Don't tell me there's no proof for evolution

Creationists need to be reminded of the basics:"Reality is what doesn't cease to exist when you stop believing in it."

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Ros, when I re read that definition you posted for genetic drift, I thought it was a bit too academic. Genetic drift used to be considered a sampling bias until the math was rechecked and found to be an actual force. Its simply a genetic reinforcement effect that occurs mostly in small populations where the entire spectrum of genetic diversity isnt available to the "parents". If they reproduce and multiply, the new resulting population is composed of only the genetic diversity that the few founders brought with them. The normal distribution is "clipped" so that the new population has a more limited genetic diversity as compared to that entire species. Its been the principal driver for humans since many populations would just "go off" and establish a new community separate from the original nation. I never liked Futuyamas definitions since he always was interested in getting the mathematical expressions in there even at the expense of his students missing the entire point.., that genetic drift causes a decay in variability due primarily to the effects of a small foundation population. Genetic drift at its most catastrophic was the huge loss of genetic variation that all humanity suffered when Mt Toba blew up and killed off most of our ancestors.

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Quote:

Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans

Professor Stanley H. Ambrose

Department of Anthropology,
University Of Illinois, Urbana, USA

Extract from "Journal of Human Evolution"

The last glacial period was preceded by 1000 years of the coldest temperatures of the Late Pleistocene, apparently caused by the eruption of the Mount Toba volcano. The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. The survivors from this global catastrophy would have found refuge in isolated tropical pockets, mainly in Equatorial Africa. Populations living in Europe and northern China would have been completely eliminated by the reduction of the summer temperatures by as much as 12 degrees centigrade.

Volcanic winter and instant Ice Age may help resolve the central but unstated paradox of the recent African origin of Humankind: if we are all so recently "Out of Africa", why do we not all look more African?

Because the volcanic winter and instant Ice Age would have reduced populations levels low enough for founder effects, genetic drift and local adaptations to produce rapid changes in the surviving populations, causing the peoples of the world to look so different today. In other words, Toba may have caused Modern Races to differentiate abruptly only 70,000 years ago, rather than gradually over one million years.

http://www.bradshawfoundation.com/stanley_ambrose.php

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Isnt it neat when many separate branches of science and evidence coalesce around a mature theory. We have ash and bentonite evidence for when toba blew and where it had its radius of effect. I always pity the Creationists as they try to tread water and come up with anything believable when most of their beliefs not only cannot be supported, they have no available evidence at all. The Creationists conveniently omit that point as they try to critique science.

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farmerman wrote:

Genetic drift at its most catastrophic was the huge loss of genetic variation that all humanity suffered when Mt Toba blew up and killed off most of our ancestors.

I was thinking of Toba when I mentioned genetic drift. In addition, I think humans are also a prime case of founder effect gone wild, especially after Toba's decimation of the population.

Human adaptability and nomadic behavior allowed us to spread into new environments and to create isolated populations more rapidly than most animals. In addition, human populations are differentiated by sexual selection as well as survival selection, so founder effects are amplified.

There are many forces involved in evolution and in differentiation of population. The Modern Synthesis isn't called a synthesis for nothing. It's not just a collection of unreleated forces which affect overall evolution, it's a collection of interrelated forces which are feedeing back on themselves; it's a synthesis of forces. To think it terms of just 'selection' as being the reason behind population differences can be misleading.

RL is focusing on selection because he's getting his material from creationist propaganda which also focuses on selection as the only reason for differentiation in population.

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farmerman wrote:

Isnt it neat when many separate branches of science and evidence coalesce around a mature theory.

This is the real beauty behind a good theory, when it pulls all the pieces together and things start to make sense.

Without evolution, nothing in biology makes any sense, and disciplines as different as geology and genetics would remain isolated. But with it, all the evidence fits together into a cohesive picture which matches reality. It's a beautiful thing.

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Thats why I think that weve been answering RLs diversionary questions. When, indeed, the only "unknowns" are the bases from which Creationist thought derives its proofs. Im gonna go out on a limb here and say that , I havent been able to find any.

