vin@meccsd.MECC.MN.ORG (Vincent J. Erickson) (02/02/89)
In any species there are individuals born who are deemed to have "subtandard" genes (physically or mentally). In non-human species, it is thought that these individuals are more likely to die, leaving the fittest of the species to reproduce and thus "improve" the species. Among humans, however, this process is being perceived to have stopped; substandard representatives of our species are being kept alive longer, allowing them to reproduce. This is being perceived as somehow "weakening" the human gene pool. This would be true if only substandard individuals were being born; they are not. Remember that even two severely mentally retarded people have no more chance of conceiving a mentally retarded child than two supposedly "normal" people. The retarded are sometimes discouraged from having children because of their supposed inability to care for the "normal" child they would have. These kinds of predjudices are just the thing mental hospital nightmares are made of. The gene pool is safe. If for some reason civilization ceased to exist, the struggle for the fittest would continue as before. We simply have the luxury of not having to have every individual with a glitch in their genes to die. This includes everything from retardation and physical deformity to nearsightedness and flat feet. The seemingly trivial flaws in our genes (like nearsightedness) would cause far more individuals to perish in a wild environment than mental retardation would. Think about that "four eyes" the next time you think of others as being inferior.
ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) (02/03/89)
In article <1254@meccsd.MECC.MN.ORG>, vin@meccsd.MECC.MN.ORG (Vincent J. Erickson) writes: > Remember that even two severely mentally retarded people > have no more chance of conceiving a mentally retarded child than two > supposedly "normal" people. This is true provided that their is no genetic basis for the retardation, which may or may not be true. Otherwise a retarded couple have a significantly higher chance of producing a retarded child. How fast this affects the gene pool adversely depends to some extent on the rate at which such mutations appear. > The seemingly trivial flaws in our > genes (like nearsightedness) would cause far more individuals to > perish in a wild environment than mental retardation would. A dubious point. However, there may be something else wrong with it. Nearsightedness may be only partially genetic. There have been claims that hunting commmunities (like the Inuit) with excellent eyesight can produce children with normal rates of myopia when they switch to a more modern life style. If true this would be a sign that myopia is as much a product of not exercising eyes properly when young as a product of genetics. I'm personally not very worried about our gene pool. Some of the genes people worry about may have arisen as *favourable* adaptations. The classical example is sickle cell anemia (although most equatorial populations exposed to malaria have similar traits). Others are simply not very common, nor are they likely to become so. Finally, as other people have mentioned, our ability to manipulate our genetic heritage directly in the forseeable future radically changes the nature of the debate. Developing the capacity to use this ability wisely is important. Worrying about the deleterious effects of keeping people alive is not. -- I'm not afraid of dying Ethan Vishniac, Dept of Astronomy, Univ. of Texas I just don't want to be {charm,ut-sally,ut-emx,noao}!utastro!ethan there when it happens. (arpanet) ethan@astro.AS.UTEXAS.EDU - Woody Allen (bitnet) ethan%astro.as.utexas.edu@CUNYVM.CUNY.EDU These must be my opinions. Who else would bother?
dd@beta.lanl.gov (Dan Davison) (02/03/89)
In article <10120@ut-emx.UUCP>, ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) writes: > [...] > How fast this affects the gene pool adversely depends to some > extent on the rate at which such mutations appear. [...] > I'm personally not very worried about our gene pool. [...] Quite right. I recall that in my freshman biology course ('73) we were offered the chance to figure this out. With a "deleterious" gene present in a population at a specific frequency (less than 20% but greater than 5%, as I recall), how long would it take for that gene to go to fixation ("permanently") part of the population. I don't recall the rest of the details. Those worried about "contamination" of the gene pool are cordially invited to go to their local library look it up, and calculate it. The upshot was that the gene's frequency never went above 20%. Ted or Henry may have more current data, but the last three times I got interested in the subject and did the calculations I found that there was basically nothing to worry about. dan davison/theoretical biology/t-10 ms k710/los alamos national laboratory los alamos, nm 875545/dd@lanl.gov (arpa)/dd@lanl.uucp(new)/..cmcl2!lanl!dd "[...] Nature cannot be fooled" R. Feynmann, Challenger report
sethg@athena.mit.edu (Seth Gordon) (02/05/89)
morimoto@intvax.UUCP (Alan Morimoto) in <674@intvax.UUCP>:
`[I]f there were a major disaster that restricted medical professionals to
`treating those who were injured, i.e. a war, then we would have a lot of
`dying people out there, dying from cronic illnesses.
