Posted on 12/21/2004 8:45:42 AM PST by PatrickHenry
The wide range of variety in domesticated dogs — from the petite Chihuahua to the monstrous mastiff — has powered a new view of what drives evolution.
Scientists have long known that the evolutionary changes that alter a species' appearance or create new species frequently occur in rapid bursts. One widely accepted theory holds that any evolutionary change results from a random switch of a single genetic unit within DNA.
These single-point mutations occur in about 1 out of every 100 million DNA sites each generation. This frequency is too low to cause rapid evolutionary change, assert John W. Fondon and Harold R. Garner, biochemists at the University of Texas Southwestern Medical Center at Dallas.
While examining human-genome data, Fondon found that small segments of repeated DNA sequences, called tandem repeat sequences, are frequently present in genes that control how an animal develops into its final appearance. Unlike single-point mutations, tandem repeat mutations occur when a cell's machinery for copying DNA makes a mistake and inserts a different number of sequence copies.
Such mistakes, which happen 100,000 times as often as single-point mutations, could alter an organism's appearance or function for successive generations.
"I was stunned by what I found," says Fondon. "It occurred to me that this might be a nifty way for [organisms] to evolve very rapidly."
To evaluate this hypothesis, Fondon and Garner looked for tandem repeat sequences in 92 breeds of domesticated dogs. For example, they examined a gene that determines nose length. They found that the number of times a particular sequence is repeated correlates strongly with whether a breed has a short or long muzzle.
Many researchers explain dog-breed diversity as the emergence of hidden traits in the genome. However, says Fondon, a more likely scenario is that genetic mutations occur in dogs at a high rate.
By comparing skulls of dogs over decades, Fondon and Garner found significant and swift changes in some breeds' appearances. For example, between the 1930s and today, purebred bull terriers developed longer, more down-turned noses.
Moreover, the researchers found more variation in tandem-sequence repeat lengths among dogs than they found in the DNA of wolves and coyotes.
These results suggest that dogs have experienced significantly higher rates of tandem repeat mutations than the related species have, says Fondon. Because tandem-repeat sequences litter the genes that control the developmental plan in many species, Fondon suggests that mutations in these regions could have a strong bearing on evolution.
"As a new finding about the biology and genetics of dogs, I'm all for it. But in terms of applying this to [evolution in general], I think there's a question mark," says Sean Carroll, an evolutionary geneticist at the University of Wisconsin–Madison.
Carroll notes that because dog owners have coddled their companions over the centuries, mutations that would have killed wild animals may have persisted in the gene pool of domestic dogs. Because domestication diverges from a standard model of evolution, he says, further experiments are necessary to add weight to Fondon and Garner's theory.
> When your fruit flies won't evolve, just call the one who notices "superstitious"...
Uh-huh. A good example of replacing critical thinking with blind faith. Bravo.
I know that is what my Weim was originally bred to do, but unfortunately she flunked out of obedience school...3 times!
Don't forget the Freemasons...
> How can someone bring down his religion by believing in it?
Because you are focussing on the fairy-tale, allegorical aspects of it and demanding that it be seen as scientific truth. Creatinists are making it *very* easy to dismiss Christians as a whole as a bunch of uneducated superstitious boobs. It is a slow process, but it's certain death for a religion to be laughed at.
> The evidence for evolution is far from conclusive.
No, it's not. It's quite conclusive. The only real debates left are the details.
> it necessarily points to spontaneous generation of life.
Defien your terms. At what point to complex chemicals become "life" in your view? Is a virus "alive" if so, scientists have assembled synthetic virii from much simpler components. The virus was as alive as virii get, and was able to reproduce.
That was in my Philosophy 101 book. :-}
You don't see that this statement argues against your spontaneous generation point?
No, it does not. What scientists do is not magic, not supernatural. They brought chemical componants together in the right environment, and the end result was a living virus.
Hmmm. Wonder why Christianity has done so well throughout history when so many of its adherents faced not only laughter but certain death for their beliefs. If your assessment above is any indication of your ability to assess facts and evidence, well, guess we know who is more likely to subscribe to a fairy tale.
I see no conflict in evolution and Creationism.
I suspect the evolutionists have it a little wrong, and I suspect the creationists are reading the Bible a little wrong.
I bet it will shake out that: God, the law-giver, created laws of nature. These shake out to be evolution in some form or fasion.
The result is consistent with Intelligent Design. Indeed, anyone who bake bread and does it just right creates something out of seeming chaos.
God spinkled in just the right ingredients in the Universe and baked us up just how he wanted. He knew exactly how the bread would rise.
The Bible is the recipe.
Evolution is the science of the rising bread (from the perspective of the yeast, no less).
I recall very asute readers of prophecy being very surprised by Christ coming along. They expected a military hero, I believe.
They read their Bible wrong. In hindsight, their error could not be more obvious.
Same with the Church going after Galileo. They relied on the Bible (and their pre-existing beliefs) to say Galelio was all wet for his Earth-is-Sphere-that-goes-around-the-Sun theory. Got him excommunicated, in fact.
Knowing what I know now, when I read Genesis, it seem perfectly consistent with the Earth going around the Sun, although I see how someone could take it differently.
Once the details are worked out, I bet it will all harmonize, as well.
(Take this all with a grain of salt. The Big Bang theory always sounded like God saying "Let there be light . . ." to me.)
scratching himself like a baseball player
either that or practicing for a superbowl half time show
To bastardize Arthur C. Clarke's saying: To the desperately deliberately ignorant, any technology is seen as magic. Evil, competing magic.
I think that was written on the inside door of a stall outside the Philosophy building, too.
There was even a phone number.
Reminds me of the joke:
God and a scientist arguing about the creation of life.
The scientist says, "I bet I can make a virus out of this dirt."
To which God replies, "I'll take the bet. But you have to use your own dirt."
> Wonder why Christianity has done so well throughout history when so many of its adherents faced not only laughter but certain death for their beliefs.
Because Christinaity had political power. Jsut a few hundred years ago, anyone who would DARE suggest somethign like evolution would be burned at the stake.
But now, Christianity is fading from the western world. It's power in Europe, formerly the central base of Christianity, is quite weak. Christians who bray nonsense about Creationism do NOT help their cause.
If you isolate virii in the marriage suite from other organisms how do they reproduce?
All my dogs are smarter and more likeable than a lot of people I meet......!especially liberals!......
> Maaaan quit yippin'.
Translation: "Please stop telling people the truth."
> Your theory has more holes than swiss cheese.
All theories have holes. However, Creationism is nothign *but* a hole.
The stuff you copied-and-pasted was amusing, but not enlightening except to show what depths of intellectual dishonesty Creationists will go to.
Quite so. What scientist do, ideally, is intelligent manipulation of pre-existing materials.
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