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Old 02-19-2007, 01:17 PM   #1
baconeatingatheistjew
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No Missing Link? Evolutionary Changes Occur Suddenly, Professor Says

Science Daily — Jeffrey H. Schwartz, University of Pittsburgh professor of anthropology in the School of Arts and Sciences, is working to debunk a major tenet of Darwinian evolution. Schwartz believes that evolutionary changes occur suddenly as opposed to the Darwinian model of evolution, which is characterized by gradual and constant change. Among other scientific observations, gaps in the fossil record could bolster Schwartz's theory because, for Schwartz, there is no "missing link."

In an examination that further challenges the Darwinian model, Schwartz and cowriter Bruno Maresca, a professor of biochemistry at the University of Salerno, Italy, examine the history and development of what the writers dub the "Molecular Assumption" (MA) in the article "Do Molecular Clocks Run at All? A Critique of Molecular Systematics," to be published in the Feb. 9 issue of Biological Theory.

The MA became a veritable scientific theory when, in 1962, biochemists Emil Zuckerkandl and Linus Pauling demonstrated species similarity through utilizing immunological activity between the blood's serum and a constructed antiserum. Upon observing the intensity of the serum and antiserum reactivity between human, gorilla, horse, chicken, and fish blood, Zuckerkandl and Pauling deduced "special relatedness"--the more intense the reaction, the more closely related the species were supposed to be.

Fish blood was most dissimilar, so it was assumed that the fish line diverged long before the other species. Human and gorilla blood were the most similar, meaning both species had the least amount of time to diverge. Ultimately, the Darwinian model of constant evolutionary change was imposed upon the static observation made by Zuckerkandl and Pauling.

To date, the scientific community has accepted the MA as a scientific truth. It is this assumption, which Schwartz is contemplating: "That always struck me as being a very odd thing--that this model of constant change was never challenged." Schwartz has his own theories regarding evolution, which are backed by recent developments in molecular biology.

Multicellular animals have large sections of genomes, the genetic material of an organism, which control their development. Schwartz argues that the structure of the genome does not keep changing, based on the presence of stress proteins, also known as heat shock proteins. These proteins are located in each cell, and their main function is to eliminate the potential for cellular error and change via maintaining normal cellular form through protein folding.

This regular cellular maintenance is what Schwartz points to regarding his refutation of constant cellular change. "The biology of the cell seems to run contrary to the model people have in their heads," says Schwartz, and he contends that if our molecules were constantly changing, it would threaten proper survival, and strange animals would be rapidly emerging all over the world. Consequentially, Schwartz argues that molecular change is brought about only by significant environmental stressors, such as rapid temperature change, severe dietary change, or even physical crowding.

If an organism's stress proteins are unable to cope with a significant change, the genomic structure can be modified. However, Schwartz notes, a mutation also can be recessive in an organism for many generations before it is displayed in its offspring. Whether or not the offspring survives is another matter. If it does in fact live, the presence of this genetically modified organism is not the product of gradual molecular change but a sudden display of the genetic mutation, which may have occurred myriad years prior.

However, it is not only the current molecular theory that intrigues Schwartz, but the failure of the scientific community to question an idea that is more than 40 years old: "The history of organ life is undemonstrable; we cannot prove a whole lot in evolutionary biology, and our findings will always be hypothesis. There is one true evolutionary history of life, and whether we will actually ever know it is not likely. Most importantly, we have to think about questioning underlying assumptions, whether we are dealing with molecules or anything else," says Schwartz.

Schwartz, who forensically reconstructed three life-size images of George Washington that are on display at Mt. Vernon, is a Fellow of the prestigious American Association for the Advancement of Science and the World Academy of Art and Science. He is the author of several books, including The Red Ape: Orang-utans & Human Origins (Westview Press, 2005) and Sudden Origins: Fossils, Genes, and the Emergence of Species (Wiley, 2000). He has spent more than 20 years contemplating the methods, theories, and philosophy of taking data and trying to interpret it for purposes of reconstructing evolutionary relationships.

