Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
6 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Please explain evolution.
Rookie
Inactive Member


Message 1 of 23 (3033)
01-28-2002 8:07 PM


Hello I am a new user here and am not really up on my evolution knowledge. I'm a "rookie" to all of this. I'm neither a creationist or an evolutionist, I just want to know about it.
So first of all, what can you tell me about evolution that is true so far?
And how did life start from your point of view?
Thanks for helping me learn!

Replies to this message:
 Message 2 by nator, posted 01-28-2002 10:18 PM Rookie has not replied
 Message 3 by Quetzal, posted 01-29-2002 2:05 AM Rookie has not replied
 Message 7 by Tranquility Base, posted 08-14-2002 10:36 PM Rookie has not replied

nator
Member (Idle past 2170 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 2 of 23 (3037)
01-28-2002 10:18 PM
Reply to: Message 1 by Rookie
01-28-2002 8:07 PM


Welcome, Rookie.
Well, a very good place on the web to start learning about current Biology dealing with Evolution, (also the age of the Earth, Abiogenesis, etc.) is
http://talkorigins.com
I reccomend reading the FAQ's, the Five Major Misconceptions About Evolution, and An Introduction to Evolutionary Biology, for sure. Then you can branch out from there and look around.
I also strongly suggest you learn exactly what science is, isn't, and how it is conducted. Most people, even undergraduates who are science majors, don't fully understand the basic tenets of science. Here is a good explanation:
http://www.skepdic.com/science.html
There is a lot to learn to get even a basic understanding of Biology, so pace yourself, and also feel free to comehere with any questions or confusions. There are folks here who have been stydying various scientific subjects in both professional and amateur capacities for years.
Enjoy the forum.
Alliso

This message is a reply to:
 Message 1 by Rookie, posted 01-28-2002 8:07 PM Rookie has not replied

Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 3 of 23 (3058)
01-29-2002 2:05 AM
Reply to: Message 1 by Rookie
01-28-2002 8:07 PM


Hi Rookie,
Since none of our resident Creationists have seen fit (or are unable) to respond to my challenge inre an operationalized theory, I'd like to draw your attention to my post #154 in this very forum. The post provides a (pretty good, if I do say so myself) non-technical explanation of evolution by natural selection. Your comments/questions are welcome. Maybe that effort will have some value...

This message is a reply to:
 Message 1 by Rookie, posted 01-28-2002 8:07 PM Rookie has not replied

Replies to this message:
 Message 4 by Brad McFall, posted 08-14-2002 12:26 PM Quetzal has not replied

Brad McFall
Member (Idle past 5033 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 4 of 23 (15434)
08-14-2002 12:26 PM
Reply to: Message 3 by Quetzal
01-29-2002 2:05 AM


Q, the link to area #154 is broke and it is not in the list your last 30 messages. Where is this # or should I address the suggestions below?

This message is a reply to:
 Message 3 by Quetzal, posted 01-29-2002 2:05 AM Quetzal has not replied

Replies to this message:
 Message 5 by Minnemooseus, posted 08-14-2002 1:23 PM Brad McFall has not replied

Minnemooseus
Member
Posts: 3941
From: Duluth, Minnesota, U.S. (West end of Lake Superior)
Joined: 11-11-2001
Member Rating: 10.0


Message 5 of 23 (15438)
08-14-2002 1:23 PM
Reply to: Message 4 by Brad McFall
08-14-2002 12:26 PM


