Yes, your request was in vain. :)
Posted on 07/18/2006 9:06:26 AM PDT by PatrickHenry
Thanks to their domestication and favored pet status, dogs have enjoyed a genetic variability known to few other species.
It may be time to revise that old maxim about humans and their canine companions. A man, it seems, is a dog's best friend, and not vice versa.
A paper in the June 29th issue of Genome Research presents evidence suggesting that the domestication of dogs by humans has given rise to the immense diversity of the canine species by allowing otherwise harmful genetic mutations to survive.
"Dogs that would have otherwise died in the wild would have survived because humans would have allowed them to," said Matt Webster, a geneticist at the University of Dublin and one of the study's authors.
The stunning diversity of dogs — Canis lupus familiaris, includes lumbering St. Bernards, sprightly Jack Russell terriers, and graceful greyhounds — has been a source of scientific interest since Darwin, who speculated that these creatures must have descended from several different species. (Scientists now know dogs have a single ancestral species, the gray wolf.)
"Within a single species you have this tremendous range of morphological variation, all this diversity — head shape, body shape, coat color, length — and a tremendous amount of variation in behavior," said Leonid Kruglyak, a geneticist at Princeton University. "Where does all this come from? The parent species, which is the wolf, doesn't show this diversity."
Webster and his colleagues collected and sequenced DNA from the mitochondria of wolf and dog cells. Using this data, they looked for genetic mutations and calculated the rate at which mutations appeared.
Genetic mutations can be divided into two broad categories: nonsynonymous mutations actually change the protein that a stretch of DNA codes for, while synonymous, or silent, mutations do not.
Webster and his colleagues found that the silent mutations occur at similar rates in dogs and wolves, but that nonsynonymous mutations accumulate twice as fast in dogs as they do in wolves. These random changes to proteins are usually harmful, and would have a weakly deleterious effect on dogs and their ability to survive, said Webster.
"That suggests that during dog evolution there's been a relaxation of selective constraint," he said. "These additional changes that have happened during dog evolution have escaped the pressure of natural selection."
Because humans made it easier for domesticated dogs to survive, random genetic mutations that reduced evolutionary fitness — and would have died out in wild dog populations — were able to persist. Furthermore, as humans bred dogs for more desirable traits, they may have exploited these random mutations, accentuating already present variation.
"A lot of the changes over dog evolution would have provided the raw material that humans have used to shape different breeds," Webster said.
The result, then, is the phenomenal diversity in characteristics among different dogs and dog breeds today.
Elaine Ostrander, a geneticist at the National Human Genome Research Institute who worked on the institute's dog genome project, praised Webster's research and its use of mitochondrial DNA.
"For them to focus on mitochondrial DNA was an insightful decision," Ostrander said. "It's been neglected in canine genetics."
Mitochondrial DNA, because it resides outside the cell nucleus, is passed down only from mother to offspring, and it accrues mutations particularly fast. While that might make mitochondrial DNA a natural place to study rates of genetic variation, it's not yet clear whether Webster's findings will apply to the nuclear genome.
"The mitochondrial genome is such a small percentage of the dog genome," said Princeton's Kruglyak. "The interpretations are somewhat speculative."
Nevertheless, he conceded that the researchers' findings and proposed explanation are reasonable, even if not definitive.
"It's difficult to figure out what exactly happened over the last 10,000 years of dog domestication," he said. "It's not clear that any other species has been pushed by artificial human selection to the same extent. There's definitely a very interesting set of questions to be answered."
Artificial selection gave Darwin and Wallace the idea for natural selection. The only missing piece was the observation that apart from humans, far more creatures are born than live to reproduce. The resulting drift of allele frequency is inevitable. You can't NOT have evolution.
So if you were going to design something new, you might twiddle with a gene here and there, see how it turns out, and allow some variations to produce more offspring.
Helen Thomas is a real dog, after concetion the mold was burned.
I've read, and it's true - dogs are wolves that never grow up.
