Posted by: Craig C. ®
06/28/2003, 15:19:40
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Hello Bahman,The situation you describe is not Lamarkian. To be Lamarkian the behavior of the father would have to alter the inherited genes of the child. That is not what is happening here. The son has inherited half of the genes of his father. Among these genes may be some nasty ones that predispose the son to violent behavior under certain conditions. But genes are typically switched on or off, depending on environmental cues, so even if the son has inherited the same nasty genes, he is not doomed to violence. If the son can avoid the conditions that activate those genes, his propensity for violence may be curbed or avoided. Of course, during childrearing, the father may expose the child to the exactly those conditions that activate the genes associated with violence. If that occurs, the sins of the father really are being visited upon the heads of the children. But it is still not Lamarkian. Craig
Modified by Craig C. at Sat, Jun 28, 2003, 15:20:20
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Posted by: Bahman ®
06/28/2003, 15:33:25
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Yes, Craig, I understand what you are saying. And I had the same feeling about it when I read the parts of the article that you cite or refer to.
However, there are other statements that seem to imply Lamarkian phenomenon, and I quote below:"Research is revealing that life experiences can alter the biochemistry of many genes. . . .
Research is revealing that the workings of genes are more complex than scientists had thought, that the brain itself is more open to change, and that the effects of everyday experience are more powerful. Indeed, growing evidence suggests that what happens in life controls the activity of many genes.” How do you read those?
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Posted by: Craig C. ®
06/28/2003, 15:47:38
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Hi Bahman,You ask how I read this statement: Research is revealing that life experiences can alter the biochemistry of many genes. . . . Research is revealing that the workings of genes are more complex than scientists had thought, that the brain itself is more open to change, and that the effects of everyday experience are more powerful. Indeed, growing evidence suggests that what happens in life controls the activity of many genes I agree with that statement. What it is saying is that our life experiences can turn on or off genes inside the brain. In fact, when we create a memory, genes inside the brain are turned on that alter the structure of the brain so as to encode the memory. Education and life experiences physically alter our brains by strengthening and weakening neural connections. They literally change our minds. Craig
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Posted by: Bahman ®
06/28/2003, 16:58:22
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"Education and life experiences physically alter our brains by strengthening and weakening neural connections. They literally change our minds."Can those changes be passed on to the offsprings?
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Posted by: Craig C. ®
06/28/2003, 17:21:03
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Hello again, Bahman, You ask whether changes in the brain are passed on to the offspring. No. The offspring receive the genes present in the DNA of the sperm and egg. The structure of the DNA in a person's egg or sperm is not affected by education or by most life experiences. I say most life experiences because certain kinds of life experiences (like exposure to radiation or certain chemicals) can increase the frequency of mutation in the DNA of the sperm or egg. These kind of changes could be passed on to the offspring. Education and life experiences can change which of the genes in our brain are turned on and off, but this does not involve a change in the structure of the DNA. Think of the DNA as a set of instructions. Other molecules within the cell have the job of reading these instructions and doing what they say. A gene is ON when these molecules are actively doing their job; a gene is OFF when these molecules are not doing their job.
Craig
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Posted by: Bahman ®
06/28/2003, 18:32:27
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OK, I want to make sure that I totally understand you. So, I make it in two questions:1) When the article says: "Indeed, growing evidence suggests that what happens in life controls the activity of many genes”, what you are saying is that these genes that can be controlled by life's activity are not the genes that pass heredity to offsprings. Right? 2) If so, then it seems to me that there is nothing much new in this article. Is there anything new in your eyes?
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Posted by: Craig C. ®
06/28/2003, 19:30:17
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You ask When the article says: "Indeed, growing evidence suggests that what happens in life controls the activity of many genes”, what you are saying is that these genes that can be controlled by life's activity are not the genes that pass heredity to offsprings. Right?I am saying that: - the genes that are passed on to offspring are the genes in the sperm and egg cell. These genes are not affected by changes in the organization of the brain. - information that enters the brain through sensory perception turns on certain genes in the neural circuits of the brain. - activation of specific genes in the brain allows for storage of information (memories) in neural structures. - activation of genes has no affect on the information that is stored in the DNA. You say, it seems to me that there is nothing much new in this article. Is there anything new in your eyes? I am glad that the linkage between gene expression and brain chemistry is receiving increasing attention in the press. This is a hot area of research. I also like the fact that this article helps to dispel the old tired idea of nature versus nurture. Our genes give a map of possibilities, but the route that a person actually takes depends on environmental factors, chance, and the decisions that a person makes, especially memories created by education and life experiences.
