The Shotgun Blog
Thursday, January 13, 2005
There seems to be widespread agreement on the two following propositions:
1) Abortion and gay rights are causes that go hand in hand: social liberals support them both while both are opposed by social conservatives.
2) It is pro-gay to argue that homosexuals are born that way. For example, a survey of the American public by the Pew Forum on Religion & Public Life found that "politically, twice as many liberals as conservatives (46% versus 22%) say people are born homosexual." UCLA genetics professor Eric Vilain, speaking of the possible implications of an hypothetical future study that would determine conclusively that homosexuality is genetic, argued that "if it's not a choice, you can't have the typical conservative argument that says you choose this lifestyle so you have to bear the consequences and society has no reason to basically give you any rights because you choose to be an outcast" and that "if you can't do anything about it, therefore you should have all the rights to be integrated into society and have the same rights as heterosexuals in terms of marriage and the rights to inheritance."
However, Steve Sailer challenges these assumptions by pointing out what is likely to happen if a gay gene is indeed discovered:
A gay gene would probably elicit responses similar to the modern responses to the chromosomal abnormality that causes Down Syndrome -- and you'll notice that there are a lot fewer Down Syndrome people around than a few decades ago, due to pregnant women having eugenic abortions.
[...] I'm sure lots of fashionable people would say that they would never abort a fetus with a gay gene, but then you don't hear a lot of people boasting that they would abort a Downs syndrome fetus either, but it sure happens a lot these days. In both cases, parents would have to decide whether they want to go through all the hard work of raising a child without much chance of getting grandchildren in return.
Even more interesting is his analysis of who is likely to abort gay fetuses:
This calculus would especially be likely to be true among blue state liberals who are only planning to have one or two children, and therefore don't feel they can afford to invest in kids who won't pay off fully ... and grandchildren are about the biggest payoff you can get out of childrearing.
A seldom-discussed paradox is that if male homosexuality is proven to originate in a particular "gay gene," then it's likely that the continued existence of gay men in future generations in America will primarily be due to Christians who oppose abortion on religious grounds. Kind of ironic, no? Gays might want to think about that before denouncing Christians.
Some gays seem to have realized this. That's why there is an otherwise implausible association called the Pro-Life Alliance of Gays And Lesbians which published a provocative op-ed in 1997 arguing that gays and lesbians need to "prepare for a time when a woman's 'right to choose' becomes a hunting license to exterminate [gays and lesbians]" and that "if [the gay and lesbian unborns] have a right to life, doesn't every other unborn child have that same right?"
But then I wonder how religious conservatives will feel if they end up being the ones to ensure the perpetuation of homosexuality.
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I'm sure there are many brilliant homophilic PhDs in genetics who can explain this, but if, in fact, a "gay gene" exists, doesn't this doom gays to extinction, even aside from the abortion angle?
If I recall my basic genetics correctly, all genes, including the theoretical "gay" gene, are passed on from generation to generation through one's progeny. If there are no progeny, there is no heredity and whatever genes are exclusive to the non-procreators soon disappear from the pool. I must admit I don't know all of the nuances of gay culture, but I'm pretty sure procreation isn't very high on the gay collective priority list.
And, yes, I know that many gays embrace the brave new reproductive technologies, but even if gays used those technologies to procreate 100 times more often than they currently do, I suspect it would be a drop in the ocean (or pool, as it were) that wouldn't come close to meeting a level of gene transmission that would prevent the eventual extinction of the "gay" gene.
I also have some understanding of the "recessive gay gene" explanation, i.e. the "gay gene" is recessive and therefore only rarely produces behaviour, notwithstanding the gene itself is relatively widespread throughout the human genome. I'm not sure the fact the "gay" gene might be recessive changes anything other than the ultimate extinction of the gene may occur later, rather than sooner.
Posted by: curiousyellow | 2005-01-13 9:26:15 AM
I for one would be delighted by every life saved by pro-life policies. Whether they hold Judeo-Christian beliefs or not, whether they vote Conservative or not, no one deserves to be killed in the womb because of genetics.
Posted by: Marc | 2005-01-13 9:40:54 AM
I might as well be the one to add gene therapy to this debate. If a gay gene is discovered, will homosexuality become "curable". Pandora! Pandora, shut that, right now! You're making a mess!
Posted by: Occam's Carbuncle | 2005-01-13 9:52:29 AM
I doubt there's a single gene that determines things ... more likely it's a confluence of genetics, hormonal changes in the womb, and early childhood developmental events.
