Posted on 01/26/2006 11:47:13 AM PST by PatrickHenry
Jeffrey H. Schwartz's Sudden Origins closed Darwin's gaps; cell biology explains how.
An article by University of Pittsburgh Professor of Anthropology Jeffrey H. Schwartz and University of Salerno Professor of Biochemistry Bruno Maresca, to be published Jan. 30 in the New Anatomist journal, shows that the emerging understanding of cell structure lends strong support to Schwartz's theory of evolution, originally explained in his seminal work, Sudden Origins: Fossils, Genes, and the Emergence of Species (John Wiley & Sons, 2000).
In that book, Schwartz hearkens back to earlier theories that suggest that the Darwinian model of evolution as continual and gradual adaptation to the environment glosses over gaps in the fossil record by assuming the intervening fossils simply have not been found yet. Rather, Schwartz argues, they have not been found because they don't exist, since evolution is not necessarily gradual but often sudden, dramatic expressions of change that began on the cellular level because of radical environmental stressors-like extreme heat, cold, or crowding-years earlier.
Determining the mechanism that causes those delayed expressions of change is Schwartz's major contribution to the evolution of the theory of evolution. The mechanism, the authors explain, is this: Environmental upheaval causes genes to mutate, and those altered genes remain in a recessive state, spreading silently through the population until offspring appear with two copies of the new mutation and change suddenly, seemingly appearing out of thin air. Those changes may be significant and beneficial (like teeth or limbs) or, more likely, kill the organism.
Why does it take an environmental drama to cause mutations? Why don't cells subtly and constantly change in small ways over time, as Darwin suggests?
Cell biologists know the answer: Cells don't like to change and don't do so easily. As Schwartz and Maresca explain: Cells in their ordinary states have suites of molecules- various kinds of proteins-whose jobs are to eliminate error that might get introduced and derail the functioning of their cell. For instance, some proteins work to keep the cell membrane intact. Other proteins act as chaperones, bringing molecules to their proper locations in the cell, and so on. In short, with that kind of protection from change, it is very difficult for mutations, of whatever kind, to gain a foothold. But extreme stress pushes cells beyond their capacity to produce protective proteins, and then mutation can occur.
This revelation has enormous implications for the notion that organisms routinely change to adapt to the environment. Actually, Schwartz argues, it is the environment that knocks them off their equilibrium and as likely ultimately kills them as changes them. And so they are being rocked by the environment, not adapting to it.
The article's conclusions also have important implications for the notion of “fixing” the environment to protect endangered species. While it is indeed the environment causing the mutation, the resulting organism is in an altogether different environment by the time the novelty finally escapes its recessive state and expresses itself.
“You just can't do a quick fix on the environment to prevent extinction because the cause of the mutation occurred some time in the past, and you don't know what the cause of the stress was at that time,” Schwartz said.
“This new understanding of how organisms change provides us with an opportunity to forestall the damage we might cause by unthinking disruption of the environment,” added Schwartz. “The Sudden Origins theory, buttressed by modern cell biology, underscores the need to preserve the environment-not only to enhance life today, but to protect life generations from now.”
Schwartz, with his colleague Ian Tattersall, curator of anthropology at the American Museum of Natural History in New York, also authored the four-volume The Human Fossil Record (Wiley-Liss, 2002-05). Together, the volumes represent the first study of the entire human fossil record. Volume 1 was recognized by the Association of American Publishers with its Professional Scholarly Publishing Award. In 1987, Schwartz's The Red Ape: Orang-utans and Human Origin (Houghton Mifflin Company) was met with critical acclaim.
Schwartz, who also is a Pitt professor of the history and philosophy of science, was named a fellow in Pitt's Center for the Philosophy of Science and a fellow of the prestigious World Academy of Arts and Science.
The journal, The New Anatomist, is an invitation-only supplement to the Anatomical Record.
Environmental stress isn't the only factor in natural selection. Sexual selection is well-recognized. Environmental stress is one of the causes of mutation, but not the only cause.
And the great hypocrisy of promoting environmental stasis in the name of maximizing the gene pool and species diversity.
Because, like *all* inheritable mutations, they first occurred *in* reproductive cells. This is such basic biology that the article didn't bother to spell it out -- it would be like an article on a new airplane design not bothering to mention that aircraft need an atmosphere to fly and don't work in a vacuum.
Nothing in the article suggests the strange scenario you described, involving all the cells in a body mutating simultaneously. That such mutations must take place in germ cell lines is a "given".
If I am missing something, please, explain it to me.
See above.
P.S. Unlike you, I have never read creationist literature.
Then it's odd that your argument is a direct repetition of one of their standard canards. If you haven't read creationist sources, you've picked up their arguments indirectly.
This is pure logical analysis and evolution has never added up in my book.
If it were "pure logical analysis", it would not contain such elementary fallacies. For a description of how new mutations enter the population and eventually lead to speciation without there ever being a point where an individual has a problem mating with the members of the population to which he/she belongs, see this.
