# Genetics and disease: Why didn't Cecil mention... **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [January 27, 2006, 1:26pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840 "2006-01-27T13:26:08Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 27, 2006, 1:26pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/1 "2006-01-27T13:26:08Z")
…how silly it is to say something like “the disease is so debilitating that it is unlikely schizophrenics would ever reproduce” in his column on .[toxoplasmosis](http://www.straightdope.com/columns/060127.html). After all, there were not a lot of Cystic Fibrosis patients reproducing, or even living long enough to do so until recently, and the disease seems to still be with us. ---
**Author:** ![Cluricaun](https://avatars.discourse-cdn.com/v4/letter/c/bb73d2/32.png) [@Cluricaun](https://boards.straightdope.com/u/Cluricaun)\ **Post date:** [January 27, 2006, 2:10pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/2 "2006-01-27T14:10:51Z")
Especially since schizophrenia dosen’t usually manifest until between the ages of [16 and 25](http://www.mentalhealth.com/book/p40-sc02.html), giving many people plenty of time to reproduce before the onset of symptoms. ---
**Author:** ![Mathochist](https://avatars.discourse-cdn.com/v4/letter/m/c89c15/32.png) [@Mathochist](https://boards.straightdope.com/u/Mathochist)\ **Post date:** [January 27, 2006, 4:23pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/3 "2006-01-27T16:23:37Z")
> [@Cluricaun](#): > > Especially since schizophrenia dosen’t usually manifest until between the ages of [16 and 25](http://www.mentalhealth.com/book/p40-sc02.html), giving many people plenty of time to reproduce before the onset of symptoms. KOFFKOFFjohnnashandsonKOFFKOFF Anyhow, what glared out at me was the mention of LSD. Does the study say that schizophrenics somehow _produce_ LSD in their own bodies? That a large number of them have _taken_ it in the past? It’d be nice if someone can find a pdf of the paper out there on the web. Overall this column looks like either there was an early deadline or the editor is slipping. of course The Great Master hisself must be up to his usual snuff. ---
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 27, 2006, 8:18pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/4 "2006-01-27T20:18:01Z")
> [@Mathochist](#): > > Overall this column looks like either there was an early deadline or the editor is slipping. of course The Great Master hisself must be up to his usual snuff. And of course I should add Cecil was simply paraphrasing what someone else said. I thought he shouldn’t have let it pass without comment, though. ---
**Author:** ![Monstera\_deliciosa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/monstera_deliciosa/32/109_2.png) [@Monstera\_deliciosa](https://boards.straightdope.com/u/Monstera_deliciosa)\ **Post date:** [January 27, 2006, 10:40pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/5 "2006-01-27T22:40:08Z")
I quite agree. I am the child of a schizophrenic, and I know three others personally. Also, the disease is often not immediately debilitating; it can progress quite gradually. While in retrospect, it is clear my father began showing symptoms around age twenty, it wasn’t until many years later that it became apparent that there was something seriously wrong. The researchers Cecil quotes should have known better. ---
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 28, 2006, 2:08am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/6 "2006-01-28T02:08:06Z")
> [@KayElCee](#): > > I quite agree. I am the child of a schizophrenic, and I know three others personally. > > Also, the disease is often not immediately debilitating; it can progress quite gradually. While in retrospect, it is clear my father began showing symptoms around age twenty, it wasn’t until many years later that it became apparent that there was something seriously wrong. > > The researchers Cecil quotes should have known better. Yep. I didn’t want to get into it here, but what the hell. My ex-wife’s mother is schizophrenic, and her symptoms manifested after her first kid was born. A diagnosis of “high strung” (please note: this was the 60s in rural Central NY) had her home in under 30 days. No symptoms have appeared so far in any of her **five** daughters. Unable to reproduce my ass. ---
**Author:** ![Ed\_Zotti](https://avatars.discourse-cdn.com/v4/letter/e/fbc32d/32.png) [@Ed\_Zotti](https://boards.straightdope.com/u/Ed_Zotti)\ **Post date:** [January 28, 2006, 2:57am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/7 "2006-01-28T02:57:41Z")
> [@saoirse](#): > > …how silly it is to say something like “the disease is so debilitating that it is unlikely schizophrenics would ever reproduce” in his column on .[toxoplasmosis](http://www.straightdope.com/columns/060127.html). After all, there were not a lot of Cystic Fibrosis patients reproducing, or even living long enough to do so until recently, and the disease seems to still be with us. That’s not what Cecil said. He wrote, “No way, scoffers say: schizophrenia is so profoundly disabling that sufferers tend not to reproduce.” This is far different from saying it’s “unlikely schizophrenics would EVER reproduce” (my emphasis). Moreover, this is in fact what scoffers say. For example, see the paper cited in the column, which so far as I am aware is not available free online but can be looked up in a med library at: Ledgerwood, Levi G. “Genes, Germs, and Schizophrenia: An Evolutionary Perspective,” Perspectives in Biology and Medicine - Volume 46, Number 3, Summer 2003, pp. 317-348 Ledgerwood and company suggest that schizophrenics are