posted
Thanks Rohan! I'll probably leave mine up now cause of the posts that came afterwards. Thanks for understanding. You are way cool.
Posts: 780 | Registered: Jul 1999
| IP: Logged |
posted
i consider mr. card and his family to be my friends. the cards (and their childred) are gracious hosts both in public and private circumstances. i have always felt welcome at card's signings, i think he goes out of his way to show appreciation for the people that read and like his books.
i love the card family. especially that cute blonde with the bizarre sense of humor.
Posts: 3936 | Registered: Jul 2000
| IP: Logged |
posted
Honest Abe-- Interesting post! I'm actually more used to hearing people say that the Genesis flood was plagiarized from other ancient legends.
Honestly, though, can't you have it both ways? If those other ancient legends exist, then the writer of Genesis was stealing material. If they don't exist, then that's proof that the Flood never happened. Perfect! Posts: 107 | Registered: Jan 2004
| IP: Logged |
posted
the writer of genisis? I don't know much about the history of the bible, who wrote it?
That post i made earlier with the Satans Rapid Deployment Force, it may be mocking, but the species and evidence is quite real. many of the "missing links" are there.
Posts: 33 | Registered: Feb 2004
| IP: Logged |
posted
I should post a recent picture, to dispel THAT idea Maybe the cartoon of me on my website will be enough of an illustration ...
Posts: 1907 | Registered: Feb 2000
| IP: Logged |
quote: (We also started Ornery in hopes people would take there political discussions there--much good it did me )
Wow, I feel so vindicated since I used to whine about the political discussions in BFFAC. And the folks there would say "it's not literally BFFAC, it's a catchall and we can post on whatever we want." Finally, I decided that if there were going to be political discussions, some conservative views should be in them. Hmm.
Posts: 11017 | Registered: Apr 2003
| IP: Logged |
posted
I feel like I'm friends with the Cards, but it's more of a one way friendship, however, on hatrack esp. that's not uncommon. I feel like I'm friends with a lot of people here I've never spoken to, at least I've spoken to the Cards.
posted
As i finished the shadow series tonight i became overcome by depression. I had finally finished what i set out to do only 3 months ago...I finished the enders series as well as the shadow series. But im left with a hunger for more bean, more peter wiggin of the outside, and ive never grown tired of Ender.
Through these last 3 months i have felt ive gotten to know Card from his writings, the way his writing and development of plot and charachter can sway my own mood and feelings as a bystander. If i had a bad day, instead of reading 50 pages at night id read 100 and feel much better.
I cant say Card is my friend, yet his writings have been the best friend ive had over the last 3 months sadly enough, and i hope that there is more of Ender, Bean, or Peter in the future (*if there is something already in progress i have not seen or been informed of it would be nice to know).
Also this post is based on threads original topic, i began to read through the pages but got lost in the nonsense on page 1
Posts: 7 | Registered: Mar 2004
| IP: Logged |
posted
It sounds like you would love the Alvin Maker series (what ^she said). His other single books are really addicting as well : The Worthing Saga, Enchantment, Lovelock (with Kathy Kidd), the first two Women of Genesis books...and all the short stories in Maps in a Mirror.
I haven't yet read the Homecoming series, so I can't recommend it to you yet, but that's a good one too!
This should keep you from being depressed at the absence of books for a while. (I know that feeling.)
posted
Yozhik asked me to reply to this thread. She described me as a "biology teacher". While that is my passion and occupation, I am also a biologist (M.S. plus 183 credit hours).
cochick wrote
quote:"Well as far as evolution goes "Man was created in Gods Image" - I don't know about you guys but my ancestors didn't climb out of no primordal swamp or evolve from apes etc."
Evolution says that you and apes have a common ancestor, not that humans evolved from apes. This is a common misconception. You also share ancestors with every other living being on the planet including yeast, plants, and bacteria.
Taalcon wrote:
quote:There's macro and micro evolution - belief in one doesn't necessitate the belief in the other.
