evolution

[Bartman]

I was thinking earlier today about evolution. Specifically if we could force evolution. What i mean by this is, for example, if you bred silkworms (i believe they come from warm climates). If you bred them and lets say kept the enclosure or incubation at the norm temps their used to. Then lets say over 60 years you droped the temp slightly. Would they learn to adapt over 60 or so year?

just a thought..maybe someone could educate me :)

[northernsnake]

I think you are thinking to much! lol thats what winter will do to you! but now you got me thinking to Hmmmmmmmm 60 years why so long how many generations would that be. I dont know.

[~Suntiger~]

I think in a species that breeds like crazy, such as fruit flies, you would be able to notice changes/mutations rather quickly in comparison to other types of creatures. By manipulating the environment I think it could be possible, depending on the species.

[northernsnake]

Originally posted by ~Suntiger~
I think in a species that breeds like crazy, such as fruit flies, you would be able to notice changes/mutations rather quickly in comparison to other types of creatures. By manipulating the environment I think it could be possible, depending on the species. You know I still have thows dam frut flies in my house

[chas*e]

The more basic the genome the faster mutations can be recognized.....if you expose some species of fruit flys to radiation(ultra and above) there are genetic changes that occur in the population...A good example is Bacteria or Viruses,whole populations can be genetically different from their original in 1 day, if under stress....The key is Stress....populations evolve due to their enviormental stimuli(stress)......Your question is possible but over many generations

[Bartman]

I think you are thinking to much! lol thats what winter will do to you!
sheesh i know im sooo bored!!!!! haha :D

You know I still have thows dam frut flies in my house
try it! :)

[Crotalus75]

"Specifically if we could force evolution."


Yes. Humans can cause what is called "artificial selection" also called BREEDING. This is a human guided selection similair to Darwinian natural selection except that humans select the traits that they want to see in their animals instead of the environment selecting the most fit specimens. We have been doing this since the dawn of civilization. Domestic plants, dogs, cats and horses are a perfect example. Remember evolution is defined as a change in the allele (gene) frequency within a population over a period of time. If all of the breeds of domestic dogs were released into one breeding pool (thus relieving human selection pressures) these animals would probably all eventually revert to a single "wild dog" like appearance similair to what is seen in many urban areas of third world countries.

[golfsk8er]

I think that Like most things it would climatise (sp) it self through generations. Just my thinking!
matt

[Zoe]

Also, it should be noted that there is a difference between ADAPTION and EVOLVING. I can only explain it in french, so I'll give you examples to understand:
Say there is a population of light grey butterflies, and they live on trunks of trees that are the same colour. Therefore, they are camouflaged and survive better. Now let's say that there are a few darker individuals of the same species - their numbers stay low, because they are easily spotted on the light trunks and eaten.
Now, a certain factor (for example polution) gets into the environment and the trunks turns dark brown over a few months. The pale individuals will diminish in number because they can no longer blend with the trunks, and the darker butterflies will reproduce and many of their offspring will survive because they are camouflaged. There are, of course, still a few light ones left, but not nearly as many.
Just to further the example, let's say that years later the trunks turn pale again (because the polution was eliminated). Most of the dark ones would die and the pale ones would again take over.

THAT is evolution.

Now, let's say that when the trunks turned dark, the butterflies developped more melanin and the same individual that used to be light was now dark, to blend with the trunks - that is Adaptation.



If these silkworms grew accustomed to the cold, that would be adaptation, even if it happened over a few generations. If certain individuals had, say, a mutation that lessened the effects that the cold had on them, and if the temps went down they survived and 'took over' the population, that would evolution.

I hope that made sense, I know it isn't completely relevant to the idea but I just thought I would mention it.

Zoe

[Crotalus75]

Adaptations are produced through evolution by process of selection. But, I think that what you are saying is that if the original individuals were able to "adapt" without "evolving" and passing the surviving resistance genes through generations then that would simply be adaptation within an individual in the present generation to a given situation. I think I may see what you are getting at....But this type of "adaptation" would also have to have been something that would have been inherited thus it is still evolution at work (hypothetically speaking).

Some of these hypothetical silk worms would survive the temp drop and some would not. The ones that survived had to have by chance recieved genes that just so happened to give them a slight advantage and render them more resistant to the lower temperature.

