Wikipedia:Reference desk/Archives/Science/2016 January 9

= January 9 =

When is technology not just equal to applied science?
When is technology not just equal to applied science? Some people seem to reject the notion, but can't everything be explained by science, including things like a human using a machine technology without fully understanding it. --Scicurious (talk) 02:46, 9 January 2016 (UTC)


 * Are you asking if there is technology that's beyond science's ability to understand? Sure - there are plenty of things we don't fully understand.  There are (for example) many drugs that we know to be effective but we don't fully understand why.  I'm sure I could come up with any number of examples given time.


 * Are you asking whether there are things that science knows that we don't yet have the technology to use? Yes, sure - we're still struggling to use quantum theory to build practical computers - or applying what we know about the behavior of gasses and liquids to provide useful application of turbulent flow.


 * Certainly there are things that can't yet be explained by science. We don't know what caused abiogenesis, we don't know what caused the big bang.  An entirely new particle may have been discovered by the Large hadron collider that lies outside of the standard model.  We don't understand everything about the human brain.  So sure - there are plenty of things we don't yet understand.  That's not to say that these things can't ever be explained by science.


 * I'm not sure what you mean by "a human using a machine". We don't fully understand every aspect of how a human works - so I guess we don't fully understand how a human uses a machine...or anything else for that matter.


 * We should be careful, however, to avoid reading any kind of mysticism into this. We often don't know something because we haven't spent the money to do the research yet...there are few phenomena that we don't believe we'll every be able to comprehend through the lens of the scientific method...but there are a few.  We know (because of chaos theory) that we won't ever be able to accurately predict the weather more than a few days into the future.  There are sharp limits in a few of these cases.


 * SteveBaker (talk) 03:38, 9 January 2016 (UTC)


 * I actually meant someone using a technology without understanding it. Indeed, I wonder if a working technology becomes automatically a scientific discovery (albeit in a rather disorganized way). Using bark of willow trees to treat fever or pains does not require to understand it. However, there was a hypothesis (willow to treat pain), a test, and a conclusion. That would us lead to the view that any technology has a scientific theory backing it somehow.--Scicurious (talk) 01:45, 10 January 2016 (UTC)


 * For the "human using a machine" part, perhaps the OP refers to the way in which people adapt so readily to certain technologies that they really become an extension of our own bodies. Driving a car is one simple example.  Despite never having evolved to use a steering wheel and brake and accelerator pedals, it soon becomes totally automatic for us.  For an even more interesting example, when electrodes are implanted in the brain of some blind patients, in the form or an array of pixels, that person soon learns to see.  Apparently connections form and the brain "learns" how to read the info from those electrodes as an image, almost like magic. StuRat (talk) 06:50, 9 January 2016 (UTC)


 * Actually I think the exact mechanism of virtually every single medication is unknown, except aspirin which was only recently understood. Quite entertaining to read FDA trial (BTW, despite tediousness, it is always interesting to read trial methods and results.  Doctors often don't and I am amused at when they prescribe things like "extended release" medication but haven't bothered to see what the drug company did.).   But to get to the OP, at some point there may be artificial intelligence where the thing applying science is not human.  Currently most every decision tree in technology is simply a human type of choice based on a human understanding of science.  The last time I looked, neural networks were the closest thing to deviate from a human application of science into a machine based application of experience.  Learning machines aren't necessarily scientific and humans have lived many generations by surviving on experience without understanding science. Aqueducts existed long before Newton and Bernoulli - we describe them now using science as we know it but the technology existed before the science.  --DHeyward (talk) 10:19, 9 January 2016 (UTC)
 * Where on Earth did you get the idea that "the exact mechanism of virtually every single medication is unknown"? In your example, it has been know since 1971 that aspirin is a prostaglandin/thromboxane suppressor, most certainly not 'recently understood'. Virtually all new drugs are explicitly designed to exploit certain mechanisms. To the OP, I am personally very happy that we can't explain everything by science, or I would be out of a job as a scientist! Fgf10 (talk) 21:40, 9 January 2016 (UTC)
 * I suppose DHeyward mean the 'exact' in a more strict sense, meaning we cannot know all and absolute all about the effect of a substance. Scicurious (talk) 01:45, 10 January 2016 (UTC)

Is there something in alternative medicine that's not considered as pseudoscience?
92.249.70.153 (talk) 05:28, 9 January 2016 (UTC)
 * If the definition given in alternative medicine is accurate, then the answer should be "No". ←Baseball Bugs What's up, Doc? carrots→ 05:31, 9 January 2016 (UTC)
 * Pseudoscience is false science, something that is presented as scientific when it is not. Alternative medicine is a broad category that can include traditional medical practices and religious beliefs from different parts of the world, and these are generally not regarded as scientific in the first place.  In that case alternative medicine could be unscientific without being pseudoscientific.  --Amble (talk) 05:53, 9 January 2016 (UTC)


 * Herbal medicine was basically traditional, but many herbs and fungi do have medical effects that have been taken advantage of by modern medicine. Some of mainstream medicine is also pseudo-science, but we may have to await time to pass before misconceptions fade. Graeme Bartlett (talk) 05:59, 9 January 2016 (UTC)


