| From: kerri | 16/10/99
7:18:23 |
| Subject: genetic intelligence | post id:
136 |
| Dear Karl Is it known where the gene (if there is one) for intelligence potential is located? I've heard it said that the gene for intelligence potential is located on the x chromosome and that, therefore, any male born will only have the intelligence potential of his mother while any female will carry the intelligence potential of both parents. If this is true, could it be natures way of coping with patriarchial paradigms? Example: if the gene for intelligence potential is located on the x chromosome, then the superior potential of women secures the success of the species in a patriachial system - because this potential expands over generations and is passed onto the men. However, if it were the other way round (located on the 'y'), then the intelligence potential of the species would only be located in men and, over time, the potential would diminish as women would not intellectually porgress. Do you get my drift? If the x' theory is true, then women are the 'natural'leaders of the world. If it isn't true, eg: intelligence potential is carried by both x & y chromosomes, then my pleasing (to me) analysis is doomed. Whaddya reackon? | |
| From: erik | 16/10/99
7:42:45 |
| Subject: re: genetic intelligence | post id:
139 |
| Science hasn't found "one gene"
for intelligence potential; however, if you mean the new gene that was
discovered to be linked to memory, it's not on a sex chromosome. It's a
gene that encodes part of a protein called an NMDA receptor, and
supposedly, I believe, it is linked to the size of the ion channel (an
NMDA receptor lets current into a cell once it's activated by letting ions
zoom into the cell). The gene was found to be correlated only with memory and the ability to recognize; it wasn't shown to have anything to do with imagination, insight, etc...other aspects of intelligence which are as important if not more so than memory. (That's what I think, anyway :) | |
| From: claire | 16/10/99
10:43:20 |
| Subject: re: genetic intelligence | post id:
147 |
| i think the whole intelligence
gene locus being on the X came about when geneticists realised that there
were about twice as many males institutionalised for mental retardation
(MR) as females and likened it to other X linked conditions. When they
carefully physically examined these boys, they found they could group i
think about a quarter of them together by specific characteristics like
large head, high wide forehead, long faces, long ears, hypergonadism, speech
difficulties and other less common features. In this early stage it was
called the Gillian Turner X linked mental retardation syndrome. (My
boss....cool hey!). When they looked at the karyotype in these boys they
were able to identify and "fragile" site on the long arm of the X , and
eventually it came to be known as Fragile X syndrome. More recently, a
site has been found for boys who possess none of the abnormal physical
characteristics associated with Fragile X, just MR, and it has
unimaginatively been termed non syndromic X linked mental retardation.
These boys are typically the totally nondysmorphic slow kids in the class
room. This has supported the idea that intelligence is if not entirely ,
at least partially coded for by a gene on the X. Now the whole thing about why then aren't women obviously so much more intelligent than men( open to debate i guess)is a bit more complicated. At the risk of being terrible offensive to both genders on one level or another, what tends to happen is that super dooper mega geniuses tend to be male, having inherited their super dooper genius gene from there mother. So how come she wasn't a super dooper genius? Well, when she was an embryo at blastocyst stage, half her X's turned off, pretty much equally half the X's she inherited form her mother and half she inherited from her father. So women are sort of a mix. If her father had happened to be very bright and both her maternal X happened to code for high intelligence then the likelihood is that she will be well above average. But say her father's X was coding for lower intelligence, well her mother's could still bring her up to average. Anyway, this stuff just confuses me, the general idea is that in a large population over all, women are more intelligent than men(no suprises there...:o)), but if you want to see mega brains at work, you gotta go to the boys (because they have a pure X...terribly depressing really). Now if intelligence were on the Y, i think you are right Kerri. I am not sure how it would work though. I mean does no Y mean no intelligence. Probably not. Just as the X thing is probably not the be all and end all I bet Helen would have something really cool to say about it all Claire | |
| From: deguello | 16/10/99
13:24:45 |
| Subject: re: genetic intelligence | post id:
165 |
| I like the discussion on fragile
X syndrome..... however, I don't think that it's the only abnormality associated with Mental retardation. There's obvious stuff such as Down's Syndrome (and extra chromosome 21), but there's also stuff like two copies of a maternal rather than paternal chromsome 15 (you get them both from your mom rather than your dad) which also leads to mental retardation (Angelman syndrome, I think). Basically any time you have a problem with any chromsome, you'll get MR. It's not really an argument for intelligence being located on your X chromosome. Oh, and those X chromosomes being turned off are called Barr bodies. | |
| From: claire | 16/10/99
18:32:07 |
| Subject: re: genetic intelligence | post id:
266 |
| What i was saying Deguello was
that nonsyndromic Xlinked MR is the only chromosomal abnormality we know
about that manifests itself only in mental retardation. All the other ones
you have mentioned are syndromic ( they have other associated physical
features). Nevertheless, i think people are basically coming to the
conclusion that the number of single gene characteristics and conditions
is minimal compared to those which are polygenic and/or multifactorial.