So don't go to war. Sounds like a good idea to me.
` My point is that maybe
`we need to look at what long term effects we are creating by breeding
`diseases into our future generations.
The effect, dear sir, is called "freedom." People with genetic diseases
have *every right* to have children, because they have *no moral
responsibility* to keep "our future generations" hale and hearty in a
"stronger gene pool."
BEING DISABLED IS *NOT* IMMORAL.
Therefore,
BEARING CHILDREN WHO ARE DISABLED IS *NOT* IMMORAL.
` I can imagine that countries that are
`not as medically advanced inherit a stronger gene pool of people simply
`because the weak will perish. Will the future of the world be inherited by
`us, the medically pampered, or the third world?
Oh, yes, I'm sure our friends in the third world are beside themselves
with *joy* that their weaker citizens perish, and haven't the
*slightest* ambition to be "medically pampered" like we are. They're
silly wogs, after all, and don't value human life the way we higher
cultures do.
` { Humans are the only animals that }
` { don't breed to improve the species. }
Thank God for that. I was just listening to the cockroaches flirting
in the kitchen this morning, and I heard one say to another, "Honestly,
George, you're a sweet guy, but I'm only going to mate with a bug that
will give our children carbomate resistance." Alas, poor George:
shut out of love because the females are so intent on improving the
species.
Get a clue, man! Join the twentieth century!
--
"To you, I'm an atheist. To God, I'm the loyal opposition." --Woody Allen
: bloom-beacon!athena.mit.edu!sethg / standard disclaimer
: Seth Gordon / MIT Brnch., PO Box 53, Cambridge, MA 02139emigh@ncsugn.ncsu.edu (Ted H. Emigh) (02/07/89)
In article <23378@beta.lanl.gov> dd@beta.lanl.gov (Dan Davison) writes: >In article <10120@ut-emx.UUCP>, ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) writes: >> [...] >> How fast this affects the gene pool adversely depends to some >> extent on the rate at which such mutations appear. [...] >> I'm personally not very worried about our gene pool. [...] > >Quite right. I recall that in my freshman biology course ('73) >we were offered the chance to figure this out. With a "deleterious" >gene present in a population at a specific frequency (less than 20% but >greater than 5%, as I recall), how long would it take for that gene >to go to fixation ("permanently") part of the population. I don't >recall the rest of the details. Those worried about "contamination" >of the gene pool are cordially invited to go to their local library >look it up, and calculate it. > >The upshot was that the gene's frequency never went above 20%. > >Ted or Henry may have more current data, but the last three times >I got interested in the subject and did the calculations I found >that there was basically nothing to worry about. How can I pass up an invitation (unless Dan is talking about some other Ted)? Let's consider the standard "genetic disease." Some trait which is currently deleterious (to some extent) and currently has a fairly low incidence in the population. Examples are: Tay-Sachs (frequency of <10^-3 => or an incidence of <10^-6); Ichthyosis congenita (freq.=10^-3; inc.=10^-6); Xeroderma pigmentosum (freq=2x10^-3; inc.=4x10^-6); or even albinism (freq=3x10-3; inc=10^-5). The frequency is the frequency of the gene in the US Caucasian population, the incidence is the rate at which these RECESSIVE traits appear. If the genetic trait is completely neutral, then it would be spread through the generation through mutation alone. However, it would take an unbelievably long time. A trait that has a mutation rate of 10^-5 would take about 10,000 GENERATIONS to increase in frequency from current frequencies to about 10% (which would lead to an incidence of people with the trait of about 1%). Note the 10,000 generations is about 200,000 years, which is older than Homo sapiens. If the genetic trait had some selective disadvantage, no