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Posted by: Craig C. ®
06/28/2003, 19:47:14
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What I don't like about this article is its title:“BEHAVIOR MAY LEAVE A MARK ON GENES" That title does sound Lamarkian. I can see why you would have questions about it. A more correct title would be: "ACTIVITY OF GENES IN THE BRAIN AFFECTS BEHAVIOR"
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Posted by: Bahman ®
06/28/2003, 20:08:19
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You are right. Moreover, reading the article reinforces that (incorrect) understanding. I'll take a little time off to read it more carefully and then I MAY come back. Thanks so far.
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Posted by: kevin ®
06/28/2003, 16:00:14
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I'm sorry to butt in here, but when you said, "But genes are typically switched on or off, depending on environmental cues...", I became curious to get more information.Please excuse my enormous lack of educaton in this matter, but my interest in this subject has been piqued. Can you recommend any books that would be a good primer on the subject for a layman such as myself? Thanks!
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Posted by: Craig C. ®
07/04/2003, 17:01:20
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Kevin, Bahman, Gunnar, TV and whoever else might be interested in nature/nurtureI just discovered that Matt Ridley has written a new book on this subject, and, although I have not read it, I am excited by the reviews. Here is the link: Nature Via Nurture: Genes, Experience, and What Makes us Human by Matt Ridley Craig
Modified by Craig C. at Fri, Jul 04, 2003, 17:13:32
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Posted by: Bahman ®
06/29/2003, 11:52:22
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This is addressed to Craig of course, but I thought it'd be better to start form the edge of the thread.After some reading and contemplating, I’ve come up with three questions.
1) What are the publication dates on the books you recommended in an earlier post?
2) I think you sometime used the term “discredited” in relation to Lamark’s theory. But I’m not focusing on words here. I want to know if there is simply no evidence for his theory, or scientific evidence has proven conclusively that it is wrong.
3) In an earlier post you said: “I also like the fact that this article helps to dispel the old tired idea of nature versus nurture.” What exactly do you mean by “old tired idea”? In other words, which idea is old and which is new?
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Posted by: Craig C. ®
06/29/2003, 13:28:31
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Hi Bahman,You asked: 1) What are the publication dates on the books you recommended in an earlier post? Genome was published in 2000. Time, Love, Memory was published in 1999. 2) I think you sometime used the term “discredited” in relation to Lamark’s theory. But I’m not focusing on words here. I want to know if there is simply no evidence for his theory, or scientific evidence has proven conclusively that it is wrong. Lamarkian theory predicts patterns of inheritance that are not observed. Modern genetic theory predicts patterns of inheritance that are observed. We accept the latter theory and reject the former because the latter provides accurate and useful predictions. 3) In an earlier post you said: “I also like the fact that this article helps to dispel the old tired idea of nature versus nurture.” What exactly do you mean by “old tired idea”? In other words, which idea is old and which is new? People have often spoken of nature vs nuture in trying to explain human behavior. I do not see how pitting one against the other is particularly useful. I'll try to explain why. What do we now know about genes? The genes that we inherit depend upon the genetic attributes of our parents. Genes affect the appearance of our body, its size, coordination, as well as temperament, disposition, and aptitudes. But the way in which genes are activated thoughout our lives depends on environmental factors: nutrition, for example, will have a big effect on body size and even on the structure of the brain. Similarly, education and life experiences can activate or deactivate genes within the brain causing the formation of memories and other changes. We know that childhood abuse affects the wiring of the brain, and that can only mean that it is altering gene expression within the brain. A loving and attentive parent is cultivating very different gene expression patterns within the brain. All these life experiences and memories activate genes that create memories which then affect behavior, and these behaviors in turn affects the expression of other genes within the brain creating still more memories and potentially alterring our capabilities. Genes and environment are like dance partners in a bear hug embrace. Hope this makes sense. Craig
Modified by Craig C. at Sun, Jun 29, 2003, 13:53:19
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Posted by: Bahman ®
06/29/2003, 14:28:45
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#1 Thank you.#2 I don't read in your answer to say that Lamakian theory is conclusively wrong (like saying flat-earth theory is wrong). Now, is there a possiblity that his theory, or some variation of it, may turn out to have merit in the future? Something like the existence of a Lamarkian element imbedded in "Modern genetic theory"? #3 Yes, it makes sense to me, espcially because I've had such a gut feeling! Now, can we put it in a nutshell and in layman's language and say: Our lives are affected by both nature and nurture to some degree or another?