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You know, FM, i hadn't thought about that aspect of the polar bear-brown bear interbreeding. We don't know if a reproductively viable offspring was produced--so it is entirely possible that a "mule" was produced. Asses and horses can interbreed, but the sterile offspring are all the evidence one needs that they have diverged into definitely separate species.

xingu's source wrote:

Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago.

I knew about Mount Toba, but hadn't really paid any attention to the date range (i can't even say that i had ever read of it). It is interesting to think, though, that homo sapiens sapiens, which arises near the low end of that date range, might be the specific product of genetic drift and a small founder population. Perhaps in extreme conditions (a drop in average global temperatures of 12 degrees centigrade is going to have a profound effect even in equatorial regions), the "higher-order intelligence" which homo sapiens sapiens seems to display in relation to other homo populations was selected for--i.e., you had to be able to figure out crucial relationships in your environment to survive and prosper.

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At about the mid time of the Toba eruption, we have the evidences of the last H. erectus and heidelbergensis and the last of the H sapiens idaltu . disappeared. H neandertthalensis lasted till about 25 K YBp in Europe and was conjectured to have interbred with us in a limited fashion (though genetic evidence isnt available except for one family in Leeds).Imagine yer paleo great grandpappy was found out to have screwed a Neanderthal chick. "I was really drunk and she didnt look that bad"??
There was a Geological Society of America Special Pub on the Toba eruption as a model for a resurgent catastrophist worldview in geologic analysis.

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The girls all get prettier at closin' time.

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Quote:

You know, FM, i hadn't thought about that aspect of the polar bear-brown bear interbreeding. We don't know if a reproductively viable offspring was produced--so it is entirely possible that a "mule" was produced. Asses and horses can interbreed, but the sterile offspring are all the evidence one needs that they have diverged into definitely separate species.

Set, Im certain that if a viable (nonsterile) offspring were produced, wed have heard about it from RL . (Im sure hes scurrying around). But even if it were nonsterile, the genetic diversity of the two species, having arose from the same common ancestor, may have allowed a successful pairing. Like the red wolf and the Timber wolf. They are separate sexually isolated species who can produce a viable offspring. Its just that, in nature, they occupy separate niches and territorial ranges so they dont pair up (red wolves pair, while timber wolves "pack" and the alpha male is the primary breeder).

The Romans used to breed Tigrons for show and circus, so RL is again, without a target for exploitation.

Im still insistent that he give us his "Beliefs" and their evidence rather than we serve as his personal sounding board.
Im afraid that he cant quickly support his doctrines with any sound science. Just as his K/Ar crap has been soundly smacked (although he apparently refuses to recognize it) his other evidence is on equally thin ice Ill wager a farthing.

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farmerman, "Doctrine" is the right word for 99% of his posts.

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farmerman wrote:

so, by not telling the labs to check on the CA /Ar ratios (that would have told them right away that they were dealing with very young material

How much Ar was present in the sample when the rock was formed?

How much Ca was present in the sample when the rock was formed?

Knowing the ratio of these doesn't tell you how much was formed in between the date of origin and today if you don't know how much there was on the date of origin.

-----------------------------------------------------------------

I asked:

In an objective test, why would the lab need a cue card to tell them what date to expect?

Your responses:

Because it will cost lots of extra money. You're a fool for doing this.

Because it's protocol. Austin was deceitful by violating 'procedure'.

are not answers at all.

The issue is the objectivity of the test.

Selecting a dating method based on the assumed age of the rock just puts a numerical value on a subjective opinion.

Radioactive methods cannot determine the age of rocks because there is a fundamental flaw in the method.

Naturally we know how rapidly the elements decay under normal conditions, and we can measure the amount in the rock now.

But without knowing how much of each was there to begin with, it isn't possible to tell how long the decay has been going on because we don't know how much of the product that is present today is the result of decay.

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Quote:

that aspect of the polar bear-brown bear interbreeding. We don't know if a reproductively viable offspring was produced--so it is entirely possible that a "mule" was produced.

from http://www.answers.com/topic/grizzly-polar-bear-hybrid

Quote:

A grizzly-polar bear hybrid is a rare ursid hybrid that has occurred both in captivity and in the wild. In 2006, the occurrence of this hybrid in nature was confirmed by testing the DNA of a strange-looking bear that had been shot in the Canadian arctic.[1] Previously, the hybrid had been produced in zoos and was considered a "cryptid" (a hypothesized animal for which there is no proof of existence in the wild).