It's good of you to note the difference. Most people are not aware of this. To add a definition, microevolution is evolution below the species level. In essence it is the change in gene frequencies within a species over time. This has been well documented. Microevolution is an indisputable fact. We rely on this to supply us with vaccines for influenza virus, to treat HIV infections, to control pest and pathogen populations in crops, and many other practical applications.
Macroevolution is evolution beyond the species level. It is the creation of new species, genera, and levels of characterization above. The key question here is: can one species diverge into two? In order to answer this question, we must define species. I'll use the biological species concept sensu Mayr which says that an organism is a different species from another organism if it cannot interbreed with another group of organisms. Based on this definition, I'll give you one well-documented case of rapid speciation. Because I'm a plant scientist, this comes from the Botanical world. O. lamarkiana, a species of flowering plant is a classical example. In a population of O. lamarkiana, a large individual was identified. This individual was vegetatively propagated, and was found to produce viable offspring with crossed with itself, yet be completely incompatibile with its' parent. In a single generation, this new species became completely genetically isolated from the parent population. The new species was called O. gigas. Chromosome analysis revealed that the plant arose by polyploidy. In essence, the plant did not undergo the reduction of chromosome number involved in meiosis, and thus doubled its' chromosome number. As a result, it was no longer fertile with its' parent, but fertile with offspring derived from vegetative propagation of itself. Genetic analysis of many plants supports the idea that speciation by polyploidy is common in the plant kingdom.
There are cases of rapid speciation in the animal kingdom as well. Fruit flies are the best studied examples I know of. I'm less familiar with the literature, but there was a study done by scientists at Cornell where two populations of fruit flies were separated for 30 years. When reintroduced to each other, reproductive barriers had arisen such that individuals from differing populations had less than 5% of their offspring survive in comparision to 95% for matings between individuals from the same population.
For further examples of observed instances of speciation, please visit the talk.origins website. Look up some of the journal articles cited on the web site and read them. If you have difficulty interpreting any of the terminology or statistics, email me. I'm a teacher and I love to teach (I don't mean to be condescending, just helpful--sorry If I come across as the former). I think you will find that macroevolution is also a testable idea which has been proven to be a fact (at least at the speciation level).
If you want to test macroevolution beyond the species level, I suggest that you compare genomic sequences of DNA. You can do this online at the National Center for Biological Information (NCBI) http://www.ncbi.nlm.nih.gov/
Once you have compared DNA sequences of different species, and understand the mathematics of mutation and evolution, I think you will be convinced that evolution is a fact.
It may well be that, as my evolution prof. asserted, "evolution is god's way of creating the beautiful diversity of living things". If true, this neither denies the fact of evolution nor the beauty of creation.
I'm not sure I want to define macroevolution so narrowly as just speciation. I'm more concerned with the big jumps like: inanimate matter to primative reproducing cell with a genetic code, single celled organisms to multicellular organisms, fish to amphibians, etc.
What I want explained is how new organs, new cellular processes come about.
Moving away from debate about evolution I also want to state this: belief in evolution doesn't necessarily mean that one doesn't believe God created anything. There is the engine of evolution to consider: is it purely natural selection? Or might not there be selection by the will of God?
Posts: 3495 | Registered: Feb 2000
| IP: Logged |
posted
I do recall polyploid fertilization in plants, now that you bring it up. But plants are at somewhat of an advantage in being essentially hermaphroditic. Indeed, the emergence of AIDS could be pointed to as the creation/evolution of a new life form in our time.
So I'll revise my position to say that non-hermaphroditic organisms have not been shown to very often add an entire chromosome. Thanks for the heads up, Skeptic.
Posts: 11017 | Registered: Apr 2003
| IP: Logged |
quote:I'm more concerned with the big jumps like: inanimate matter to primative reproducing cell with a genetic code, single celled organisms to multicellular organisms, fish to amphibians, etc.
What I want explained is how new organs, new cellular processes come about.
