21 November 2006
There are more things in heaven and earth, Paul, Than are dreamt of in your philosophy.
DaveScot
It’s funny how Paul Myers, Richard Dawkins, Eugenie Scott, et al say that evolution isn’t about religion yet you can’t swing a dead cat without hitting one of their rants on religion. But that’s not the point of this article.
I have a problem with these people in that they arbitrarily limit what science can potentially explain. The so called supernatural remains supernatural only as long as there’s no metric by which to measure it. Once a metric is discovered the supernatural becomes the natural.
Paul quotes someone on the virgin birth of Christ saying that it defies everything science has revealed in regard to mammalian reproduction. This is utter dreck. Even (especially!) Myers should know that meiosis is a two stage process wherein the first stage results in the production of two perfectly viable diploid cells. The second stage of meiosis then splits these two cells into four haploid gametes. Interrupting the process at the completion of the first stage results in parthenogenesis. Indeed, there are number of organisms in nature that have lost the second stage of meiosis and now reproduce parthenogenetically. See here for more detail. Moreover, it has also been scientifically established that an XX genome can produce phenotypical male offspring. Morever, while all observed XX males in humans are sterile, pathenogenetic populations can still reproduce sexually if sexual reproduction still exists in the species (Da Vinci Code fans will be happy to know this). While it was widely believed that mammals had completely lost the ability for parthenogenetic reproduction, in 2004 researchers in Tokyo managed to create viable parthenogenetic mice. So Paul, science now reveals that the virgin birth of a human male is quite possible. Put that in your pipe and smoke it. What I want to know now is whether ignorance or dishonesty explains why you’d quote someone who claims the virgin birth of Christ defies everything we know about mammalian reproduction. Neither explanation becomes you of course and it gives me immeasurable delight to put you in the proverbial position of choosing between a rock and a hard place. 
The next thing I’d like to debunk in Paul’s latest diatribe is his assertion that matter and energy is all that exists in the universe and science can explain it all without reverting to anything else.
The latest findings in cosmology are that the universe is composed of 5% visible matter, 20% dark matter, and 75% dark energy. The theory of gravity applied to the visible matter and energy in our solar system and local region of the galaxy predicts with exquisite precision the motion of visible bodies. However, when applied to larger structures such as our galaxy and our local galactic cluster the predictions break down. In order to explain those motions there must be 5 times the amount of visible matter existing in some form of normal matter that is not visible. That’s not very incredible and many hypothesis based on known physics are on the table to characterize the dark matter component. See here for more detail. What’s more bizarre is that recently it was discovered that in the universe writ large (relative motions of galactic clusters) it is revealed that the universe is expanding at an accelerating rate. This was not predicted by the theory of gravity and the amount of matter and energy inferred from the motion of local galaxies. In point of fact there must be something completely unknown going on in the universe. 75% of the “stuff” which makes up the universe is an unknown coined dark energy that diffuses the universe.
So you see, Paul, matter and energy that we know about are only a small fraction of what makes the universe go ’round, so to speak. Who’s to say at this point in time that this huge amount of unknown “stuff” is incapable of organization that produces intelligence? Could God be lurking in the dark energy of the universe? Can science investigate the nature of dark energy? You bet it can. The jury is still out, Paul. You don’t know half what you think you know about the nature of nature nor of what you presume to be the bounds of science’s capacity to investigate it. Hence the subject line of this article.
Update: It has been suggested in the commentary from Professor of Biology Allen MacNeil of Cornell that I don’t know what I’m talking about regarding meiosis in that there is no stage wherein 2 diploid cells are present. I present to you The Phases of Meiosis from Biology 032 at Brown University.
Meiosis begins with Interphase I. During this phase there is a duplication genetic material, DNA replication. Cells go from being 2N, 2C (N= chromosome content, C = DNA content) to 2N, 4C.
further down
In Cytokinesis I, the cells finally split, with one copy of each chromosome in each one. Each of the two resulting cells is now 2N, 2C.
Now I don’t know exactly where the good Professor MacNeil learned his elementary cell biology but where I did a 2n,2c cell is a diploid cell with the normal diploid chromosome count (2n) and the normal amount of DNA (2c). But I’d like thank the professor for keeping on my toes. For a moment there I’d thought I’d had a senior moment and forgotten basic things I learned 30 years ago.
Update 2: The preponderance of literature calls the intermediate cells 1N,2C. This appears to be just semantics. The cells contain 1n unique chromosomes but 2n total chromosomes. I can’t find a definition of “diploid” anywhere that says two identical paired chromosomes only counts as one chromosome. The situation is 23 paired chromosomes that are 100% homozygous. It’s still diploid except perhaps to a pedant.
1
Allen_MacNeill
11/21/2006
3:18 pm
Unfortunately, Dave, the first division of meiosis does NOT produce two “diploid” cells. It produces two HAPLOID cells (i.e. two cells that have a single set of chromosomes), in which the chromosomes are double stranded. The second division of meiosis simply divides the sister chromatids in these two cells, which doesn’t change the fact that they are already haploid at the end of the first division.