quote:
Originally posted by Brad McFall:
Q, the link to area #154 is broke and it is not in the list your last 30 messages. Where is this # or should I address the suggestions below?
When Percy reorganized the site (a good thing) it resulted in the previously created internal links becoming bad (a bad thing).
I did a Google search for the old (bad) address, and then looked at Google's cached version of the page. That gave me the topic name.
The message in question now resides at:
http://EvC Forum: why creation "science" isn't science -->EvC Forum: why creation "science" isn't science
Isn't it amazing, how much that Google has cached?
Regards,
Moose
-----
Added by edit on 8/14/2002 - In case anyone is interested in the precise process:
I went to Google, and entered
EvC Forum: Objection to subtitle of this forum
into the to be searched for box.
That got me to this page:
http://www.google.com/search?...
{Shortened display forum of URL, to restore page width to normal - Adminnemooseus}
which, I now notice, in itself does give the topic name "why creation "science" isn't science".
Anyhow, I went beyond that, and clicked on the "Show Google's cache" link, which got me to Google's copy of the page, as it existed when Google had found it (pre Percy's reorganization).
Scroll down to message #154, and there it is.
OR SOMETHING LIKE THAT.
-----
------------------
BS degree, geology, '83
Professor, geology, Whatsamatta U
Old Earth evolution - Yes
Godly creation - Maybe
[This message has been edited by minnemooseus, 08-14-2002]
[This message has been edited by minnemooseus, 08-15-2002]
This message has been edited by minnemooseus, 10-26-2004 11:24 PM

This message is a reply to:
 Message 4 by Brad McFall, posted 08-14-2002 12:26 PM Brad McFall has not replied

Replies to this message:
 Message 6 by Quetzal, posted 08-14-2002 2:47 PM Minnemooseus has not replied

Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 6 of 23 (15441)
08-14-2002 2:47 PM
Reply to: Message 5 by Minnemooseus
08-14-2002 1:23 PM


Wow Moose! I'm impressed. I'd have never found it. Thanks!
Brad: I guess that answers your question...

This message is a reply to:
 Message 5 by Minnemooseus, posted 08-14-2002 1:23 PM Minnemooseus has not replied

Tranquility Base
Inactive Member


Message 7 of 23 (15454)
08-14-2002 10:36 PM
Reply to: Message 1 by Rookie
01-28-2002 8:07 PM


Rookie
As a creationist let me say that we have no problem with natural selection, 'speciation' (new species evolving), evoltuion of drug resistance in viruses etc. Where we disagree with the evoltuionists is (i) how much evolution could really achieve and (ii) how much it did achieve.
So we have no problems with birds evolving new beak shapes as Darwin discovered. We have no porblem with dog breeding generating incredibly diverse dogs, with hybridisation and selection generating brocolli/cauliflower/cabbage from the same wild stock, with moths evoelving from light to dark and back again. Why? Becasue all of these processes are simply mixig and matching of existing traits (and underlying genes) together with mutaitons. None of these processes has a new enzyme which does something new! All of these processes simply mix and match pre-exisitng traits, switch of programmed functions or, through mutaitons, strengthen the fucniton of an exisitng biochemical process - eg an enzyme.
So there is a huge chasm between these 'microevotluioanry' processes and 'macroevoltuion' which tries to explain the origin of eyes, limbs, organs, senses and cellualr mechanisms. For example, the processes inside cells have factories that translate DNA to proteins or converts glucose to energy. They all involve numerous enzymes (coded for on genes). None of the Darwinian processes I described earlier have ever generated a single new enzyme but our body has tens of thousands of differnet enzyme types for tens fo thousands of different jobs!
So extrapolating eovlution of eyes, organs, limbs and clellualr systems from finch beak shapes changing sounds good but at the gene level it is a fairy tale - it is faith.
So what is evoltuion? Good question. What is known is differnet to what is preached.
[This message has been edited by Tranquility Base, 08-14-2002]

This message is a reply to:
 Message 1 by Rookie, posted 01-28-2002 8:07 PM Rookie has not replied

Replies to this message:
 Message 8 by Quetzal, posted 08-15-2002 4:54 AM Tranquility Base has not replied

Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 8 of 23 (15470)
08-15-2002 4:54 AM
Reply to: Message 7 by Tranquility Base
08-14-2002 10:36 PM