Inanimate matter to primitive reproducing cell is a large step indeed. Many models for how this might have happened exist. I’ll suggest you read John Maynard Smith’s book The Origins of Life (Szathmary, E., Maynard Smith, J. (1999). The origins of life. Oxford University Press). A cell is membrane-bound. If you put phospholipids into water, they spontaneously form spherical bilayers like membranes around cells. These are called coacervates (see http://www.daviddarling.info/encyclopedia/C/coacervate.html Clearly not living cells because they do not grow or divide, but they look like simple cells under the microscope. RNA is probably the best candidate for the first genetic material. Like DNA, it can contain information in sequences of nucleotides. Like Protein, RNA forms complex 3 dimensional structures that can act as catalysts. RNA catalysts are called ribozymes. An autocatalytic group of RNA’s inside a coacervate is one model. That ribozymes can mutate and have novel functions has been demonstrated ( http://www.mpibpc.gwdg.de/inform/MpiNews/cientif/jahrg5/9.99/scta.html ).
How do new organs come about? PBS produced a series called “Evolution” which my students find to be very accessible. One segment discusses the evolution of the eye. You can view it online here http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.html Keep in mind that this is a speculative model that fits the available evidence. This is not proof that the eye actually evolved this way.
How did fish evolve from amphibians? The PBS series did a pretty good job with this as well. It doesn’t tell the entire story, but it does address how you could go from a fish to something with limbs similar to an amphibian. You can view it online here http://www.pbs.org/wgbh/evolution/library/03/4/l_034_03.html
The transition from single cellularity to multicellularity is an easy one to explain. In fact, many species of yeast are able to live as either a single-celled free floating organism, or as a filamentous multicellular organism depending on the amount of moisture in the environment. It only involves a very small number of genes involved in the separation of cells after division.
pooka wrote
quote:So I'll revise my position to say that non-hermaphroditic organisms have not been shown to very often add an entire chromosome.
To minimally address your assertion, I will point to the many disorders caused by nondisjunction in humans. Down Syndrome is caused, in most cases, by an extra chromosome 21. Klinefelter’s Syndrome is caused by being at least XXY, sometimes with more X chromosomes than that. Individuals are also known to show XYY, and other combinations of sex chromosomes. Now, these are not different species, but individuals in which additional chromosomes lead to changes in physical appearance. Addition, subtraction, inversion, and translocation are all types of chromosomal rearrangements. Here are some examples linking chromosomal rearrangements and speciation:
Here’s one in rodents: Hereditas Vol. 139 Issue 1 Page 13 September 2003 Karyotype evolution in South American subterranean rodents Ctenomys magellanicus (Rodentia: Octodontidae): chromosome rearrangements and (TTAGGG)n telomeric sequence localization in 2n=34 and 2n=36 chromosomal forms
posted
That is because skeptic accidently put a period at the end of them. Get rid of the period and they work.
That said, skeptic, I'm quite aware of many of the examples used. I am still not entirely convinced that natural selection could be responsible for such a thing. All that has been shown is the steps in evolution. The flaw in such an intellecutal field trip is to assume that these steps could only have been accomplished by natural selection.
There is a real problem with that assumption, and that is that there almost seems to be purpose. And we know that there can be no purpose in natural selection.
The eye is actually simpler than most examples, because the transitory steps are, in fact, better than what came before. However, where did the rounded, transparent layer in the eye come from?
Every computer simulation involves intelligent design. It only proves that evolution can happen, but humans select for the desired outcome.
Posts: 3495 | Registered: Feb 2000
| IP: Logged |
quote:The flaw in such an intellecutal field trip is to assume that these steps could only have been accomplished by natural selection.
I'd like for you to point out where, in my post I made such an assumption. In fact I pointed out that these were models of how these things might have happened. As for the underlying mechanisms, I'd include sexual selection, genetic drift and endosymbiosis as mechanisms of evolution.
quote:And we know that there can be no purpose in natural selection.
The word purpose seems to imply someone with an idea about where the process ought to end up. The outcome (analogous to purpose without the need for an entity to guide it) of evolution is organisms better adapted to the environmental conditions in which the parent generation found itself.
quote:It only proves that evolution can happen, but humans select for the desired outcome.
If evolution could happen the way the model describes, then it seems reasonable to believe that that was the way it did happen until a better model is presented.