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Posted by: Craig C. ®
06/29/2003, 15:23:24
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You say, #2 I don't read in your answer to say that Lamakian theory is conclusively wrong (like saying flat-earth theory is wrong). Now, is there a possiblity that his theory, or some variation of it, may turn out to have merit in the future? Something like the existence of a Lamarkian element imbedded in "Modern genetic theory"? Modern genetic theory provides an adequate account of inheritance. I don't see how Lamarkian theory could improve our understanding of our biology. However, Lamarkian ideas are useful for the development of computer code that evolves (genetic algorithms), and culture evolves in a Lamarkian way. So Lamarkian theory is not useless; it just has other areas where it applies. #3 Yes, it makes sense to me, espcially because I've had such a gut feeling! Now, can we put it in a nutshell and in layman's language and say: Our lives are affected by both nature and nurture to some degree or another?
Yes! Absolutely! ...and I know how much you like those nutshells! ;o) Craig
Modified by Craig C. at Sun, Jun 29, 2003, 15:24:15
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Posted by: The Vines ®
06/29/2003, 17:34:33
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The media... The predispositions in brain activity are inherited. The environment can trigger the activation of some rather than others. In other words, the possibility that I kill a person in cold blood just isn't their right now, but the predisposition to do so could be activated and develop if sometime in my life the conditions were right. It is likely that there are deadlines for the development of certain neural circuits, just like in the case of things like stereopscopic vision, language centers in the brain, etc. Studies show that humans are VERY similar across the whole world. The environment can trigger the development of certain tendencies, but the predisposition toward those existed previously. Their relevance is determined by the conditions of the environment. If you think about that, its actually a pretty smart setup. I would like to have the ability to kill if such an ability is important to the survival of my race, or family... I don't have this ability because my life circumstances didn't warrant its development. If I were in the circumstance to have to defend myself I might be a poor defender. I think its a good thing that these genes are around because it allows future generations to be able to defend themselves in less favourable circumstances. Selection is not a pleasant affair. Their are a few family groups that could attest to the horrors that can come your way. Before someone decides to misunderstand, I am saying simply that it is a good thing, IMO, that such a predisposition is available. Certainly, nature doesn't always activate these genes the way we see as appropriate or good. No one would want criminals, but we should ask ourselves why their are criminals. What triggered the activation of these tendencies. The consequent social implications of responsibility hit each and every one of us. I side with Maher who criticized the USA by saying something to the extent of "Why should terrorist be angry at the USA... The fact that we deprive the rest of the world of prosperity to maintain our competitive edge and capitalistic societal structure should not matter...." (of course said sarcastically). I have developed a very pessimistic view of humanity I must say. The more I read about what we actually do as a species, and the more I grow convinced of our temporaneity. It would be a miracle that we would grow to the point of being able to withstand the trials millions of years of evolution would eventually bring our way. TV
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Posted by: Bahman ®
06/29/2003, 17:41:34
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Welcome back TV.
You know, while I was reading your post, I was thinking of the answers I could give. Until I got to, "I have developed a very pessimistic view of humanity I must say."Now, I don't know what to say!