Hi TB: Although I think our friend Rookie is long gone (there wasn't a reply since January until Brad resurrected the thread), I'd like to address (again, I think) your stand on gene evolution.
quote:
For example, the processes inside cells have factories that translate DNA to proteins or converts glucose to energy. They all involve numerous enzymes (coded for on genes). None of the Darwinian processes I described earlier have ever generated a single new enzyme but our body has tens of thousands of differnet enzyme types for tens fo thousands of different jobs!
This is a very misleading statement. There is quite ample evidence that novel genes do arise. Obviously, it's easier to detect these genes in organisms which have been fully sequenced (duh). Drosophila melanogaster has probably the most thoroughly investigated genome on the planet. This insect contains at least two completely novel genes. Here's an abstract for one:
quote:
Nature 1998 Dec 10;396(6711):572-5
Selective sweep of a newly evolved sperm-specific gene in Drosophila.
Nurminsky DI, Nurminskaya MV, De Aguiar D, Hartl DL.
Harvard University, Department of Organismic & Evolutionary Biology, Cambridge, Massachusetts 02138, USA.
The pattern of genetic variation across the genome of Drosophila melanogaster is consistent with the occurrence of frequent 'selective sweeps', in which new favourable mutations become incorporated into the species so quickly that linked alleles can 'hitchhike' and also become fixed. Because of the hitchhiking of linked genes, it is generally difficult to identify the target of any putative selective sweep. Here, however, we identify a new gene in D. melanogaster that codes for a sperm-specific axonemal dynein subunit. The gene has a new testes-specific promoter derived from a protein-coding region in a gene encoding the cell-adhesion protein annexin X (AnnX), and it contains a new protein-coding exon derived from an intron in a gene encoding a cytoplasmic dynein intermediate chain (Cdic). The new transcription unit, designated Sdic (for sperm-specific dynein intermediate chain), has been duplicated about tenfold in a tandem array. Consistent with the selective sweep of this gene, the level of genetic polymorphism near Sdic is unusually low. The discovery of this gene supports other results that point to the rapid molecular evolution of male reproductive functions.
Now you'll simply say that this represents evolution within a "gene family" (i.e., microevolution), although it appears to me to be indicative that brand new functions CAN arise.
That being the case, I'd like to draw your attention to the jingwei gene in the same fly. This is another novel gene. More importantly, it's a chimera - a combination of two completely different gene families.
quote:
In a 1993 issue of Science, Manyuan Long, and CH Langley published their findings of a novel Drosophila gene, located on chromosome 3, that is found in sister species D. teissieri and D. yakuba and thus presumably first appeared in the common ancestor of both. They dubbed this new gene jingwei (jwg). The evidence that they uncovered, especially the lack of introns, suggested that the gene was derived from a retrotransposed mRNA from an alcohol dehydrogenase (adh) gene on chromosome 2. Further results suggested that jwg is not a pseudogene as was first thought, but is rather a functional novel gene, though its exact function is still not clear. The gene not only has specific RNA expression patterns, but has also undergone extensive evolution without suffering from any frameshift or nonsense mutations that are the hallmark of pseudogenes; the evidence strongly suggests that jwg has been under positve Darwinian selection. Not only that, but Long and Langely’s results suggest that selection is playing a role throughout the origin of new genes, rather than being initially relaxed as was previously thought.
Perhaps the most interesting aspect of jwg is that its gene product is a chimera, meaning that it has function portions that are derived from different ancestral genes (aka gene fusion). The C-terminal portion of jwg was almost certainly derived from the ancestral adh gene via retrotransposition, but that left the origin of the N-terminal exons still unexplained. Did they come from non-coding upstream regions of DNA, or were they derived from parts of non-related functional genes? Further study by Long et al. (1999) demonstrated that the N-terminal regions were the result of duplications of exons from a gene named yellow-emperor (ymp). A follow-up study by Wang et al. (2000) showed that ymp is also a functional gene whose first three exons are the donor for the recruited portion of jwg.
Here's how it looks graphically:
(originally posted by theyeti here)
Original references:
Wang, W., Zhang, J., Alvarez, C., Llopart, A., and Long, M. 2000. The origin of the Jingwei Gene and the complex modular structure of its parental gene, Yellow Emperor, in D. melanogaster. Mol. Biol. Evol. 17: 1294-1301.
Long, M., W. Wang, and J. Zhang, 1999, Origin of New Genes and source for N-terminal `domain of the chimerical gene, jingwei, in Drosophila. Gene. 238: 135-142
Some other interesting references for novel genes from the same group:
Long, M. 2001. Evolution of Novel genes. Curr Opin Genet Dev 11:673-680
Wang W, Brunet FG, Nevo E, Long M. 2002. Origin of sphinx, a young chimeric RNA gene in Drosophila melanogaster PNAS 99:7, 4448-4453, April 2, 2002
Basically, your contention that novel genes can't arise is falsified by the existence of genes generated by mutations and fusion of genes or parts of genes across "families".
The second part of your argument, that specific gene families somehow prevent macroevolution, also needs to be addressed. Since this is your claim, for it to be valid you need to show that there are identifiable gene families that are unique to specific taxa. What is the evidence (the specific gene families) that defines, for example, the difference between Aves and Mammalia? Or for that matter, between chordate and invertebrate? Obviously, there are going to be significant genetic differences between these wildly different organisms. In other words, specify which families belong to which taxa. Be careful: if there are genes within a given family that are shared among different organisms, then your contention is falsified. Please be specific.
If you are unable to delimit - scientifically - the family differences between taxa, AND show how these provide a barrier, then all you are doing is restating at the genetic level the long-discredited concept of taxic discontinuity. The same falsifications to discontinuity at the species level would apply. (Hint: you're on shaky ground since you already acknowledge that speciation can occur.)
[edited to fix attribution]
[This message has been edited by Quetzal, 08-15-2002]