matter how slight, eventually the population would reach an equilibrium. If the trait were completely recessive, then the equilibrium gene frequency would be sqrt(u/s), where u is the mutation rate and s is the selective disadvantage of the recessive individuals (a number between 0 and 1). If we take a modest selection coefficient of 1/100 and a mutation rate of 10^-5, then the equilibrium gene frequency is .03 and the rate of incidence is .001. You can work out for yourselves the gene frequency for other selection coefficients. A more reasonable selective disadvantage for these traits AFTER MEDICAL SCIENCE HAS ELIMINATED DIFFERENTIAL MORTALITY may be more like 1/10 or higher. That would lead to an equilibrium gene frequency of .01 and a rate of incidence of .0001. It should be pointed out that the selection coefficient is NOT merely whether individuals survive to reproduce. One way of looking at it is to define the selection coefficient as the ratio of the expected family size of a newborn individual with the genetic trait to the expected family size of a newborn individual without the trait. This not only includes survival, but also fertility, etc. I refer you to Steve VanDevender's comments to understand how there is selection against genetic traits even if we can use medical science to exclude mortality. -- Ted H. Emigh, Dept. Genetics and Statistics, NCSU, Raleigh, NC uucp: mcnc!ncsuvx!ncsugn!emigh internet: emigh@ncsugn.ncsu.edu BITNET: emigh%ncsugn@MCNC.UUCP or emigh%ncsugn@ncsuvx.ncsu.edu
arrom@aplcen.apl.jhu.edu (Ken Arromdee) (02/08/89)
>If the genetic trait is completely neutral, then it would be spread >through the generation through mutation alone. However, it would take >an unbelievably long time. ... Gee, what about "genetic drift"? -- EARTH | --Kenneth Arromdee smog | bricks | UUCP: ....!jhunix!ins_akaa AIR mud FIRE| INTERNET: arromdee@crabcake.cs.jhu.edu soda water | tequila | BITNET: g49i0188@jhuvm WATER |(please, no mail to arrom@aplcen) Element chart from "Science Made Stupid". (The chart seems rather popular...)
ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) (02/08/89)
In article <5579@ncsugn.ncsu.edu>, emigh@ncsugn.ncsu.edu (Ted H. Emigh) writes: > > How can I pass up an invitation (unless Dan is talking about some other > Ted)? Let's consider the standard "genetic disease." Some trait which > is currently deleterious (to some extent) and currently has a fairly > low incidence in the population. Examples are: Tay-Sachs (frequency of > <10^-3 => or an incidence of <10^-6); ....{other examples omitted}. > > If the genetic trait is completely neutral, then it would be spread > through the generation through mutation alone. However, it would take > an unbelievably long time. A trait that has a mutation rate of 10^-5 > would take about 10,000 GENERATIONS to increase in frequency from current > frequencies to about 10% (which would lead to an incidence of people with > the trait of about 1%). Note the 10,000 generations is about 200,000 years, > which is older than Homo sapiens. > Not being a geneticist, I have frequently wondered, but never looked into, the question of why an infrequent mutation like Tay-Sachs, which has such a devastating effect on those unfortunates who are homozygous for it, has such a relatively *high* incidence among Ashkenzaic Jewry (I believe that 1/30 individuals is heterozygous). The obvious answer would be that being heterozygous for it is good in some way. Has anyone ever found anything it might be good for? I suppose a tolerance for kosher wine would fit with the data (from extensive personal experience I know that I lack that trait), but are there any serious answers? -- I'm not afraid of dying Ethan Vishniac, Dept of Astronomy, Univ. of Texas I just don't want to be {charm,ut-sally,ut-emx,noao}!utastro!ethan there when it happens. (arpanet) ethan@astro.AS.UTEXAS.EDU - Woody Allen (bitnet) ethan%astro.as.utexas.edu@CUNYVM.CUNY.EDU These must be my opinions. Who else would bother?
