This relates to a topic that a previous thred veered off into (but I don't have the time or patience to try to find it [img]/phpBB/images/smiles/icon_redface.gif[/img] ) dealing with genetic diversity and how humans have interfered with the natural process of evolution by selective breeding and stuff like that.

Anyway, this study deals with tracing the genetic history of dogs to find where and when they originated.

http://www.cnn.com/2002/TECH/science...gin/index.html

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"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

Neb, it will be really hard to give this thread any kind of astronomical dimension, but it is interesting. Why do you suppose we have been able to introduce through selective breeding such a wide diversity of forms in the common dog, canis familiaris?
Although I know they are, when I look at a chihuahua and a bull mastiff, it's hard to see that they're the same species. I'd guess if these two extreme ends of the dog scale don't interbreed (and just try to visualize how they'd do so [img]/phpBB/images/smiles/icon_smile.gif[/img] ) they will in time become different species entirely, incapable of even artificially induced breeding.
If we remember that the divergent traits were natural mutations that were amplified through selective breeding, it appears that dogs have an unusually large mutation rate. We don't, for example, see the same divergence among the breeds of domestic cats, even though, presumably there was just as much incentive to create them.

Any ideas how to tie this topic to astronomy?

(Added by edit) Isn't there a Dog Star - I don't mean Lassie or Rin Tin Tin, but a celestial object? (Looking for any shred of legitimacy for this thread.)

<font size=-1>[ This Message was edited by: DaveC on 2002-11-22 12:14 ]</font>

I don't think cats have been domesticated nearly as long. Even so, I've seen cat breeds change appearance just in my lifetime, with Persians now looking ever more like bulldogs and Siamese looking ever more like rats (neither development seeming desirable to me, personally).

Yes, there's Sirius, and there's also constellations Canis Major and Canis Minor.

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Everything I need to know I learned through Googling.

I thought that it was common knowledge that that's the way it was, that dogs are decendants of wolves via human intervention.

Well, like I said, I'm piggy-backing off a divergent topic off of a previous thread, but for the life of me I can't find it. I do remember this being mentioned, though. (I think it came off one of the "evolution" threads, but try sorting through that mess to find anything. Oy!

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"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

We could talk about how Laika of Sputnik fame would have been immpossible to put into Sputnik had she been a wolf. (Of course, she probably would have lived longer then, too).

Bingo! Thanks, Zathras. We now have some relevance for this topic. [img]/phpBB/images/smiles/icon_smile.gif[/img]

The human intervention initially was some sort of "partnership" with those wolves that were less timid and hung around human campfires. These "wolves" gradually became genetically divergent from their wild cousins, splitting into the two subgroups we classify as canis lupus (wolf) and canis familiaris (dog). But I don't think the intervention in terms of selective breeding started until about 500 years ago, which probably isn't a lot different than the time during which we've been manipulating cat genes too.

I wonder what the Russians would have put in Sputnik 2 if we hadn't created small dogs? Imagine the scratches they'd get trying to lock a kitty in there!

Just to nip a misconception in the bud, cats were not domesticated by Man.

Just the opposite.

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Never attribute to malice what can be adequately explained by ignorance or stupidity.
Isaac Asimov

Thanks, Jim. I think that's what I had in mind with my comment about getting kitty in Sputnik 2.

Actually the two species are not genetically distinct yet. Some, but not all, dogs are still able to breed with wolves. I know some people who live in a rural area and have a couple of half-wolves. Picture a REALLY big German Shepherd.

With respect to the selective breeding, different breeds started at different times. The one breed I know a lot about, Great Danes, emerged about 1100 AD in Germany. Other breeds can be traced as far back as the Roman Empire.

Yes, that's why I characterized them as sub-groups and used the term genetically divergent as opposed to distinct. I agree that where it is physically possible, dogs can still breed with wolves.