 * Agreed. For example, aspirin comes from willow bark, and at one point willow bark would have been used, but unproven, as an alternative medicine.  Alternative medicine means it hasn't been scientifically proven to work yet.  So, when the actual science is done, some are found to work, and others do not.  Then there's also the problem that, there being no requirement for scientific evidence, they can also try to sell anything for any purpose, even when they know it doesn't work.  For example, there is a chiropractic core that seems plausible, which is adjusting misaligned vertebrae, but then, being largely unregulated, they also make outrageous claims that they can cure anything and everything simply by manipulating the spine.  StuRat (talk) 06:43, 9 January 2016 (UTC)
 * The short answer is that once something is proven to work it becomes "medicine" rather than "alternative medicine." Shock Brigade Harvester Boris (talk) 23:18, 9 January 2016 (UTC)
 * And when it's proven not to work but people keep doing it, it becomes "pseudo-science". ←Baseball Bugs What's up, Doc? carrots→ 23:27, 9 January 2016 (UTC)
 * Examples of near current medical practice that could be classed pseudo science are Lobotomy, Psychoanalysis, Antibiotic misuse and some drugs, particularly those withdrawn or proved ineffective. Graeme Bartlett (talk) 00:10, 10 January 2016 (UTC)
 * The "science" behind the first two of those items has been questioned, to say the least. Misuse of any drug or substance is questionable too. On the other hand, the use of leaches leeches was considered pseudo-science for a long time, but now it's back within the realm of science, for certain specific situations. ←Baseball Bugs What's up, Doc? carrots→ 00:27, 10 January 2016 (UTC)
 * See leach and leech.—Wavelength (talk) 00:34, 10 January 2016 (UTC)
 * OMG. A misspelling. ←Baseball Bugs What's up, Doc? carrots→ 00:41, 10 January 2016 (UTC)
 * That's not really accurate. The thing that was and still is pseudoscientific is the idea that many diseases can be fixed by removing blood from the patient. This was part of humorism, the idea that diseases are caused by an imbalance in the body of the "four humors", of which one was blood. Medical leeches are used today for things where the blood circulation is involved, like grafts and phlebitis, and of course the treatment is administered to the relevant body parts, rather than just sticking leeches all over. --71.119.131.184 (talk) 01:58, 10 January 2016 (UTC)
 * That's why I said "for certain specific situations". ←Baseball Bugs What's up, Doc? carrots→ 18:50, 10 January 2016 (UTC)


 * It's difficult to show when alternative medicine isn't pseudoscience, because either (a) it is confirmed and incorporated into "regular" medicine, (b) it is pseudoscience, or (c) mainstream medicine hasn't caught up yet and will not admit anything until it does. For example, consider the news about a miracle cure for cataracts from last year: lanosterol, administered on the eye that clarifies cataracts.  Well, two thousand years ago, Roman doctors prescribed cyclamen salves for cataracts, and cyclamens are loaded with triterpenes, the class of compound from which lanosterol is drawn.  But I don't expect to hear any acknowledgement given at least until the patent expires... Wnt (talk) 11:36, 10 January 2016 (UTC)
 * I would strongly disagree with the implication given by (c) mainstream medicine hasn't caught up yet and will not admit anything until it does. I believe this is actually the very opposite of what happens in reality %99.9 of the time. If ever in the 0.01% "alternative medicine" is ahead of "mainstream medicine", it's purely by dumb chance. To really plumb the depths of this argument you have to delve into epistemology and what it actually means to "know" something, but if you study science and the wisdom of the "ancients", like TCM or Ayurveda, it's not hard to see there was very little good reason (or evidence) to suggest they have ever been "ahead" of mainstream medicine in any way. Vespine (talk)
 * I may exaggerate the smaller part of the distribution, but to my way of thinking, the only alternative medicine of interest is that which works. To give another example, consider that Culpeper (if only briefly) recommended wintergreen for heart pain in 1652  - far more recently I remember physicians started to recommend aspirin for patients suspecting a heart attack.  Also, the salicylate drugs of many early cultures were of higher quality than aspirin, in some cases willow glycoconjugates that would hold together deeper into the digestive system than aspirin, hence lacked some of the harmful GI effects.  The thing about trial and error is that you never know what remarkable things it will accomplish, and has accomplished. Wnt (talk) 02:32, 11 January 2016 (UTC)
 * But the critical part that is MISSING from trial and error is the double blind process. Trial and error is pretty much solely responsible for such great stalwarts as homeopathy and acupuncture. The former is clear and demonstrable nonsense and the latter is not far behind. The fact that there are such strong pockets of resistance in both cases I think exposes several salient points, not only how powerful a motivator "wellness" can be, but also how powerful "personal experience" is over empirical evidence. Critically, if you look at the epistemology, Culpeper, and in fact the roman physicians you mentioned earlier actually appeared to at least attempt a roughly 'scientific' approach, embracing the idea of naturalistic causes and observation, over tradition and in many cases (like homeopathy) what appears not much different to witchcraft. Vespine (talk) 03:07, 11 January 2016 (UTC)
 * I think the guiding principle behind [high-dilution variants of] homeopathy is "It is difficult to get a man to understand something, when his salary depends on his not understanding it." Trial and error can't be blamed for it, except maybe that Hahnemann found by trial and error that it worked as an excuse to sell water.  Put it this way:  there are homeopathy sites that sell dozens of different dilutions of thousands of different drugs -- and I don't believe for a minute they have in their possession anything but money-handling software, empty tubes, a faucet and a label printer.  But there has been dishonesty in "scientific" varieties of medicine also, so this isn't really a distinctive difference.  The scientific method represents a small but significant improvement over trial-and-error methods, in that it has the insight to make the "error" (the control group) intentionally, and to repeat experimental and control conditions precisely to permit statistical comparisons.  This improvement, however, comes at the cost of less reliable care for the experimental subjects - indeed, in a throwback to older methods, even today studies can be stopped and controls de-randomized if enough benefit is observed in the experimental group. Wnt (talk) 17:37, 11 January 2016 (UTC)
 * This is going too far off topic but I would like to say in conclusion that while I think we are mostly not in disagreement, however I do not agree with except maybe that Hahnemann found by trial and error that it worked as an excuse to sell water. I see no reason to doubt that Hahnemann completely believed his discovery was "real" and was going to help a lot of people. Just like I see no reason to believe that the people who came up with Astrology, Feng Shui, reiki and countless other "nonsense" traditions had nothing but the best of intentions. It is a mistake to think that "money" is the only thing (or even the main thing) that motivates all practitioners and promoters of alternative medicine. Vespine (talk) 21:56, 11 January 2016 (UTC)
 * Well, I believe many acupuncturists believe in their practice, for example. Faith healers, even more so -- the unsuccessful ones, that is.  The ones that present successful results every Sunday, not so much.  Astrology... to a degree.  It has a certain body of "theory" behind it, but its practitioners know how much they disagree with one another.  Feng Shui, I shouldn't guess since it's not my culture, yet I suspect that (like lawyering and CEOing) it is largely a polite way to disguise a business's bribe budget.  Reiki, the same, but it seems too recent to be an honest mistake.  And I'm pretty confident that homeopathy is a straight up scam and has been from the start. Wnt (talk) 23:48, 12 January 2016 (UTC)