This means that the products of the first division of meiosis are totally incapable of producing a fully functioning organism. This would be like producing a fully functioning organism from a sperm or egg cell; impossible, in other words.
Those vertebrates that are parthenogenetic (a few species of whiptail lizards in the southwestern US and the Caucasus mountains in Russia) do not produce fully functioning offspring from first division daughter cells. They produce them from hybrids between several sets of chromosomes from different species (see http://en.wikipedia.org/wiki/Parthenogenesis for the details).
This is freshman biology, Dave. If one of my students had made a statement this egregiously wrong, I would have flunked him or her on the exam.
2
Joseph
11/21/2006
3:31 pm
Sorry Dave,
Yup Bio 101:
Telephase I- the cytoplasm of the germ cell divides at some point. There are now two haploid (n) cells. Each cell has one of each type of chromosome that was present in the parent (2n) cell. However, all chromosomes are still in the duplicated state. (italics in original)
Biology- concepts and applications Starr fifth edition page 142
3
Joseph
11/21/2006
4:22 pm
Allen,
Would you flunk the student even if he/ she got everything else correct and that was only one of perhaps 100 questions they flubbed?
4
Robin Levett
11/21/2006
4:34 pm
DaveScot said:
So Paul, science now reveals that the virgin birth of a human male is quite possible.
From a phenotypically male human (which is what the discussion is about)?
5
Robin Levett
11/21/2006
4:54 pm
Whoops - looking more closely, you may be referring to the XX male as the offspring of the posited virgin birth. But that certainly hasn’t been shown possible. 80% of XX males are male because one X chromosome has acquired SRY from the father’s Y chromosome - and the reason for the other 20% isn’t yet known, so contribution from the father’s Y (or even any other) chromosome hasn’t been ruled out.
6
crandaddy
11/21/2006
5:23 pm
Actually it takes a measure of faith for Prof. Myers to accept that even matter and energy exist independently of Mind. What is more real in our experience are conscious, first-person perceptions of matter and energy. I’d like to see him explain that in physicalistically acceptable terms. Good luck, Paul. (You’ll need all of it you can get.)
7
Reed Orak
11/21/2006
6:17 pm
“It’s funny how Paul Myers, Richard Dawkins, Eugenie Scott, et al say that evolution isn’t about religion yet you can’t swing a dead cat without hitting one of their rants on religion.”
I’m glad someone is calling these folks out on their anti-religious bias. Could it be a coincidence that the staunchest darwinians are also the staunchest atheists? Hmmm…
“The so called supernatural remains supernatural only as long as there’s no metric by which to measure it. Once a metric is discovered the supernatural becomes the natural.”
This has been my position on the matter for some time. But it raises an interesting question–is the ID movement really trying to expand science to include supernaturalism, or is it trying to expand science so that it might naturalise what is now considered to be ’supernatural’. The former seems easier to support than the latter. After all, can’t something only remain supernatural if it can’t be explained? And doesn’t science purport to explain things? I consider these (at least somewhat) open questions.
“Who’s to say at this point in time that this huge amount of unknown “stuff†is incapable of organization that produces intelligence? Could God be lurking in the dark energy of the universe?”
I’m afraid this is where I must respectfully disagree. (I won’t comment on the section on parthenogenesis.) I’m more than a little bothered by the idea of a god that recedes into the far reaches of the universe where we have yet to probe–simply because we have yet to probe there. This is the ‘god-of-the-gaps’ par excellence. No god worth having should need to retreat into the darkness like that, and this position is simply not scientific.
Apart from that, it seems a little absurd. Dark matter has a few things in common with familiar matter, and it differs in a few important details, but there’s no theoretical reason to posit something so radical as that it has intelligence! Not only is there no theoretical basis for such a prediction, but there’s also no theoretical framework in which it would make sense. That doesn’t rule it out by any means, but it makes such speculation unscientific–at least until we have more data about dark matter.
8
DaveScot
11/21/2006
6:36 pm
Allen
Excuse my ignorance. Pedantry in the definition of “diploid” and “haploid” in describing meiosis is beyond me. I was under the impression that haploid and diploid refer to no more than the the normal number of chromosomes (haploid = n = 23 and diploid = 2n = 46 for humans) . The second stage of meiosis involves no DNA replication so I’m wondering how two cells with haploid number can become four cells with haploid number without DNA replication. Is there some sort of magic involved here or do the two daughter cells from the first stage of meiosis each contain 46 chromosomes arranged in 2 duplicate sets of 23 where they can then divide into four unpaired groups of 23 chromosomes each in another slightly modified mitotic division?
Meiosis is described as two mitotic divisions with a little bit of modification to normal mitosis such that the first division instead of producing two heterozygous daughters identical to the mother cell produces two homozygous daughters, one with a pair of 23 chromosomes from the maternal side and the other with 23 chromosomes from the paternal side (with a little bit of crossover between maternal and paternal sides to make a novel result instead of an identical copy).
If this is not correct then the literature is very misleading.
This makes all kinds of sense in an evolutionary POV. Mitosis ostensibly evolved long before meiosis. The first stage of this evolution would simply be a modification of mitosis that resulted in two homozygous but perfectly viable cells. Then the second stage evolved where the homozygous cells divide again in a slightly modified mitosis into two haploid cells.