I'd also like to address the intelligent design idea you brought up. There are two main problems with intelligent design. The first is that for it to be true, there must be a designer. To prove intelligent design, you must prove that the designer existed. I've not seen a convincing proof that such a designer existed. In fact, if one does, then I'd like to talk with him about misdesigning my carpal-tunnel so that I had to have it improved through surgery. This is the second problem with intelligent design. If you study organisms in any depth, you will find suboptimal design. The eye is an excellent example. It would be possible to engineer a more effective eye. The eye has a blind spot where the optic nerve runs through the retina. An intelligent designer would have placed the nerves behind the retina to optimize its receptive surface. Unfortunately, because the eye evolved from simpler structures in which neurons were in front of the retina, we are stuck with a suboptimal design that works well enough.
posted
Your problems with the designer assumes you know the motives and methods of the intellegent designer. What if the designer simply desired its organisms to have sight. It did not manufacture the organisms, as you'd like to imply. It simply dropped the purpose into the selection process.
There is no goal in naturalistic evolution. Organisms simply live long enough to reproduce or die. There is so much chance other than natural selection that the tiny, non-harmful mutations required can't even be selected for. They need to be immediately and substantially beneficial to the creature in order for it to be a trait that causes its owners to survive more often to reproduce.
I get really irritated when biologists speculate on the development of parts, and this speculation is taken as important evidence. The eye, for instance, requires photosensitive cells in the first place. Such a small thing, but... how did the cell come to have the ability to produce such a chemical? A retina is the next step, so an organism acquires it. An ability to decrease the opening so that images can be distinguished simply appears. A lens is more efficient, so that comes onto the scene. See? When you show the steps it is so obvious.
No, not to me. I still ask: how did those steps happen. Every one requires new structures, and most need new chemicals as well. Only small mutations happen, and none of those steps can harm the chances of the organism to reproduce. And they must be helpful or be such a common mutation that enough organisms have these new intermediate structures so that evolution to the next tiny step occurs. In many of those necessary micro steps, I fail to see how it could be beneficial.
Genetic drift is simply a way to show how populations can diverge, not how important evolutionary steps occur. Endosymbiosis is a fascenating occurance that can really only explain a few important occurances in primative evolution.
As to intellegent design: One does not have to prove that it exists in order to recognize the possibility of it presented within nature. In fact, it can be argued that the study of the history of life is a part of the evidence for the larger question of 'intellegent design or not?'. My assumption (of an intellegent designer) leads me to be able to explore more options than your implied assumption (that there is no intellegent designer), because along with every other mechanism I can try to determine if there was purpose or not, where you cannot even accept the possibility of purpose.
Posts: 3495 | Registered: Feb 2000
| IP: Logged |
quote: If you study organisms in any depth, you will find suboptimal design. The eye is an excellent example. It would be possible to engineer a more effective eye. The eye has a blind spot where the optic nerve runs through the retina. An intelligent designer would have placed the nerves behind the retina to optimize its receptive surface. Unfortunately, because the eye evolved from simpler structures in which neurons were in front of the retina, we are stuck with a suboptimal design that works well enough.
Skeptic, Would you call an engineer who is designing a robot an "intelligent designer?" I'm sure he would call himself one! When you talk about "suboptimal design", are you comparing the construction of your eye and the rest of your body to something you (or the most intelligent engineer on the planet) could create? I don't notice the blind spot because my brain was designed to compensate for the placement of the optic nerve, and it most certainly works "well enough" for me!
Skeptic wrote:
quote: There are two main problems with intelligent design. The first is that for it to be true, there must be a designer. To prove intelligent design, you must prove that the designer existed. I've not seen a convincing proof that such a designer existed.
I see evidence of a designer all around me, in the same way I see evidence of a designer of a building--the person who designed life is just a lot smarter than the person who designed my house! I don't know who designed it or built it, but I know someone did, because its here.
It really all depends on your perspective and how you interpret the data with which you are presented. I prefer to believe that there is an engineer (who in comparison to us, is most certainly God) who designed this universe. Others prefer to believe that random processes created something that is far better than anything we can even understand, much less create ourselves. The more I study the world around me, the more I'm convinced that human beings, intelligent designers though we might be, will never understand the complexity of even a single bacterial cell, or be able to create one, even with the millions of templates we see all around us.
