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Four arguments against ‘Darwinism’ and PZ Myers’ response
Posted: 18 May 2008 03:01 PM   [ Ignore ]
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Good practice for us all.
A “Renew America” WWWsite had this discussion on
“Defeating Darwinism in Four Steps”

I don’t really recommend that link;
The Four Topics are: 
1. First Law of Thermodynamics (matter & energy cannot be destroyed)
2. Second Law of Thermodynamics (reactions run to lowest energy state)
3. Fossils
4. Genes
I do recommend PZ Myers blog where he goes through the points and explains the error:

http://scienceblogs.com/pharyngula/2008/04/four_bad_arguments_against_evo.php

PZ Myers’ discussion of the last topic Genes is interesting. This is covered in more detail in a 2007 entry in the Sandwalk blog (another pro-evolution blog)
http://sandwalk.blogspot.com/2007/07/mutation-rates.html
This is not my area but I read this as indicating that there is a higher mutation rate (more than 10x) for the sperm than the egg.  Maybe {again this isn’t my area} this is because a woman has relatively few eggs but guys have to ‘make’ lots of sperm.

[ Edited: 18 May 2008 03:18 PM by Jackson ]
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Posted: 21 May 2008 06:59 AM   [ Ignore ]   [ # 1 ]
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Jackson - 18 May 2008 03:01 PM

The Four Topics are: 
1. First Law of Thermodynamics (matter & energy cannot be destroyed)
2. Second Law of Thermodynamics (reactions run to lowest energy state)
3. Fossils
4. Genes

I didn’t read the material.  Does it come down to…

1. “Science proves my point! Yay science!”
2. “Science proves my point! Yay science!”
3. “Science is wrong!  Don’t believe it!”
4. “Science is wrong!  Don’t believe it!”

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Posted: 21 May 2008 07:43 AM   [ Ignore ]   [ # 2 ]
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This is funny:

Bryan Fischer:
“Second Law of Thermodynamics teaches us, then, that the universe is headed toward increasing randomness and decay. But what does the theory of evolution teach us? The exact opposite, that the universe is headed toward increasing complexity and order.”

PZ Myers’s response:
“Point to the creationist: ask whether he was a baby once. Has he grown? Has he become larger and more complex? Isn’t he standing there in violation of the second law himself? Demand that he immediately regress to a slimy puddle of mingled menses and semen.”


grin

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Posted: 21 May 2008 08:16 AM   [ Ignore ]   [ # 3 ]
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menses and semen? That’s crude. sick

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Posted: 21 May 2008 08:50 AM   [ Ignore ]   [ # 4 ]
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traveler - 21 May 2008 08:16 AM

menses and semen? That’s crude. sick

Crude but immensely funny

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Posted: 21 May 2008 11:44 AM   [ Ignore ]   [ # 5 ]
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“It kind of takes your breath away” pretty accurately describes the original article.  When I read that line, I imagined Lewis Black delivering it.

Jackson, I think your proposed answer is partially correct, but Myers’ post answers the rest of your question—it takes 30 divisions to create a female egg and 400 in a sperm cell and with each division, there is a factor of 0.3 mutations in the copied genome passed to the daughter cell.  The greater number of divisions obviously raises the mutation rate. 

You know this raises an interesting question to me, I’m not a biologist or a geneticist, but I like the subject.  Everyone knows that females arise from 2 X chromosomes and males from an XY.  The Y chomosome contributes far less genetic material than the X chromosome.  My understanding is that the Y chromosome is a bit of a mystery in terms of its purpose.  I will add that in all us men, the Y chomosome remains unchanged from generation to genration so your Y chomosome is essentially the same as your father’s, grandfather’s, and so on.  Perhaps the lower complexity of the Y chromosome assists in restricting the amount of mutation from generation to generation while allowing for significant change over time.  It could also be because there is an advantage in the sons looking like their fathers.  Maybe both.  Of course, if the Y chromosome restricts mutation, why don’t females have a similar mechanism?

Unfortunately, I know just enough to pose questions, not offer an answer. 

JRM

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Posted: 21 May 2008 12:30 PM   [ Ignore ]   [ # 6 ]
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[quote author=“JRM5001” date=“1211409863] I will add that in all us men, the Y chomosome remains unchanged from generation to genration so your Y chomosome is essentially the same as your father’s, grandfather’s, and so on.  Perhaps the lower complexity of the Y chromosome assists in restricting the amount of mutation from generation to generation while allowing for significant change over time.  It could also be because there is an advantage in the sons looking like their fathers.  Maybe both.  Of course, if the Y chromosome restricts mutation, why don’t females have a similar mechanism?

