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 Posted: Mon Dec 03, 2007 1:28 pm
Recently a group of friends and I were discussing various aspects of human genetics. In the course of this conversation, someone brought up chimera syndrome. There are several different kinds of chimera syndrome, but for the purpose of this thread I will only be talking about one. The type of chimera syndrome I wish to discuss is tetragametic chimerism. Here is a short explanation on this kind of chimerism:Quote: Chimera (genetics)Tetragametic chimerism is a less common cause of congenital chimerism. It occurs through the fertilization of two ova by two sperm, followed by the fusion of the zygotes and the development of an organism with intermingled cell lines. This happens at a very early stage of development, such as that of the blastocyst. Such an organism is called a tetragametic chimera as it is formed from four gametes — two eggs and two sperm. Put another way, the chimera is formed from the merger of two fraternal twins in a very early (zygote or blastocyst) phase. As such, they can be male, female, or hermaphroditic. As the organism develops, the resulting chimera can come to possess organs that have different sets of chromosomes. For example, the chimera may have a liver composed of cells with one set of chromosomes and have a kidney composed of cells with a second set of chromosomes. This has occurred in humans, and at one time was thought to be extremely rare, though more recent evidence suggests that it is not as rare as previously thought. Most will go through life without realizing they are chimeras. The difference in phenotypes may be minute, or completely undetectable (eg: having a hitchhiker's thumb and a straight thumb, eyes of slightly different colors, differential hair growth on opposite sides of the body, etc).
But what would someone who held such a view have to say about tetragametic chimerism? In this process, you have two very early stage humans that fuse together to make a new whole. You start out with entities X and Y, but you end up with entity Z. For me (who believes that you can have a human without having a person) there is no question. You started out with human non-person X and human non-person Y but ended up with human non-person Z. But if you think that personhood starts at conception, what has just happened to human/person X and human/person Y? Did they both go out of existence so that a new person/human could come into being? Are they both still present in some new form? Is an individual who has tetragametic chimerism really two people? Or is the answer something else entirely? I'd like to hear/read your thoughts. 3nodding
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Posted: Mon Dec 03, 2007 2:02 pm
We don't think that Embryo = Dave from down the street. I believe that a fetus is a human at an earlier stage of development. Everything that a person witnesses, they witness becuase they survived through this first stage.
Anyway, I think it's one person with the genetic coponents of two. Thought defines existence. (this is not to say that Feti carry on deep intellectual ponderings at 8 weeks, but they have one set brain and one mind, albeit noti ncredibly advanced)
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Posted: Mon Dec 03, 2007 2:18 pm
divineseraph We don't think that Embryo = Dave from down the street. I believe that a fetus is a human at an earlier stage of development. Everything that a person witnesses, they witness becuase they survived through this first stage. Anyway, I think it's one person with the genetic coponents of two. Thought defines existence. (this is not to say that Feti carry on deep intellectual ponderings at 8 weeks, but they have one set brain and one mind, albeit noti ncredibly advanced)
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Posted: Tue Dec 04, 2007 9:35 am
Well, it is a person. But I don't think that it has any of the characteristics of who it will be until later. This is not saying that embryos are not people, but that who and what they are is determined later. This allows for twins to not be the same person, as they have different experiences, and makes chimeras a single person because the thoughts and mind, if not the genetic composition, are of one.
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Posted: Wed Dec 05, 2007 3:47 pm
I am reminded of the show on TLC about the girl with two heads ... or the two girls with one body ... there was a lot of controversy over whether the 'girls' could/should be considered one entity, or two separate entities. Their names are Abigail and Brittany Hensel.
Perhaps bringing this up may allow those of us that don't believe in personhood at conception to still discuss this topic? Just wondering if it may help, as there's no denying that they are persons.
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Posted: Wed Dec 05, 2007 4:15 pm
I don't see it as a conflict, but probably because I've watched too much science fiction in my life. I'll try and explain my feelings on it. Maybe it's easier to start with a computer.