You might also try this. Not as authoritative as Ichneumon, but it's readable.
How can you claim to have anything of value to add to these discussions if, after all this time, you're *still* unclear on the distinction between the fact of evolution and the theories about how it proceeds in specific instances?
Hint: Evolution is slow in some instances, not so slow in others, depending on the circumstances. This article addresses some particular types of circumstances which affect the tempo and mode of evolutionary change. There's no contradiction with prior research.
This article is nothing more than wild speculation
It's based on a great deal of work, which puts it far beyond "wild speculation". It may or may not turn out to hold water when further investigated, but your desperate creationist habit of trying to hand-wave away all research and considered conclusions based on a thorough examination of the real-world evidence as "nothing more than wild speculation" just makes you guys look goofy. Sorry, but "wild speculation" is what *creationists* do when they make up things based on their total ignorance of actual biology and then mistake their presumptions for established facts. For example, like *you* did here when you made wildly incorrect assumptions about how biology "must" work... Now *that* was "wild speculation"!
presented in an attempt to overcome the obvious weaknesses of the many theories of evolution speculated about by others.
And what exactly would those "obvious weaknesses" be? Be specific, let's see if you have any clue what you're talking about. Be sure not to repeat any of these other long debunked creationist canards about the "weaknesses" in evolutionary biology.
If anything, this article casts further doubt on evolution.
It doesn't, but your post casts further doubt on your ability to keep up with technical discussions.
I like the idea of mutations remaining recessive over time until drift makes them co-recessive at which point the trait gets expressed; but I don't think a saltation event even in this scenario would be likely to have a high survival index. I suspect this is more like what happens with segmentation where a simple mutation on a HOX gene can confuse enzyme production resulting in multiple segments. Or multiple wings for that matter.
Interesting when viewed together with gene duplication followed by a partial-gene mutation on the regulatory gene.
BTW, my mind is a toaster right now, so don't blame me if'n I'm incoherent.
True, but randomly occuring mutations (random with respect to the selection function) will yield a system that moves with jumps of all sizes.
There is also the genotype-phenotype relationship. It may take several small changes in genotype to make any change at all in phenotype. Likewise, some small genotypical changes may result in large phenotypical change.
I think that "random" here would be shorthand for "mutation not necessarily related to selection."
Dear Lady, don't get the idea this concept is saying a large scale saltational event is occurring, it is more like a slow 'partially or totally hidden' bit of evolution occurring before its relatively sudden expression.
If this mechanism, or process if you prefer, is the active process in a population... oh, evolving legs let's say, the legs would not end up being full blown legs like yours or mine, but simply a larger scale 'change' to existing features, such as fins, than we would normally expect, or it could result in 'leg buds' where an existing skeletal feature is replicated in another place or modified in place - such as an additional segment of bone is added. For true legs to result from these 'buds' it would still take hundreds of generations. Remember what geological time really means.
Neither do farmers.
Don't ask me, I don't know...
2x2=4 4x4=8 8x8=16 16x16=....
Well I only 'stinct' a little.
Interesting point here. It is environmental stress which interferes with the genetic "proofreading" mechanism and allows the effective mutation rate to climb in times of deep crisis.
The more I think about this, the less impressed I am by the randomness of mutations. It seems that mutations are very common. I've read that each human conceived may have 100 mutations (of various types, most irrelevant). Given that kind of genetic background, we could almost consider mutations as a given, much as we assume that the origin of life is a given. By that I mean that it almost doesn't matter where life (or mutations) come from. They're here! That said, natural selection is the whole game. And that's not random. But I suppose mine is a fringe view. No big deal.
Is there some new definition of speculation for which I am unaware?
Did you have a relevant comment, or are you just reduced to non sequitur questions?
True, but for several reasons mutations of large "size" (i.e., a large effect on the phenotype) will be far more likely to be harmful (as well as immediately fatal) than small changes.
In fact, for a continuous fitness function it can be shown mathematically that as the size of the change approaches zero (i.e., for smaller and smaller changes), the odds of a mutation being beneficial (albeit to a correspondingly small degree) approach 50%.
Dawkins discusses this point in a few of his books (including "The Blind Watchmaker" and "The Ancestor's Tale"), giving credit to statistician and biologist R. A. Fisher for having made the point originally. A direct consequence of this observation is that evolution is far more likely to proceed via accumulated small changes than by mutational "leaps" of larger effect.
Would all of the particular species acquire legs? What if a particular species were separated by great distances? If they were in close proximity to one another, would genetic drift affect all of them at the same time?
They say that when something seems laughable or nonsense it might indicate a misunderstanding.
Agreed. Sudden Origins does not contradict Intelligent Design it works Hand in Hand with it.
Gradual or rapid, depending upon the nature and severity of the enivronmental pressure, it's still solidly evolution.
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