This then handily explains why formerly meiotic organisms could devolve into parthenogenetic reproducers and also why the Tokyo researchers could coax a mouse into producing viable parthenogenetic offspring.
Of coures I didn’t come up with the semi-meiotic theory of evolution. That credit goes to J.A. Davison who published it in 1984 in the peer reviewed Journal of Theoretical Biology.
http://hkusua.hku.hk/~cdbeling/Semi-Meiosis.pdf
Why don’t you be a maverick and be the first to find fault in Davison’s work. I sure can’t. It’s as much as I can do to count up the chromosomes at the end of prophase 2 and arrive at a number of 46 in each of the daughter cells.
Barring that maybe it’s really you that should flunk out of Biology 101 for failing to count up the number of chromosomes at the end of prophase 2 and not coming up with the 2n number for humans.
9
DaveScot
11/21/2006
6:47 pm
Reed
You confused dark matter with dark energy.
Given the typically transcendant portrayals of God existing outside the physical universe as we know it, and dark energy existing outside the physical universe as we know it… I’m just connecting some hypothetical dots there.
10
DaveScot
11/21/2006
6:53 pm
Robin
Yes, Christ would ostensibly be an XX male through parthenogenesis. The fact remains that 20% of the XX males have no SRY so while it remains to be explained how that happens the fact that it DOES somehow still happen is still there.
11
William Dembski
11/21/2006
6:53 pm
Frank Tipler writes about the Virgin Birth of Jesus as follows (I’m not sure how much to buy here, but it’s in the same ballpark as DaveScot’s post):
12
DaveScot
11/21/2006
7:59 pm
Allen
This would be like producing a fully functioning organism from a sperm or egg cell; impossible, in other words.
Allen, are you familiar with automictic parthenogenesis by any chance? Clearly females of sexually reproducing species in most of the plant and animal taxa are capable of virgin birth. Mammals and gymosperms are the sole exceptions but maybe it just hasn’t been observed in those yet and it can indeed happen.
Davison in the paper I referenced refers to experiments with frog eggs that were induced into producing offspring both with needle pricks to simulate sperm entering the egg and by using sperm that had been irradiated to destroy their DNA.
Going back to Kayuga, the parthenogenetic mouse… I quote from the article:
http://www.newscientist.com/article.ns?id=dn4909
This basically says that you’re all wet about reproduction being impossible from just an egg. Not only does it occur in many species the process can even begin in mammals with cell division proceeding for a few days. I note you don’t qualify your statement that reproduction from just an egg is impossible only in mammals. Would you take this opportunity to qualify the statement and then we can proceed to discuss why it might not be possible in mammals.
13
DaveScot
11/21/2006
8:18 pm
Allen
Maybe you can correct this description of meiosis I found at Brown University.
http://www.brown.edu/Courses/B.....seIB1.html
Again, forgive my ignorance but isn’t a cell that is 2N, 2C a cell with the diploid number of chromsomes (2n) and the normal amount of DNA (2c) whereas haploid cells are 1n, 1c?
Help me out here, Allen. Either Brown University’s Biology 032 course is mistaken regarding meiosis or you are.
Maybe you might have flunked me but methinks Brown would flunk YOU.
14
Robin Levett
11/21/2006
8:42 pm
DaveScot said:
Yes, Christ would ostensibly be an XX male through parthenogenesis. The fact remains that 20% of the XX males have no SRY so while it remains to be explained how that happens the fact that it DOES somehow still happen is still there.
But until it has been explained, and involvement of the father’s Y chromosome or its effects discounted, it’s not correct to claim that this phenomenon demonstrates that the virgin birth of a human male (without the involvement of a male) is possible.
The other point to note is that the XX males without the SRY gene are more likely to have “ambiguous genitalia, hypospadias, and/or undescended testicles” inter alia; that is, physically to show their condition. Both types of XX male are also shorter than the average human male.
15
DaveScot
11/21/2006
9:33 pm
This appears to be a semantic issue. At the end of cytokinesis there are two daughter cells each with 46 chromosomes. However, it has only 23 unique chromosomes in two 100% homozygous pairs. I can’t find anywhere in the literature where the diploid number is defined as 2n unique chromosomes. In humans, 23 unique chromosomes paired up as 46 total chromosomes is still a diploid number. If someone can point me point me to a defintion of diploid that says identical pairs of chromosomes only count as one chromosome then I’ll concede I made a mistake in semantics (but still no mistake in principle). Good luck.
16
DaveScot
11/21/2006
9:51 pm
I deleted a previous response to Robin as it was unnecessarily offensive. I found a non-offensive rebuttal.
Robin writes:
The other point to note is that the XX males without the SRY gene are more likely to have “ambiguous genitalia, hypospadias, and/or undescended testicles†inter alia; that is, physically to show their condition. Both types of XX male are also shorter than the average human male.
http://www.springerlink.com/co.....c402w3k6n/
From the journal “Human Genetics”
Furthermore, parthenogenesis has been observed in all taxa except gymnosperms and mammals. This makes the capability a rule and mammals a rare exception. Now you have have to ask yourself why the exception. Unless you can explain why it’s impossible in mammals it is reasonable to conclude the capability is present but not yet observed (not observed if you don’t count Christ).