[Zoe]

Adaptations are produced through evolution
Actually, it's the opposite. Following enough adaptations, there will be some form of evolution, be it macro (larger scale, occuring over geologic time and resulting in a new taxonomy) or micro (smaller... such as a new subspecies).
Adaption isn't produced through selection, either. It's simply a trait that asserts itself (or disapears) in a single generation or over a few, following an environmental change of some sort. In one respect, it is selection, because the weaker individuals - those incapable of adaption - will die. But it's not selection in the same sense as the natural selection that occurs during evolution.

If these silkworms were to evolve, there would have to be formation of a new species or subspecies (or the one species might separate into two). Otherwise it's just adaption.

I think that evolution is a term thrown around too easily, sometimes where it isn't supposed to be placed. Like here:
But this type of "adaptation" would also have to have been something that would have been inherited thus it is still evolution at work
I would think it would be the opposite (I know, I'm splitting hairs ;)) it's more like the eventual evolution that would come of a large-scale adaption would be adaptation at work.

But the question remains the same - will silkworms be able to deal with the change in temperature. IMO, probably not. If it happened over a few centuries maybe, but I don't think 60 years will produce enough generations to adapt to such a severe change in temperature. Other, more versatile species, perhaps, but silkworms are really stuck in their niche and I don't see them exitting it (alive) anytime soon! :)

Zoe

[CDN-Cresties]

Originally posted by Zoe
But it's not selection in the same sense as the natural selection that occurs during evolution.

Zoe,

Are you saying that natural selection causes evolution????


-Steve-

[Crotalus75]

I hear what your saying, but the definition of evolution is quite simply "a change in allele frequency within a population over a period of time". Adaptation (whether it be a light sensing structure such as an eye or a degree of resistance to fluctuation in temperature or some other type of advantage for the organism) is a result of certain genes being selected for or against by the environment.

It sound like you are speaking of speciation (the evolution of a biological species).

Splitting hairs is what science is all about! :)

[Zoe]

Yes... natural selection is evolution (it can also be adaptation). According to Darwin, natural selection is the process of animals more suited to their environments surviving and those less suited or less capable of adapting and evolving dying off.

This is a pretty good link for info on it: http://www.biology-online.org/2/10_natural_selection.htm

[Zoe]

Depending on where you look, the definition of evolution can be significally more complicated: "Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species."

I suppose that in the end, evolution can be classified as a large, era-scaling adaptation.

Zoe

[CDN-Cresties]

Hmm were to start.... Ok if natural selection causes evolution, then that must mean that the process of evolution is slow and gradual. That being so, why do we not see these gradual changes in the fossil record? Even Darwin saw this problem but he just gave the lame excuse that the fossil record is terribly incomplete. With Natural Selection being the cause of evolutionary change, that would mean that speciation would occur thorought this slow process and therefore some form of transitional stage between species would exist in the fossil record but that is not the case.

Another problem with Natural Selection causing evolutionary change is how does it account for complex structures such as the eye and wing. What would be the first use of the wing, it wouldnt be flying because that wouldnt be gradual. Darwin recognized these problems again, alonog with others. He writes about them in his book Origin of Species, I think the chapter is called "Problems with the theory".

There is so much to say about evolution and no doubt that this thread has gone astray because of me :) Look at some work by Stephan J Gould. If you like I just wrote a essay about evolution, PM me and then I can email it to you if you like or anyone else. Then if you have anymore questions I can direct you to some good readings. :D
Thanks

-Steve-

[Crotalus75]

Evolution is simply as you stated "a change in the genetic composition (allele frequency) of a population during successive generations (over a period of time)" and yes it is due to natural selection. But in any given situation evolution may or may not result in a new species. The formation of a new species through the process of evolution is SPECIATION.

[CDN-Cresties]

Evolution is NOT due to Natural Selection. Read some Stephan J Gould, he states that Punctuated Equilibrium is the mechanism for evolutionary change. Ill post some good books and chapters to read from his work, I just have to find my course kit.
Thanks :)

-Steve-

[Crotalus75]

"therefore some form of transitional stage between species would exist in the fossil record but that is not the case"

One word.......Archaeopteryx!

I think that this is a fantastic conversation. A little healthy debate is good for the mind. We just need to be careful how we word the rest of this conversation, because the moderators will shut this thread down (I'v seen it happen several times with this line of topic). I think this is fantastic and relevant stuff so I hope that we can keep this thread going no matter where this topic may lead. :)

[CDN-Cresties]

Yes i agree, this topic is awesome!!!

