evolution

[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.
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]

Fossil of archaepoteryx

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!!!!

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.