 * In what way is feng shui and astrology like CEOing? People really believed that when it was invented, and there really are people today with minds that mushy. (I agree that CEO is such a useless job that it could be done by a parliament of an odd number of executives (CFO, COO and anyone else important) saving gazillions of CEO pay).


 * (I have no time for homeopathy - it's pseudo-science of the worst kind...but...)


 * The charitable view of Hahnemann is that in the 1780's - when he came up with this idea - many so-called medical treatments were extremely harmful to the patient - bleeding them, starving them, giving them large doses of stuff like mercury, performing trepanation and all manner of unnecessary amputations were par for the course. Doing nothing at all would very often have produced better outcomes for the patient than the best treatment options available.  Since homeopathy is just a complicated way of doing nothing at all - it was a reasonable way to improve on standard medical thinking 1780-style.  Better still, the nonsense about doing serial dilutions and "succussing" would convince both the doctor and the patient that the treatment should work.  The resulting double-blind placebo effect would surely be significantly better even than doing nothing at all.


 * So I have little doubt that Hahnemann was inadvertently helping his patients - and may even have saved a few lives by not killing them with his treatments.


 * That said, Hahnemann was not a good scientist - and he came up with a whole raft full of other nonsense theories as time went on. For example, he believed that a huge range of diseases were caused by coffee...and it's hard to imagine how this couldn't be tested with the simplest of experiments.  (eg Ask all of your sick patients: "Do you drink coffee?" and if any of them say "No!" then you know you're incorrect!)


 * SteveBaker (talk) 15:51, 13 January 2016 (UTC)
 * This is an extremely complex topic. Let me just say I've been personally "touched" by alternative medicine, i was brought up in a very "new age" receptive environment and I even "studied" it before I came of age and started thinking for myself. The last 15 years or so I have had countless discussions with people who support and promote alternative medicine and I've investigated and even written articles about some alternative medicines. I was actually once interviewed by a USDJ prosecutor about a particular alternative medicine they were prosecuting the distributor of. This isn't the place to have this discussion, but I just want to say in closing that WNT you are making a mistake thinking that ANYTHING is easy to prove to some people. Some people have a different world view from you, there are MANY people who believe in the "power of prayer" or reiki who genuinely don't believe the scientific evidence that has been collected disproving those things. It's a world view problem, they would rather believe that "atheist materialist scientists are not doing the experiments properly because god is real and heals the sick if you pray hard enough. Uncle Fred was given 6 months to live and we prayed really hard and he's still alive 5 years later." All it takes is ONE anecdote like this and it turns people into life long vehement believers. Scientific thinking, critical thinking is only a few hundred years old, most people don't think critically, it seems "OBVIOUS" to someone who knows about evidence and and empirical testing, but to a lot of people what their friend says "happened to a friend of mine" TRUMPS what a hundred scientists studied in some university. Vespine (talk) 21:53, 13 January 2016 (UTC)