ogil@tank.uchicago.edu (Brian W. Ogilvie) (02/08/89)
In article <9091@bloom-beacon.MIT.EDU> sethg@athena.mit.edu (Seth Gordon) writes: > >BEING DISABLED IS *NOT* IMMORAL. > >Therefore, > >BEARING CHILDREN WHO ARE DISABLED IS *NOT* IMMORAL. > >: Seth Gordon / MIT Brnch., PO Box 53, Cambridge, MA 02139 This doesn't follow. While it is not immoral to be blind, it is immoral to blind someone. I'm not certain whether bearing children who will be congenitally blind is immoral or not, but my gut feeling is that yes, it's just the same as blinding someone who was formerly sighted. One can argue that the blind child will not have an unblinded state to which to compare his blindness, but that argument seems specious. A congenital condition which results in the child undergoing excruciating pain seems to definitely support this position. Pain is pain regardless of whether one can compare it to not-pain; neurology backs me up here. To knowingly bear children who would suffer this pain would be immoral. Correctable disabilities are perhaps not immoral to propagate (obviously myopia; phenylketonuria presents some problems). But making grand moral pronouncements from on high without considering their implications is no way to decide moral issues. -- Brian W. Ogilvie / ogil@tank.uchicago.edu "Cartesianism is the most popular 'popular science' ever invented." --Noel Swerdlow
emigh@ncsugn.ncsu.edu (Ted H. Emigh) (02/08/89)
In article <10276@ut-emx.UUCP> ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) writes: >Not being a geneticist, I have frequently wondered, but never looked into, >the question of why an infrequent mutation like Tay-Sachs, which has such >a devastating effect on those unfortunates who are homozygous for it, has >such a relatively *high* incidence among Ashkenzaic Jewry (I believe that >1/30 individuals is heterozygous). The obvious >answer would be that being heterozygous for it is good in some way. >Has anyone ever found anything it might be good for? I suppose a >tolerance for kosher wine would fit with the data (from extensive >personal experience I know that I lack that trait), but are there any >serious answers? I have heard of two possible explanations for the high frequency of T-S in Ashkenazy Jews. The first is random drift. Because of the relatively high inbreeding among this group (as least when they were developing as a group) it is possible that the high frequency arose through random sampling. The second has been proposed by Jared Diamond. In this explanation, the heterozygote is supposed to confer resistance to TB. This particular group was one of the few successful groups of people to populate cities of Europe in the Middle Ages (where selection was quite severe). TB was particularly common in cities at the time. I do not know of direct evidence for his theory, and when he gave a talk here a couple of years ago he did not have any solid "proof". -- Ted H. Emigh, Dept. Genetics and Statistics, NCSU, Raleigh, NC uucp: mcnc!ncsuvx!ncsugn!emigh internet: emigh@ncsugn.ncsu.edu BITNET: emigh%ncsugn@MCNC.UUCP or emigh%ncsugn@ncsuvx.ncsu.edu
elliston@rob.UUCP ( Keith Elliston) (02/09/89)
In article <1755@tank.uchicago.edu>, ogil@tank.uchicago.edu (Brian W. Ogilvie) writes: > In article <9091@bloom-beacon.MIT.EDU> sethg@athena.mit.edu (Seth Gordon) writes: > > > >BEING DISABLED IS *NOT* IMMORAL. > > > >Therefore, > > > >BEARING CHILDREN WHO ARE DISABLED IS *NOT* IMMORAL. > > > >: Seth Gordon / MIT Brnch., PO Box 53, Cambridge, MA 02139 > > This doesn't follow. While it is not immoral to be blind, it is immoral > to blind someone. > > -- > Brian W. Ogilvie / ogil@tank.uchicago.edu I know that this discussion is rather heated, but I wanted to put in my $0.02 worth. I am NOT an Eugenecist (sp??), but I do feel that we have been weakening the Gene Pool by increasing our medical expertise. That is, we have allowed people who are harboring increasing doses of "bad" genes to survive to the age where they reproduce. The best example of this (at least, the best that comes to mind) is the case of hemophilia. Hemophilia is an X-linked recessive (well, not completely recessive) trait. When present in a female as a homozygouts set, it causes hemophilia. This had, before the invent of Factor VIII and (of course, no homozygous recessive females occurred before hemphiliac males came onto the scene.....) other such treatments, been fatal at an early age. When male children were born with the hemophilia gene on their X (due to a carrier female), they too died at an early age. Thus, the occurrance of Hemophilia remained fairly low. Now, since all (almost all, at least