Crotalus can you please explain to me the term Archaeopteryx? I never heard this term before.
Thanks:)

-Steve-

[Crotalus75]

Archaeopteryx is a bird like reptile that is considered to be a defining transitional fossil between birds and reptiles. their is also another that is very famous. It was a bird like reptile that had four wings. The name escapes me at the moment though.

[CDN-Cresties]

OK here are those readings I mentioned. All works are by Gould.

"Ever Since Darwin" read chapter 7 "The Child as Man's Real father"

"The Flamingo's Smile" Read the chapter called "The Cosmic Dance of Siva"

"The Panda's Thumb" Read the chapter called "Episodic evolutionary Change" and " Return of the Hopeful Monster"

Also read Darwins book, "Origin of the Species" the chapter called "Difficulties within the theory" (Or something to that effect)

These readings arent very long but they are very interesting. I seriously recommend reading them.:)

-Steve-

[CDN-Cresties]

Very cool, ill read up on Archaeopteryx and ill mention it to my prof.

-Steve-

[Crotalus75]

Thanks for the info. I recommend "The Beak of the Finch" Jonathan Weiner and "Darwins Black Box" by Michael J. Behe. I am about 100 pages into both of these books at the moment. I like "the Beak of the Finch" and I agree with the findings that are chronicled in this book, BUT I wholeheartedly DISAGREE with some of the more grandios inferences that are made. I don't think that their evidence reaches to the cosmic proportions that the tone seems to imply. You'll see what I mean if you read it.

[CDN-Cresties]

Thanks, Ill try to check out those books as soon as I can.

-Steve-

[Zoe]

http://www.paleontology.uni-bonn.de/institut/museum/images/archaeopteryx.jpg
Fossil of archaepoteryx

http://www.damisela.com/zoo/photo/cq4/archaeopteryx.jpg Artists rendition


Ok if natural selection causes evolution, then that must mean that the process of evolution is slow and gradual.
Evolution IS slow and gradual. Adaptation isn't, but evolution happens over geological eras ; it takes a long time for one species to evolve into another - an example that is still in existance is the mudskipper. Now this little creature is not quite a fish, not quite an amphibian, but a transitional species between the two (guess he's a little late huh ;))
There have been a number of transitional fossils (homo and otherwise) found but it must be understood that the fossilization of a carcass is a very rare occurance. Think of all the species must have existed! We'd be overrun by them if most of them didn't decompose.

With Natural Selection being the cause of evolutionary change, that would mean that speciation would occur thorought this slow process and therefore some form of transitional stage between species would exist in the fossil record but that is not the case.
I hate to reiterate, but that IS the case. Look at cro-magnon, neanderthal (although, yes, neanderthal never turned into homo sapean). All of the early Equus fossils - between horse and zebra, for example. Or how about the giraffes with short necks? that gradually got longer?

Evolution is a gradual process - we've yet to see one species become another (in recorded history) but the evidence is there - the slow changes that will eventually (perhaps) result in new species or subspecies ; transitional fossils and animals.


And yeah, I think we can keep our cool ;)

Zoe

[Crotalus75]

I have heard some theories that stated that it is thougtht that Homo sapiens neanderthalis was able to interbreed with Homo sapiens sapiens and was actually assimilated into the gene pool.

[Jeff Hathaway]

Great topic! Nice to see some intellectual debating... Here's some thoughts:

Evolution doesn't cause adaptation. Adaptation happens randomly (via mutations and genetic variability due to crossover if I recall correctly), and the environment selects for or against these adaptations through various pressures (i.e. climate). 'Successful' adaptations will increase in proportion/allele frequency, and therefore the species has evolved. A couple of unusual mutants does not constitute evolution (though it may be in the process of occurring), but when those mutants have taken over, it has definitely occurred. At what point it could be said to have taken place is pretty grey, as are lots of things in this area. Nature doesn't like to follow human definitions and categories:-)

Evolution is generally considered to happen gradually, and over long time scales. There are some examples, however, of things which seem to have evolved very rapidly, with sudden jumps instead of baby steps. Keep in mind, though, that on an evolutionary scale, 'rapid' is still a very long time.