Mirrors flip...
Mirror image answers the old question "Why do mirrors flip left and right, but not top and bottom?". The oldest source used there is a paper from 2000, citing another from 1998. But of course, answers have been given much earlier, as in Nature 353, 1869 (but I can't see a preview in my country). As far as reconstructable: What was the first publication of a) the question, b) an answer, c) a somewhat thorough answer? --KnightMove (talk) 10:13, 9 January 2016 (UTC)
 * That paper is from 1991, not 1869. 1869 is the year Nature was first published. -- BenRG (talk) 21:01, 10 January 2016 (UTC)
 * A start might be found in Chirality. --DHeyward (talk) 10:31, 9 January 2016 (UTC)
 * This term was first coined in 1893, only after the Nature article above had been published - and I'm actually not quite sure whether this concept is that important for understanding the answer to this question, even though it is undoubtedly closely related. --KnightMove (talk) 10:43, 9 January 2016 (UTC)
 * To answer the first part, the oldest publication of the question was in the Timaeus by Plato followed by Lucretius in the poem De Rerum Natura. As to who first published the answer to the question of what's known as the "Mirror paradox", I can't find an answer. Maybe that's because people still argue about what the right answer is - see . However, there does need to be some serious work done on our article Mirror image as it only has one citation. Richerman    (talk) 11:18, 9 January 2016 (UTC)
 * Try lying on your side and you'll see a mirror does not flip left and right as it does not flip your head and toes.Dmcq (talk) 11:28, 9 January 2016 (UTC)
 * I use a mirror on the floor, or the ceiling, as example. --KnightMove (talk) 11:48, 9 January 2016 (UTC)
 * This is a more a Humanities question, looking for the first known presentation and refutation of a myth; both probably date to prehistory. To natives of a space station it would be obvious enough it flips top to bottom, since they would flip around to an upside-down orientation with left and right preserved all the time. Wnt (talk) 13:54, 9 January 2016 (UTC)
 * The original post asks about the first publication of the question and answers - that doesn't date to prehistory. Richerman    (talk) 16:00, 9 January 2016 (UTC)
 * There's a paper with practically exactly the same title as how you phrased it at
 * Why do Mirrors Reverse Right/Left but not Up/Down by N.J.Block
 * That dates to 1974 but it talks about it as a common question. Dmcq (talk) 17:26, 9 January 2016 (UTC)


 * Y'all are overthinking this. Flat mirrors don't really "flip", they merely reflect your image straight back toward its source, and to us it looks flipped. ←Baseball Bugs What's up, Doc? carrots→ 17:50, 9 January 2016 (UTC)
 * I think everybody in the discussion here understands that, Bugs. The question is not about what mirrors do, but when what they do was first explained in print. {The poster formerly known as 87.81.230.195} 2.123.25.88 (talk) 19:44, 9 January 2016 (UTC)
 * A mirror does not reverse left and right. A mirror reverses front and back.  This is equivalent to a reversing of left and right with a 180 rotation.  Robert McClenon (talk) 21:09, 10 January 2016 (UTC)
 * Correct answer. I figure this out when I was young. I ask myself why "mirror flip left and right but not up and down. So in space where there is no up or down, how does the mirror know which direction is up and down so as to not to flip?". My conclusion is same as yours. Mirror flip front and behind instead of flipping left and right. 175.45.116.66 (talk) 00:35, 11 January 2016 (UTC)


 * Stop using "left" and "right" and "top" and "bottom" and instead paint one hand red and the other blue, your face yellow and your feet green. Now forget about which color is in which location on your body and you may observe that: The yellow part of your body is nearest the yellow reflection in the mirror, the red part is nearest the red reflection, ditto for green and for blue.  So why are we even saying that something is "flipped" in one way and not the other?  It makes no logical sense.  Yet we all talk that way and the left/right flip is a profound illusion that all humans seem to fall for!


 * What's interesting is why, when you replace the words "top/bottom/left/right" with non-directional words "yellow/green/red/blue" and try to describe the mirror anomaly - it seems to go away in our minds.


 * This must be something strange going on in our brains.


 * Presumably, at some low level of cognitions, we see the "person" in the mirror as being another human being seen through a clear glass window. We think that we're smart enough to recognize that this is a reflection of ourselves - but we know that most animals don't see that (that stupid Red Cardinal bird who keeps pecking at our bedroom window in an attempt to chase off the "other" male bird has that problem!).  So probably, at some low level of our perception, we're making the exact same error.


 * Under those circumstances, we'd expect the other persons left hand to be nearest to our right hand - and it's not. So what's confusing us isn't that the mirror flips the sides - but that it doesn't flip them as a 180 degree rotation would.  But if people lived in zero-g and some cultural norm required that they routinely greeted each other with one person's head nearest the other person's toes - then our left hand would be on the same side as their left hand.  Would we not then claim that the mirror flips us from top to bottom and not from left-to-right?  I think we would.  So this weirdness is undoubtedly due to our built-in mindset of gravity and the way our bodies naturally align when we stand in front of each other.


 * The 'standard' explanation is that the mirror flips front to back. So how come we can't read words reflected in the mirror?  Well, if you use a really wet magic marker on a thin sheet of paper so it soaks all the way through - then you can see that turning the paper around and looking at the reflection of the back side of it makes it perfectly legible.


