Uncommon Descent Serving The Intelligent Design Community

There are more things in heaven and earth, Paul, Than are dreamt of in your philosophy.

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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.

Comments
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).Allen_MacNeill
November 21, 2006
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"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...Allen_MacNeill
November 21, 2006
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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...Allen_MacNeill
November 21, 2006
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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.DaveScot
November 21, 2006
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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.DaveScot
November 21, 2006
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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.Allen_MacNeill
November 21, 2006
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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?DaveScot
November 21, 2006
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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.Allen_MacNeill
November 21, 2006
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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.DaveScot
November 21, 2006
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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...Allen_MacNeill
November 21, 2006
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"...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.Allen_MacNeill
November 21, 2006
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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)Allen_MacNeill
November 21, 2006
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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...Allen_MacNeill
November 21, 2006
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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?Allen_MacNeill
November 21, 2006
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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"...Allen_MacNeill
November 21, 2006
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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. DaveScot
November 21, 2006
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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.DaveScot
November 21, 2006
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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/Glossary/Glossary.cfm?TermEnglish=diploid http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookglossD.html http://www.stanford.edu/group/hopes/sttools/gloss/d.html http://worms.zoology.wisc.edu/frogs/glossary.html#D http://www.ggc.org/glossary.htm http://webpages.charter.net/teefile/biognomen/glossary.html http://naturalsciences.sdsu.edu/classes/lab2.5/glossary.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.php?lang=en_GB&word1=diploid+glossary+parent&word2=diploid+glossary http://googlefight.com/index.php?lang=en_GB&word1=diploid+glossary+parents&word2=diploid+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?DaveScot
November 21, 2006
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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.Allen_MacNeill
November 21, 2006
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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/library/glossary/bldefdiploid.htmJoseph
November 21, 2006
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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.Joseph
November 21, 2006
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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.
Chromatid From Wikipedia, the free encyclopedia Jump to: navigation, search A chromatid is one of two identical strands making up a chromosome that are joined at their centromeres, for the process of nuclear division (mitosis or meiosis). The term is used so long as the centromeres remain in contact. When they separate (during anaphase of mitosis and anaphase 2 of meiosis), the strands are called daughter-chromosomes. [1] In other words, a chromatid is "one-half of a replicated chromosome" [2] It should not be confused with the ploidity of an organism, which is the number of homologous versions of a chromosome. The term chromatid was proposed by Hector from Glenbard South for each of the four threads making up a chromosome-pair during meiosis. It was later used also for mitosis. The term derives from the Greek chroma (colour); for the derivation of -id, see diploid.
HodorH
November 21, 2006
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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/content/dxpf68yc402w3k6n/ From the journal "Human Genetics"
We report a Mexican family in which two sibs were identified as "classic" XX males without genital ambiguities. Molecular studies revealed that both patients were negative for several Y sequences, including SRY. A review of familial cases disclosed that this is the first family where a complete male phenotype was observed in Y-negative XX male non-twin brothers. These data suggest that an inherited loss-of-function mutation, in a gene participating in the sex-determining cascade, can induce normal male sexual differentiation in the absence of SRY.
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).DaveScot
November 21, 2006
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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.DaveScot
November 21, 2006
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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.Robin Levett
November 21, 2006
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Allen Maybe you can correct this description of meiosis I found at Brown University. http://www.brown.edu/Courses/BI0032/gentherp/phaseIB1.html
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.
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.
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.DaveScot
November 21, 2006
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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:
In parthenogenesis, the egg becomes the sole source of genetic material for the creation of an embryo. It is a mode of reproduction in some species, though not in mammals. 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. This is because of there a biological phenomenon known as imprinting. During sperm and egg formation in mammals, certain genes necessary for embryo development are shut down with a series of chemical marks, or imprints, some in the sperm, other in the egg. Only when sperm and egg meet are all of the key genes available, allowing proper development.