17
HodorH
11/21/2006
10:14 pm
18
Joseph
11/21/2006
10:41 pm
DaveScot:
If someone can point me point me to a defintion of diploid that says identical pairs of chromosomes only count as one chromosome then I’ll concede I made a mistake in semantics (but still no mistake in principle). Good luck.
Ibid page 129:
“We say the chromosome number is diploid, or 2n, if a cell has two of each type of chromosome characteristic of the species.”
It goes on to say it is NOT just the number of chromosomes that count.
After Meiosis I our germ cells have 23 + 23 homologous chromosomes, which then get split down to just 23 in each of the 4 final gametes (end of Meiosis II).
However I don’t think DS was “egregiously wrong”. And if we were in Allen’s class and he flunked Dave for that minor “error”, there would be he[[ to pay.
I also found the following:
diploid:
Definition: A cell that contains two sets of chromosomes (one set donated from each parent).
Biology on-line concurs.
19
Joseph
11/21/2006
11:04 pm
I guess my last comment got caught in the filter-
Definition: A cell that contains two sets of chromosomes (one set donated from each parent).
http://biology.about.com/libra.....iploid.htm
20
Allen_MacNeill
11/22/2006
1:15 am
DaveScot wrote:
“I can’t find anywhere in the literature where the diploid number is defined as 2n unique chromosomes.”
I don’t know what literature you’re reading, Dave. I have over twenty introductory biology textbooks in my library (the publishers keep sending them to me for free, hoping I will adopt them), and every single one of them defines “diploid” as consisting of two complete sets of chromosomes deriving from two genetically different parents. “Haploid” is defined as one complete set of chromosomes, which is what is in each daughter cell at the end of the first division of meiosis. Each of these first division chromosomes is double stranded, but that doesn’t make them homologous, it makes them identical. They are identical because, during the S phase of interphase, the single stranded chromosomes become double stranded, as a prelude to meiosis (and mitosis).
Admittedly, a small number of my students get confused on this same topic every year, and so the fact that you misunderstood the definitions of “diploid”, “haploid”, and “homologous” isn’t unique. I would almost certainly be prone to the same kind of errors if I were to try to make statements concerning computer programming, as subject about which I am almost entirely ignorant. That’s what happens when people try to make definitive statements on subjects of which they have only an amateur’s understanding.
Furthermore, I never meant to imply that development from a non-fertilized egg is impossible in any animal, only that it is virtually impossible in mammals. Indeed, in the order Hymenoptera (ants, bees, and wasps) all males (i.e. drones) are produced from unfertilized eggs, while all females (queens and workers) are diploid, a condition called haplodiploidy.
And the link to Wikipedia that I included in my original post has a pretty good explanation of what parthenogenesis is, and in which groups of organisms it has been observed. Among vertebrates it is exceedingly rare, being common only among a few peculiar groups of lizards (the whiptails that I mentioned). In those organisms, the parthenogenetic individuals (which are all female, by the way) are able to develop from unfertilized eggs to adults because their genomes are a chimera produced by the hybridization of several closely related species. Apparently the complement of genes from such hybridization is sufficient to compensate for the lack of a homologous set of chromosomes from gametes from males in those species, thereby making haploid-to-diploid fertilization unnecessary.
Come on, Dave, this is extremely basic introductory biology. Why can’t you simply admit that you were wrong on this one and move on? I’ve done it on many occasions (including several at this website). Remember, pride is the first and deadliest of the deadly sins (and humility the first and highest of the cardinal virtues)…
P.S. As several other commentators have already pointed out, although parthenogenesis is common in plants, some protists, and the aforementioned whiptail lizards, it is virtually unknown in mammals. Speculation about how something “might” have happened isn’t science at all, it’s wishfull thinking.
21
DaveScot
11/22/2006
1:19 am
Joseph
I’ll see your definition of diploid from “about.com” and raise you these:
http://ghr.nlm.nih.gov/ghr/glossary/diploid
http://www.genome.gov/glossary.cfm?key=diploid
http://anthro.palomar.edu/biobasis/glossary.htm
http://filaman.ifm-geomar.de/G.....sh=diploid
http://www.emc.maricopa.edu/fa.....lossD.html
http://www.stanford.edu/group/.....oss/d.html
http://worms.zoology.wisc.edu/.....ary.html#D
http://www.ggc.org/glossary.htm
http://webpages.charter.net/te.....ssary.html
http://naturalsciences.sdsu.ed.....ssary.html
This is just a small sampling of definitions of “diploid” which exclude the requirement that paired chromosomes are one copy from each parent.
I arranged two googlefights to resolve this situation.
http://googlefight.com/index.p.....d+glossary
http://googlefight.com/index.p.....d+glossary
Add up the two searches with parent and parents and subtract from the search without either. The result is about an even match with a marginal lead in your favor. However, since it’s likely that many glossaries will contain the word parent or parents not contained within the definition of diploid I think that swings it back in my favor but that’s just conjecture.