at a reproductive disadvantage relative to the general population. They write: “Schizophrenics have a high suicide rate, few children, and a high rate of abnormality in their children … defective alleles causing such a high rate of severe damage would tend to be weeded out by natural selection.” Cecil is well aware that the hypothesis sketched in this paper is a little farfetched; that’s why he wrote, “A word of caution: our authors’ impressive theoretical edifice is built on some pretty thin evidence. It’s simplistic to say T. gondii works by triggering the production of LSD–among other problems with the idea, acid mainly gives rise to visual hallucinations, whereas the delusions of schizophrenics are primarily auditory (e.g., hearing voices). No doubt genetics plays some role,” etc. Cecil’s purpose was not to debate whether Ledgerwood et al are right, but simply to present an interesting theory. If you don’t buy the theory or dispute the facts, fine, but your quarrel is with Ledgerwood. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [January 28, 2006, 3:21am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/8 "2006-01-28T03:21:20Z")
And, of course, evolution isn’t geared for modern technological civilization. The operative question is: how likely was a schizophrenic to have children that lived to have children themselves under paleolithic conditions? ---
**Author:** ![Monstera\_deliciosa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/monstera_deliciosa/32/109_2.png) [@Monstera\_deliciosa](https://boards.straightdope.com/u/Monstera_deliciosa)\ **Post date:** [January 28, 2006, 3:59am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/9 "2006-01-28T03:59:08Z")
> [@KayElCee](#): > > I quite agree. I am the child of a schizophrenic, and I know three others personally. I wasn’t quite clear here. What I meant is that I know three other persons with a schizophrenic parent. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [January 28, 2006, 4:20am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/10 "2006-01-28T04:20:12Z")
Some other references, to support **Cecil’s** statement: [Genetic epidemiology and schizophrenia: a study of reproductive fitness.](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11278140&dopt=Abstract) > [@](#): > > Genetic epidemiological studies have demonstrated markedly reduced rates in reproduction among schizophrenic patients. [Reproductive rates in schizophrenic outpatients.](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8356891&dopt=Abstract) > [@](#): > > We investigated the marriage rates, the reproductive rates and the marital reproductivity of schizophrenic outpatients in Japan . . . . Our findings indicate that the reproductivity of schizophrenics is reduced, even though the sample consists of outpatient population and modern operational diagnostic criteria have been used. Of course, it is not necessary for schizophrenics to never reproduce to have the condition selected against, only that their reproductive rate be lower than average. My father was schizophrenic, and I am one of six siblings (none of whom have the condition). But his sister, and my first cousin, were also schizophrenic, and neither of them ever married or had children. I have two friends with fairly mild schizophrenia; neither of them has had children. So even though my father had a large number of offspring, the schizophrenics known to me personally have had well below the average number of children as a group. ---
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 28, 2006, 11:58pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/11 "2006-01-28T23:58:59Z")
> [@Ed Zotti](#): > > That’s not what Cecil said. He wrote, “No way, scoffers say: schizophrenia is so profoundly disabling that sufferers tend not to reproduce.” This is far different from saying it’s “unlikely schizophrenics would EVER reproduce” (my emphasis). Moreover, this is in fact what scoffers say. Then I will say for a third time that I was surprised he let it pass without comment. I wouldn’t expect him to argue with the assertion, by now I expect him to dismiss it in a humorous way which demonstrates what a foolish thing it is to say. > [@John W. Kennedy](#): > > And, of course, evolution isn’t geared for modern technological civilization. The operative question is: how likely was a schizophrenic to have children that lived to have children themselves under paleolithic conditions? Again, Cystic Fibrosis is certainly genetic. Until very recently, it was nearly impossible for someone with CF to live long enough to reproduce. How did this disease survive paleolithic conditions? ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [January 29, 2006, 12:42am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/12 "2006-01-29T00:42:53Z")
> [@saoirse](#): > > Again, Cystic Fibrosis is certainly genetic. Until very recently, it was nearly impossible for someone with CF to live long enough to reproduce. How did this disease survive paleolithic conditions? Like a great many recessive defects there is probably some survival advantage for carriers that outweighs the penalties. We can see this most clearly with diseases like sickle cell and thallasemia that are deadly in the worst cases but confer a large enough advantage that they persist in the population. There has been speculation that CF carriers are less prone to the osmotic problems associated with severe diarrhoea, especially brought on by cholera, hence the reason why the disease is most prevalent in western Europeans and rare amongst other groups who lived in lower population densities or more open conditions. Of course it’s entirely possible for schizophrenia to have the same sorts of benefits. The problem lies in the fact that nobody has been able to find a schizophrenia gene desipte much searching. That indicates that if the disease is genetic then it is caused by a range of mutations that just happen to coincide in some unfortunates. That’s not impossible, and we see something similar with thallasemia. ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [January 29, 2006, 12:51am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/13 "2006-01-29T00:51:22Z")