The grizzly bear and polar bear are sufficiently similar genetically that they can interbreed and produce fertile offspring. By the strict interpretation of the biological species concept, this would imply that brown bears and polar bears are variants of the same species

X and Y are separate species because they don't interbreed except when they do interbreed.

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real life wrote:

X and Y are separate species because they don't interbreed except when they do interbreed.

Horsie poop. You apparently didn't even bother to read and understand what you quoted yourself:

'real life's' source wrote:

By the strict interpretation of the biological species concept, this would imply that brown bears and polar bears are variants of the same species

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Setanta wrote:

real life wrote:
X and Y are separate species because they don't interbreed except when they do interbreed.

Horsie poop. You apparently didn't even bother to read and understand what you quoted yourself:

'real life's' source wrote:
By the strict interpretation of the biological species concept, this would imply that brown bears and polar bears are variants of the same species

See this is science at it best. When new evidence presents itself, the theories and data change. Science is adaptable to new data as it is discovered. Scientists are able to say "Whoops, we must have been wrong about the seperate species thing with grizzlies and polar bears, instead they're distant cousins". Of course scientists will always use evidence and data to make these decisions.

Religion, not so much.

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maporsche wrote:

Religion, not so much.

Allow me to offer a slight correction:

Religion, not at all.

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Set is right; religion has no option to change their thinking based on what they learn from the bible. Even then, many theologians differ in their interpretations of it.

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Setanta wrote:

real life wrote:
X and Y are separate species because they don't interbreed except when they do interbreed.

Horsie poop. You apparently didn't even bother to read and understand what you quoted yourself:

'real life's' source wrote:
By the strict interpretation of the biological species concept, this would imply that brown bears and polar bears are variants of the same species

You apparently didn't even bother to read FM's post that it doesn't matter. They are STILL considered separate species even if they are shown to be interbreeding. He clearly considers them to be two species , regardless of the interbreeding.

farmerman wrote:

Why did a polar bear interbreed with a brown bear in the case displayed, its a mystery to me, but not an example of a definition in distress since the Polar bear and brown bears were derived from a common ancestor. The arbitrariness of this would be ,in my field, where we would merely assign a species name to Arctos and maritimus based solely upon morphology of fossils cause thats all weve got. How about if I give and say that, perhaps the evolution of the two species is undergoing some radical environmentally induced change bringing the two species into contact and limited congress

Why ? Because they don't interbreed. (or apparently not often enough. the frequency of the act seems to be the main thing. Which is why I say it is an arbitrary label.)

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real life wrote:

You apparently didn't even bother to read FM's post that it doesn't matter. They are STILL considered separate species even if they are shown to be interbreeding. He clearly considers them to be two species , regardless of the interbreeding.

You are the one with reading comprehension problems. FM has acknowledged that these might be variants of the same species--and has pointed out that another criterion in determining speciation is sexual isolation. Under ordinary climatic conditions (those which obtained when the two species developed separately), brown bears and polar bears would not be in the same range--and hence would be sexually isolated.

But you're missing another big point (no surprise there). The criterion for speciation which entails the question of interbreeding refers to successful interbreeding--i.e., does it produce a reproductively viable offspring. Horses and asses can interbreed, but they produce sterile offspring, so there is no violence done to the species distinction between them. You won't have an argument unless you can demonstrate that the brown bear-polar bear interbreeding produced a reproductively viable offspring, and not a sterile offspring.

If you could prove that that were the case, the way science works (unlike imaginary friend superstition scripture), the species distinction would be dropped--and the suggestion in the article you quoted, that they are variants of the same species, would apply. Unlike imaginary friend superstitions, science can acknowledge mistakes, and correct the record. We already know it doesn't work that way with the Bobble.

Have any evidence that the offspring of a brown bear and a polar bear will not be sterile?

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Don't tell me there's no proof for evolution

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