This message is a reply to:
 Message 7 by Tranquility Base, posted 08-14-2002 10:36 PM Tranquility Base has not replied

Lucifer
Inactive Member


Message 9 of 23 (153218)
10-27-2004 12:07 AM


I thought different combinations of genes would result in production of different enzymes. That's because a certain code in a gene would code for a certain enzyme, so even the slightest change would cause the enzyme that is produced to differ. That's like having two words, "too" and "two", which look very similar, and are different by only one letter, but they have different functions in a sentence (one's a noun, the other is an adverb), just as enzymes could be coded similarly, but aren't the same, and don't have the same function.

Replies to this message:
 Message 10 by crashfrog, posted 10-27-2004 12:21 AM Lucifer has not replied
 Message 11 by Adminnemooseus, posted 10-27-2004 1:08 AM Lucifer has not replied
 Message 13 by Wounded King, posted 10-27-2004 6:21 AM Lucifer has not replied

crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 10 of 23 (153223)
10-27-2004 12:21 AM
Reply to: Message 9 by Lucifer
10-27-2004 12:07 AM


I thought different combinations of genes would result in production of different enzymes. That's because a certain code in a gene would code for a certain enzyme, so even the slightest change would cause the enzyme that is produced to differ.
Actually, genetic protein sequences are quite resistant to change. The first layer of protection from mutation is redundancy in the genetic code itself:
shape>

This message is a reply to:
 Message 9 by Lucifer, posted 10-27-2004 12:07 AM Lucifer has not replied

Replies to this message:
 Message 12 by Wounded King, posted 10-27-2004 6:10 AM crashfrog has replied

Adminnemooseus
Administrator
Posts: 3974
Joined: 09-26-2002


Message 11 of 23 (153259)
10-27-2004 1:08 AM
Reply to: Message 9 by Lucifer
10-27-2004 12:07 AM


Wow, you dredged up a relic of the past
Inactive for 2+ years!
Since that topic was created, the "Great Debate" forum has been redefined as a place for 1 on 1 debate (2 people only).
I could move it, but I guess I'll just leave it alone and see what happens. But note - Not a "Great Debate" topic, as such is currently defined.
Adminnemooseus

Comments on moderation procedures (or wish to respond to admin messages)? - Go to
Change in Moderation?
or
Thread Reopen Requests
or
Considerations of topic promotions from the Proposed New Topics forum