before AIDS) hemophiliacs survive, both male and female. So, when only hemophiliac males occured, and then died, we had no Hemophiliac (true hemophiliac) females. there was simply no way for them to get 2 doses of the hemophilia gene (ok... no "normal way", I am not including duplications and other fun genetic phenomena ). Any way, the crux of the situation is.... we now have hemphiliac females (both X's carry the gene) and hemophiliac males (their X carries the gene), and the occurrence of hemophilia (and the representation of the hemophilia gene in the gene pool) is increasing. Exactly what it will level off at is unknown. I dont advocate any sort of sterilization or anything for folks carrying genetic diseases, but I do promote the idea that we should accept the responsibility for the determination of the genetic makeup of our offspring. That is... if I found that I had (or carried) a genetic disease that would affect my children (hemophilia for example), I would simply not have children. I would actively consider artificial insemination for my spouse, assuming that she was genetically ok. I dont think that we can make such decisions for others, but we can make them for ourselves. And, I think that we owe it to future generations, to make these types of decisions, based on good information. "Know thyself...." can be extended to .. "Know thy genes". Any intelligent person should be considering his/her genetic makeup when thinking of having children. So... those are my $0.02 worth... Go ahead and flame away!!!! Keith uunet!rob!elliston
oconnor@nuke.steinmetz (Dennis M. O'Connor) (02/09/89)
An article by sethg@athena.mit.edu (Seth Gordon) says:
] morimoto@intvax.UUCP (Alan Morimoto) in <674@intvax.UUCP>:
] `[I]f there were a major disaster that restricted medical professionals to
] `treating those who were injured, i.e. a war, then we would have a lot of
] `dying people out there, dying from chronic illnesses.
Chronic illnesses are not genotypes, and are rarely phenotypes.
A tendency towards a chronic illness is a phenotype.
If you don't understand the difference between a genotype and
a phenotype, you can't rationally argue this issue.
] So don't go to war. Sounds like a good idea to me.
Besides a MAJOR disaster would bring about novel selection pressures.
What these pressures might be is not predicatable with certainty.
Therefor, it can be seen that what genotypes are "desirable" to
ensure the survival of the species is not decidable with certainty.
More on this later.
] ` My point is that maybe we need to look at what long term effects
] ` we are creating by breeding diseases into our future generations.
]
] [...] People with genetic diseases have *every right* to have children,
Consider:
Is this a "natural right" ( assuming such exist ) or a right guaranteed
by some "social contract"? Justify your answer. And please read on.
] because they have *no moral responsibility* to keep "our future
] generations" hale and hearty in a "stronger gene pool."
Consider:
Is this "absolute morality" or just Western morality ? What role
does morality have in legislation anyway ? "Ethical" instead of
"moral" would make a stronger argument, though it gets more
complex : Is it ethical to have willingly have children who can not
support themselves and then demand that others (society) support them ?
How about if there's just a high probability of the child being unable
to support itself ? How about if the child can ALMOST support itself,
but not quite ?
Therefor, I think resorting to moral or ethical arguments is weak.
There is no need to resort to them to make the case anyway.
] ` I can imagine that countries that are
] `not as medically advanced inherit a stronger gene pool of people simply
] `because the weak will perish. Will the future of the world be inherited by
] `us, the medically pampered, or the third world?
Who cares ? What use is this "US versus THEM" mentality ? In fact, the
citizens of this arbitrarily-defined "Third world" of yours, being
under more selection pressure, have a smaller (per capita) gene pool
and therefor are less likely to adapt to novel selection pressures.
] ` { Humans are the only animals that }
] ` { don't breed to improve the species. }
This is statement is severly flawed on several counts.
1. It assumes a species can be improved. "Improved" implies
some sort of judgement criteria. How do we judge a
species, specificly, what is the measure of man ?
"Species survival" has only one criteria : propagation of the species.
If the species survives, it passes. Else it fails. Regardless of
whether the species gets dumber, larger, faster or whatever to do so.