So, either there's a God, or we're literally dumber than rocks (or RNA at any rate!).
Posts: 107 | Registered: Jan 2004
| IP: Logged |
quote:Your problems with the designer assumes you know the motives and methods of the intellegent designer. What if the designer simply desired its organisms to have sight. It did not manufacture the organisms, as you'd like to imply. It simply dropped the purpose into the selection process.
My problems with the designer assume no such thing. I don’t have proof that such a thing exists. To accuse me of believing that I know the motives of something I don’t believe exists seems ridiculous (not that I believe that a designer does not exist—I simply have no evidence one way or the other). You obviously believe it exists without proof and that it wanted organisms to have sight, but didn’t take the time to do the job right, even though it is omnipotent.
quote:There is no goal in naturalistic evolution. Organisms simply live long enough to reproduce or die. There is so much chance other than natural selection that the tiny, non-harmful mutations required can't even be selected for. They need to be immediately and substantially beneficial to the creature in order for it to be a trait that causes its owners to survive more often to reproduce.
This is simply incorrect. You are arguing against a misunderstanding of evolutionary theory. Please read a textbook on evolution such as the one written by Futuyama. The fact that non-harmful mutations aren’t selected for or against is vital to modern evolutionary theory. Mutations do not need to be immediately or substantially beneficial. In fact, most mutations are silent.
quote:I get really irritated when biologists speculate on the development of parts, and this speculation is taken as important evidence.
Your irritation or lack thereof has no impact on the truth/untruth of an idea. Still, I did not present any speculation as important evidence. In fact, I pointed out that in answering your questions I was presenting speculation. I get irritated when people don’t read what I wrote and accuse me of doing things that I haven’t done.
quote:See? When you show the steps it is so obvious.
Simply because I do not know exactly how something happened does not mean that it didn’t happen by evolution. Alternative models are fine. However, if you are going to postulate a designer, then I want you to prove that a designer exists.
quote:Genetic drift is simply a way to show how populations can diverge, not how important evolutionary steps occur. Endosymbiosis is a fascenating occurance that can really only explain a few important occurances in primative evolution.
This is simply not true. Genetic drift is at the heart of how speciation occurs. Most speciation events rely on some kind of isolation followed by genetic drift. Please read any basic evolution text.
quote:My assumption (of an intellegent designer) leads me to be able to explore more options than your implied assumption (that there is no intellegent designer)
I never said that there was no intelligent designer. I simply said that I wanted to talk to him if he existed. Clearly the lack of an intelligent designer is a simpler model than a model that includes one. If you want a model that includes an intelligent designer, then I want you to explain how he came into existence, what his properties are, and provide some testable experiment which demonstrates his existence.
quote:where you cannot even accept the possibility of purpose.
If you go back and really read what I wrote, you will find that your statement here is way beyond reality. You have responded to something you think I believe without evaluating what I wrote. I certainly can accept the possibility of purpose. I’m just sorry to see that you are so blinded by preconceptions that you don’t read what I wrote.
Posts: 57 | Registered: Jun 2003
| IP: Logged |
quote:I'm convinced that human beings, intelligent designers though we might be, will never understand the complexity of even a single bacterial cell, or be able to create one, even with the millions of templates we see all around us.
I have to agree with you here. I'm glad you appreciate the complexity of a single bacterial cell. We probably will never understand them in their entirety or be able to create one. Still, it's worth some time trying.
quote:you cannot even accept the possibility of purpose
AFAIK skeptic is an agnostic, not an atheist. He is arguing purely from the viewpoint of what science can discover, while Amka's and Shepherdess' arguments involve faith. You're not playing under the same ground rules, therefore the discussion is likely to devolve into an apples-to-oranges comparison.
As for me, I believe that God is real. But I don't believe that his actions can be found or proven by scientific means. That's not what science is FOR.
(Also, I think that God deliberately didn't leave any proof for us. Otherwise we would have knowledge, not faith, and our agency would be compromised.)