I don't believe that the 'basicness' of an organism's genome has anything to do with it's rate of evolution. Bacteria, virii, etc. evolve quickly because they have incredibly short generation times. Therefore, mutations which are selected for can reach large proportions of the population very quickly, at least with our human sense of time.

Mudskippers are fish:-) They just behave like amphibians...

Jeff Hathaway
Sciensational Sssnakes!!

[CDN-Cresties]

Im am not doubting that evolution is a long and slow process but the theory of Punctuated Equilibrium is a much better theory then Natural Selection to explain evolutionary change. I'll breifly tell you what it is.

Punctuated Equilibrium - Species do in fact tend to remain stable for long periods of time and then to change relatively abruptly-or rather, to be replaced by newer and more successful forms.

These "Punctuations" can be caused by mainly three things:
regulatory gene change, neoteny, and the Cometary Impact theory.

READ GOULD for more info!!!!:D

Crotalus75, I have also heard those same theories that state homo sapiens neanderthalis were able to interbreed with Homo sapiens sapiens.

-Steve-

:) Later on ill just post my essay on the thread, it should give you a good idea of what Punctuated Equilibium is all about.

[ChokeOnSmoke]

You guys need a glossary for this thread.
Interesting from what I can understand though keep it going.

[Bartman]

WOW..i just learned a lot more then i thought :)
Keep it comming, this is very interesting

[Crotalus75]

"Evolution doesn't cause adaptation. Adaptation happens randomly (via mutations and genetic variability due to crossover if I recall correctly),"

But natural selection for or against these mutations is the process of evolution. Ultimately evolutionary forces are what gives rise to all new adaptations. Migration is a source of new alleles in a population, but mutation and recombination (during prophase 1 of meiosis) are the cause of ALL completely new alleles.

[Zoe]

Ultimately evolution is the force that gives rise to all new adaptations.
Perhaps I'm not understanding how you're saying things, but I still think you have the two terms backwards. Adaptations often eventually lead to evolution - not the other way around.

Im am not doubting that evolution is a long and slow process
Isn't that what you are saying, though? That species stay the same then very rapidly, over a few generations, become a new species? If that's what you're saying, then IYO evolution is rapid.

Species do in fact tend to remain stable for long periods of time and then to change relatively abruptly-or rather, to be replaced by newer and more successful forms.
See, I just don't see the logic in that. Obviously, the period of time during one species is actually becoming another is shorter, but I don't see how one species could remain exactly the same over geological eras, despite climate changes, natural disasters, etc etc etc and then suddenly be replaced by an entirely differnent species.
For example, punctuated equilibrium can't be solely responsible for the Compsognathus(a little dino that archaeopteryx is believed to have evolved from)-Archaeopteryx transition. Now, archaeopteryx lived during a relatively short period of time during the upper jurassic era - it obviously wasn't "meant" to survive as a species but "meant" to become another. If punctuated equilibrium were true, archaeopteryx never would have existed and Compsognathus would have been immediately replaced by birds. Or even, Archaeopteryx would have become a bird - but it didn't. There were several intermediate steps between Archaeopteryx and birds.

Zoe

[Bartman]

Im not as educated as you guys :) but from reading all your posts what i think im understanding, on one side of things, is that if for example you have a leopard gecko. Over lets say 10000 years the ground on where they live was gradually becoming to harsh for them to live on..would they, over 10000+ years, begin becomming aboreal? Or adapt some new way to survive in the environment that slowly became un-livable?

[Zoe]

They could, or they might simply die. It could go either way depending on what the change is and the mutations the leos are capable of.

Zoe

[Bartman]

How is determined what mutations they are capable of? Is it just a 50/50 chance they die or not?
Thats the only thing i dont understand..is how they decide that they can or cannot mutate

[CDN-Cresties]

Zoe please explain how something as complex as the the eye be created through Natural selection?

