Evolution: common descent not shown by genetics (Introduction)

by David Turell , Sunday, January 28, 2018, 20:02 (2273 days ago) @ David Turell

Studies of DNA at various levels of evolution do not fit common descent:

http://nautil.us/issue/9/time/evolution-youre-drunk

"Amoebas are puny, stupid blobs, so scientists were surprised to learn that they contain 200 times more DNA than Einstein did. Because amoebas are made of just one cell, researchers assumed they would be simpler than humans genetically. Plus, amoebas date back farther in time than humans, and simplicity is considered an attribute of primitive beings. It just didn’t make sense.

"The idea of directionality in nature, a gradient from simple to complex, began with the Greeks, who called nature physis, meaning growth. That idea subtly extended from changes over an organism’s lifetime, to changes over evolutionary time after Charles Darwin argued that all animals descend from a single common ancestor. When his contemporaries drew evolutionary trees of life, they assumed increasing complexity. Worms originated early in animal evolution. Creatures with more complex structures originated later. Biologists tweaked evolutionary trees over the following century, but generally, simple organisms continued to precede the complex.

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"Before the advent of rapid, accurate, and inexpensive DNA sequencing technology in the early 2000s, biologists guessed that genes would provide more evidence for increasing complexity in evolution. Simple, early organisms would have fewer genes than complex ones, they predicted, just as a blueprint of Dorothy’s cottage in Kansas would be less complicated than one for the Emerald City. Instead, their assumptions of increasing complexity began to fall apart. First to go was an easy definition of how complexity manifested itself. After all, amoebas had huge genomes. Now, DNA analyses are rearranging evolutionary trees, suggesting that the arrow scientists envisioned between simplicity and complexity actually spins like a weather vane caught in a tornado.

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"To their surprise, anemones had more genes than insects, including some genes that humans possess but flies do not. Even more perplexing: Sea anemones evolved before flies and humans, some 560 million years ago. That meant animals might have been genetically complex from the start. “When I was younger, and we knew less, we thought that organisms gained genes over millions of years and that the earliest animals were genetically very simple,” says Bill Pearson, a computational biologist at the University of Virginia who developed some of the first techniques to compare protein sequences among organisms. “We think that less now,” he adds.

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"Late last year, the animal evolutionary tree quaked at its root. A team led by Joseph Ryan, an evolutionary biologist who splits his time between the National Genome Research Institute in Bethesda, Md. and the Sars International Center for Marine Molecular Biology in Bergen, Norway, analyzed the genome from a comb jelly, Mnemiopsis leidyi, a complex marine predator with muscles, nerves, a rudimentary brain, and bioluminescence, and found that the animals may have originated before simple sponges, which lack all of those features.

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"Both hypotheses run counter to scenarios in which organisms evolve to be increasingly complex. In one, a complex nervous system and muscles were lost in the sponges. In the other, the sponges had the genetic capability for complex features but stayed simple, while a more primitive group, the comb jellies, acquired brains and muscles that help them chase down prey. Furthermore, the idea that complex parts like a brain and nervous system—including nerve cells, synapses, and neurotransmitter molecules—could evolve separately multiple times perplexes evolutionary biologists because parts are gained one at a time. The chance of the same progression happening twice in separate lineages seems unlikely—or so biologists thought. “Traditional views are based on our dependence on our nervous system,” says Ryan. “We think the nervous system is the greatest thing in the world so how could anything lose it,” he says. “Or, it’s the greatest thing in the world, so how could it happen twice.”

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"Perhaps the fact that people are stunned whenever organisms become simpler says more about how the human mind organizes the world than about evolutionary processes. People are more comfortable envisioning increasing complexity through time instead of reversals or stasis.

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"Casey Dunn, an evolutionary biologist at Brown University in Providence, R.I. who took part in the still-contentious comb jelly project, now doubts all notions of increasing complexity. Instead, he says the environment selects whatever form handles the challenges at hand, be it simple, complex, or plain ugly. Mother Nature, with her 4 billion years of experience, does not work like Steve Jobs, continuously designing sleeker versions. When asked whether de-evolution, a reversal from the complex to the simple, happens frequently, Dunn replies, sure. “But,” he adds, “I wouldn’t call that de-evolution, I’d call it evolution.'”

Comment: This is a Darwinist showing her prejudice. DNA does not support common descent, but she can't think of it as God guiding. I've had to skip many of her examples of evolution running backward.