That said, if it were to become possible to abort a gay fetus, then it would also be possible a little further down the line to guarantee a fetus will be gay, using a combination of genetic screening, hormonal regimens, or what have you. Homosexual couples (who have to use in vitro techniques to reproduce anyways) might well choose to have homosexual children.
Homosexual behaviour occurs throughout the animal kingdom, from fruit flies up to bonobos. If natural selection hasn't weeded it out, it must be adaptive at some level, and genetic engineering and other reproductive choice technologies are unlikely to make it go away. Life will find a way!
Posted by: Matt Shultz | 2005-01-13 10:01:02 AM
Let us not forget James Taranto's (OpinionJournal) parallel theory that the Democrats in the US have been eroding their own voter base ever since Roe vs. Wade became law.
Posted by: MLM | 2005-01-13 10:46:09 AM
Hm... My wife and I are pro-choice yet have both discussed abortion and have agreed that it is something we would never consider unless it put her health at risk, or if the fetus was not going to be viable.
Being gay doesn't stop one from being viable, but having Down's Syndrome certainly does. I don't think either of us would think twice about aborting a pregnancy where we knew the fetus had Down's Syndrome.
Posted by: Sean | 2005-01-13 11:07:25 AM
"If I recall my basic genetics correctly, all genes, including the theoretical "gay" gene, are passed on from generation to generation through one's progeny. If there are no progeny, there is no heredity and whatever genes are exclusive to the non-procreators soon disappear from the pool"
You aren't recalling your basic geentics correctly.
A) There's no evidence that a "gay" gene precludes fertility.
B) If recessive, a 1 in 100 frequency of homosexuality in the population would indicate around a 19% carrier rate in the heterozygous population.
Posted by: Kate | 2005-01-13 11:16:12 AM
I've met quite a few people with Downs Syndrome. Not only did they appear to be fully viable, in each instance, they gave every indication of actually being alive, breathing, speaking, moving about, that sort of thing.
Posted by: Occam's Carbuncle | 2005-01-13 11:18:41 AM
"I doubt there's a single gene that determines things ... more likely it's a confluence of genetics, hormonal changes in the womb, and early childhood developmental events."
I agree completely, but it does not serve the purpose of gay rights advocates for there to be any explanation for homosexual behaviour BUT genetics. In other words, confirmation of the existence of the "gay" gene allows those advocates to complete the analogy that homosexuality is no different than gender, race, etc., i.e. a personal characteristic someone is powerless to change (other than through the radical intervention of science) and, accordingly, worthy of equivalent state protection. A "gay" gene supports the argument that homosexuality is not simply a lifestyle choice whose practitioners are no more deserving of state protection than smokers or drinkers.
As an outsider, I've always wondered why gays think they need to make this "we're born this way" argument in defense of their rights. Other well entrenched rights (freedom of religion, freedom of association, freedom of speech) are unquestionably rights that derive from "choices" that persons make.
Posted by: curiousyellow | 2005-01-13 11:23:07 AM
"A) There's no evidence that a "gay" gene precludes fertility."
There's also no evidence an "alcoholic" gene precludes sobriety, but it ain't much of a gene if it doesn't actually produce the behaviour it's intended to produce. It also doesn't do much to help the gay rights argument that "we're born that way and can't change".
"B) If recessive, a 1 in 100 frequency of homosexuality in the population would indicate around a 19% carrier rate in the heterozygous population."
Fair enough, but if every time a male and female carrier of the recessive gene procreates, the fact their progeny are far less likely to procreate themselves means that particular line of the recessive gene likely ends there. Hence my comment the "recessive gay gene" explanation, if valid, merely postpones extinction.
Posted by: curiousyellow | 2005-01-13 11:32:38 AM
"I've met quite a few people with Downs Syndrome. Not only did they appear to be fully viable, in each instance, they gave every indication of actually being alive, breathing, speaking, moving about, that sort of thing."
But viable enough to earn multiple PhDs at Harvard so that they can lavishly support their parents in their latter years?
Posted by: Sean | 2005-01-13 11:34:26 AM
"But viable enough to earn multiple PhDs at Harvard so that they can lavishly support their parents in their latter years?"
The ability to earn multiple doctorate degrees and the ability to hold down a job - aren't those mutually exclusive?