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Posted by: The Vines ®
06/29/2003, 19:08:27
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Hi BM, I hope you didn't think that I was referring to your writing as nonesense. No rather I was referring to what the media presents in its "scientific reports."The idea that science and research has shown that: "Research is revealing that life experiences can alter the biochemistry of many genes. . . . " ... is complete nonesense. There is no such evidence in science. If anything, environment can determine how genes are activated, but doesn't re-write the genetic code. If genes are altered by environment the best we get is cancer. The alteration has no underlying sense to it, its not an adaptation of any kind, its simply random intrusion of harmful environmental conditions. I don't know how to interpret your response, but I just wanted to specify that I wasn't criticizing you. TV
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Posted by: Bahman ®
06/29/2003, 19:48:25
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Yes TV, I knew you were criticizing the media. But I just passed by it. But now that you more explicitly stated your comment, I'll have to answer. If I may be brave (bold!) enough to say what I think, I'd say that you make very harsh judgments easily. More later.
But, first let me clear up a smaller problem. You say you don't know how to interpret my response. Well, I see as my duty to intrerpret it for you! When you stated as being very pessimist, I told myself how can I struggle (intellectually) with someone who professes to be a card carrying member of the "pessimist club" (!) when I can't do a good job of interacting with less pessimist people. That's why I gave up!Now to the media and genes. First, I don't think you should put the blame on the media. The two authors of this article are long-time staff members of the LA Times (not that I know them but I have read their articles.) LA Times is among the good newspapers and not a raggedy smalltown paper. If anyone should be blamed (and I am not saying there is) it is the scientists they talked to and interviewed.
All this aside, as for the content, your statement that "Research is revealing that life experiences can alter the biochemistry of many genes. . . ." is a complete nonsense, seems to be wrong. As you know, I am hardly an expert on this, but from what I've seen from Craig he seems to agree with this. If you still have questions, maybe he will clarify it.
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Posted by: Craig C. ®
06/29/2003, 19:57:31
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I guess we were posting at the same time. Please tell me if my response to TV makes sense to you.
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Posted by: Bahman ®
06/29/2003, 21:22:46
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Not surprsingly, I don't understand the distinction that you draw in explaining the headline to TV. So, it remains between you two to sort it out!
However, what I can and want to say is that misinterpretation of "headlines" and "soundbites" is a common occurance. That is why it is always wise to read the text.
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Posted by: Craig C. ®
06/29/2003, 22:09:38
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Bahman,OK, let's see if I can explain this in a way that makes sense to you. DNA molecules are stored in each cell of your body. These DNA molecules are basically all the same. Genes are pieces of these DNA molecules Your life experiences do not change the composition of your DNA molecules (although the DNA in some cells may becomes mutated by radiation or a chemical agent). Your life experiences can influence which genes in your DNA are "turned on". When you were a baby, different genes were on than the ones that are on now. When a gene turns on, a molecule binds to the DNA and makes a copy of the instructions encoded in the gene. The copied instructions are used in biochemical reactions to make proteins. The turning on of a gene and the copying of DNA does not change the instructions encoded in the gene. When the authors of the article talk about changing the "biochemistry" of DNA, it sounds like they are saying that the instructions encoded in the gene have been changed. That is not what happens. What they should say is that life experiences affect which genes turn on and off. Craig
Modified by Craig C. at Sun, Jun 29, 2003, 22:16:49
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Posted by: Bahman ®
06/29/2003, 22:25:26
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Craig Sir (TLC style!), what I understood from our previous exchanges in a nutshell was that life experiences affect the genes in the brain but not the genes in eggs and sperms, and that is why such changes can't be passed on to offsprings. And that is why I was happy that I FINALLY understood the problem!
Now, first f all, please tell me if the above understanding is correct or not.
Then, explain why in your above post there was no mention of sperms and eggs which seemed to me to be a crucial factor. I also must mention that I only read your post above just once. I'm going to have read it more carefully later, especially if you add something to it. Oh, why isn't life ever simple!PS: TV, if you are reading, can you give us your input?