If I have two computers, I take them apart, take pieces of them, combine them, and then use the resulting machine, it's a completely different computers than the two computers before, but it's still a computer, and the computers before were still computers.
In the world of star trek there is a species known as Trill. 1 out of 4 trill humanoids end up becoming host to a parasitic Trill, completely of their own free will. In fact, they compete to be joined. They start out as two separate entities, and very individual entities, yet in the end, you have a new entity.
I don't see it as a conflict if two people become one new person.
As for Abigail and Brittany, if they think of themselves as two individuals, some schools of thought would mean that's enough for them to be individuals. If they've got different personalities, which Wikipedia seems to be saying, then that's a point in favor of different people. On the other hand, that would mean people with split-personality disorders would be two people too. On some other appendage, people with split personality disorders tend not to have two bodies in one body; conjoined twins are actually twins, not one human, but two in one body.
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Posted: Wed Dec 05, 2007 5:04 pm
lymelady I don't see it as a conflict, but probably because I've watched too much science fiction in my life. I'll try and explain my feelings on it. Maybe it's easier to start with a computer. If I have two computers, I take them apart, take pieces of them, combine them, and then use the resulting machine, it's a completely different computers than the two computers before, but it's still a computer, and the computers before were still computers. In the world of star trek there is a species known as Trill. 1 out of 4 trill humanoids end up becoming host to a parasitic Trill, completely of their own free will. In fact, they compete to be joined. They start out as two separate entities, and very individual entities, yet in the end, you have a new entity. I don't see it as a conflict if two people become one new person. As for Abigail and Brittany, if they think of themselves as two individuals, some schools of thought would mean that's enough for them to be individuals. If they've got different personalities, which Wikipedia seems to be saying, then that's a point in favor of different people. On the other hand, that would mean people with split-personality disorders would be two people too. On some other appendage, people with split personality disorders tend not to have two bodies in one body; conjoined twins are actually twins, not one human, but two in one body. It's called Dissociative Identity Disorder now, and was Multiple Personality Disorder before then (and there might have been another name), it hasn't been called "Split Personality" for a very long time, actually. Anyway, people who have more than one personality also have more than one sets of brain wave patterns. From their brain waves alone, one would think they were separate people.
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Posted: Wed Dec 05, 2007 5:12 pm
WatersMoon110 It's called Dissociative Identity Disorder now, and was Multiple Personality Disorder before then (and there might have been another name), it hasn't been called "Split Personality" for a very long time, actually. Anyway, people who have more than one personality also have more than one sets of brain wave patterns. From their brain waves alone, one would think they were separate people.
I'm also interested in knowing whether or not a pro-lifer would consider the chimera incident a 'loss of life' or possibly of two lives, I suppose. confused
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Posted: Wed Dec 05, 2007 5:34 pm
1 and 2. That may seem odd, but I'm comfortable with the idea that something can be one yet multiple at the same time.
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Posted: Wed Dec 05, 2007 7:37 pm
I apologize for using the wrong term. If medicine can change the brain patterns, does that mean that it's killing off a person and should we outlaw meds that do that? Just a random thought. Also, our brain wave patterns can be altered in our lives due to certain events, does that mean we become new people when this happens?
But anyway, like I said, I believe it's a new person. In one aspect, it is a loss of an individual life, just like a miscarriage at the same time would be (well...there wouldn't be a miscarriage at that time, technically, because a woman wouldn't really be pregnant by that time, would she? I was under the impression this all happens before implantation). On the other hand, or I'm probably on a foot by now, it's a new life as well. I don't speak for all people who are pro-life considering a lot of people aren't as fixated on personhood as they are on humanity; everyone has a different view on when personhood starts. There is only one point in time when an individual human life begins.
Though I'd also like to state, a fertilized egg is different in value to me than a zygote. Two haploid cells are different than one distinct, unique diploid cell. Doesn't matter quite so much since Chimerism happens after that anyway.
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Posted: Thu Dec 06, 2007 7:09 am
miyo_esparanza So then a question may be this: Does the chimera have separate brainwaves?