I also don't believe in any type of "God-of-the-gaps" theory, i.e., "We don't understand how it happened so God must have done it." I see this approach as ultimately faith-destroying, because once we DO understand whatever it is, then whoops, there goes our faith.
quote:The more I study the world around me, the more I'm convinced that human beings, intelligent designers though we might be, will never understand the complexity of even a single bacterial cell, or be able to create one, even with the millions of templates we see all around us.
I think we will. Maybe not me personally, but SOMEBODY, someday. And it will be really, REALLY cool.
[ March 13, 2004, 02:16 AM: Message edited by: Yozhik ]
Posts: 1512 | Registered: A Long Time Ago!
| IP: Logged |
quote:AFAIK skeptic is an agnostic, not an atheist. He is arguing purely from the viewpoint of what science can discover, while Amka's and Shepherdess' arguments involve faith. You're not playing under the same ground rules, therefore the discussion is likely to devolve into an apples-to-oranges comparison.
Thanks for clarifying this. Yozhik is right. I am an agnostic. I would like to believe in God and an afterlife but I can't without some evidence. I can't simply accept God on faith, and all of the religious training I have had asserts that this is exactly what you must do. I believe that the existence of god is untestable.
My intention in posting on this topic was not to challenge anyone's belief in god, but to teach what modern evolutionary theory really is. There seems to be much misunderstanding and false knowledge being presented in this forum. It was my intention to clarify so that you can make informed decisions on the issue. It doesn't really matter to me whether you reject all of evolutionary theory after you understand it, but the teacher in me simply can't stand the idea of people rejecting ideas without understanding what they are rejecting.
For evidence of macroevolution beyond the species level, I think the most compelling is in the genetic code itself. Here is a link to the NCBI website's primer on molecular phylogenetics: http://www.ncbi.nlm.nih.gov/About/primer/phylo.html
posted
Yozhik and skeptic, The point I was trying to make in my post (which may have been missed) is that we are not comparing apples and oranges. We are comparing different perspectives of looking at the evidence. Believing in macroevolution beyond the species level does involve some faith, whether or not the scientists want to admit it. When it comes to that, I think we have to agree that neither one of us have convincing enough proof to change the other person's perspective, and so it becomes a matter of faith.
I think it would be thrilling if someone could create a bacterial cell in the lab. However, whoever did it would most likely be using gene sequences that had been isolated from other cells, not to mention the same protein synthesis mechanisms that are used in living cells already. When and if we create life, we will be using building blocks and genetic code that is already here, because it is better than anything we can come up with on our own. We will be imitating the original designer, at least in my perspective.
When I do multiple sequence alignments comparing genes from different species, I see evidence that the same intelligent designer created it all, not that we had the same ancestor. I am in awe of the engineer who, starting from scratch, created the genetic code, not to mention DNA replication mechanisms (with redundant systems for genetic fidelity). I see evidence for a finely controlled system involving resistance to change at the DNA replication level, but allowing for variation to preserve and diversify species, mostly through genetic recombination.
But that's just my perspective, and I'm certainly not going to imply that people who believe otherwise are inferior or less evolved than I am.
Posts: 107 | Registered: Jan 2004
| IP: Logged |
posted
I guess my only reaction to this is that I would appreciate it if there would be more admission that these things are not known and that intellegent design is a possibility.
Unfortunately, things are sometimes more complex rather than simpler. Newton's physics were far more simpler than Einstein's, but it was the General Theory of Relativity that won out because it explained more. Heck, the Genetic Code (A language, even!) is far more complex than earlier pictures of how traits are inherited.
The difficulty is that an intellegent designer is a wild card, indescribable and unpredictable by science. And therefore science cannot be used. And this is where I get irritated. I'm not attributing this to skeptic, just shouting out my pet peeve in general. Believing in something that cannot be scientifically verified is not irrational when science is not even the proper tool to describe it.
My experiences in life are, by nature, not scientific, yet I cannot deny things that have happened to me and if I am to keep my integrity, I must act on them.