The 500 year period is, as I understand it, the time during which humans have been deliberately (I almost said intelligently) designing dogs. There are clearly examples of dogs that were substantially different from wolves from far beyond 500 years ago, but it appears that these were more by accident than design, because there aren't any records to show that it was deliberate human manipulation. We know about these unwolflike dogs from fossils and artworks. I'm not wedded to the 500 years though. It's clear that wolves adopted us and modified our behaviour long before we returned the favour.

This article should clear a few things up about the origins of dogs and wolves.

http://www.grapevine.net/~wolf2dog/wayne2.htm

BTW, dogs can breed with wolves, foxes, coyotes, and even jackals, yet all are distinctly different. Still, dogs are closest to gray wolves genetically.

Just to fuel the fire--in many states, my own included, it is illegal for veterinarians to vaccinate wolves or wolf crosses, primarily because there is no dependable research to insure that the type of rabies virus used will not actually cause the disease in a wolf. In other words, when push comes to shove, it looks like some experts don't want to stake their reps (or public health) on saying that wolves and domestic dogs are the same species. Of course, many disease outbreaks in domestic dogs (like parvovirus) can be traced to contact with coyotes, wolves, etc., but so can humans get monkey b virus from monkeys.

Thanks for the link. I didn't get from that material that dogs and foxes could interbreed. Presumably the chromosome number has to be the same in order for interbreeding to occur. Dogs, wolves jackals, coyotes all have 78 chromosomes. Foxes have varying numbers depending on the subspecies, but none has 78 (unless the Asian dhole is a fox. (It sure looks like a big red fox to me.)

Gethen, that's interesting info about the rabies vaccine. I'm due to take my dog in for his annual immunization this week. I plan to ask the vet whether that's an issue here. We have a fairly large local population of coyotes which are becoming quite "cityfied". Undoubtedly there are lots of dog/coyote crossbreeds showing up at vet clinics.

God in the DNA!

http://www.wired.com/wired/archive/1...pic=&topic_set

????????? [img]/phpBB/images/smiles/icon_confused.gif[/img] [img]/phpBB/images/smiles/icon_confused.gif[/img] [img]/phpBB/images/smiles/icon_confused.gif[/img]

Random observation: it took ten million years of natural selection to get from something that looked like a rat all the way to a wolf. It only took humans about 1000 years to turn wolves into chihuahuas.

Talk about progress, eh?

Chihuahuas are probably the most useless breed of dogs.. Even the other toy dogs at least have fur so they don't freeze to death outside in summer.

Where exactly did the ancestor of house cats come from? The closest thing I have seen are the few types of jungle cats in South America. -Colt

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Be not afraid of any man no matter what his size; when danger threatens, call on me, and I will equalize.

Don't tell that to Taco Bell! [img]/phpBB/images/smiles/icon_lol.gif[/img]

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"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

For any breed of dog, there are some people out there that think it's wonderful. I'm not big on chihuahuas either (and about a dozen other breeds I could name). But then, I have an Old English sheepdog, also very unwolflike except in size perhaps, and I suspect that's not everyone's cup of tea either.

I think the point is, we have manipulated the poor wolf six ways from Sunday and created a whole host of weird variations. I'm still curious as to how that was possible in such a short time. We sure haven't made the same dramatic changes to any other creature. Cows at least bear some passing resemblance to their ox ancestors. Cats still look like cats - even though I'm not sure where the domestic cat arose initially.

We've managed to tweak the genes of one other critter rather well... custom-made drosophilia flies are available at the bottom of this page. How long it takes to breed makes a big difference. 1 generation of flies is a matter of days, dogs are longer, and it takes a while to grow a cow.

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Once bread has become toast, it can never become bread again...

Grow a cow?

[Pictures cows srouting out of the ground across the field]
Well, I gues if you can have cow pies, you can have cow plants!?

Edit: changed the tease to something more amusing, or at least I think it is . . . .
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"Once again, we find that science is a two-headed beast. One head is nice, . . . but the other head of science is bad! Oh beware the other head of science, Arthur, it bites!" - The Tick vs. Dinosaur Neil

<font size=-1>[ This Message was edited by: nebularain on 2002-11-28 21:09 ]</font>