Sorry let me clarify when I say the word rapid, I dont mean over a couple of generations, i meant to say rapid in terms of geological time.
Thanks

-Steve-

[CDN-Cresties]

Here is my essay that I wrote. Its a bit long but hopefully it will add to the thread :)


Comparing Natural Selection and Punctuated Equilibrium
The theory of evolution is one of the best-known scientific theories around. “The subject is fascinating because it attempts to answer one of the most basic human questions: Where did life, and human beings, come from? The theory of evolution proposes that life and humans arose through a natural process” (Howstuffworks). In 1959, Charles Darwin’s Origin of Species revolutionized evolutionary thought (Bowler 141). Within Origin of Species, Darwin provides the mechanism through which evolutionary change can occur-Natural Selection. Natural Selection is, “Individuals with qualities that made them better adjusted to their environments or gave them higher fitness. Because more individuals are born than survive to breed, constant winnowing of the less fit- a natural selection- should occur, leading to a population that is well adapted to the environment it inhabits. When environmental conditions change, populations require new properties to maintain their fitness. Either the survival of a sufficient number of individuals with suitable traits leads to an eventual adaptation of the population as a whole, or the population becomes extinct” (Funk & Wagnells 20). However, this essay does not only plan to discuss only Darwin’s theory of Natural Selection, it plans to compare it to another famous mechanism for evolutionary change, Stephan J Gould’s Punctuated Equilibrium. In 1972, Gould and his colleague, Niles Eldredge, proposed this idea of Punctuated change. According to this theory, “Species do in fact tend to remain stable for long periods of time and then to change relatively abruptly-or rather, to be replaced by newer and more successful forms. These sudden changes are the ‘punctuations’ in the state of equilibrium that give this concept its name” (Funk & Wagnells 24). Both theories were very influential, however they differ in the way they produce evolutionary change in how they explain the fossil record, and in the problems associated with the theories.
The theories of Natural Selection and Punctuated Equilibrium differ greatly in terms of the mode in which evolutionary change is produced. Darwin’s Natural Selection requires four fundamental aspects, V.O.S.S. (Nichols Oct 1, 2003). The first of these is Variation which, according to Darwin, is a precondition for evolutionary change. This is an empirical observation that illustrates biological individuality; all animal populations have differences of heredity and variation in the species. Without this variation, evolutionary change would not occur according to the theory of Natural Selection. The second letter of the V.O.S.S. formula is Offspring of Offspring. This states that in every generation, more offspring are born then will ever survive. This point will be drawn upon later on in the essay in terms of external influences on the theory. The third letter in the formula is Struggle for Existence. This is the result of V+O, or in other words, competition within the species. If most potential life does not survive, it creates enormous pressure to compete for the available resources. Variation within the species plays a role in sorting out the survivors who will go on to breed from those who do not survive, resulting in the genetic difference being lost. The final part of the formula is Selection. Slow gradual change takes place in an animal population if the environment is stable. Genetic traits that allow animals to survive are conservative during this time. If the environment changes in significant ways, those individuals who deviate from the norm offer a solution for survival. (Nichols Oct 1, 2003) It is also worth mentioning that, “What natural selection cannot do, is to modify the structure of one species, without giving it any advantage” (Darwin 51). Now that the mechanism for evolution under natural selection is clear, Gould’s mechanism for evolutionary change under Punctuated Equilibrium will be discussed.
According to the theory of Punctuated Equilibrium, species tend to stay the same until some “punctuation” occurs (Funk & Wagnells 24). Gould suggests that there are three different things that can cause this “punctuation,” they are: regulatory gene change, neoteny, and the Cometary Impact theory. Gould draws upon Richard Goldschmidt’s “Synthetic Theory of Evolution.” In Gould’s essay, “Return of the Hopeful Monster,” from his book “The Panda’s Thumb,” he states that, “Goldschmidt specifically invokes rate genes as a potential maker of hopeful monsters: ‘ This basis is furnished by the existence of mutants producing monstrosities of the required type and the knowledge of embryonic determination, which permits a small rate change in early embryonic processes to produce a large effect embodying considerable parts of the organism’” (Gould 192). Gould goes on further to state that, “If we do not invoke discontinuous change by small alteration in rates of development, I do not see how most major evolutionary transitions can be accomplished at all” (Gould 192). This regulatory gene change leads into the second manner in which punctuated change can occur, neoteny. In Gould’s essay, “The Child as Man’s Real Father” from his book “Ever Since Darwin” Gould states his belief that neoteny can lead to evolutionary change; “But since neoteny and ******** development are generally linked, retardation does provide a mechanism for the easy retention of any juvenile feature that suits the adult life style of descendants. In fact, juvenile features are a storehouse of potential adaptations for descendants, and they can be utilized easily if development is strongly ******** in time (Gould 68). This point was made more clearly in Professor Nichols November 5, 2003 lecture. According to this lecture, new species evolve because they retain and re-shuffle the juvenile characteristics of their ancestors. The