Posted by: Occam's Carbuncle | 2005-01-13 11:42:00 AM
"The ability to earn multiple doctorate degrees and the ability to hold down a job - aren't those mutually exclusive?"
Only for those who earned their PhD in the Liberal Arts, although there is still some home for them too.
'Would you like some fries with that, sir?'
Posted by: Sean | 2005-01-13 11:47:21 AM
Statistics show that most parents of perpetual doctoral students will have expired by sometime during the defence of the second dissertation, thus rendering moot any purported capacity on the part of the aging student to support his ma and pa, lavishly or otherwise.
What was the original topic here again? Something about gay babies wearing jeans?
Posted by: Occam's Carbuncle | 2005-01-13 12:48:46 PM
Your genes can be passed on even if you do not have any children because your siblings (who share on average 50% of your genes) can still have children.
Steve Sailer has covered the issue of a gay gene vs. a gay germ here: http://www.vdare.com/sailer/gay_gene.htm
"Trying to come up with a Darwinian justification for the spread of a gay gene, Dean Hamer adapted a hypothesis put forward thirty years ago by the brilliant manic-depressive sociobiologist Robert Trivers and popularized by his deeply sane colleague Edward O. Wilson. He suggested that the gay gene might lend 'inclusive fitness.' Gay uncles might have so many more nephews and nieces than straight uncles that the effect of the gay gene would be positive across the whole extended family."
Sailer is skeptical of this theory because he points out that, if we assume the average person has two surviving children, gays would have to have twice as many nephews/nieces in order for the gay gene to perpetuate, which seems unlikely. However, it might be plausible if we assumed a larger family size (as was common in the past) which would require a proportionally lesser boost in the number of nephews and nieces.
This does not imply that there is indeed a gay gene or gay genes, but this means a genetic basis for homosexuality cannot be ruled out a priori.
Posted by: Laurent | 2005-01-13 12:59:03 PM
"These are worded to protect only inherent attributes, resulting either from genetics (race, skin colour) or upbringing (language, nationality, religion)."
I appreciate your explanation for why the "gay" gene is important to gay rights activists, but I find it unconvincing. In particular, I don't see how language or religion are an "inherent" attribute (or, for that matter, "nationality", if by nationality you mean citizenship). I can always choose to learn french, convert to buddhism or become a Canadian and, in each case, my newly acquired language, religion and nationality are Charter protected. Why should the fact a person might simply be choosing a homosexual lifestyle, rather than being "born that way", preclude a rights recognition analogous to language, religion or nationality?
Posted by: curiousyellow | 2005-01-13 1:35:20 PM
"What was the original topic here again? Something about gay babies wearing jeans?"
Er, that or gay babes wearing tight jeans. Erf. If this keeps up I'm going to need a cold shower.
Okay, all jokes aside, we're talking about eugenics here, right? Assuming that the existence of 'alcoholic' and 'schizophrenic' genes is proven in the future, would parents be justified in aborting those fetuses?
Posted by: Sean | 2005-01-13 1:37:31 PM
"Gay uncles might have so many more nephews and nieces than straight uncles that the effect of the gay gene would be positive across the whole extended family."
It seems to me this would be a pretty easy theory to prove or disprove - just analyse the numbers of nephews and nieces of several thousand gay people and compare it to a test group. In fact, I would be very surprised if such a study hasn't already been done. The fact that "inclusive fitness" has not been widely put forward in support of the existence of a "gay" gene suggests to me no substantive proof of it has been established.
Posted by: curiousyellow | 2005-01-13 1:44:21 PM
>Okay, all jokes aside, we're talking about eugenics here, right?
You are, but is it (in law) strictly required to give a reason for an abortion, or may an abortion be denied on any particular basis? Might that be something we want to change before genetics presents us with a fait accompli (the ability to determine most potential shortcomings - perceived or actual - early in the womb)?
Posted by: lrC | 2005-01-13 2:26:40 PM
Here’s some more grist for this mill.
Environmental factors in the womb such as temperature and nutrition are known to alter fetal development affecting both appearance and behaviour. So, for example, if you cloned your mild mannered grey cat the result might be a calico terror. Similarly, if you cloned your straight brother your new sibling could well be queer (not that there’s anything wrong with that).
This seems as likely an explanation as any for “gayness”.
Posted by: JR | 2005-01-13 3:13:54 PM
"Fair enough, but if every time a male and female carrier of the recessive gene procreates, the fact their progeny are far less likely to procreate themselves means that particular line of the recessive gene likely ends there. Hence my comment the "recessive gay gene" explanation, if valid, merely postpones extinction."