I'm also interested in knowing whether or not a pro-lifer would consider the chimera incident a 'loss of life' or possibly of two lives, I suppose. confused I think, if they had two sets of dna in their brain, that might be possible. But I don't know if someone can live with parts of two different brains (that's what it would be right?). It's interesting that chimeras are only known about when fraternal twins are absorbed into one body, as identical twins have the same dna. There was a woman who had two children and was pregnant. She needed, I don't remember, something, and they tested to see if her dna matched her children, and they found that it didn't. Then, after her baby was born, they found that she didn't match her newborn either, and they tested her dna from another part of her body, and found that matched. She was a chimera and had no idea. Most often chimeras are only really noticed when the combined twins have different fathers of different races. For some reason, when there are human chimeras of different skin tones, they combine in a squarish pattern. Where as cats (the only really noticeable cat chimeraism is when a red male cat fetus absorbs a black cat fetus) have more stripy, normal cat patterns. I think I would consider a chimera to be only one person, since they have only one body and one set of organs and such, even though they have two different sets of dna.
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Posted: Thu Dec 06, 2007 7:14 am
lymelady I apologize for using the wrong term. If medicine can change the brain patterns, does that mean that it's killing off a person and should we outlaw meds that do that? Just a random thought. Sorry, I have a friend who used to suffer from that, and so I sort of feel the need to correct people about it. Usually DID is treated with therapy, not medication. But, unless someone is a potential danger to themself or others, an adult with DID isn't going to be forced into therapy. So someone(s?) who is functioning fine wouldn't have to integrate if they didn't want to. lymelady Also, our brain wave patterns can be altered in our lives due to certain events, does that mean we become new people when this happens? I think so, but I guess that would be up to the individual to decide for themself.
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Posted: Thu Dec 06, 2007 9:31 am
divineseraph Well, it is a person. But I don't think that it has any of the characteristics of who it will be until later. This is not saying that embryos are not people, but that who and what they are is determined later. This allows for twins to not be the same person, as they have different experiences, and makes chimeras a single person because the thoughts and mind, if not the genetic composition, are of one.
I personally would say that twins are separate people because, as you said, they have two separate minds/consciousnesses/whatever. But similarly, I believe that because a fertilized egg doesn't have a minds/consciousnesses/whatever, a fertilized egg wouldn't be a person at all. So I'm not a good judge on this. ninja lymelady I don't see it as a conflict, but probably because I've watched too much science fiction in my life. I'll try and explain my feelings on it. Maybe it's easier to start with a computer. If I have two computers, I take them apart, take pieces of them, combine them, and then use the resulting machine, it's a completely different computers than the two computers before, but it's still a computer, and the computers before were still computers. lymelady In the world of star trek there is a species known as Trill. 1 out of 4 trill humanoids end up becoming host to a parasitic Trill, completely of their own free will. In fact, they compete to be joined. They start out as two separate entities, and very individual entities, yet in the end, you have a new entity.
lymelady I don't see it as a conflict if two people become one new person. lymelady As for Abigail and Brittany, if they think of themselves as two individuals, some schools of thought would mean that's enough for them to be individuals. If they've got different personalities, which Wikipedia seems to be saying, then that's a point in favor of different people. On the other hand, that would mean people with split-personality disorders would be two people too. On some other appendage, people with split personality disorders tend not to have two bodies in one body; conjoined twins are actually twins, not one human, but two in one body. miyo_esparanza WatersMoon110 It's called Dissociative Identity Disorder now, and was Multiple Personality Disorder before then (and there might have been another name), it hasn't been called "Split Personality" for a very long time, actually. Anyway, people who have more than one personality also have more than one sets of brain wave patterns. From their brain waves alone, one would think they were separate people.
I'm also interested in knowing whether or not a pro-lifer would consider the chimera incident a 'loss of life' or possibly of two lives, I suppose. confused
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Posted: Thu Dec 06, 2007 11:47 am
ShadowIce divineseraph Well, it is a person. But I don't think that it has any of the characteristics of who it will be until later. This is not saying that embryos are not people, but that who and what they are is determined later. This allows for twins to not be the same person, as they have different experiences, and makes chimeras a single person because the thoughts and mind, if not the genetic composition, are of one.