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Posted by: The Vines ®
06/29/2003, 23:40:35
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Genes are segments of the DNA molecule that accomplish a specific function in the bodies biochemical functions.The article was probably referring to (correct me if I am mistaken CC) regulatory genes, or genes that can be activated or inhibited by the circumstances in which we find ourselves(eg. internal chemistry of the body, temperature, and all the various aspects of homeostatic functions). The problem I was outlining was that the environment has absolutely no effect on rewriting any genes... unless you would want to include a geneticist doing gene therapy on people as an environmental factor. Life experiences, or their perception, do not affect the genes in the brain except in the sense of activating some rather than others. This is a proven fact. There are certain brain functions that must be activated by a certain time in the growth of a child or they will never be activated. However, I would be careful to ask you what exactly you mean by "life experiences" because I have a hunch you and CC may be talking about different things. BTW, as to my pessimism, I would refer you to the fact that I spoke about the endurance of Homo Sapiens over evolutionary time. I didn't talk about a few decades, not to say that we wouldn't be able to cause significant damage to ourselves in a short time. You seem to take on a condescending attitude toward this statement, but you sure didn't defend your attitude. TV
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Posted by: Bahman ®
06/29/2003, 23:53:44
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It seems to me that I am still not in a position to come close to deciding whether the article makes sense or is nonsense. So, I'm going to leave it to you and Craig.
As for your pessimism, I reread your original post and I quote:"I side with Maher who criticized the USA by saying something to the extent of "Why should terrorist be angry at the USA... The fact that we deprive the rest of the world of prosperity to maintain our competitive edge and capitalistic societal structure should not matter...." (of course said sarcastically). I have developed a very pessimistic view of humanity I must say. The more I read about what we actually do as a species, and the more I grow convinced of our temporaneity. It would be a miracle that we would grow to the point of being able to withstand the trials millions of years of evolution would eventually bring our way." Now, if you are saying that your pessimism ONLY was confined to the second paragraph and had nothing to do with the first paragraph, I'll happily accept, and take my words back.
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Posted by: The Vines ®
06/30/2003, 10:22:08
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In the first part I was referring to our responsibility as individuals to provide each other with the circumstances that would make of us a functional world-society, and that we cannot go calling people in third world countries "evil" as our dear president does if we are also going to make sure that we live in prosperity and to maintain the financial edge we are also going to suffocate their economies. The connection with my statements regarding my pessimism is clearly there, and I don't apologize for that. In fact I will say that I stand by it. The point is that my pessimism was regarding our species's ability to survive in evolutionary time while possessing these attitudes.My pessimism regards the nature of man. Our knack for disregarding reason, our self-destructive attitudes, our group, pack, or family-alliance mentality, along with our inability to exert power while factoring in the consequences over time - all these make of us a perfect example of a species that could easily head downhill in a heartbeat. I see USA officials calling other nations "evil", and I shake my head... The same old tendencies constantly emerge. The most educated of people seem to be able to justify and validate these mental tendencies without a problem. Does that cause my pesssimism to increase? Certainly. Again, you have launched a criticism toward this pessimism but have not defended this. You have simply questioned my feelings, but have not justified this questioning with any reasoning. TV
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Posted by: Bahman ®
06/30/2003, 12:21:38
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OK, here is a "launch" to discussion and reasoning! I'm going to make two separate discussions.1) "My pessimism regards the nature of man. Our knack for disregarding reason, our self-destructive attitudes, our group, pack, or family-alliance mentality, along with our inability to exert power while factoring in the consequences over time - all these make of us a perfect example of a species that could easily head downhill in a heartbeat." My short comment at this point is that, THAT is human. We are not "angels." Humans are full of all kinds of emotions and not everything is science/logic/reason. That is how things are and we should work to improve things keeping that reality and perspective in mind. This may not be a stisfactory answer for you, but I wait for your more specific points for discussion. 2) "I see USA officials calling other nations "evil", and I shake my head... The same old tendencies constantly emerge. The most educated of people seem to be able to justify and validate these mental tendencies without a problem." I don't know if in this passage you are pointing out US as being particularly more "evil," or one among other countries and cultures (which brings us back to #1)? In any case, again in general terms, clashes between nations and cultures have been around "since the dawn of history" and it is not going to end in the foreseeable future. More specifically, I didn't much pay attention to the rhetoric of Bush calling the three nations evil (even tho I'm in one of them!). What counts is deeds and actions. Again you won't probably agree, but I supported the war in Afghanistan, I had a qualified support for war in Iraq (last resort), and I don't think the US is going to go to war any time soon anywhere (unless of course some catastrophic event like 9/11 happens).
