil fishes from nearly 500 species led by the University of Pennsylvania’s John Clarke revealed that the teleosts’ success story is not as straightforward as once believed. Examining the first 160 million years of teleost and holostean evolution, from the Permian to the early Cretaceous periods, the scientists show that holosteans were as evolutionarily innovative as teleosts, and perhaps even more so.

Fat chance (PhysOrg): This headline undermines a hoary story by evolutionists: “Obesity genes probably didn’t evolve to help us survive famine.” The tale went that our ancestors gorged themselves when food was plentiful to compensate for lean times. Certain evolutionists now claim, “there is now evidence that nearly all the common obesity-related genes show no properties of traits that evolved because they provide an adaptive advantage.” So much for the “thrifty gene hypothesis,” a weak strand in the web of belief. Darwinians will just compensate by shoring up other strands.

Aquatic ape theory drowns (The Conversation): Alice Roberts of the University of Birmingham takes aim at a prominent TV host’s pet theory: “Sorry David Attenborough, we didn’t evolve from ‘aquatic apes’,” she states. The drawing resembles Lucy in a wetsuit. It was a cute story, but it does not account for our hairlessness as mammals or our propensity for being in water, even if it made for a book and TV shows. It’s both too extravagant and too simple, Roberts claims. “Occasionally in science there are theories that refuse to die despite the overwhelming evidence against them,” she says. Does her sermon go far enough?

BM-EmperorCharlie-smDespite the evidence stacked up against the theory, it is strangely tenacious. It has become very elastic, and its proponents will seize hold of any mentions of water, fish or shellfish in human evolution, and any archaeological sites found near coasts, rivers and lakes as supporting evidence. But we must always build our hypotheses on, and test them against, the hard evidence: the fossils, comparative anatomy and physiology, and genetics. In that test, the aquatic ape has failed – again and again.

It is a great shame the BBC recently indulged this implausible theory as it distracts from the emerging story of human evolution that is both more complex and more interesting. Because at the end of the day science is about evidence, not wishful thinking.

New legs for a squirmy story (The Conversation): Can roundworms tell about the evolution of legs? Sure, with a little creative storytelling. Martin Smith of Durham University first tells how a rare worm fossil challenges simple ideas of gradual evolution of the muscles that, back in the Cambrian, would some day emerge into legs. The new plot of the story calls on “radical experiments” by the silent hand of Darwinian evolution:

BM-Darwine-smThis shows how important the fossil record is in unravelling the early threads of animal evolution. A cursory look at the animal kingdom today makes it look like the evolution of legs was almost inevitable. But it seems legs actually arose in a period of substantial evolutionary innovation among primordial worms, whose body architecture was much more versatile than today.

The radical reshuffle seen in our new fossil suggests that legs had a convoluted evolutionary journey. This probably required a substantial period of time, with lots of wacky-looking dead ends. Eventually, a lucky muscle arrangement allowed a fortunate early worm to make good use of the bumps or appendages that would eventually become legs.

We can’t test the idea, of course, because today’s worms aren’t as versatile as they used to be. This is known as ad hoc special pleading, generally frowned on in scientific explanations—except when it comes to Darwin-style confabulation.

It gets so tiring to hear all the excuses. This is what happens when a powerful group usurps science and rules out all contenders. The insiders just play games with data, molding it into whitewash to cover their idol, making it look stronger than it is.

 

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