 * SteveBaker (talk) 15:28, 11 January 2016 (UTC)
 * This is sometimes done with emergency vehicles, like an ambulance with the world "ambulance" on the front flipped, so that it looks normal in the rear-view mirror and presumably speeds up recognition. ←Baseball Bugs What's up, Doc? carrots→ 15:47, 11 January 2016 (UTC)

does Truvada (used in anti-HIV pre-exposure prophylaxis) have significant binding activity to human telomerase reverse transcriptase?
Our article on one of Truvada's reverse transcriptase inhibitors (tenofovir disoproxil says that tenofovir only weakly interferes with DNA polymerases. But what about human telomerase reverse transcriptase? Can PrEP or HAART cause premature aging?

I also ran a pBLAST comparing the homology of human versus HIV reverse transcriptases as follows. Is there enough homology for there to be a good chance for Truvada to affect human telomerase reverse transcriptase? While running the pBLAST alignment of the hTERT FASTA sequence in the Uniprot virus database I also noted that human reverse transcriptase's closest match is a protein/gene product BHLF1 in the Epstein-Barr virus. Does that mean that novel antiviral treatments targeting the Epstein-Barr virus might be more likely to interfere with human reverse transcriptases?

Query= sp|O14746|TERT_HUMAN Telomerase reverse transcriptase OS=Homo sapiens GN=TERT PE=1 SV=1 Length=1132

Sequences producing significant alignments:                     Score (Bits)  E-Value

Query_129897 1HMV:D|PDBID|CHAIN|SEQUENCE                          18.9    1.0

ALIGNMENTS >Query_129897 1HMV:D|PDBID|CHAIN|SEQUENCE Length=440

Score = 18.9 bits (37), Expect = 1.0, Method: Compositional matrix adjust. Identities = 12/40 (30%), Positives = 18/40 (45%), Gaps = 8/40 (20%)

Query 212  VPLGLPAPGARRRGGSASRSLPLPKRPRRGAA  243 V LG+P P  ++         G A  S+PL +  R+  A Sbjct  90   VQLGIPHPAGLKKKKSVTVLDVGDAYFSVPLDEDFRKYTA  129

Score = 16.9 bits (32), Expect = 3.9, Method: Compositional matrix adjust. Identities = 8/29 (28%), Positives = 12/29 (41%), Gaps = 6/29 (21%)

Query 236  KRPRRGAAPEPERTPV--GQGSWAH  258 K P G   +P +  +      GQG W + Sbjct 311  KEPVHGVYYDPSKDLIAEIQKQGQGQWTY  339

Score = 16.9 bits (32), Expect = 4.0, Method: Compositional matrix adjust. Identities = 6/14 (43%), Positives = 9/14 (64%), Gaps = 0/14 (0%)

Query 711  VDVTGAYDTIPQDR  724 +DV AY ++P D Sbjct  109  LDVGDAYFSVPLDE  122

Score = 16.5 bits (31), Expect = 5.3, Method: Compositional matrix adjust. Identities = 8/20 (40%), Positives = 11/20 (55%), Gaps = 6/20 (30%)

Query 632  PIVNMDY--VVGARTF  645 P+V + Y     +VGA TF Sbjct  421  PLVKLWYQLEKEPIVGAETF  440

Score = 16.2 bits (30), Expect = 5.6, Method: Compositional matrix adjust. Identities = 23/105 (22%), Positives = 37/105 (35%), Gaps = 7/105 (7%)

Query 745  AVVQKAAHGHVRKAFKSHVSTLTDLQ--PYMRQFVAHLQETSPLRDAVVIEQSSSLNEAS  802 A +QK  G     ++ +     +L+   Y R   AH  +   L +AV    + S+    Sbjct  327  AEIQKQGQGQW--TYQIYQEPFKNLKTGKYARMRGAHTNDVKQLTEAVQKITTESI--VI  382

Query 803  SGLFDVFLRFMCHHAVRIRGKSYVQCQGIPQGSILST-LLCSLCY  846 G   F   +           Y Q   IP+   ++T  L  L Y Sbjct  383  WGKTPKFKLPIQKETWETWWTEYWQATWIPEWEFVNTPPLVKLWY  427

Yanping Nora Soong (talk) 11:04, 9 January 2016 (UTC)


 * The sequence isn't really a good way to guess this, but typically, much more closely related sequences are still discriminated between by small molecule therapeutics. This has no more than three amino acids conserved in a row.  So the only issue is whether the drug is chemically, mechanistically, so closely tied to the act of reverse transcription that any RTase will be affected -- actually, looking into it on PubMed (you must learn to use this - it gave me the answer right off) I get this study.  However, IMHO that study is immoderately worded, in that people vary a lot in telomere lengths with little obvious impact on their health.  The whole idea that telomere shortening cause aging is just one of several competing models, and I think it's running well behind right now.  That article points out they may lengthen again simply with diet and exercise, and of course, shortening serves as a useful safeguard against cancer.  Also note that this study looked at effect of 123 weeks average usage, and HIV itself interferes with telomerase and of course otherwise shortens lifespan, so pre-exposure prophylaxis still seems to have a strong rationale. Wnt (talk) 13:15, 9 January 2016 (UTC)