(note: I accidentally typed "heterozygous" instead of heterosexual in my initial comment.)
Actually, when one removes homozygous affecteds from a population, the carrier rate _increases_.
The only way that a hypothetical recessive "gay gene" would be eliminated from the population is by preventing heterosexual carriers from having children at all.
And, keep in mind, that "affected" homosexuals who have natural children (very common) would pass a recessive gay gene along to all of them, regardless of the genetic status of their spouse.
Posted by: Kate | 2005-01-13 6:19:05 PM
At the risk of turning this into "Genetics For Dummies":
"Actually, when one removes homozygous affecteds from a population, the carrier rate _increases_."
I'm afraid I'll need chapter and verse on this one - how does a carrier rate (which, at the end of the day, is the number of occurances of gene "A" in a particular population) increase when the phenotype of the gene is a propensity NOT to reproduce itself?
"The only way that a hypothetical recessive "gay gene" would be eliminated from the population is by preventing heterosexual carriers from having children at all."
I'll concede this may be true in a population experiencing a relatively high rate of growth, but the fact that 3 to 5% of the individuals in a population are not reproducing the gene in question represents a pretty significant drag on "growth potential" of that particular gene.
"affected" homosexuals who have natural children (very common)"
Common it may well be, but it sort of weakens the argument gays are prisoners of their genes, n'est pas?
Posted by: curiousyellow | 2005-01-13 7:19:49 PM
Background: I'm a long time purebred dog breeder, with some familiarity with population genetics. (I am co-author of a peer-reviewed paper in which I contributed the genetic background of the genetic defect in question).
To understand how carrier rates rise, try a simple exercise: Hardy-Weinberg Law states that for every homozygous affected, there will be a ratio of 18 heterozygous carriers, and 81 non-carriers in the population. Thus, the carrier rate is 18%.
When one removes the affected, there are now 18 carriers in a remaining population of 99, increasing the actual carrier rate ever-so-slightly.
We have seen this phenomenon in some purebred dog breeds - testing and culling affecteds has little or no effect on reducing the frequency of recessive defects (other than preventing affecteds from breeding and increasing gene frequencies even more quickly).
It is only when we are able to identify "hidden" carriers (dna testing, test-breeding programs) that we have been able to make progress in eliminating defects from populations.
Posted by: Kate | 2005-01-13 7:39:39 PM
This is the most brilliant, thought provoking article I've read in a long time. I almost celebrated the idea that moral relativism could accept the idea that "if we have a right to life, doesn't every other unborn child have that same right?"
Then I remembered this is Canada not America. Canada is not about equality. Canada is about protecting the rights of minorities through affirmative action.
It is still conceivable that Canada could uphold a woman's right to choose, while restricting abortions for any fetus with the gay gene under Svend Robinson's Bill C-250 amendment to the criminal code.
Imagine that? Free, unfettered access to abortions for any reason except the gay gene. Sadly, it is not that far fetched.
Posted by: Michael | 2005-01-13 10:50:15 PM
Kate, the carrier rate in your example is 19%, not 18%. (unless you define "carrier" as meaning "non-phenotype carrier.)
In any case, before selection, 19% of the population possessed the genetic code. After selection, 18.2% posess the genetic code. selection against a trait reduces its prevalence.
Your example helps me get my head around this but curiousyellow still makes sense.
Posted by: Pete E | 2005-01-14 1:18:03 AM
"19%" was a typo. Read the comment as is. If you remove only affecteds from a population, the gene frequency rises. The same principle applies whether there is a 18% carrier rate or a 30% carrier rate. As I pointed out - it is not theoretical - it's a problem animal breeders have always struggled with. One cannot reduce the incidence of recessive disease without a means to identify carriers.
Posted by: Kate | 2005-01-14 8:36:13 AM
Last word from me, I promise (to the applause of dozens).
Two comments re: Kate's dog-breeding example:
1. Dogs ain't humans meaning, among other things, we can't compete in terms of litter size. Hence, while it may be true the number of carriers of a recessive gene may actually increase in a population experiencing a high rate of growth, the rate by which the number of recessive gene carriers grows will still be equal or less than the population growth rate itself, unless the gene produces better fitness in the carrier population. Kind of a moot point when your population has actually fallen below sustainable reproduction rates, as is the case in much of the western world, including Canada.