There is no reason to think that intelligence would be any different. The
nice thing about the X theory though is that it rings true in reality
..:o) Claire | |
| From: bob s | 17/10/99
17:27:57 |
| Subject: re: genetic intelligence | post id:
531 |
| I have a couple of problems with
this topic. Firstly, the assumption seems to be that intelligence is a single definable characteristic. After all, to locate a gene for intelligence, you first have to know what intelligence is. But intelligence can mean many things: spatial perception, logical reasoning, artistic ability, mathematical aptitude, emotional intuition, abstract thinking, ability to cope with novel situations and capacity to learn from experience are just a few. Secondly, to measure the effects of a gene on intelligence, it must be possible to accurately measure intelligence. But because intelligence covers so many abilities, it is doubtful (to say the least) that it can be measured by one, or a few, simple tests. On such topics, I recommend reading Stephen J Gould's book, The Mismeasure of Man. As for the chromosome theory: Obviously we can rule out straight away that the "intelligence gene", if one exists, is found on the Y chromosome, since, demonstrably, women are at least as intelligent as men and they don't have a Y chromosome. I find it difficult to follow some of the arguments made above in favour of the X chromosome: I've heard it said that the gene for intelligence potential is located on the x chromosome and that, therefore, any male born will only have the intelligence potential of his mother while any female will carry the intelligence potential of both parents. Surely this would be to the benefit of women, since they would have a double chance of getting a good "intelligence potential" gene? And if one of the genes was defective, women would be less likely to manifest the defect since they would have a backup copy. Example: if the gene for intelligence potential is located on the x chromosome, then the superior potential of women secures the success of the species in a patriachial system - because this potential expands over generations and is passed onto the men. However, if it were the other way round (located on the 'y'), then the intelligence potential of the species would only be located in men and, over time, the potential would diminish as women would not intellectually porgress. It is possible that intelligence potential might increase on average from generation to generation, as a result of the natural selection process. But surely women would benefit from this as much as men (?) After all, women are as necessary as men for the survival of the species. Can you give a good reason as to why intelligence potential would be expected to diminish over time if carried on the Y chromosome? And where does patriarchy come into it? More recently, a site has been found for boys who possess none of the abnormal physical characteristics associated with Fragile X, just MR, and it has unimaginatively been termed non syndromic X linked mental retardation. These boys are typically the totally nondysmorphic slow kids in the class room. This has supported the idea that intelligence is if not entirely, at least partially coded for by a gene on the X. A genetic defect could certainly lead to mental retardation. However, to say that this is evidence for an intelligence gene is not a very strong hypothesis. A genetic defect could have effects on a child at a much "lower" level in the brain than the level of conscious reasoning. It could, for example, affect the proper development of the physical structures in the brain itself. My guess would be that these boys display other, more easily characterised, effects of their genetic defect other than apparent lack of intelligence. ... what tends to happen is that super dooper mega geniuses tend to be male, having inherited their super dooper genius gene from there mother. So how come she wasn't a super dooper genius? Well, when she was an embryo at blastocyst stage, half her X's turned off, pretty much equally half the X's she inherited form her mother and half she inherited from her father. So women are sort of a mix. If her father had happened to be very bright and both her maternal X happened to code for high intelligence then the likelihood is that she will be well above average. But say her father's X was coding for lower intelligence, well her mother's could still bring her up to average. What this appears to be saying is that men get just one "intelligence gene" from their single X chromosome, while women get a sort of averaged effect from their two intelligence genes. As I understand it, this is not usually how genetics works. Either the "intelligence gene" is dominant or recessive. If dominant, then female geniuses should be just as common as male ones. If recessive, then female geniuses would be somewhat less common, though if genetic factors were the sole reason for the higher success of men in the "genius" category, we'd still expect to see more female geni | |
| From: bob s | 17/10/99
17:28:53 |
| Subject: re: genetic intelligence | post id:
532 |
| (continued...) If recessive, then female geniuses would be somewhat less common, though if genetic factors were the sole reason for the higher success of men in the "genius" category, we'd still expect to see more female geniuses, since every now and then a woman would inherit two "super-genius" genes. Personally, I think it is more likely that female geniuses are as common as male ones, but have not been given the opportunities or recognition accorded to men of equal talent. The theory also predicts that if a woman has more than one male child then either none will be "super geniuses" or all will be (since they all get the same X chromosome). In addition, male "super geniuses" should be statistically more likely to produce daughters of above average intelligence. Have either of these factors been investigated? I suspect that at least the first factor mentioned would not be supported by the historical evidence. I am not a biologist, but my personal opinion is that intelligence, whatever it is, results from a combination of many genetic predispositions, combined with the effects of the environment and upbringing of the individual. I don't believe that there is such a thing as a gene for intelligence. JR | |
| From: bob s | 19/10/99
0:36:59 |
| Subject: re: genetic intelligence | post id:
943 |
| The only references I can find on
the web relating to intelligence genes on the X chromosome relate to work
published in 1996 by Gillian Turner ("Intelligence and the X chromosome."
The Lancet, 347(9018), 1814-1815). Does anyone know of any later work which supports or refutes this? JR | |