 * PrEP in NYC is aggressively marketed towards high-risk populations (LGBT homeless youth, sex workers, sexual assault victims with a high risk of revictimization) but with recent ads on the subway beginning to be marketed towards non-queer people as well. However, impacts on human telomerase reverse transcriptase are almost never discussed. I'm trying to calculate the social utility of such widespread acceptance given the likelihood of HIV infection without PrEP, versus longer-term pro-aging deleterious effects from the PrEP if HIV infection never occurs. After all, the risk of infection from body fluid exchange with an HIV-positive individual is about 1 in 300. (According to the pamphlets they hand out in rape kits.) The literature is ambiguous on the issue. in part, because HAART has historically been prescribed to HIV-positive people only. I guess my key question is, "what is the risk of accelerated aging on PrEP / HAART if HIV infection risk remains low?" (i.e. if the opportunity never arises for PrEP to be able to "do its job" and prevent a nascent infection from taking root in the body.) Yanping Nora Soong (talk) 14:34, 9 January 2016 (UTC)
 * The short answer is that as of now there exists absolutely no evidence that HAART causes premature aging. Ruslik_ Zero 20:08, 9 January 2016 (UTC)
 * Premature and accelerated aging: HIV or HAART?: "We propose here that the premature and accelerated aging of HIV-patients can also be caused by adverse effects of antiretroviral drugs, specifically those that affect the mitochondria. The nucleoside reverse transcriptase inhibitor (NRTI) antiretroviral drug class for instance, is known to cause depletion of mitochondrial DNA via inhibition of the mitochondrial specific DNA polymerase-γ. Besides NRTIs, other antiretroviral drug classes such as protease inhibitors also cause severe mitochondrial damage by increasing oxidative stress and diminishing mitochondrial function."
 * Yes, they propose but offer no evidence. In fact, even in round worms it is not proven that HAART actually shortens lifespan. Ruslik_ Zero 18:31, 10 January 2016 (UTC)
 * Expanding on my previous comment. The HIV-infected individuals who does not have other risk factors (which they are often have), are properly treated, start the treatment early and strictly adhere to the regimen may plausibly have the same life span as the general population. In other words the fact that HIV-infected individuals have shortened lifespans is disputed. See, for instance, this and this. The life expectancy has actually grown significantly during the last 20 years and now is approaching that of the uninfected population (excluding some sub-populations like drug users). Ruslik_ Zero 18:56, 10 January 2016 (UTC)
 * Wnt has given a great answer, but just to emphasise, as he has not explicitly said it, your alignments are not very similar at all. Also, as he correctly states, even very similar sequences can be discriminated by small molecules, this is partly because the primary sequence (what you have aligned) is to an extent meaningless. The actual chemistry happens in the 3D folded protein. Similar primary sequences may still have different 3D structures. Fgf10 (talk) 21:45, 9 January 2016 (UTC)
 * A PatchDock and PyMol assay would take hours to properly evaluate, but I'll do that later. Yanping Nora Soong (talk) 00:40, 10 January 2016 (UTC)
 * I'm surprised to hear you say that - I know you are familiar with the field - my impression has been that when primary sequence is conserved, there's usually a reason, which is to say, conserved structure(s). Even the moderate level of homology depicted is sufficient that I would expect that key amino acids from the active site can be extrapolated from one protein to the other.
 * It's true that you can never be sure in biology, and unless long term study of this specific issue is done in people using the preexposure prophylaxis, we don't know for sure. But there is no rule against guessing, and my guess is that telomeres seem to be in an active equilibrium.  As I described above, various factors seem to change their length one way or another.  Various tissue stem cells, at least, are free to renew them at any time.  So my guess would be that any telomere-shortening effect of the drugs may turn out to be a "kinetic" effect, operating in the relatively short term, while the overall equilibrium of the telomeres is more likely to be unchanged and eventually restore itself.  On the other hand, note that in the paper I cited above, a four-week protocol didn't in and of itself change telomere length significantly.  The question is whether you need to inhibit telomerase activity for a long time to make telomeres notably shorter, and then they restore themselves anyway if the drug is removed -- but that paper didn't really answer it, because the "off-NRTI" error bars in Figure 3 are atrocious - I mean, there are only so many things you can figure out with under a dozen people, and answering this isn't one of them. Wnt (talk) 02:09, 10 January 2016 (UTC)
 * , that is certainly true in a lot of proteins, my point was that you can't make any a priori assumptions on 3D structure and binding based on primary structure alone. Fgf10 (talk) 13:05, 10 January 2016 (UTC)
 * Well, there are sites that encourage such a priori assumptions, such as this one - even, in that case, encouraging extrapolation from catalytically active enzymes to one which seems catalytically inactive (unless I missed something recent). And honestly, I think that is quite likely still a valid extrapolation to make, because at the moment the secondary structure actually changes to some not previously existing, the new structure is not very stable and there is going to be need for a lot of rapid evolution to develop new contacts, while the old ones will no longer be conserved. Wnt (talk) 13:29, 10 January 2016 (UTC)