Cystic fibrosis is a recessive trait. Judging from the Internet in general (and, frankly, from the last 24 hours of traffic on this very board), if schizophrenia is genetic, it’s dominant… ---
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 29, 2006, 1:46am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/14 "2006-01-29T01:46:59Z")
> [@John W. Kennedy](#): > > if schizophrenia is genetic, it’s dominant… I don’t understand why you’d say that. There are many children of schizophrenics who have none of the symptoms. Why would you assert that it’s dominant? > [@John W. Kennedy](#): > > (and, frankly, from the last 24 hours of traffic on this very board) And this is mystifying. Explain, please? ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [January 29, 2006, 3:16am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/15 "2006-01-29T03:16:16Z")
> [@saoirse](#): > > I don’t understand why you’d say that. There are many children of schizophrenics who have none of the symptoms. Why would you assert that it’s dominant? I said _if_ it’s genetic, it’s dominant. (The equivalent contrapositive, of course, being that if it’s not dominant, it’s not genetic – at least, not in a classically Mendelian way.) > [@saoirse](#): > > And this is mystifying. Explain, please? It would be contrary to the rules of the forum to go into detail, but there are several ongoing threads for which schizophrenia is the kindest explanation, and thousands of other such threads in other venues. (Ever try to argue rationally with a Shakespeare denier?) ---
**Author:** ![kjkolb](https://avatars.discourse-cdn.com/v4/letter/k/3ec8ea/32.png) [@kjkolb](https://boards.straightdope.com/u/kjkolb)\ **Post date:** [January 29, 2006, 12:53pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/16 "2006-01-29T12:53:27Z")
What evidence is there for it being dominant, rather than recessive or caused by multiple genes? Is the transmission rate about 50%? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 29, 2006, 6:06pm UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/17 "2006-01-29T18:06:46Z")
The notion that a genetic disorder is common in no way implies that it’s dominant. It just implies that the gene for it is common. You would only be able to conclude that a disease is dominant or recessive by studying the family histories of those with it. ---
**Author:** ![saoirse](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@saoirse](https://boards.straightdope.com/u/saoirse)\ **Post date:** [January 30, 2006, 1:09am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/18 "2006-01-30T01:09:12Z")
> [@Chronos](#): > > The notion that a genetic disorder is common in no way implies that it’s dominant. It just implies that the gene for it is common. You would only be able to conclude that a disease is dominant or recessive by studying the family histories of those with it. Right, but a dominant gene’s characteristic should be common in people who carry the gene. My argument, once again, is not that schizophrenia must be genetic. It is rather that the statement, > [@](#): > > “‘schizophrenia is so profoundly disabling that sufferers tend not to reproduce.’” misrepresents evolutionary biology in a way that a reasonably intelligent 10th-grader could point out. Many clearly genetic diseases are far more disabling than schizophrenia. The I thought that Cecil should have done so. ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [January 30, 2006, 4:44am UTC](https://boards.straightdope.com/t/genetics-and-disease-why-didnt-cecil-mention/341840/19 "2006-01-30T04:44:32Z")
> [@Mathochist](#): > > Anyhow, what glared out at me was the mention of LSD. Does the study say that schizophrenics somehow _produce_ LSD in their own bodies? That a large number of them have _taken_ it in the past? It’d be nice if someone can find a pdf of the paper out there on the web. Cecil was saying, that some research indicated, that the toxo organism produces LSD (and/or other hallucinogens) in order to make the rodents it infects easier for cats to catch, ensuring a transmission path for itself. I do recall reading something about this in New Scientist some years ago … ahh yes, here we are, from Oct 2002: > [@](#): > > … researchers already know that toxo can manipulate rodents, its natural “intermediate host”. Remarkably, rats and mice behave more recklessly when they are infected. Joanne Webster and her team at Oxford University have found that the hapless rodents are more active and less scared of new things. They are even attracted to cat urine. And research by Jaroslav Flegr and colleagues at Charles University in Prague has shown that rats have slowed reaction times. All this makes them much more vulnerable to a feline pounce, which is exactly what the parasite wants. After all, toxo needs to infect a cat (the “definitive host”) to complete its life cycle and spread its genes. So no mention of LSD but definite alteration of rodent behaviour. The burden of the article was, does this affect humans this way too? Apparently toxo sufferers are over-represented in drivers involved in car accidents, and their reaction times were measurably slowed.