Unfortunately, I know just enough to pose questions, not offer an answer. 

JRM

Could you please referrence the source of this information. I’ve never heard that the Y choromosome is preserved to any greater degree than the rest of the genome. Being much smaller than the other chromosomes, there will certainly be fewer mutations per unit of time, but the number of mutations per base pair should be no different than on any other chromosome.

Most mutations occur during cell division and the process that replicates the Y chromosome is exactly the same process used to replicate all the other chromosomes. This sounds like either a high school bio class myth or a misunderstanding of the facts ( ie: there are fewer mutations, but perhaps not when you consider the size of the chromosome and calculate the mutation/ base pair ratio).

Anyway, if you could site your reference for that statement I would like to read it.

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Posted: 22 May 2008 11:04 AM   [ Ignore ]   [ # 7 ]
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Like I said, I’m not a geneticist, but I am aware of that principal re: the Y chromosome.  I may have left a false impression by unintentionally implying there was no mutation.  I didn’t mean to say that, I meant to say that the genes on the Y chomosome don’t change from generation to generation. 

I live in Virginia and there is a lot of controversy surrounding the Thomas Jefferson/Sally Hemmings controversy.  For those interested in cluttering their minds with historical trivia, Sally Hemmings was a slave of Jefferson and allegedly his paramour and mother of several of his children including a male, Madison Hemmings.  Madison’s idenity and parentage was the subject of a nasty rumor started by publisher James Callendar shortly after the 1800 presidential race between Adams and Jefferson. 

Tests were performed on the Y chromosomes and the results wer were somewhat inaccurately reported as confirming that Jefferson was the father of Madison’s brother Eston.  All they could really prove was that Eston had the Jefferson Y chromosome which could have included a number of Jefferson’s relatives.  For the record, I’m not a denier, Jefferson is the most likely candidate, but if this were a criminal case I wouldn’t say the evidence was beyond a reasonable doubt. 

Sorry to get sidetracked, I would normally try to find a more scientific source but did not feel like looking forever.  If you are unconvinced by the link below, search google, there are myriad sources discussing the characteristics of intergenerational Y chromosomes:

http://genealogy.about.com/library/authors/ucroderick1e.htm

When you research on the net, sometimes one comes across random but interesting pages such as this one that tried to connect 4 generations of men through their Y chromosome:

http://freepages.genealogy.rootsweb.ancestry.com/~glennholliday/holliday/dna_project/index.html

[ Edited: 22 May 2008 11:07 AM by JRM5001 ]
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Posted: 22 May 2008 05:33 PM   [ Ignore ]   [ # 8 ]
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OK. I think I see the misunderstanding. While the Y chroosome is certainly passed down through the male lineage and does allow you to trace heritage, the implication that the genes do not mutate, or mutate less than those on other chromosomes is not true. It’s unlikely that it will change much over aperiod of 4 or 5 generations, but neither will any other chromosome.

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Posted: 23 May 2008 10:06 AM   [ Ignore ]   [ # 9 ]
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Actually Mcgyver, the X chomosome mutates more in a single generation than the Y because it is so much larger.  Further, if you are a man, you can only get one X chromosome, your father’s.  If you are a woman, you may get your father’s or your mother’s X.  It has long been thought that one of the X chromosomes in females goes inactive in a process known as lyonization which would mean the female offspring could get either the father’s or the mother’s X. 

I think there is some evidence that the “inactive” X chromosome is more active than people thought so if there is interaction between mother’s and father’s X chromosome, the X chromosome in the female offspring may be something of a combination and therefore different. 

Anyone reading this should not take my word as definitive on this.  I welcome any corrections from someone with more genetics knowledge than me.

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Posted: 23 May 2008 10:56 AM   [ Ignore ]   [ # 10 ]
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JRM5001 - 23 May 2008 10:06 AM

Actually Mcgyver, the X chomosome mutates more in a single generation than the Y because it is so much larger.  Further, if you are a man, you can only get one X chromosome, your father’s.  If you are a woman, you may get your father’s or your mother’s X.  It has long been thought that one of the X chromosomes in females goes inactive in a process known as lyonization which would mean the female offspring could get either the father’s or the mother’s X. 

I think there is some evidence that the “inactive” X chromosome is more active than people thought so if there is interaction between mother’s and father’s X chromosome, the X chromosome in the female offspring may be something of a combination and therefore different. 

Anyone reading this should not take my word as definitive on this.  I welcome any corrections from someone with more genetics knowledge than me.