Furthermore, how do we describe asexual diploids if all all diploids must have genes from two parents?
22
DaveScot
11/22/2006
1:31 am
Allen
I don’t know what literature you’re reading, Dave. I have over twenty introductory biology textbooks in my library (the publishers keep sending them to me for free, hoping I will adopt them), and every single one of them defines “diploid†as consisting of two complete sets of chromosomes deriving from two genetically different parents.
See my previous comment for definitions of diploid that don’t specify two parents.
23
DaveScot
11/22/2006
1:35 am
Allen
it is virtually impossible in mammals
Do I detect a bit of backpeddling here?
Surely you didn’t think I’d miss that “virtually” qualification did you?
What do you figure are the odds that a parthenogenetic mammal might slip through that crack you left open. Please support your estimate of the odds.
And you’re darn right this is basic biology. 46 is the diploid number in humans and 46 is the exact number of chromosomes in the first two daughter cells produced during meiosis. About half the glossary definitions of “diploid” from reliable sources say it’s one set of 23 from each parent and the other half don’t make that qualification. If you marked me wrong on a test question and the class text used the latter definition I’d hound you until the cows came home to mark it correct and change the question on future tests.
24
Allen_MacNeill
11/22/2006
1:42 am
The Mexican males that you refer to in comment #16 are both diploid; they are phenotypically male simply because of an alteration in the expression of the SRY gene. This is totally unlike the situation that would have necessarily been the case for Jesus to have been born to Mary as the result of parthenogenesis. This would require that Jesus develop from an unfertilized, and therefore haploid egg cell, which even Tipler admits is a biological impossibility in mammals. Yes, parthenogenesis is possible in mammals, but the resulting individuals would be diploid and would necessarily be female, as they would have developed from egg cells in a female that does not include either a Y chromosome or a functional copy of the SRY gene.
The mice described in the experiment in comment #12 were diploid (i.e. had two sets of chromosomes), but were parthenogenetic because the two sets were converted from a single set by chromosome duplication without cell division. However, this process can only result in an XX individual in mammals, since mammalian egg cells from females only contain X chromosomes. The author of the quote you supplied states this quite clearly: “In mammals parthenogenesis can begin if an egg is accidentally or experimentally activated as if it had been fertilised - but this parthenote never grows past a few days.”
Tipler’s speculations are founded on a biological impossibility: that a phenotypically female mammal could somehow produce (by any mechanism at all) a diploid cell that could develop into a male without an SRY gene hidden somewhere in her genome. The reason? If a copy of the SRY gene were somehow inserted into Mary’s genome, she would have developed into a phenotypic male, because that’s what the SRY gene does: it throws a switch that produces (mainly via hormonal processes) a phenotypically male individual.
Furthermore, if somehow a haploid egg cell of Mary could have undergone the same kind of chromosome duplication event described in the case of Kayuga’s mice, the resulting diploid cell would be female, as it would lack a copy of the SRY gene, which is normally only found in the Y chromosome.
In other words, Tipler’s suggestion is quite literally impossible, given any known mechanism of mammalian development. However, a competing hypothesis has a lot going for it: Mary got pregnant the way nearly all other female humans do – by copulating with a human male. This requires absolutely no magic, nor stretching of the known principles of developmental genetics at all.
Given the relative probabilities of the two hypotheses (i.e. birth of a male as the result of parthenogenesis from an unfertilized haploid female egg versus birth of a male as the result of normal fertilization by a male sperm), I (and virtually any scientist worthy of that name) would judge the latter hypothesis as the more likely. To accept the former would absolutely require a detailed genetic analysis of the subject in question, which (barring the Second Coming) would seem to be impossible for the foreseeable future.
In other words, keep reminding yourself “magic isn’t science” and “science isn’t magic”…
25
Allen_MacNeill
11/22/2006
1:48 am
Come on, Dave, since when are links on the web considered superior to biology textbooks? Having written one, I can tell you that if I had stated in it that the cells that result from the first division of meiosis are diploid, I would have lost the contract for that (and any other) textbook.
Yes, it is a “semantic” distinction, but it’s one that every biologist agrees with: the first division of meiosis produces haploid cells, in which the chromosomes are double-stranded. Once again, double-stranded chromosomes are NOT homologous, they are identical as the result of chromosome replication during the S phase of interphase.
Once again, why is it apparently impossible for you to admit you are wrong on this?
26
Allen_MacNeill
11/22/2006
1:50 am
DaveScot wrote:
“Please support your estimate of the odds.”
Tipler has obligingly done this for me: they are 1 in 120 billion. Now, you supply the odds that Mary got pregnant the old fashioned way…
27
Allen_MacNeill
11/22/2006
1:57 am
Tipler also calculates:
“Adding all these numbers gives about 60 billion people as the total number of people who have ever lived.”
By his own admission, all of those people were conceived the old fashioned way. That is, given all of the human beings that have ever existed on the planet (i.e. somewhere in the ballpark of 60 billion), by Tipler’s own calculation not one of them would have been expected to have arisen as the result of the extremely convoluted (and virtually biologically impossible) mechanism that he himself proposes.