regulatory genes represent a pattern of growth, which leads to an adult appearance in the species; the regulatory genes turn on and off at particular times. This process is most active during the maturation process. A final, and most drastic explanation for punctuated evolutionary change put forth by Gould is the Cometary Impact theory. In Gould’s essay, “ The Cosmic Dance of Siva” from the book, “The Flamingo’s Smile,” he states his belief in mass extinction as a cause of evolutionary change. The idea is that materials have collided with Earth and led to mass extinctions. Gould does have some compelling evidence for this view. First of all, “High levels of iridium in rocks at the Cretaceous Tertiary boundary provided the first solid evidence for coincidence between extraterrestrial impact and time of extinction…Iridium in surface rocks arrives largely from extraterrestrial sources-asteroids, meteorites, and comets” (Gould 440-441). Another impressive fact stated in the essay mentioned is that, “David Raup and Jack Sepkoski, working from extensive compilations of the life and death times for fossil families, found a 26-million-year periodicity in extinctions during the past 225 million years” (Gould 441) This coincides with what, “Walter Alvarez and Richard A. Muller find of periodicity, similar in timing and spacing of 28.4 million year to the Raup-Sepkoski extinction peaks, for well-dated impact craters on Earth with diameters in excess of ten kilometers” (Gould 441). To conclude this point Gould states, “If mass extinctions are so frequent, so profound in their effects, and caused fundamentally by an extraterrestrial agency so catastrophic in impact and so utterly beyond the power of organisms to anticipate, then life’s history either has an irreducible randomness or operates by new and undiscovered rules for perturbations, not by laws that regulate predictable competition during normal times” (Gould 446). The ideas proposed by Gould clearly operate in a world of stasis and are abruptly punctuated causing macro evolutionary change. It is easy to see the major difference between Natural Selection and Punctuated Equilibrium; Natural Selection is a gradual and continuous process while Punctuated Equilibrium is discontinuous.
Since the two theories are opposite to one another, can the fossil record provide any information as to which one is more accurate? First, let’s start with Natural Selection. Charles Darwin recognized the problem with this own theory in terms of the fossil record. He states, “Why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms?” (Darwin 75). The only answer Darwin can give is this, “I will here only state that I believe the answer mainly lies in the record being incomparably less perfect than is generally supposed; the imperfection of the record being chiefly due to organic beings not inhabiting profound depths of the sea, and to their remains being embedded and preserved to a future age only in masses of sediment sufficiently thick and extensive to withstand an enormous amount of future degradation; and such fossiliferous masses can be accumulated only where much sediment is deposited on the shallow bed of the sea, whilst it slowly subsides. These contingencies will concur only rarely, and after enormously long intervals. Whilst the bed of the sea is stationary or is rising, or when very little sediment is being deposited, there will be blanks in our geological history” (Darwin 76). The evidence for Punctuated Equilibrium in the fossil record is diametrically opposed of Natural Selection. Gould states his view on this topic in his essay “Episodic Evolutionary Change” from his book, “The Panda’s Thumb, “The history of most fossil species includes two features particularly inconsistent with gradualism: 1. Stasis. Most species exhibit no directional change during their tenure on earth. They appear in the fossil record looking much the same, as when they disappear, morphological change is usually limited and directionless. 2. Sudden appearance. In any local area, a species does not arise gradually by the steady transformation of its ancestors; it appears all at once and ‘fully formed’” (Gould 182). It is difficult to state that one theory has an edge over the other; it all depends on how the fossil evidence is interpreted.
With any theory, there comes criticism and problems. There are many problems and criticisms for Natural Selection. Once again Darwin acknowledges his theory’s flaw, “ Can we believe that natural selection could produce, on the one hand…on the other hand, organs of such wonderful structure, as the eye, of which we hardly as yet fully understand the inimitable perfection?” (Darwin 75). Darwin tries his best to explain how the eye came about but even he has his doubts, this is revealed when he says, “To suppose that the eye, with all it inimitable contrivances for adjusting the focus to different distances…could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree” (Darwin 85). A criticism that follows Natural Selection is that it, “Bears an uncanny resemblance to the political economic theory of early capitalism as developed by the Scottish economics” (Lewontin 10). During the November 26, 2003 lecture, Professor Nichols mentioned Gould’s criticism, which wed his science with his political beliefs. Gould feared that a nuclear war would lead to mass extinction resembling that of the Cometary Impact theory. This could have been a reason why Gould took to the Cometary Impact theory; he went against his own word that one cannot draw any moral/political lessons from nature.
In light of what has been discussed, it is evident that both theories have left a major imprint on the science of Evolution. Gould is often said to be the greatest evolutionary thinker since Darwin. Both men have contributed a great deal, and their ideas will linger with us for a long time if not forever. Darwin’s theory of Natural Selection is still talked about today. In fact Gould insists that Natural Selection is still involved in the process of evolution, just not to the point where it is causing major evolutionary change (Gould 188).