Sure thing:
"...But these speak evil of whateve they do not know; and whatever they know naturally, like brute beasts, in these things they corrupt themselves..." Jude 10
You'll have to investigate the phrase "...like brute beasts..." to determine a deeper understanding. Suffice to say, brute beasts are nothing more or less than an animal that knows nothing, feels nothing, thinks nothing, but merely act on the basest of instinct which if a human acted upon would be considered wretched, cruel, evil and wholly uncivilized--which as every pet owner can tell you is pure rubbish.
Elsewhere in the Bible dogs are described as nothing more than scavengers and are metaphors of evildoers. Nothing is said of their personality, or their usefulness beyond what I just mentioned.
In point of fact, if you were to take a fundamentalist, die-hard view of the Bible and live accordingly to its every line, dogs, pigs, and frogs would be considered absolute taboo seeing their place in the world of religious thought.
But hey, that's just my opinion based on 20 years of study.
Yes, your request was in vain. :)
Sad...
Thank you for finding that Darwin passage as it describes much better what I've been trying to say. Most people have never read this idea, and it certainly isn't mentioned in public school when they are teaching Darwin's ideas on natural section.
You are right, Darwin does not outright say that we killed off the Neanderthals in war, reducing the humanoid genetics pool from two species down to one. But one thing very strange about humanoids as compared to say the variety of fish, is why there is only ONE humanoid species still alive? This is very odd. Obviously there is enough food in the world for many similar species to survive. The only explanation that makes sense is we killed them off in anger or competition. This fits with Darwin's ideas in the Descent of Man.
There is only one species of humanoid still alive. One. That is a pretty narrow genetic pool. War is the reason behind this narrowing. Can you think of any alternative explanation? Maybe the other humanoid species suddenly forgot how to eat?
O.K. I'd agree. I was off on a tangent. :)
I was more referring to the difference between a domesticated bunny or cat, and a domesticated dog. We've "been" with dogs for so long and so closely that not only have we caused them to have certain inate traits (as a generality - obviously the strengths and utilizations of these traits varies considerably between individuals), but they appear to have induced in us a sort of "tool set" that we can use in relating specifically to dogs, if we don't forget them while we reprogram our brains (grow up).
You realize, of course, that your speculations on this are worth every penny you are charging us for them. The fact that you can only imagine a couple of cuses simply means you haven't given it much thought.
That doesn't indicate greater genetic complexity. You can get more complex brains with simple variations to the default program, like letting the brain simply grow larger, or longer, or delaying cell death, etc.
The anti-evolutionists today are arguing on one hand for complexity in the genome and on the other hand for variations in in the expression of existing genes. It's good of creation science to discover all these possible explanations and to give us the intellectual tools with which to sort them out.
This is almost as important as the role creation science played in unmasking the Piltdown hoax. Where would we be without creation science?
What are your ideas that all other similar hominids died out? It's mathematically odd the number of survivors is exactly one and I don't believe it's just a coincidence.
Intelligent design at work.
Nearly every species that ever lived is extinct.
The cystic fibrosis gene is fairly common because the carriers are resistant to cholera. Similar to the relation between carriers of sickle-cell and malaria, or carriers of Tay-Sachs and tuberculosis. Source: "Guns Germs and Steel" be Jared Diamond.
I believe your take is that the passage is referring to animals in a critical way. I don't believe this is so. I believe the focus is on the apostates and the comparison is that they are like beasts which only know what they can see and deal with on a physical level - as opposed to understanding spiritual things.
Since gnostics claimed special knowledge, Jude points out that they are like beasts in that they only know what they can see physically. I don't see that as a cut against animals.