In other words, the odds are:
60 billion/60 billion = 1/1 = 1 = 100% in favor of non-virgin birth of a male (minus 0.5/120 billion, to compensate for the probability that Tipler’s “magical” parthenogenesis actually occurred)
versus
1/120 billion in favor of virgin birth of a male
Honestly, I’ve never encountered a more skewed comparison of probabilities, and don’t expect to again (outside of this website, that is)
28
Allen_MacNeill
11/22/2006
2:00 am
“…46 is the exact number of chromosomes in the first two daughter cells produced during meiosis”
Here is precisely the problem: a double stranded chromosomes are always counted as one chromosome, and so are single-stranded chromosomes. That’s the way chromosomes are defined in biology. The daughter cells that are produced by the first division of meiosis in humans therefore contain 23 (not 46) chromosomes. True, those chromosomes are double-stranded, but that doesn’t matter; they still only comprise 23 chromosomes.
29
Allen_MacNeill
11/22/2006
2:02 am
And yes, I’ve read Davison’s semi-meiotic hypothesis, and that’s all that it is: a hypothesis. As far as I’m aware, neither he nor anyone else has any empirical evidence to directly support it (i.e. actual organisms that have genomes that are unambiguously the result of semi-meiosis). Interesting, but without empirical verification, it’s just airy speculation…
30
DaveScot
11/22/2006
2:05 am
Allen
The Mexican males articles was only to point out that XX males absent any SRY aren’t necessarily different in outward appearance. It was totally to address Robin’s contention that if Christ was an XX male he’d necessarily be all weird looking.
Haploid eggs in humans can be easily stimulated to double their chromosome count and begin dividing as diploid cells. I should think their subsequent diploid form would be 100% homozygous to so would that make them still arguably haploid among pedants? They just don’t live very long after becoming diploid. At this point in time I don’t think anyone can say what mechanism might be disabled that would prevent them from dying young. Observed parthenogenetic reproduction in other species speaks to there being some simple mechanism in mammals and gymnosperms that is preventing them from maturing.
Secondary sexual characteristics aren’t always dependent on SRY. That’s speculation on your part and doesn’t hold up in the literature as the SRY gene is definitively NOT expressed in some XX males and the Mexican sibs demonstrate that SRY negative males can be quite indistinguishable from normal males. Granted this makes the probability even smaller that Christ was a parthenogenetic XX SRY negative male but by your own admission this isn’t quite impossible.
I’m still waiting for those odds… nobody said virgin birth in humans was common. In fact there’s only one claim of it in history. Our purpose here is only to determine if it is possible or not. You’ve already hedged in saying it’s virtually impossible which is really an admission that it is indeed possible but improbable.
31
Allen_MacNeill
11/22/2006
2:19 am
Precisely: “possibility” and “probability” are two entirely different things. Sure, it’s “possible,” but so “improbable” as to be virtually impossible.
In science, that’s all we have: comparative probabilities. As I pointed out, the comparative probabilities are so overwhelmingly in favor of Jesus having been conceived as the result of normal copulation/fertilization as to render the “possibility” of “virgin birth” moot.
By the way, my wife (a magna cum laud from Cornell in classics, with a specialization in Mediterranean religions around 0 A.D. and fluent in six classical languages, including Aramaic and Biblical Hebrew) just pointed out that the Aramaic word that is usually translated as “virgin” in English bibles can just as easily be translated as “young woman”…which also makes all of the foregoing debate moot as well.
32
DaveScot
11/22/2006
2:19 am
Allen
When the definitions of diploid are in online biology glossaries from many major institutes of higher learning and so very many of them (about half) don’t define diploidy as requiring chromosomes from two parents you bet I’m going to argue the point. It’s inconceivable that so many of them would have erroneous definitions and I’d bet dollars against donuts most of those glossary definitions online were pulled straight out of text printed on dead trees.
I have no dispute that the vast majority of texts call the first daughter cells of meiosis “haploid” but it appears that’s just by tradition. It’s a damn confusing tradition too. There should be a qualifier saying it’s a diploid number but we still consider them haploid cells because they are 23 identical pairs.
Perhaps you can answer my question to Joseph: what do we call asexual diploids that don’t have a contribution from both parents in their 2n number? The literature still calls them diploid but their genetic compliment is derived from a single parent. That seems to dash the definition requiring two parents does it not?
33
Allen_MacNeill
11/22/2006
2:21 am
And, once again, where is the empirical evidence in favor of the “virgin birth” hypothesis? Airy speculation isn’t evidence, either direct or indirect. Simply showing that something is “possible” says absolutely nothing at all about whether it actually happened.
34
DaveScot
11/22/2006
2:22 am
If you’re asking me personally if I believe Christ was born to a virgin the answer is no. I’m an agnostic and that puts me pretty darn far from a biblical literalist. As an agnostic however I don’t deny the possibility that stories in the bible are literal truth. Science has demonstrated that Christ’s virgin birth IS possible. That’s all that matters. The door is left open a crack for it to be true.