WorK Cited
Bowler, Peter J. Evolution, The History of an Idea. Los Angeles: University of
California Press, 2003.
Darwin, Charles. The Origin of Species. New York: W.W Norton and Company, 1975.
Funk & Wagnells. “Evolution.” New Encyclopedia. 1985ed.
Gould, Stephan J. Dinosaur in a Haystack. New York: Harmony Books, 1995.
Gould, Stephan J. Eight Little Piggies. New York: W.W. Norton and Company, 1993.
Gould, Stephan J. Ever Since Darwin. New York: W.W. Norton and Company, 1977.
Gould, Stephan J. The Flamingo’s Smile. New York: W.W. Norton and Company, 1985.
Gould, Stephan J. Full House. New York: Harmony Books, 1996.
Gould, Stephan J. The Episodic Nature of Evolutionary Change. New York:W.W. Norton
and Company, 1980.
Gould Stephan J. Return of the Hopeful Monster. New York: W.W. Norton and
Company, 1980.
Howstuffworks, http://science.howstuffworks.com/evolution!.htm
Lewontin, R. C. Biology as Ideology. Toronto: House of Anansi Press, 1991.
Nichols, Christopher. Social Science. York University, Toronto, Ontario, 1 Oct, 2003.
Nichols, Christopher. Social Science. York University, Toronto, Ontario, 5 Nov, 2003.
Nichols, Christopher. Social Science. York University, Toronto, Ontario, 26 Nov, 2003.

[Zoe]

I didn't mutate as in they all of a sudden develop a fifth leg or anything - i meant a change in the alleles within the population. It's not a 50/50 chance, but it could go either way.

http://www.exchangedlife.com/Creation/think/eye.shtml
Here ya go. The text is ambiguous at time, but some passages are interesting and plausible.

Organisms are in a constant state of flux - look at any populations from humans to fruit flies: they have adapted, perhaps slightly, in the past dozen generations. Have you ever been in a house that was built 200 years ago? You have to stoop to walk in some of them - humans have grown to be much taller. Eventually, following enough adaptations, the species will evolve into something different (assuming they don't die out for whatever reason). That happens over many, many thousands-millions of years. That seems to be what you are saying?

Zoe

Zoe

[CDN-Cresties]

The blanked out words are r e t a r d e d. Also sorry about the format, it guess it lost it when I pasted it in the thread.

-Steve-

[Crotalus75]

The dogma goes like this DNA -> RNA -> protein

Mutation is change (errors) in the sequence of a DNA molecule that is caused by a number of factors. Some mutations can be caused by radiation (ex. UV radiation can cause bulky pyramidine dimers). Tautomeric shifts can cause bases to mispair. 5-bromouracil can mimic bases and cause mispairing. Insertions and deletions can cause an entire shift in the DNA reading frame. etc...etc....etc....

When a mutation occurs in in the germ line (a gamete) it can be passed to offspring.

When mutated DNA is transcribed into RNA it may be translated into a different sequence of amino acids (building blocks of proteins) than the original molecule was capable of coding for. These new proteins may hold a slight selective advantage for an organism and would therefore be passed on to offspring with greater frequency. It should be noted that almost all mutation is deleterious and some is neutral. Most is NOT positive or advantageous.

[Crotalus75]

To understand this jargon I recomend getting a copy of "Genetics - a conceptional approach" by Benjamin A. Pierce. This is one of the texts that we used when I took General Genetics.