Which organs of human body can be regenerated?
92.249.70.153 (talk) 15:13, 9 January 2016 (UTC)
 * There is no human anatomical organ that can completely regenerate, though advances in Tissue engineering are opening possibilities for organ growth in the laboratory. A laboratory-grown penis was reported in 2008 but the concept has as yet been tested only on rabbits. Wound healing is the process by which skin or other body tissue repairs itself, in which Angiogenesis is the vital process of regeneration; it is however also a step in the transition of a tumor from a benign to malignant state, requiring the use of angiogenesis inhibitors in cancer treatment. AllBestFaith (talk) 15:48, 9 January 2016 (UTC)


 * "The liver is the only human internal organ capable of natural regeneration of lost tissue; as little as 25% of a liver can regenerate into a whole liver." liver regeneration. μηδείς (talk) 17:26, 9 January 2016 (UTC)


 * Unless I'm missing something, you seem to have paraphrased the lead of that article, but presented the material in a way that suggests a full quote, to misleading effect. The original wording is markedly more accurate, if a little un-clinically phrased: "[The] liver is the only visceral organ that possesses remarkable capacity to regenerate." Your alternative ("The liver is the only human internal organ capable of natural regeneration of lost tissue" is just plain wrong; all human organs possess some capacity to regenerate some degree of tissue.  This is true, to very limited extent, even of the brain-- despite its quasi-folkloric reputation for being unable to generate any new cells.  S n o w  let's rap 19:40, 9 January 2016 (UTC)


 * I quoted the first sentence of the liver regeneration section of the liver article exactly, and linked to both main articles. Here's the |editor Hausinger, Dieter, p.1 ref from the liver article.

Your skin regenerates itself every 27 days. Richerman    (talk) 17:42, 9 January 2016 (UTC)

el Chapo escape engineering
When el Chapo escaped from prison six months ago, it was through a tunnel constructed from a mile away, a remarkable feat of engineering given that the tunnel had to connect to a small opening in the prison cell. What knowledge and skills did the builders have to have in order to do it? --Halcatalyst (talk) 17:51, 9 January 2016 (UTC)


 * You're assuming that the prison personnel were honest. ←Baseball Bugs What's up, Doc? carrots→ 18:01, 9 January 2016 (UTC)


 * Where has he assumed that? Anyway, to actually address the OP's question, it might help you to know that this is not Guzman/Sinaloa's first impressive tunnel; long before the Altiplano prison break, the cartel was known for constructing kilometers-long tunnels in several towns which served as major hubs in their drug trade.  They have been said to have been extremely high-tech, refined and stable.  So, while I know of no reports explicitly claiming that individuals with formal engineering backgrounds were involved, I would dare say that it is a reasonable presumption and barely feel as if I was brushing up against WP:OR :).


 * What I'd like to know is how they figured it out. What knowledge and skills would an honest engineer have to have to accomplish something similar? --Halcatalyst (talk) 20:05, 9 January 2016 (UTC)


 * In terms of what degree of education would they have to have attained? Or the exact kinds of structural principles they would have to know? If the latter, it's a little outside my wheelhouse, so I'll wait for someone more versed in this area to provide the real detail and sources on the specific skills, but certainly, at a minimum, the designer would have to be familiar with loads, excavation, ventilation, basic electrical engineering (the tunnel was lit), surveying, and I'm sure at least one or two major obvious areas I must be neglecting.  Obviously a cut and cover tunnel was not an option in this instance and this restriction, along with the limited size of the entrance and the need for secrecy, suggest a fair amount of manual labor.  It's also worth noting that the shaft which connected with Guzman's cell had to enter through the sub-structure of the prison and negotiate its way to the cell, all without arousing suspicion, which would have required an even more heightened degree of planning and coordination.  Some photos and dimensions for the tunnel can be found here.   S n o w  let's rap 20:36, 9 January 2016 (UTC)


 * I don't think they would need to know anything about electrical engineering to plug in lots of extension cords and work lights. You can buy all that at any home improvement store.  I'm not sure if the outside end of the tunnel was on the power grid, but, if not, some electrical generators, also available at the home improvement store, could power the lights.  It might seem surprising they bothered to add lights to a one-time use tunnel, rather than use portable lights.  But I suppose the electrical lines were also used to power digging and ventilation equipment, so then they might as well plug in lights, too.  StuRat (talk) 23:51, 9 January 2016 (UTC)


 * Running a generator inside a mile long tunnel is a bad idea. As is connecting an extension cord to an extension cord. It might not melt with only two but I'm sure you need many many cords for a mile. Sagittarian Milky Way (talk) 23:58, 9 January 2016 (UTC)


 * Of course you wouldn't put the generator in the tunnel. You would put it at the entrance. StuRat (talk) 04:54, 10 January 2016 (UTC)


 * Agreed, thousands of feet of extension cord and workshop lamps strikes me as a silly and unlikely notion (unless the contractors were Clark Griswold and Red Green!), for a number of practical reasons and especially in light of the complexity of this operation. It's difficult to make out, but if you look closely at the pictures of the Altiplano tunnel, they seem to be employ building wiring, which would be consistent with most every Sinaloa tunnel uncovered so far: .  S n o w  let's rap 03:01, 10 January 2016 (UTC)