35
DaveScot
11/22/2006
2:25 am
Allen
Simply showing that something is “possible†says absolutely nothing at all about whether it actually happened.
You got that right. How much of evolutionary theory regarding events in the distant past are possible but say nothing at all about whether it actually happened?
I’ll be quoting you on that one. This possibility stuff cuts both ways.
36
Allen_MacNeill
11/22/2006
2:36 am
Re comment 32:
Indeed, asexual diploids are still just that: diploids. And yes, it is sometimes confusing (as I stated, some of my students are confused by this every year). The point here is that the definitions of “diploid” and “haploid” are ultimately based on what objects are moved around by the microtubules of the spindle apparatus in meiosis. Anything that is moved as a single unit by a spindle fiber is, by definition, one chromosome, regardless of whether it is single or double stranded.
This definition has several implications. As I point out to my students every year, since we count chromosomes by counting independently segregating units, the chromosome number of a cell dividing by mitosis temporarily doubles during anaphase, since the two chromatids of each double-stranded chromosome are separated by the cleavage of the centromeres that hold them together. Then, following cytokinesis (which usually happens during telophase) the original chromosome number is restored in the two daughter cells.
In meiosis, however, something quite different happens. During the first division of meiosis, the chromatids of the double stranded chromosomes are not segregated from each other. Instead, the homologous chromosomes from each parent (which paired up during prophase I of meiosis) are segregated from each other.
In humans, this means that each of the 23 chromosomes pairs up with its homolog during prophase I, and is then segregated from its homolog during anaphase I. These chromosomes are all double stranded, but they still only count as one chromosome each. Hence, once the two daugher cells separate from each other during interkinesis, each daughter cell contains one complete set of double stranded chromsomes: i.e. 23, the haploid or 1N number.
Yes, it’s semantically tricky, but the trickiness is necessitated by the complexity of the process. We have to have some way of distinguishing between the genetically identical sister chromatids of a double stranded chromosome and the homologous (but not necessarily identical) chromosomes that line up during prophase I of meiosis.
And in most animals (but not plants) the haploid and diploid numbers are essential; if they don’t match up, the organisms don’t develop normally. This is the basis of Down syndrome, in which there are three homologous chromosome 21s, a condition that results in mild to severe cognitive and developomental abnormalities. And chromosome 21 is the only chromosome that can be triploid (except for the X and y, for reasons peculiar to their developmental genetics), probably because it contains so few genes. None of the other homologous pairs can be anything except diploid; the result of any departure from diploidy in all other pairs (except the Xy pair) is spontaneous termination of development, usually in a very early developmental stage.
I know; my wife and I lost a baby that way last Christmas…
37
Allen_MacNeill
11/22/2006
2:43 am
“I’ll be quoting you on that one. This possibility stuff cuts both ways.”
Indeed, and I hope you do. As I hammer away with my students, scientific hypotheses are worthless if they (a) cannot be used to generate empirically testable predictions, and (b) are not supported by the results of empirical tests.
By those criteria, evolutionary biology passes in most cases. For example, one can predict on the basis of the hypothesis of descent from common ancestors that species that appear to be related by descent (such as chimpanzees and humans) will have nucleotide sequences that are consistent with the hypothesis that they are indeed descended from a common ancestor. The observation that this is, indeed, the case is why Michael Behe accepts descent with modification from common ancestors, as do virtually all biologists.
Furthermore, I would be the first to agree that if a scientist makes a statement that cannot be either empirically tested and either validated or falsified, that scientist is not talking about science. For this reason, I find Richard Dawkins’s pronouncements on the non-existance of God to be utterly outside the realm of the empirical sciences. But nobody who does actual field or lab work would rate Dawkins as “their kind of scientist” anyway; he does no field or lab work, but rather lots of semi-mathematical speculation and public relations. A lot like one of the founders of this website…
38
Allen_MacNeill
11/22/2006
2:53 am
And as to the “problem” of making scientific statements about events that happened in the past (and therefore cannot be directly observed), all forms of “historical” science have the same problem. As I tell my students, none of us can be certain that the people who claim to be our parents are, in actual fact, our parents. After all, we quite literally weren’t there until after we were conceived, and so can’t possibly know beyond a shadow of a doubt.
However, there are empirical means of inferring events we cannot observe directly, either because they happened in the past or because our senses cannot detect them (as in the case of atomic structure). In those cases, we devise empirically testable hypotheses that can be validated/falsified that can allow us to infer whether those unobservable phenomena have, in fact, happened. That’s how we infer the existance of sub-atomic particles and the former existence of Homer’s city of Troy at what is now the “hill of Hysarlik” in Anatolia.
Much of evolutionary biology is tested and validated in the same way. However, it is quite literally impossible to “prove” (i.e. beyond any shadow of a doubt) that descent with modification has occurred, or to “prove” that the principle mechanism for it has been natural selection. That just happens to be what most of the observable evidence points to so far. If someone eventually comes up with new evidence that points unambiguously to the contrary, then we’ll all have to change our minds on that score. Hasn’t happened yet, and won’t until the other side starts doing some empirical research (and publishing it).