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Posted by: Craig C. ®
06/30/2003, 01:04:12
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Bahman.You are right that I neglected to mention sperm and eggs in my previous post. That was an oversight. I'm afraid a more complete explanation will be more than you want to hear, but I'll give it a shot and hope you do not find it boring. The sperm and egg cells are special: they have only half the DNA of other cells in the body. A chromosome is a string of DNA, and human egg and sperm cells each contain 23 chromosomes. When the sperm and egg combine, the fertilized cell contains 46 chromosomes. When that fertilized egg divides, each daughter cell receives 46 chromosomes. During the construction of the human body, each new cell receives 46 chrmosomes, and that is why, with the sole exception of the sex cells, every cells in the adult body, including the brain cells, contain 46 chromosomes. As new cells are produced, they begin to experience a different local chemical environment. Differences in the local chemical environment cause differences in which genes get turned on and off. Because of this, cells begin to change: some turn into brain cells; some into skin cells; others into liver cells; and so on. All these changes occur because of differences in the expression of genes. Even though the same DNA is present in all these cells, different parts of the DNA are turned on or off resulting in different cell types. Whether or not a gene gets turned on depends on chemical signals. When I post this message to you, electrical signals will be generated inside your eyes and these signals will enter your brain where the information in this post will be interpreted by your brain cells. In order to create a memory of this information, your brain cells will need to reorganize themselves into a specific pattern. Specific genes will have to be turned on and off. These genes will cause reorganization of your brain cells creating networks that store memories. The other cells in your body will respond to their local chemical environment, but they do not experience what the brain cells experience. The activity and structure of DNA inside sperm and egg cells, for instance, are not affected by mental processes occurring inside the brain. Hope this helps. Craig
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Posted by: Bahman ®
06/30/2003, 08:12:33
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Thank you Craig. After reading it through, I filed your post for more reading later when my mind works better. (this is early morning!). BTW, I've been copying and storing the posts (mine and others') that are worthy to me so that I won't regret the possible loss of archives later.
Now, just "from the top of my head" if we add the word, "brain" to the headline of the article, to read:"BEHAVIOR MAY LEAVE A MARK ON GENES IN THE BRAIN" Does that make it fully correct and CLEAR, with no ambiguity?
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Posted by: Craig C. ®
06/30/2003, 10:01:09
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Hi Bahman, Your revised title gives the impression that DNA molecule are marked in some way, and that is not correct. A better title would be "BEHAVIOR AFFECTS HOW GENES WORK IN THE BRAIN". Craig
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Posted by: The Vines ®
06/30/2003, 10:43:26
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Behavior does not leave a mark on genes. Behavior leaves a mark on the way structures are created as the genes express themselves.If you consider the genes as blue prints for building something, for example brain connections, the blue prints can be used for building when a permit is obtained. The blueprint instructions are present(the genetic code), and in them are various plans available for building various structures, but the permit will determine what will be built. A small house, or a large building can be built, one facing north or one overlooking the port, one with balconies, or one with glass exterior, all depending on the permit. It all depends on the permits they get. The permits are the chemical signals. The various aspects of brain activity triggered by our experience are like the permits. They trigger specific a specific intracellular chemical interaction, which will cause certain genes to become active or to be inhibited. This expression will lead to the execution of a specific building blueprint. The actual building blueprints are not changed, what we see rather is the choosing of some blueprints rather than others. The DNA contains all these blueprints(genes), but which get activated or inhibited depends on the chemical circumstances. In the case of the brain, the interactions(some of which are perceived) that occur in the brain may determine the activation or inhibition of genes. SO BEHAVIOR MAY LEAVE A MARK ON GENES is not right. Furthermore, considering the fact that neural cells do not reproduce, selection doesn't even need to be considered. TV
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Posted by: Bahman ®
06/30/2003, 11:57:22
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OK, I accept your, and Craig's, criticism of the headline. But now let's move on to the text of the article. Do you think that is also misleading? Note that I am asking your opinion in this regard and I honestly can't absorb any more technical material at this point. Just give some concise layman-friendly answer!