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.DaveScot
November 21, 2006
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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):
We first have to understand how a virgin birth of a human male can be accomplished using only known molecular biological mechanisms. There is now an extensive scientific literature on virgin birth in vertebrates. Virgin births have been extensively studied in Caucasian rock lizards [34], and also in turkeys ([35], [36]). There is one strain of turkeys ([35], [36]) in which more than 40% of all births are virgin births. What happens in these turkeys is that often a haploid egg cell begins to divide without being fertilized by a sperm cell. If at some point early in the cell division process, the chromosomes duplicate so that a diploid cell is formed, a normal turkey is born. This parthenogenetic turkey is always a male, because in birds, a male results if the two sex chromosomes are the same (a male bird has two Z chromosomes and a female is WZ.). It is easy to induce a human oocyte (egg cell) to begin cell division without first being fertilized by a sperm ([37]-[40]). The oocytes thus induced to begin division can be either haploid or diploid. This human oocyte cell division is so easy to induce in the laboratory that many researchers in this field have suggested that virgin births may be quite common in humans, perhaps as common as identical twins, which on the average occur 1 out of every 300 births (Encyclopaedia Britannica, "Multiple Births", 1967 and 2003 edition). This conjecture on the rate of virgin births could be easily tested. One would merely conduct a DNA identity test on female children who are observed to closely resemble their mothers. (Almost all virgin birth children would be expected to be females. The extremely rare exception I shall discuss below.) To date, no such investigation has been carried out, probably because of ethical objections. With human oocytes, again for ethical reasons, no attempt has yet been made to implant these virginally conceived fetuses into a womb. An attempt was made a few years ago to complete a virgin birth in a marmoset monkey [37], but it was unsuccessful. Because of a peculiarity in the centromeres of primate cells (they are inherited from the father), I myself suspect a primate virgin birth could result only if a diploid oocyte started to divide. Of course, in every case of a virgin birth, all the genetic information has to be already present the mother. There are at least three ways to generate a male human being from genetic information which comes entirely from the mother. I shall discuss only one such method here (for another, see [18], p. 44, and below.). I propose that Jesus was a special type of XX male ([44]-[49]). Approximately one out of every 20,000 males is an XX male. Such males are normal in behavior and intelligence, but have smaller teeth, shorter statue, and smaller testis than normal males. They are usually identified as XX males because they cannot have children, and ask doctors to cure the infertility. Normal males are XY, but there are only 28 genes on the Y chromosome, as opposed to thousands on the X chromosome. Of these 28 genes, 15 are unique to the Y chromosome, and 13 have counterparts on the X chromosome [41]. The gene with counterparts on both the X and the Y chromosomes are called "homologous genes." An XX male results when a single key gene for maleness on the Y chromosome (the SRY gene) is inserted into an X chromosome. I propose that ALL (or at least many) of the Y chromosome genes were inserted into one of Mary's X chromosomes, and that in Mary, one of the standard mechanisms used to turn off genes were active on these inserted Y genes. (There is an RNA process that can turn off an entire X chromosome. This is the most elegant turn-off mechanism.) Jesus would then result when one of Mary's eggs cells started to divide before it became haploid and with the Y-genes activated. (And of course with the extra X genes deactivated.) If a sample of Jesus' blood and/or flesh could be obtained, my proposal could easily be tested by carrying out two distinct DNA tests for sex: (1) test for the Y genes and (2) test for two alleles (different gene forms) of X chromosome genes. In other words, a male born of a virgin would have two X chromosome genes for each of its counterpart Y gene. Normal males would have only one X chromosome gene for each of its Y counterpart gene. This pairing would apply to each of the 13 genes on the Y chromosome that has an X counterpart. Such a Virgin Birth would be improbable. If the measured probability that a single Y gene is inserted into an X chromosome is 1 in 20,000, then the probability that all Y genes are inserted into an X chromosome is (1/20,000) raised to 28 power, the power corresponding to the number of Y genes. (Assuming that the insertion of each Y gene has equal probability, and these insertions are independent.) There have been only about 100 billion humans born since behaviorally modern Homo sapiens evolved between 55,000 and 80,000 years ago ([74], p. 704). The number of humans that have ever lived is roughly computed as follows. In the first 60,000 years of modern human existence, there were roughly 10 million humans living world wide, with complete replacement every generation, roughly every 30 years. With 2,000 generations in 60,000 years, this means 20 billion people lived in this period. Over the next 6,000 years, humans had agriculture, which allowed the support of a population of roughly 300 million. With 200 generations in 6,000 years, this means that 30 billion people lived in this period. Finally we come to the modern period, essentially the period of the people now living. There are now 6 billion people in the world. Adding all these numbers gives about 60 billion people as the total number of people who have ever lived. Thus, the virgin birth of such an XX male would be unique in human history even if there were only 2 such Y genes inserted into an X chromosome. (I assume an upper bound to the rate of virgin birth is 1/300. Then the probability of a virgin birth of a male with 2 Y genes is 1/(300)(20,000)(20,000) = 1/120 billion.) SOURCE: http://home.worldonline.nl/~sttdc/tipler.htm
William Dembski
November 21, 2006
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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.DaveScot
November 21, 2006
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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. DaveScot
November 21, 2006
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