2. If you allow (for sake of argument) that you can judge
whether one human is an "improvement" on the other, the
notion that humans AREN'T breeding to improve the species
is ridiculous : Most people choose the mate they choose
because, by THEIR personal criteria, that human is
"improved" with respect to other available humans.
3. The vast majority of human adaptations are exosomatic :
i.e. outside the body, i.e. technological. Humans pass
proportionally more information to their offspring as
technology as opposed to genes than any other creature.
This DOES have an effect on the gene pool : For example,
once knives are present in a population, the selection
pressure for strong teeth and jaws is markedly reduced.
If we include exosomatic adaptations as part of the
inheritance we get from our ancestors, humans are constantly
improving the species.
Now for an example of how difficult (if not impossible) judging
a genotype as "good" or "bad" is : Sickle cell anemia is an
inherited condition. In the US, it's BAD : makes you anemic,
does you no good. However, in the parts of the world where
it originated, the very same genotype confers an improved
resistance to a king of malaria present there, so it's VERY GOOD.
Now, do you want to eliminate it from the global gene pool ?
Also, a particular "bad" phenotype ( i.e. physical attribute ) may
be the result of a particular combination of genotypes that each
is generally beneficial, and are only "bad" in that combination.
Do you eliminate ALL those genotypes to prevent that phenotype ?
Finally, remember that a hypothetical dinosaur eugenist would
have thought SIZE to be the most important survival characteristic
of an animal. Human eugenist tend to think INTELLIGENCE is.
A cockroach eugenist would pick FECUNDITY. The cockroach has
the strongest argument, believe me.
Remember : if the "marching morons" DO take over, it must be
counter-survival to be intelligent, BY DEFINITION.
In summation, what it is :
Selection pressures diminish the frequency of occurence of
one set of genotypes in a population, and increase the frequency
of occurence of some other. A species becomes extinct only
if a necessary genotype is diminished to nothing, without a
replacement genotype or set of genotypes existing or coming
into existence. Therefor, given the near certainty the novel
unknown selection pressures will come into existence, the best
way to maximize the probability of species survival is to
try and have as diverse a gene pool as possible.
Which is to say, the unnecessary eliminating a genotype usually
decreases the long-term viability of the species.
Check out cheetahs for an actual example of such a case.
--
Dennis O'Connor oconnor%sungod@steinmetz.UUCP ARPA: OCONNORDM@ge-crd.arpa
"Is it fair? If Social Security taxes are considered just another tax, then
$40K pays a 35% incremental rate, while $200K pays a 28% incremental rate."ayermish@asylum.SF.CA.US (Aimee Yermish) (02/09/89)
In article <10276@ut-emx.UUCP> ethan@ut-emx.UUCP (Ethan Tecumseh Vishniac) writes: >Not being a geneticist, I have frequently wondered, but never looked into, >the question of why an infrequent mutation like Tay-Sachs, which has such >a devastating effect on those unfortunates who are homozygous for it, has >such a relatively *high* incidence among Ashkenzaic Jewry (I believe that >1/30 individuals is heterozygous). I think that a large part of the answer is that Ashkenazi Jews are a (compared to the whole world) small population with relatively strong (although not so much in recent times) beliefs against intermarriage. As far as what the defect is or how it could possibly interact with other diseases, I don't know what is known, but might be able to look it up if you are interested. --Aimee -- Aimee Yermish ayermish@asylum.sf.ca.us Program in Cancer Biology ayermish@portia.stanford.edu Stanford University 415-594-9268
bauwens@newton.Berkeley.EDU (Luc Bauwens) (02/10/89)
In article <336@rob.UUCP> elliston@rob.UUCP ( Keith Elliston) writes: >I am NOT an Eugenecist (sp??), but I do feel that we have been weakening Do you mean an Eugenist, or do you mean a geneticist? About the substance of your posting, it seems to me the bottom line is: when is a genetically transmitted problem serious enough for you to consider it better not to have children? This is of course a very relative matter. If you would be suffering from hemophilia, perhaps you would be happy to be alive even so, hence you would think, so would your kids? Luc Bauwens