*************************************

http://www.sciencedaily.com/releases...0210170623.htm

It is my limited understanding that gradual and sudden evolution can both occur. Take the cane toads of Australia and their longer legs. The idea of missing link is a creationist term. Darwin is all about common ancestry. And this Shwartz dude doesn't refute it. What am I missing?
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Old 02-19-2007, 05:06 PM   #2
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This whole subject is beautifully explained in Richard Dawkins "The Blind Watchmaker". There's a whole chapter on sudden vs gradual evolution and Richard explains in brilliantly.
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Old 02-19-2007, 06:28 PM   #3
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Quote:
Some Jewish Evilutionist wrote
The biology of the cell seems to run contrary to the model people have in their heads," says Schwartz, and he contends that if our molecules were constantly changing, it would threaten proper survival, and strange animals would be rapidly emerging all over the world.


Beaj, to answer your topic's question, I'd say because it conveys the author's point and will suck in readers. :)

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Old 02-19-2007, 08:10 PM   #4
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One of the most irrational of all the conventions of modern society is the one to the effect that religious opinions should be respected....That they should have this immunity is an outrage. There is nothing in religious ideas, as a class, to lift them above other ideas. On the contrary, they are always dubious and often quite silly.
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Old 02-19-2007, 09:30 PM   #5
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Old 02-19-2007, 10:18 PM   #6
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Even the most prestigious scientific publications (e.g. New England Journal of Medicine, Nature etc.) have some pretty sensational headlines for their articles.
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Old 02-20-2007, 03:44 AM   #7
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Yeah. This is about saltation (sudden jumps in evolution) as opposed to gradualism. Darwin is about more than common descent - he proposes a mechanism for evolution (natural selection) and argues that evolution is gradual (although it may look sudden in the fossil record because a "gradual" change in biological terms can be very rapid in geological time). He argues that evolution does not proceed by sudden leaps. There's a whole 19th century scientific argument here - gradualism versus catastrophism - that's interesting but probably irrelevant. The gradualists won and for a long time the idea of sudden changes in Earth's history was dismissed on principle, which is why the Alvarez meteorite theory was controversial when it came out.

Mendelian genetics seems to support this because most mutations are deleterious, and the chances of several mutations at once being advantageous are almost nil. So the fusion of genetics with Darwin is called the "neoDarwinian synthesis". In its standard formulation it's gradualistic and this is Dawkins' position as mentioned by GaryM.

However, it's also fairly clear that small genetic changes can create large changes in form in one step, as with the 4 legged duck, if these changes are in genes that regulate other genes in development, such as the homeobox genes, or in neotenous animals such as axolotls (and possibly humans). Some people are arguing that this could produce saltations, because there only has to be one genetic mutation for some of these steps, so the probability argument above is no longer valid. Dawkins is aware of this but argues that these changes are usually nonfunctional - for example the extra legs sometimes grown by mammals and birds don't usually work because the rest of the animal isn't built for it (the duck, for example, would probably need two pelvises as well as the extra legs).

So the prof is right - he is challenging the Darwinian model, but he's not challenging evolution as such.

edit - I'm not sure that the prof is addressing the molecular clock issue though. Molecular clocks work by looking at neutral mutations - single base mutations that do not change the amino acid that is manufactured, or mutations in DNA that does not express - and the prof's critique appears to refer to functional DNA. /edit

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Old 02-20-2007, 06:50 AM   #8
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adt wrote
it's also fairly clear that small genetic changes can create large changes in form in one step, as with the 4 legged duck
Interestingly, PZ Myers posted a pic of a 4-legged duck this week. He writes, "This is almost certainly not the result of a mutation, and it's one of my pet peeves when the media makes this wrong assumption, that every change in a newborn is the product of a genetic change. This is the result of a developmental error, not a genetic one, most likely caused by a fusion of two embryos in a single egg."

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Old 02-20-2007, 07:19 AM   #9
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If this is the case, fair dos on the duck. I assumed it was a mutation. I should have linked to the fruit flies with legs and eyes in all the wrong places instead which are definitely hox gene mutations, but the duck was cuter.

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Old 02-20-2007, 07:24 AM   #10
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cuter, and twice the swimmer of a mortal duck

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Old 02-20-2007, 08:33 AM   #11
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a different tim wrote
Yeah. This is about saltation (sudden jumps in evolution) as opposed to gradualism. Darwin is about more than common descent - he proposes a mechanism for evolution (natural selection) and argues that evolution is gradual (although it may look sudden in the fossil record because a "gradual" change in biological terms can be very rapid in geological time). He argues that evolution does not proceed by sudden leaps. There's a whole 19th century scientific argument here - gradualism versus catastrophism - that's interesting but probably irrelevant. The gradualists won and for a long time the idea of sudden changes in Earth's history was dismissed on principle, which is why the Alvarez meteorite theory was controversial when it came out.