Science simply cannot explain or describe everything.
quote:To minimally address your assertion, I will point to the many disorders caused by nondisjunction in humans. Down Syndrome is caused, in most cases, by an extra chromosome 21. Klinefelter’s Syndrome is caused by being at least XXY, sometimes with more X chromosomes than that. Individuals are also known to show XYY, and other combinations of sex chromosomes. Now, these are not different species, but individuals in which additional chromosomes lead to changes in physical appearance.
Thank you for minimally addressing my assertion
Though this is something I don't know. Is xy/xx a mechanism for the differentiation of sexes in all primates? Mammalians? Chordates? How common of a mechanism is that? Does polychromosome artifacts show up much in other species? I think in environments where natural selection is still operative, such individuals tend to not live very long. But I think I asked about XXYs and whether they can reproduce earlier in the thread. P.S. Sex Chromosome abnormality site Apparently, XYY and XXX are fertile, though I don't know whether the duplicated chromosomes pass on to offspring. Another site I saw while googling this said that multiple sex chromosomes are more common in fertility treatments where a sperm is injected into the egg.
posted
The XY chromosome arrangement is universal among mammals (to the best of my knowledge), and some other groups have a similar method (some insects, for instance). However, other vertebrates use different methods. In birds, the reverse is true (and Z & W are used); a female bird has the ZW karyotype, a male ZZ. Among reptiles, amphibians, and fish the method varies widely. Some are chromosomally determined, some are determined by genes on normal paired chromosomes, and some are determined by environmental factors. Crocodilians, for instance, are at risk because their sex is determined by temperature before hatching. An environment that becomes too hot or too cold will result in all offspring being of the same sex.
Posts: 1114 | Registered: Mar 2004
| IP: Logged |
Oh, and something else: only two trisomies not involving the sex chromosomes are nonlethal (Down's syndrome and another very similiar condition; I don't recall the chromosome numbers), and every monosomy except Turner's Syndrome (XO) is also lethal. I do not have any research before me, but I would be surprised if the same was not true for most animal species.
So it would be very unlikely to produce a new species by this means, at least among animals. There are a few animal species that are polyploid (they have more than one entire set of chromosomes), such as parthenogenetic whiptail lizards. It might be worth taking note of that aside from the parthenogenesis, these species are virtually identical to other whiptail lizards. In fact, being essentially clones of each other, further evolution would have to be very very slow. There is no sexual recombination occurring, so all that is left is mutation.
Posts: 1114 | Registered: Mar 2004
| IP: Logged |
posted
I beleive it is Trisomy 18. When i worked for UCP, there was a little girl with T18. I remember that at the age of three, she had the size and developmental ability of a two moth old. Sadly, she died at 7.
Posts: 2711 | Registered: Mar 2004
| IP: Logged |
posted
Hmmm...my reading indicates that there are some children with other trisomies who live for some time. This site indicates that certain children also have trisomy 13 and 14, and possibly others. Still, these children tend to die very young; they certainly do not reach maturity and reproduce. I hate to discuss it so clinically--the death of children is very saddening--but that is the topic, and it is important.
Posts: 1114 | Registered: Mar 2004
| IP: Logged |
posted
The lower the number of the gene the trisomy occurs on, the greater the defectc and the shorter the lifespan. I think that Angelman's is caused by Trisomy 15.
Posts: 2711 | Registered: Mar 2004
| IP: Logged |
posted
The smaller the chromosome number, the larger the chromosome (and therefore the more DNA it contains). This means that the smaller the number of the chromosome with trisomy, the less likely of survival.
Posts: 12 | Registered: Feb 2004
| IP: Logged |
posted
from most of his books his religion doesnt look like it has limitation over his writing. but there still good Posts: 12 | Registered: Mar 2004
| IP: Logged |
Printer-friendly view of this topic
![[Evil Laugh]](graemlins/evillaugh.gif)
![[Smile]](smile.gif)
Maybe the cartoon of me on my ![[Grumble]](graemlins/grumble.gif)
![[No No]](graemlins/nono.gif)
![[Cry]](graemlins/cry.gif)
![[Wave]](graemlins/wave.gif)
![[Cool]](cool.gif)
![[Roll Eyes]](rolleyes.gif)
![[ROFL]](graemlins/rofl.gif)