39
Allen_MacNeill
11/22/2006
2:56 am
And I’m an agnostic too (and most emphatically NOT an atheist). I agree with T. H. Huxley (who coined the term) and Bertrand Russell (who most ably defended it): it’s the only philosophically justifiable position vis-a-vis assertions that are beyond any possibility of empirical verification/falsification…
40
DaveScot
11/22/2006
3:03 am
Allen
How do you think meiosis evolved? Note I’m trying to conform to convention in calling 2n cells haploid if they don’t have two parents and making the distinction with 1n,2c to indicate there are really twice the number of chromosomes to work with. I’m still confused by the convention and probably got it wrong.
My theory:
Step 1: A 1n,1c haploid organism doubled its chromosome count through duplication.
Step 2: Mitotic crossover was invented in the 1n,2c haploid above.
Step 3: Segregation of the duplicate chromosomes evolved but still produced viable 1n,2c daughters.
Step 4: The next mitotic division from the above failed to duplicate the DNA producing 4 1n,1c haploid daughters.
Step 5: Automictic parthenogenesis where one of the 1n,1c cells from above merged with another to make a viable 1n,2c haploid.
Step 6: Close proximity of single celled organisms from step 5 resulted in 1n,1c cells from two parents to merge into the 2n,2c diploid.
Step 7: Automitic parthenogenesis was largely abandoned in favor of the two parent model.
I just made that up on the fly. Anything in particular wrong with it that can’t be fixed?
41
Allen_MacNeill
11/22/2006
3:14 am
Actually, it probably got started by the fusion of two haploid cells to form a diploid “chimera.” This is very common among protists, and my friend Lynn Margulis has strongly defended the idea that the ancestors of all diploid organisms did this. Meiosis would simply be the mechanism by which the “temporary” diploids could get back to being “normal” haploids. After all, haploid organisms have a complete set of chromosomes.
And then, once the haploid-haploid fusion to form diploid, followed by meiosis to form new haploid pattern became established, multicellularity followed, along with sex (with all its joys and sorrows).
Lynn and her son Dorion have also proposed that the original fusion event was favored because it:
(a) produced an organism that had a “backup copy” of its genome, thereby minimizing the damage caused by random mutations, and
(b) allowed such organisms to use one genome to “proof-read/edit” the other.
Sex, in other words, started out as editing.
BTW, I just checked that old thread and read your comments about Scotland. Damn, son, are you a scot in addition to being a Scot? Is that where the Scot of DaveScot comes from? If so, we have a LOT more in common besides agnosticism…
BTW, the clan Neil was on the side of Bonny Prince Charlie during the rising of ‘45 (and has historically had little or no respect for the Campbells of Glencoe infamy). Where might you fall on these *ahem* rather touchy issues?
42
Allen_MacNeill
11/22/2006
3:15 am
gotta get some shut-eye; will check tomorrow…
43
DaveScot
11/22/2006
3:34 am
Allen
Hmmm… skipping straight up to step 6 leaves a lot of meiosis to evolve in one fell swoop does it not?
re Scotland - No, Scot is my middle name and contrary to the way everyone wants to spell it, it has only 1 t in it. My ancestors centuries ago were English (been in the new world since colonial times). We built the English Empire. The Scottish Empire (if you can call it an empire) was tiny in comparison. You hitched a ride with us in 1707, moved your parliament to London, and we called the combined empire the British Empire. I’ll grant that Scotsmen are fierce as individuals but we English are the ones that figured out how to be a fierce nation. Hence your family coat of arms puts family above nation and mine puts nation above family. It all makes perfect sense.
I personally wouldn’t dream of flying any flag above the stars and stripes but I’d respect your right to do so and any local statutes to the contrary are probably a violation of your first amendment rights. The constitution doesn’t speak of how to fly the national flag so it’s a right reserved to the states and they could make the statutes on those grounds but the 1st amendment freedom of expression still seems to stand in the way and the 14th amendment means the 1st applies to all the states. I tend heavily towards libertarianism (with a few exceptions to the party plank) but since my vote is thrown away if I check the L candidate (if there IS an L candidate) I vote the lesser of two evils (R). My libertarian tendency stems from thinking adults should be treated like adults and if they want to do any damn foolish thing that harms no one other than themselves then let ‘em. Darwin will weed out the damn fools and we’ll be better off as a herd for it in a generation or three. I grew up in upstate New York and really love it there for a lot of reasons but it’s about as far from a libertarian’s dream as one can get. Texas is a great improvement in that regard but it just isn’t home for me and never will be no matter how long I live here.
In closing, in the immortal words of Clint Eastwood playing Marine Gunnery Sergeant Highway in the movie Heartbreak Ridge, just because we agree on a few things “This doesn’t mean we’ll be swapping spit in the shower.”
44
Robin Levett
11/22/2006
3:49 am
DaveScot said:
I deleted a previous response to Robin as it was unnecessarily offensive. I found a non-offensive rebuttal.
I’d prefer it if I saw the offensive responses, as well as the non-offensive ones. If you’d prefer the blog not to be polluted, then send it by email.
Allen has taken on the discussion on the remainder of your post…
45
Joseph
11/22/2006