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Posted by: Craig C. ®
06/30/2003, 12:14:05
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Good morning Bahman,As TV pointed out earlier, what may be misleading in this article is this statement: "Research is revealing that life experiences can alter the biochemistry of many genes". The reason this statement is misleading - or at least ambiguous - is because a layperson reading it might draw the conclusion that life experiences alter the structure of the DNA - and since most people relate genes to inheritance - the reader might even conclude that some kind of Lamarkian process was being reported. Such an interpretation would be incorrect.
This ambiguous phrase could be rendered clear by substituting the word "expression" for "biochemistry", although I'll admit that not everyone understands what is meant by gene expression.
Craig
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Posted by: Bahman ®
06/30/2003, 12:30:58
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While reading this another question clicked!
Suppose, for the sake of argument, that life experiences DID "alter the structure of the DNA" in the brain. Then, would it be correct to say that the changes could be passed on to the offsprings?
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Posted by: Craig C. ®
06/30/2003, 13:35:49
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Nope. A change in the DNA of the brain cells would have no way of getting into the sex cells. Sperm and eggs are manufactured in an entirely different part of the body (at least, I sure hope so!).
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Posted by: The Vines ®
06/30/2003, 13:51:50
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B, you ask:"While reading this another question clicked! Suppose, for the sake of argument, that life experiences DID "alter the structure of the DNA" in the brain. Then, would it be correct to say that the changes could be passed on to the offsprings?" OK. The answer is no. The brain develops as the fetus does and continues to change throughout life as genes are expressed and various neural structures take form as memory. When we reproduce the genes that are passed on are the ones in the sperm and egg cells. Lets say there were a mutation in the brain cells. This would not effect the DNA in our seed. At that point they are separate structures in the body. The structure of the body once developed represents the expression of the overall DNA instructions. There might be a mutation in - lets say - our pancreas cells. When the cells in the pancreas replicate, and new ones substitute aging and dying ones, something that occurs periodically as our body renews itself, the mutation in the cell will almost always cause a cancer cell to emerge. Usually this will be destroyed by our white blood cells, but at times it can develop into a tumor. The fact is that the mutated cell in the pancreas CANNOT communicate with the DNA in the sperm or egg cells to record its mutation and pass it on to future generations. The DNA that would get passed on to the posterity would be completely separate from the mutated DNA in the pancreatic cell. Similarly, a brain structure representing "memory" cannot be passed on. So when we have a traumatic experience causing a specific memory structure to be formed in the brain, this cannot be recorded in genes and passed on. In essence, once cells differentiate during development, they take on a sort of life of their own. They form groups of cells with very specific functions. Overall they all contribute to the homeostatic functions of the body, or the overall machinery that keeps us alive. They all have the same DNA, but based on the group, organ, or tissue they belong to, certain aspects of the DNA are active and others are not. A heart cell executes aspects of the DNA(genes) that are specific for hearts, and so forth. As the body develops, all these specific functions are clearly established for every group. While they were all connected in the beginning, once they differentiate - their genetic codes work separately to produce specific structures. So even if experience were to alter the DNA in brain cells, this would not affect the genes being transmitted to offspring. ----------- At this point let me point out something to you. There are many aspects of behavior that seem to be transmitted genetically and are not learned. For example the way we learn language, or the way we focus are attention on moving objects, or our fear of loud noises, heights, or the dark, etc... How does a child know to fear these things? How does a child know to suck on a nipple for milk? This instictual knowledge seems like learning transmitted. In reality its transmitted genetic instructions interpreted by our brain as knowledge. We do not "learn" these behaviors they are part of what we do spontaneously. We learn to rationalize these behaviors and give them meaning. Martin once presented a very interesting post regarding "consiousness being a metaphor" of some type. Got to go, but more later. TV
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Posted by: Bahman ®
06/30/2003, 14:43:05
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. . . yours and Craig's! Thanks.
Now, you bring in instinct into discussion, which is a good idea. You say:"This instictual knowledge seems like learning transmitted. In reality its transmitted genetic instru | |
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