You are only repeating what I said. I think we are saying the same thing. The Y chromosome is smaller so it will have fewer mutations per unit time, but the number of mutations per base unit will be the same as any other chromosome, and that’s the important number. Its been a while since I graduated medical school and even longer since I got my BS in biology and MS in human physiology, but I don’t recall any mention of more frequent mutations per base pair in any of the genetics courses I took along the way.

One thing that actually does make the Y chromosome more conserved from father to son is that it does not ‘swap’ genes with other chromosomes. All of your other chromosomes ( including the X in women) go through a process during meiosis that creates increased genetic diversity through the exchange of genetic material between chromosomes in each pair. This process is called recombination and results in new genetic combinations within chromosomes. Since the Y chromosome can not recombine with the X chromosome it is much more conserved from father to son than other chromosomes, but not because there is a lower mutation rate.

I hope that clears things up.

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Posted: 23 May 2008 03:03 PM   [ Ignore ]   [ # 11 ]
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JRM5001 - 21 May 2008 11:44 AM

“It kind of takes your breath away” pretty accurately describes the original article.  When I read that line, I imagined Lewis Black delivering it.

Jackson, I think your proposed answer is partially correct, but Myers’ post answers the rest of your question—it takes 30 divisions to create a female egg and 400 in a sperm cell and with each division, there is a factor of 0.3 mutations in the copied genome passed to the daughter cell.  The greater number of divisions obviously raises the mutation rate. 

I thought it was an interesting article. I don’t think your description is correct—why do you think “it takes 400 divisions” to make a sperm cell. I was thinking (quite possibly in error, of course) that this just meant that sperms are made throughout an adult male’s reproductive life, while eggs are only made at the beginning of a female’s reproductive life.

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Posted: 23 May 2008 05:42 PM   [ Ignore ]   [ # 12 ]
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JRM5001 - 23 May 2008 10:06 AM

Actually Mcgyver, the X chomosome mutates more in a single generation than the Y because it is so much larger.  Further, if you are a man, you can only get one X chromosome, your father’s.

Truly I am either missing something, or I am in need of an emergency biology lesson. If you have received your Y from your father (making you male), and (if you are a male) your X from your father as well doesn’t this make any male a clone of his father—what did he get from his mother? I always thought the male received an X from his mother (thus the inhertance of the sex linked conditions such as hemophelia and colorblindness where the female has the extra X to protect her).

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Posted: 23 May 2008 07:19 PM   [ Ignore ]   [ # 13 ]
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I don’t think he meant to say that asanta. You are correct. A son gets his Y from dad and his X from Mom. Girls get one X from each parent.

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Posted: 24 May 2008 06:37 AM   [ Ignore ]   [ # 14 ]
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I think the X chromosome that male or female children receive is a blend of the Xs from mother and father. The Y can only come from the father, though, since the mother doesn’t have one.

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Posted: 24 May 2008 10:10 AM   [ Ignore ]   [ # 15 ]
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As mentioned, the X that the son gets comes directly from mom unchanged, however that X is a blend of the X’s she got from her mom and dad since they go through rearrangement and swap sections during meiosis. In other words, mom’s X’s are pure grandpa or grandma X’s until she gives them to her kids. When the egg is formed the X’s swap genes and each X she passes on to her kids is a blend of grandma and grandpa. Girls get two X’s. One from mom and one from dad. Each of those is purely from mom or dad and not a mixture from each. As with the X chromosome in boys though, each X chromosome that came from mom represents a blend of the two grandparents on the mothers side. The X chromosome that came from Dad has no other X to recombine with during meiosis, so he passes on his mother’s X chromosome essentially unchanged.

To further complicate things for anyone who’s interested, the discussion above refers only to nuclear DNA. We also have mitochondrial DNA. All the mitochondria in the fertilized egg come from the egg itself.  As a result all the mitochondrial DNA that we have came from our mothers ( this is true for men and women). The genes in your mitochondrial DNA are essentially the exact same one’s (with the exception of some natural mutations) that your mother’s, mother’s,....mother’s, mother had, umpteen generations ago. There is no mixing or blending that occurs with mitochondrial DNA. As a result its a great way to track lineages, and if you know the average mutation rate (which we do) you can estimate how many generations one individual is removed from another individual who has the same maternal line. In fact for anyone who is really interested, you can have your mitchondrial DNA examined for a price and then see what the worldwide distribution of you particular mitochondrial DNA is. This will give you a rough idea of where your ancient maternal ancestors are most likely from.

If you’re interested here are a couple of links: 

https://www3.nationalgeographic.com/genographic/

http://www.dnaancestryproject.com/

[ Edited: 24 May 2008 12:20 PM by macgyver ]
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