2. It's not the ratio of a gene in "G1" that's relevant, it's G2, G3 and beyond. In other words, your example of the carrier rate actually increasing when a homozygous pair are removed from a population holds true only for that generation, but not the next. All other things being equal, carrier rates for less fit genes in subsequent generations cannot go any direction but down. Hence the need for "gay" gene theorists to come up with other explanations as to why, notwithstanding its phenotype is to constrain reproduction, a "gay" gene is more "fit" than others (see Laurent's "inclusive fitness" post).
Again, at the end of the day, I remain perplexed as to why the "gay" gene seems so critical to at least some gay rights advocates - doesn't arguing homosexuality is a sacrosanct "choice" dovetail nicely with another rather notorious right?
Posted by: curiousyellow | 2005-01-14 9:19:16 AM
The principles and probabilities governing population genetics applies to all species, whether they have litters or single births. The probability that you will inherit a "double dose" of any specific gene is a function of the genetic status of your parentage - not a function of the number of siblings you have.
I mentioned my experience dog breeding because we attempt to do exactly what your theory proposes: eliminate undesirable recessive genes from populations. They do not eliminate themselves - even defects that cause the death of the homozygote will remain in the population at unabated levels if carriers are allowed to continue breeding.
The reason for this is that for every affected offspring, two phenotypically normal carriers are born to carry on and reproduce.
If your theory that a "gay gene" would eventually eradicate itself due to "unfitness" were correct, we wouldn't have any genetic disease in humans at all.
Posted by: Kate | 2005-01-14 10:28:09 AM
(Yes I know I'm breaking my promise)
"The probability that you will inherit a "double dose" of any specific gene is a function of the genetic status of your parentage - not a function of the number of siblings you have"
Kate, we're talking apples and oranges. Yes, the probability of inheriting a specific gene is a function of the genetic status of one's parents, but the absolute incidence of a specific gene in subsequent generations of a single species must invariably decrease if the full expression of the gene in homozygotes is to completely constrain reproduction, which ELIMINATES the possibility the gene will be transmitted on that occasion.
"even defects that cause the death of the homozygote will remain in the population at unabated levels if carriers are allowed to continue breeding."
Again, Kate, I'll need chapter and verse, since this is completely counter-intuitive (and, I might add, turns the "survival of the fittest" aspect of evolution theory on its ear). A recessive gene will "remain in the population" but most assuredly NOT "at unabated (relative) levels".
"If your theory that a "gay gene" would eventually eradicate itself due to "unfitness" were correct, we wouldn't have any genetic disease in humans at all."
Most genetic disease results from mutation, not heredity. Gene mutation can "refresh" carrier rates that would otherwise be in decline, hence the continued existence of certain genetic diseases. Perhaps the "gay" gene, if it exists, is a result of mutation (although I wouldn't want to be the author of THAT particular paper) - see my previous comments re: "incidental fitness".
Although genetic disease may not have disappeared, if evolution theory is correct, and assuming a low or no mutation "refresh" rate, it must certainly be in relative decline (or absolute decline in populations not reproducing at sustainability levels) and will, invariably, become as extinct as those species whose genetics rendered them less "fit".
With that, I must now depart from this thread - thanks for the enjoyable discussion - I know who to contact if I need a purebred dog!
Posted by: curiousyellow | 2005-01-14 12:13:36 PM
Most genetic defects are not due to spontanious mutation.
Mutations are relatively rare, genetic disease extremely common - (most organisms carry an average of 5 defective genes). Even the majority of our so-called "lifestyle" disorders have a genetic predisposition at their base. (See diabetes).
Are you familiar with the Punnet square?
If two heterozygous carriers mate (or marry) the probabilities generated for their offspring are as follows:
(N = normal gene, n = defective recessive)
Nn x Nn = 25% NN normal, 50% Nn carrier, 25% nn affected.
Thus, the probability that any child will be a phenotypically normal carrier is double the probability of being affected, or of not carrying the gene.
In a pairing of a NN parent and a Nn parent, the probabilities are 50% NN normal, 50% Nn carrier.
No matter how dangerous, recessives have a strong tendency remain at stable, or increasing frequencies in populations. This is because carriers are continually producing far, far more carriers than they do affecteds.