I personally would say that twins are separate people because, as you said, they have two separate minds/consciousnesses/whatever. But similarly, I believe that because a fertilized egg doesn't have a minds/consciousnesses/whatever, a fertilized egg wouldn't be a person at all. So I'm not a good judge on this. ninja lymelady I don't see it as a conflict, but probably because I've watched too much science fiction in my life. I'll try and explain my feelings on it. Maybe it's easier to start with a computer. If I have two computers, I take them apart, take pieces of them, combine them, and then use the resulting machine, it's a completely different computers than the two computers before, but it's still a computer, and the computers before were still computers. lymelady In the world of star trek there is a species known as Trill. 1 out of 4 trill humanoids end up becoming host to a parasitic Trill, completely of their own free will. In fact, they compete to be joined. They start out as two separate entities, and very individual entities, yet in the end, you have a new entity.
lymelady I don't see it as a conflict if two people become one new person. lymelady As for Abigail and Brittany, if they think of themselves as two individuals, some schools of thought would mean that's enough for them to be individuals. If they've got different personalities, which Wikipedia seems to be saying, then that's a point in favor of different people. On the other hand, that would mean people with split-personality disorders would be two people too. On some other appendage, people with split personality disorders tend not to have two bodies in one body; conjoined twins are actually twins, not one human, but two in one body. miyo_esparanza WatersMoon110 It's called Dissociative Identity Disorder now, and was Multiple Personality Disorder before then (and there might have been another name), it hasn't been called "Split Personality" for a very long time, actually. Anyway, people who have more than one personality also have more than one sets of brain wave patterns. From their brain waves alone, one would think they were separate people.
I'm also interested in knowing whether or not a pro-lifer would consider the chimera incident a 'loss of life' or possibly of two lives, I suppose. confused The fertilized egg is a person in development, the chimera embryo is a person in development. It will develop only one mind and will thus be one person.
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Posted: Thu Dec 06, 2007 7:54 pm
WatersMoon110 I think so, but I guess that would be up to the individual to decide for themself. I hope so. I don't feel like a new person. Then again, personhood, for me, doesn't hinge on brainwave patterns, or consciousness, but humanity, simply because I can't logically think of any other way to justify giving rights to the humans that we do without giving them to certain animals as well. ShadowIce See, in this situation I would say that the two original computers "died" (insofar as a non-living entity can die) so that a new computer could come into being. Thus, if I applied this to chimerism, I’d say that entity X and entity Y died so that entity Z could come into being. And I agree with you. I honestly have no problem with that. Quote: I don't know a lot about the Trill (although I too have watched Star Trek) but given what I do know of them, I would be of the opinion that the Trill host and the Trill are two different people. Two people who highly influence each other? Yes. One person? No. If I applied this standard to chimerism, I would say that entity X and entity Y both still exist.
They aren't really two people though. It's one person. The difference is, they can be split into two...sort of. The parasitic one can be removed and placed in a new host, but it will kill the humanoid one. The parasitic one will never be the same as it was beforehand, even though it lives if put into a new host within a certain amount of time. Quote: I guess what I'm wondering is what happens to the two original people when they merge into one. Are they both still there? Did they both die? But I may be asking a question that I can't understand the answer to. ninja I believe they both die in a way. They will never be the way they started out, certainly. Two unique organisms become one new unique organism. Quote: I'm firmly willing to say that Abigail and Brittany are two different people. Split personality disorder? That's trickier. As you said, if someone has split personalities and they go on medication to get rid of the extra personalities, have they in some sense killed some number of people? What are we supposed to do if one personality wants to go on meds and the others don't want to "die?" Freaky thought! That is a freaky thought! Would it also depend on who the dominant personality is? I wonder if they've looked into whether any people with Dissociative Identity Disorder are also Chimeras. Though, that's a bit too science-fictiony for my tastes.
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