[chas*e]

There are many aspects to Evolution....adaptation and natural selection are only parts of the theory

[Jeff Hathaway]

Nice essay, Steve. I think the last sentence is perhaps the most relevant to our current debate. I believe it is fair to say that both natural selection and punctuated equilibrium theories have their place. Both are mechanisms for evolutionary change, one gradual, and one 'rapid' (in the geological sense). They are not mutually exclusive.

I don't recall much about regulatory genes, but neoteny (and it's cousin, paedomorphisis) makes sense as a mechanism for rapid change. As for cometary impact (and other sudden drastic environmental shifts), this would account for a rapid reduction in species diversity, which would then provide a wealth of unfilled niches in the environment. Since competition for resources in these niches would be reduced or eliminated, organisms would move in as fast as they could, using either existing forms, or modifications from mutations, etc. The development of new adaptations, and thus eventually new organisms, might happen more rapidly in such a scenario, but it would still be natural selection at work after the environmental shift.

Bartman- they don't decide to mutate or not. They either live to reproduce, or die. If they happen to mutate (or other forms of variation) and that happenstance makes them more likely to reproduce, then said mutation will become more common, and the organisms and offspring may survive whatever occurs.

As Tad said, almost all mutation is deleterious (bad:-)). It's not 50/50. But with enough offspring, hopefully a few will survive and reproduce, regardless of mutation or not. Well said, Tad, about how mutations in DNA cause physical changes to the body.

Jeff Hathaway
Sciensational Sssnakes!!

[Crotalus75]

I agree. There are so many aspects to the evolutionary debate that science must step outside the confines of traditional darwinian dogma to fully explain all of the evidence. Very interesting to say the least. I must confess that I have only read a few snippets of Gould's work. He is definitely one of the next authors on my reading list.

[Mr.Lizard]

I've read a few books by Gould. He has a lot of intriguing evidence and ideas. His ideas on punctuated equilibrium make a lot of sense...more sense to me than the inexorable change of one species into a new and improved form.
Personally,I believe in the idea of genetic memory and that genetic memory is responsible for "taking notes" on the environment,making an evaluation of it and then using this evaluation as a blueprint with which to build new structures or modify existing ones to perform new tasks.
There is a vast storehouse of genetic combinations previously used in the the organism's ancient ancestry with which it can use to redesign or invent with.
This same idea applies in the far more rapid and fluid evolution of someone's mind. You collect memories all throughout your life and use these memories collectively to form new ideas---using these ideas you can build and invent what you can conceive.
One of Gould's books---"Hen's Teeth and Horse's Toes" talks about the collection of characteristics stored in this genetic warehouse. The book's title refers to the ability of organisms to draw upon ancestral characteristics,for the better or otherwise.
In the book he describes how unborn chicks can be induced to grow teeth simply by providing them with the necessary material.
The blueprint already exists,merely the material required for making teeth was not needed for any other reason than teeth so it was given up-----"use it or lose it". In fact,early species of birds did have teeth,hesperornis( a diving bird),archeopteryx and others. Another interesting characteristic of some birds is their ability to grow claws on their wings similar in at least one species to archeopteryx. The hoatzin of S. America,as a juvenile nesting in the trees over rivers is provided with these claws with which it climbs up the tree when it has fallen out or fled it's nest.
As the bird matures and becomes capable of flight these fingers are absorbed by the body. Interestingly enough,you can still find a vestigial thumb claw on a plucked chichen wing. While the other four fingers have become fused.Unlike the teeth,the material for making the thumb claw is still in use to produce claws upon the feet. Note also the retained clasper claws in some boids.
The horse also retains an unused "thumb" which can be seen on the inside of the foreleg. In rare instances known as atavisms,this other toe is present next to the single toe which the horse walks upon.This goes back to the horse's ancestry when it was once used. In fact,at some point in embryonic developement five digits can be discerned in many vertebrate species...pigs,whales,birds.
Sorry if I digressed a bit,one of my favorite subjects is the mechanism of evolution.
Some other good reads are "Jurassic Park" and the "Lost World" by Michael Crichton.They're sci-fi of course but there's a lot of real science put into these books. H.G. Wells' "Time Machine" is another on which touches on evolution a bit.

--Kevin--

[Crotalus75]

I like the genetic memory idea. Organisms have a large percentage of DNA that is not used to code for proteins (introns). Wouldn't it be interesting to find that these unused portions had some role in evolution and adaptation by holding necessary genetic information? Just a stray thought.