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Who did we evolve from?

Discussion of everything related to the Theory of Evolution.

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Postby alextemplet » Tue Jan 24, 2006 2:46 am

Well said, bd. 8)
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Postby mith » Tue Jan 24, 2006 5:16 am

Springer wrote:Selective breeding of dogs has been occuring for 5,000 years. Despite the phenotypic diversity (microevolution), as you pointed out, they are all 100% dogs. A St. Bernard is no closer to any non-canine species than a poodle or any other breed. If evolution were possible, then we should see evidence of it in domestic breeding. Breeding of dogs is easily explicable by variations in the gene pool. The evolution from a hippo-like ancestor to a whale is an entirely different matter, requiring major changes such as the development of a different physiology to change from salt water to fresh water, restructuring of the caudal musculature to change from a side to side to an up and down tail movement, development of echolocation, changes in physiology to allow suspension of respiration.... to name a few.
The fallacy of extrapolation of microevolution to macroevolution is apparent even to a young child. It is extremely poor science... It is totally illogical and only underscores the weakness of the evolutionary position.

Read the link I posted. Plus I also mentioned the caulflower and other derivatives from the wild mustard. As for the dogs, is it really that hard to see that even if they are dogs, larger varieties such as the great dane will be more and more reproductively isolated from others such as chihuahuas? Dogs are closely associated with wolves and can even produce viable offspring but they are considered different species. How long do you think would it take for the existing varieties of dogs to actually split and be categorized as different animals like the wolves and dogs are?
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Postby MrMistery » Tue Jan 24, 2006 7:30 pm

sorry to debate for the other side, dave but dog is Canis lupus familiaris, a subspecies of the grey wolf, Canis lupus. Reclasified about 20 years ago. But this is just an arbitrary taxonomy, makes no difference in the debate
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Postby catfishjim » Tue Jan 24, 2006 10:22 pm

I can recommend a good book, "Science: A History" by John Gribbin. Thick as a Harry Potter book, but you won't want to put it down.
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Postby mith » Tue Jan 24, 2006 10:34 pm

thanks for correcting me andrew :) and you're right it doesn't make much of a difference, first subspecie, then soon fully different specie
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missing link

Postby AstusAleator » Tue Jan 24, 2006 10:50 pm

Hello,
I'm new to the forum so bear with me if I commit any feau pauxs. My name is Dave and I'm an Undergraduate at Albertson College of Idaho, majoring in Conservation Biology. I'm currently conducting an independent study on Evolution.
Anyhow, I had a couple of comments to add to the current discussion.

Regarding "missing links": (mind you this is my understanding of the topic and is thus susceptible to errors. Please correct me if I'm wrong)

The likelihood of having an extant evolutionary ancestor is very low (except in micro-organisms and cases of selective breeding and genetic modifications by humans). Consider the time and selective pressures that would be required to completely speciate a population, and then consider what kind of selective pressures or random mutations must have been occuring in the parent population during that time. It is more likely that the parent population itself has undergone its own path of speciation or extinction.

The reason we don't see an extant common ancestor of chimps and humans today is because the environment has changed and while Homo and Pan speciated and adapted to the changes, the species that was their common ancestor did not survive as its survival traits were not sufficient to keep it alive.

In the case of dogs and wolves: the wolves we have today (Canis lupus lupus, arctos, irremotus, etc) are not the ancestors of dogs. They do, however, have a very close (genetically and chronologically) common ancestor that walked the earth some 10-30 thousand years ago. Yes it was Canis lupus, but the current subspecies existing today do not (probably) have the full ancestral genetic code. This hasn't been completely proven, as genetic and mitochondrial DNA studies are still being done to determine Canis lineage.

On the other hand, speciation is occuring quite rapidly in the realms of microbiology and genetic engineering. It is possible that with improved technology (both for observing the speciation of micro-organisms and for genetic engineering) that we will see the formation of new species in our lifetime. Rapid speciation could result in the coexistence of an ancestral and derived species.

I guess I'm trying to show that, in response to Springer, looking for extant ancestors is a slippery slope and can lead to false hypotheses.

Dogs are a difficult example, as they are the result of selective, nonrandom mating, more specifically, inbreeding. The selective forces driving dog adaptation are many and complicated. A detailed analyses of these selective pressures would probably show that dogs are not being driven to necessarily form a new species, but simply exist in their varying phenotypic states. No selective pressure is being directed against the core of what a dog is, and they are in no threat of being eliminated.
If there was a focused effort to create a new species of canis, it could probably be done, but the current selective pressures don't really seem to be directed towards that.

Anyhow, I've run out of steam. Refute and disprove to your hearts' contents.

Dave
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Postby b_d_41501 » Tue Jan 24, 2006 11:48 pm

Yes, you are correct. There ISN"T going to be an extant "missing link". Otherwise it would be very easy to discover this missing plank in the whole matter.
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Postby alextemplet » Wed Jan 25, 2006 2:28 am

Well said, Astus. And welcome. I look forward to reading more of your posts in the future. 8)
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Postby catfishjim » Wed Jan 25, 2006 8:15 pm

mithrilhack wrote:
Springer wrote:Selective breeding of dogs has been occuring for 5,000 years. Despite the phenotypic diversity (microevolution), as you pointed out, they are all 100% dogs.


I would like to point out that, in evolutionary terms, 5,000 years is not a very significant time period. Some researchers now claim that dogs and humans have had a symbiotic relationship for 100,000 years. So selective breeding may have been going on for much longer than 5,000 years.

On the other hand, my guess would be that other typical domestic animals like cows and sheep have not been bred as long as dogs. What is their genetic relationship to wild species still in existence?

One reason I wonder about this is because I assume that cows, sheep, and goats on the one hand, and dogs on the other hand were always a part of transhumance, that is the practice of driving your sheep or cows up to higher pastures in the summer and back down the mountain in the fall. This practice is supposedly much older than farming*. So if dogs have always been a part of human culture, then a good piece of their development must have run parallel to that of cows, sheep, and goats.

*One theory is that transhumance just sort of developed by itself out of the seasonal wandering involved in following wild animal herds.
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Postby b_d_41501 » Wed Jan 25, 2006 11:26 pm

According to most of my textbooks, dogs were only domesticated around 12,000 BCE? :?
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Postby catfishjim » Thu Jan 26, 2006 6:37 am

b_d_41501 wrote:According to most of my textbooks, dogs were only domesticated around 12,000 BCE? :?


I wasn't there personally, but as I mentioned, there is a new theory that came out a couple of years ago that says the "man's best friend" relationship goes back a lot farther.

BTW: Not long ago, "most textbooks" claimed that the world was created in about 5,000 BC...
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Postby AstusAleator » Thu Jan 26, 2006 7:48 am

An ancient grave in what is now Israel contained the body of a child holding a small dog/puppy. The grave was dated to be 12,000 yrs old.
I tried looking up some primary literature but I can't access it from off-campus. when I can get back on a computer at school I'll try to post some references.
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