I know this is as you put it = genetics 101, but it is relevant to any argument that a gay gene would remove itself through "lack of reproduction" in successive generations. The majority of the so-called "gay genes" are reproducing merrily regardless of what the tiny minority of homozygotes might decide to do in terms of producing children themselves.
Posted by: Kate | 2005-01-14 12:47:30 PM
"Homosexuals do not claim the protection of law out of any general liberty."
This is an obviously wrong statement. Most gay rights advocates do make such a claim. Certainly libertarian ones do, but so do most others, all across the political spectrum. The fact that many (mostly left-wingers, I imagine) also insist on a genetic origin of homosexuality could be explained by many things. One is pragmatism. If there's a genetic root, it would be a shortcut to recognition of rights.
But ask most gay rights advocates whether, even if is shown that there is no genetic basis for sexual orientation, they think homosexual acts should be punished or homosexuals given unequal treatment under law, and the overwhelming answer would still be "no". They may be inconsistent, but they are far more committed to the view that gays have rights than they are to the view that homosexuality is genetic.
I think part of the commitment to the "gay gene" theory may be less political in nature. It may be just a mistaken reaction to those who claim, essentially, that sexual preference is no different from ice cream preference or choice of a favorite color. Anyone with an ounce of introspective ability knows that their preferences in sexual partners -- and certainly their preferences in the gender of that sexual partner -- are not things that are under one's direct control. In other words, being gay and being straight are not choices, in any meaningful sense. (Whether or not to act on those preferences is, of course, a choice under one's direct control, but let's leave that aside for the moment.) Well, if homosexuality is not a choice, many will say, it must be genetic. But this is a false dichotomy. It's just as plausible, if not more plausible that one's sexual preference is set due to psychological and environmental factors very early in one's childhood and not alterable after that.
Personally, I don't think it matters a bit whether homosexuality is genetic, psychological, or even a simple choice like vanilla or chocolate. People should be treated no differently by the government based on what they prefer to do in the bedroom.
Posted by: Mark | 2005-01-14 5:09:11 PM
To return to the original topic of the post, I should also add that I don't see any problem, if there does turn out to be a gay gene, with parents choosing to abort a fetus that has it. But more relevant, I don't think there is any conflict here as proposed. Most people are either going to support or oppose abortion for the purposes of selecting ANY genetic trait, be it eye color, hair color, IQ, sexual orientation, or anything else. And a negative stance on this issue in no way precludes a positive one on the issue of whether a woman, outside of a narrow genetic selection scenario, has the right to abort her fetus.
Posted by: Mark | 2005-01-14 5:35:22 PM
Erudite and informative as the genetic discussion is there seems to be a disconnect between the claim of genetic gayness and the legal status of abortion.
At the moment Canada has no law with respect to abortion. Have one, have several, have them in the third trimester, have them because the ultrasound discloses that Freddy fetus is actually Fredrica; our current law does not constrain you in any way. (And, yes, I know that as a practical matter it is difficult to obtain a third trimester abortion.)
While Laurent via Steve Sailer raises a provocative point, especially on this forum, a more interesting one is whether the "female drought" which is the demographic reality in China and India and has been for the last decade, is occuring in Canada.
I suspect it is and base my suspicion on a single, personal, experience. When we trotted off to have Max scanned in utero we had decided to ask what sex he was - pure curiousity. We did. The tech looked us straight in the eye and said, "I'm sorry, I can't tell you." Which is a change from three years before when the tech began the Sam scan with, "Would you like to know the sex of your baby."
Long before the question of blue staters aborting babies who test positive for the gay gene is important, we might ask whether people are currently aborting for chromozonal malfunction.
Posted by: Jay Currie | 2005-01-14 6:25:21 PM
19% is NOT a typo. I combined your 18% carrier and 1% affected since both of them carry the gene Would you re-read my post and respond?
Your Hardy-Weinberg example illustrates that 19/100 dogs (=19%, including 18 unaffected carriers and 1 affected) had at least one gene before selection and 18/99 dogs (=18.2%) after selection. Therefore, your illustration SUPPORTS curiousyellow’s point.
I agree that there will be more carriers than affecteds. And yes, that means it will take many generations to select out a trait. And yes, I see how that is a problem for dog breeders who want results in less than 10 years. It is not a problem for nature over thousands of years.
(Details: if I have the math right, a gene that starts off at 10% prevalence (1% affected, 18% carrier) will be down to 5% prevalence (.25% affected) after 10 generations of perfect selection. 100 generations yields 1% prevalence (0.008% affected).)