Mendelian genetics seems to support this because most mutations are deleterious, and the chances of several mutations at once being advantageous are almost nil. So the fusion of genetics with Darwin is called the "neoDarwinian synthesis". In its standard formulation it's gradualistic and this is Dawkins' position as mentioned by GaryM.

However, it's also fairly clear that small genetic changes can create large changes in form in one step, as with the 4 legged duck, if these changes are in genes that regulate other genes in development, such as the homeobox genes, or in neotenous animals such as axolotls (and possibly humans). Some people are arguing that this could produce saltations, because there only has to be one genetic mutation for some of these steps, so the probability argument above is no longer valid. Dawkins is aware of this but argues that these changes are usually nonfunctional - for example the extra legs sometimes grown by mammals and birds don't usually work because the rest of the animal isn't built for it (the duck, for example, would probably need two pelvises as well as the extra legs).

So the prof is right - he is challenging the Darwinian model, but he's not challenging evolution as such.

edit - I'm not sure that the prof is addressing the molecular clock issue though. Molecular clocks work by looking at neutral mutations - single base mutations that do not change the amino acid that is manufactured, or mutations in DNA that does not express - and the prof's critique appears to refer to functional DNA. /edit
Is the nylon eating bacteria gradualism or catastrophism? How about the fact that within 40 years, the majority of cane toads today have longer legs than those from 40 years ago....note, the original short legged ones are still around.
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Old 02-20-2007, 09:03 AM   #12
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The nylon bug is gradualism, I think. I'd assume it's one mutation away from whatever it used to metabolise. It would count as a gradual change. The thing is, that when you get to the molecular level everything goes in short leaps because you can't get less than one base change in a DNA mutation. Gradualism argues that these small leaps are what add up to large evolutionary changes. A catastrophist or saltationist view would argue that some other mechanism is at work that can produce large changes all at once.

Hox genes kind of confuse the issue because a small molecular change (gradual) can produce a large change in form (saltation). Other small molecular changes might produce much smaller changes in form. From a DNA point of view there is no difference between these two but they would look very different in a line of animals. Bacteria confuse the issue as well because they can actually swap useful genes between species so one species might suddenly aquire useful genes from another.

Gradualism, I think, works OK for the cane toad legs but what the prof seems to be saying is that the sort of change that leads to speciation can happen in one leap. The cane toads haven't speciated and the longer legs may be part of normal variation. The standard position is that speciation is what happens when normal variation gets so great that parts of the species can't interbreed, and - I think- the prof is saying different.

I have to admit it's a bit hard to tell from the precis. The title of the paper suggests that he's arguing that the molecular clocks we use to construct animal "family trees" don't work in the way we think they do, but the precis is about something entirely different.

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Old 02-20-2007, 09:34 AM   #13
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Thanks Tim. I left a request at Pharyngula's blog to put this in layman's term. It is right up his alley.
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Old 02-20-2007, 03:10 PM   #14
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Just a quick brainstorm brought to my attention that punctuated equilibrium and gradualism can both occur. The main factor being the environment. If the environment changes requiring individuals to posses a certain trait, those without the trait will quickly die and those with will find their genes rapidly spreading through the population. Since the environment is always changing evolution will always be occurring, be it gradual or in quick spurts. But hey, that's based on no evidence - just a hypothesis I suppose. :P
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Old 02-20-2007, 03:33 PM   #15
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I like this theory too:

The Red Queen's Hypothesis, Red Queen, "Red Queen's race" or "Red Queen Effect" is an evolutionary hypothesis to explain two different phenomena: the advantage of sex at the level of individuals, and the constant evolutionary arms race between competing species. In the first (microevolutionary) version, by making every individual an experiment when mixing mother's and father's genes, sex may allow a species to adapt quickly just to hold onto the ecological niche that it already has in the ecosystem. In the second (macroevolutionary) version, the probability of extinction for groups (usually families) of organisms is hypothesized to be constant within the group and random among groups.
http://en.wikipedia.org/wiki/Red_Queen
I got it from a Who Wants To be a Millionaire Question. I figured out the right answer, because I remember Alice Through a Lookinglass...but I had no idea that it was an evolution theory until I saw the question on the show and looked it up.
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