Here is an explanation from J. Vernon's work. It is as good as any since I'm pressed for time. I've briefly looked at the words and it seems he is right on those. : I would like, as best I can, to make this verse understandable to you because it is another very important verse in this epistle. When Jude says, “But these speak evil,” the Greek word is blasphemeō which by transliteration is our English word blaspheme. The apostates actually blaspheme. “These speak evil of [blaspheme] those things which they know not: but what they know naturally.” Jude uses two different words here which are both translated “know.” May I say, without recognizing that, it is difficult to determine exactly what Jude means here. The first “know” is eidō which speaks of “mental comprehension and knowledge  referring to the whole range of invisible things,” as Vincent defines it. Knowledge is not confined to what you can pour into a test tube or look at under a microscope, although a great many people think that it is. The finer things of life are things you cannot put under the microscope; you cannot pour them into a test tube. For example, what about a wonderful piece of music? What happens if you try to stick it down a test tube or look at it under a microscope? Music needs to be translated into sound, and the ear needs to hear it—you cannot see it at all; it is actually invisible. Love is also invisible—you couldn’t put love under the microscope. How about faith?—you can’t put it under the microscope. My friend, there are a great many things I know, and I know them without any proof from the laboratory. I know them because I have experienced them. The Holy Spirit has made them real to my own heart. “But these speak evil of those things which they know not.” That Washington, D.C., preacher thought he was very brilliant to say that he no longer believed in the Resurrection. May I say to you, there are many things he doesn’t know. The second word for “know” which Jude uses here is epestamai, which means “to understand.” Vincent says that it was used “originally of skill in handicraft” and that it “refers to palpable things; objects of sense; the circumstances of sensual enjoyment.” These are things you can pour into the test tube. All that these folk know is what they can handle and what they can see. They are like brute beasts because, after all, a brute only knows about the hay or the grass or the corn or another animal that it can eat. This refers to that which they know by instinct. For example, in the fall of the year, the ducks are in Canada, having had a nice summer up there, but all of a sudden they take off. Somebody says, “Boy, are they smart! Those ducks know that before long it will be winter, that snow will be on the ground, and that the lake is going to freeze over. So they take off for the south, and they go all the way down to Mexico and into Central America. They are really very smart!” No, they are not. They move just like a beast, just like a bird moves—by instinct. There is no comprehension, no understanding. This generation that thinks it is so smart because it only believes what it can pour into a test tube is a poor generation. They do not understand anything that a brute beast couldn’t understand. They have not reached the higher plane of knowledge, what Paul called epignōsis. Paul says, “You can know that the Bible is the Word of God. You can know that Jesus is the Savior of the world.” These men, knowing just physical things, think they know everything that can be known, and they corrupt themselves in these things. This is the picture of the apostates that Jude gives to us. McGee, J. V. (1997, c1981). Thru the Bible commentary. Based on the Thru the Bible radio program. (electronic ed.) (5:862). Nashville: Thomas Nelson. But these speak evil of those things which they know not: but what they know naturally, as brute beasts, in those things they corrupt themselves [Jude 10].
I'm a big dog fan, btw. Thanks again, ampu
My apologies for the funky characters in the last post.
I think js and I are just pointing out that there is no compelling evidence for your claim that Neanderthals were driven to extinction by competition (or even warfare) with anatomically modern humans. There are at least some reasons to think otherwise.
For one thing, well last I knew of anyway, there's still debate about whether Neanderthals and anatomically modern humans ever overlapped in space and time at all.
Second, stress analysis of Neanderthal leg bones suggests they were subjected to a good deal of lateral stresses, but show an absence of stress patterns associated with a steady, striding gait (which are consistently found in anatomically modern humans). The suggestion here, and I believe it's consistent with other evidence as well, is that Neanderthals seldom traveled long distances. The typical Neanderthal may have spent its entire life in a single valley.
So that's a significant behavior difference that may have mitigated against contact and competition between Neanderthals and moderns, even if they did overlap. Add to that the fact that Neanderthals are specifically cold adapted compared to moderns.
I'm not saying that moderns did not have a role in driving Neanderthals to extinction. They (or some other lineage of archaic sapients) MAY have. I'm just saying we don't have (to my knowledge) any good positive evidence of that hypothesis.
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