Posted by: Pete E | 2005-01-15 2:27:28 AM
Pete E wrote:
"19% is NOT a typo. I combined your 18% carrier and 1% affected since both of them carry the gene Would you re-read my post and respond?"
"Your Hardy-Weinberg example illustrates that 19/100 dogs (=19%, including 18 unaffected carriers and 1 affected) had at least one gene before selection and 18/ 99 dogs (=18.2%) after selection. Therefore, your illustration SUPPORTS curiousyellow’s point.
But Hardy/Weinberg does no such thing.
"Carrier" is specific terminology -to designate a phenotypically normal heterozygote. You don't combine them because the carriers remain in the breeding population, the affecteds do not.
"I agree that there will be more carriers than affecteds. And yes, that means it will take many generations to select out a trait."
Again - we deal with this on a practical, not theoretical basis in dogs. Programs that target only affecteds have no impact at all on the prevalence of disease. Only the retirement of dogs who produce the defect has much effect.
In my own breed, a recessive cataract was discovered in the 1960's. It seemed to pop up sporadically in a number of lines. Dogs were affected at birth, and often blind by a year - and thus, few affecteds were bred from.
Eventually, a formal, breed-wide test breeding program was established, in which normal eyed dogs destined for breeding were mated to affecteds. (Actual colonies were maintained for that purpose) If affected puppies were produced, the normal eyed dog was proven to be a carrier, and retired.
When all was said and done, it was discovered that the breed had been sustaining a 40% carrier rate - yet even at 40%, only 16% of breedings would be between Nn x Nn individuals, with an affected rate of 4%.
" And yes, I see how that is a problem for dog breeders who want results in less than 10 years. It is not a problem for nature over thousands of years."
Dog breeders watch the transmission of traits on an accelerated scale. 10 years can cover 5 or more generations. - We see the results of many, many generations over a single breeder's lifetime. We also maintain extensive pedigree databases, publish testing results and can plot the travel of new (or previously rare) recessives as they emerge and travel through previously unaffected family lines. Plus, we select far more aggressively than any human population ever has for non-lethal disease. If ever there was an opportunity to eliminate disease through selection - dog breeding should be the gold standard.
And again - why does childhood recessive disease exist at all in human populations? How did cystic fibrosis, tay sachs, sickle cell endure the crucible of Darwin?
Posted by: Kate | 2005-01-15 11:23:31 AM
So, let me get this straight. There’s only ONE reason in the entire world that it is NOT ok to kill a pre-born child? As the pro-aborts are fond of saying regularly “Who are YOU to decide for ANY woman what to do with her body?” But, it’s ok to kill a pre-born child because he or she will grow up poor or fatherless or adopted or with a mental or physical disability?
I am laughing my butt off at some of the comments from “pro-choice” people who are also “pro-gay”. Some of them are verbatim from pro-life organization sites. They fail to see the irony in their "suddenly offended by abortion" objections. The horror of the gay community is understandable, yet the pro-aborts have consistently discounted the same objections to abortion that disability advocate groups have had for decades. NO ONE has the right to decide whether a life is worthy of being lived…except God.
Quite a dilemma, no? The hypocrisy is overwhelming yet predictable, and I’m watching closely to see how the pro-aborts handle this one.
Posted by: Michelle | 2007-04-08 1:54:45 PM
Homosexuals are not born that way. It's a choice. Anyone can change their sexual orientation.
Many homosexuals claim tha they were born gay and it was not someting they chose. They "believe they were born gay because it supplies then with comfort and relieves them of any responsibility to change, [yet] there is no solid scientific evidence that people are born homosexual" (Worthen). Homosexuality is not innate (something you're born with) because it has nothing to do with genetics, many become homosexual as a choice after a tragic event, and it can be cured.
Posted by: Autumn | 2008-02-08 8:56:56 AM
You make some fine points, but I believe you are only partly correct. I think there might be different degrees of gayness that have different levels of self determination.
Some examples of homosexuality as a lifestyle choice could be; Dennis Rodman, British soldiers stationed abroad, federal prisoners, your ex-boyfriend.
Some who could have been cured might include; Rock Hudson, Ted Haggart, my cousin Claire.
Some cases can only be explained by genetics: Liberace, Freddy Mercury, Richard Simmons.
You see, it may be more complicated than you think.
Posted by: dp | 2008-02-08 9:19:47 AM
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