This message is a reply to:
 Message 9 by Lucifer, posted 10-27-2004 12:07 AM Lucifer has not replied

Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 12 of 23 (153318)
10-27-2004 6:10 AM
Reply to: Message 10 by crashfrog
10-27-2004 12:21 AM


As you can see, a change in one or two bases per codon probably won't change the residue sequence of the resulting protein.
Come on Crash, thats clearly not true! Just look at your figure, a change of 1 base pair probably won't be a problem provided that it is the third base of the codon, but even a 1 bp change in the 1st or 2nd base will almost always produce a non-synonymous substitution. Only ~30% of 1bp changes will be synonymous, for 2bp your even more wrong.
What is more important is that most of the time the resulting non-synonymous substitutions are functionally synonymous in as much as the resulting amino acid substitution is for one with a similarly structured side chain. This is much more important for the maintenance of correct conformation than having exactly the right residue involved. 70% of residues may well survive changing and allow a protein to function, although a reference would be nice to know exactly what research you are drawing from, but I doubt that if you changed 70% of the hydrophilic residues in a protein to hydrophobic residues you would get a functioning protein.
This reference shows the amount of leeway in the hydrophobic core of a protein. 12 of 13 amino acids can be substituted while maintaining normal enzymatic activity, provided those substitutions are hydrophobic.
Active barnase variants with completely random hydrophobic cores
Axe DD, Foster NW, Fersht AR.
Proc Natl Acad Sci U S A. 1996 May 28;93(11):5590-4.
TTFN,
WK

This message is a reply to:
 Message 10 by crashfrog, posted 10-27-2004 12:21 AM crashfrog has replied

Replies to this message:
 Message 16 by crashfrog, posted 10-27-2004 12:41 PM Wounded King has replied

Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 13 of 23 (153319)
10-27-2004 6:21 AM
Reply to: Message 9 by Lucifer
10-27-2004 12:07 AM


Dear Lucifer,
You seem to be confusing several things here.
I thought different combinations of genes would result in production of different enzymes.
I can see a few ways to interpret this. 1) The expression of different combinations of protein products of genes may well lead to the expression of diferent genes coding for zpecific enzymes. 2) The way Crash interpreted it, that you meant that changes in the genes would lead to the structur of the enzymes being produced being altered. 3) That you are thinking of some sort of multimeric protein where different components can be incorporated depending upon what is available in the cellular environment.
That's because a certain code in a gene would code for a certain enzyme, so even the slightest change would cause the enzyme that is produced to differ.
This certainly suggests the 2nd option to which Crashfrog has already responded.
You seem to be getting confused between genes and the DNA sequence of those genes.
TTFN,
WK

This message is a reply to:
 Message 9 by Lucifer, posted 10-27-2004 12:07 AM Lucifer has not replied

Lucifer
Inactive Member


Message 14 of 23 (153325)
10-27-2004 8:11 AM


You haven't really mentioned too much about DNA sequence. Do you mean the changes in the DNA sequence cause the enzyme that is formed to change or do you mean changes in the genes?

Replies to this message:
 Message 15 by Wounded King, posted 10-27-2004 8:37 AM Lucifer has not replied

Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 15 of 23 (153331)
10-27-2004 8:37 AM
Reply to: Message 14 by Lucifer
10-27-2004 8:11 AM


Dear Lucifer,
All of the base changes we have been discussing are occurring in the DNA sequence. A gene is nothing more than a specific DNA sequence, usually but not always containing the regulatory elements for correct expression and protein coding sequence for a particular protein or related set of proteins. A change in the DNA sequence of the protein coding region of a gene may lead to an enzyme with functional differences, or to a protein with different binding specificities or something along those lines.
It doesn't sound like you really have much grasp of some fairly basic concepts in molecular biology, which will make it pretty hard for you to understand many of the answers you are likely to get.
TTFN,
WK

This message is a reply to:
 Message 14 by Lucifer, posted 10-27-2004 8:11 AM Lucifer has not replied

Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024