 * Common 12-gauge home wire has a resistance of about 1.6 ohms per 1000 ft, or 3.2 ohms counting both conductors. By Ohm's law we get a voltage drop of 3.2 volts per amp of current per 1000 ft. There's probably not a huge amount of current being carried. So even with ordinary house wire the voltage drop would be tolerable for running light bulbs or other applications that aren't particularly sensitive to voltage. Using heavier wire would reduce losses further. Shock Brigade Harvester Boris (talk) 04:00, 10 January 2016 (UTC)
 * You can get 12-gauge or thicker extension cords, too, and taking the time to splice wires, etc. in the tunnel seems unwise. Better to use components you can just snap together. StuRat (talk) 04:56, 10 January 2016 (UTC)
 * Car batteries and $30 110v inverters would seem like a vastly easier way to deal with this. You can place those at intervals down the tunnel for lighting or running power tools - you just need people to get in there every couple of hours to swap out the batteries.  When money is no object, this is very do-able. SteveBaker (talk) 15:23, 13 January 2016 (UTC)

I was most curious about how they were able to home in on the shower stall itself. He surely had inside help getting it started on hi end. But how close would they have to get for noise to help? And how would they do that, over 1500 meters? --Halcatalyst (talk) 20:00, 11 January 2016 (UTC)


 * With such tunnels the most impressive asset is the willingness to put in the work. The rest seems pretty optional.  Mining (military) has gone on since ancient times, and this is a fairly straightforward instance.  Ventilating a straight shaft doesn't seem exceptionally complex.  Tools required, as at Stalag Luft III, may be rather minimal, depending on terrain.  One impressive bit is to come out at the right point, but I presume they would have arranged some help from inside, i.e. for Guzman to make some kind of distinctive noise for them to hone in on.  Though a tape measure, laser level, and aerial photos of the facility would all help.
 * What surprised me more was the lack of preparation when Guzman was caught. He had a way out of where he was staying to the sewers, sure ... what he didn't have was a car with a secret compartment waiting to be driven away by loyal men at the far end.  He was caught because he had to steal a car to try to get away -- and that, I don't understand. Wnt (talk) 02:35, 10 January 2016 (UTC)


 * I'm confused, here. I hadn't heard any reports that his eventual capture this last week had anything to do with his stealing a car immediately following the escape; can I ask where you came across this detail?  S n o w  let's rap 03:05, 10 January 2016 (UTC)
 * Here. Wnt (talk) 11:38, 10 January 2016 (UTC)

I was most curious about how they were able to home in on the shower stall itself. He surely had inside help getting it started on his end. But how close would they have to get for noise to help? And how would they do that, over 1500 meters? --Halcatalyst (talk) 20:00, 11 January 2016 (UTC)


 * The could get pretty close by dead reckoning, if they had precise building plans and knew which cell he was in, maybe close enough to pick up sounds (low frequency would work best) with a microphone. Or perhaps a lawyer visiting him brought a precise GPS unit to the cell and reported the coords to those outside, and they then used their own GPS unit in the tunnel (would it work there ?) to get to that location. StuRat (talk) 04:55, 12 January 2016 (UTC)
 * A standard GPS unit is only accurate to 5 meters - not really good enough to reliably hit the correct cell. There are enhancement techniques - but they wouldn't be inconspicuous. SteveBaker (talk) 15:21, 13 January 2016 (UTC)


 * If I had to do this, I'd make a long, stiff pole about the same length as the depth I intended to dig...and mount a visible light laser at right angles at each end, both carefully aligned to project perfectly parallel beams. Dig vertically down to whatever depth you need, then carefully lower the pole into the hole.  The top laser can then be aimed with high precision at the precise part of the building you're tunneling towards and the bottom laser will point in the same direction.  Digging wherever the laser spot hits the dirt would result in a perfectly straight tunnel that would reach unerringly towards the designated target.  Getting the right distance at which to stop digging is a much simpler problem - and could probably be solved by listening for pre-arranged sounds. SteveBaker (talk) 15:21, 13 January 2016 (UTC)


 * This works well ideally, at least. Does anyone have any information as to what the criminals actually did? --Halcatalyst (talk) 21:30, 13 January 2016 (UTC)

Opposite sex monozygotic twins without Turner syndrome
Is it theoretically possible to produce monozygotic identical twins of opposite sexes without inherent Turner syndrome in the girl, presumably by correction of natural fertilization or by artificial insemination? Brandmeistertalk  20:16, 9 January 2016 (UTC)
 * They would not be identical in that case. Even if the only difference was that one had an X chromosome and the other had a Y.  A transgender process could artificially alter one of a twin, so it is theoretically possible.  Also there could be an error on a birth certificate, so it could be geneologically possible. Graeme Bartlett (talk) 20:27, 9 January 2016 (UTC)
 * "Error on the birth certificate" sounds like a very cisnormative thing to say tp me. Yanping Nora Soong (talk) 00:44, 10 January 2016 (UTC)
 * In what way? I read Graeme's scenario as saying that two identical children of the same sex were born, but one was mistakenly listed as the other sex. People can construct as many cultural genders as suites them, but there are only two genetic/physiological/developmental sexes--and the rare intersexed individual, of course). Mind you, I think it's an exceedingly odd notion to suggest that we would regard that situation as an example of "dual-sexed identical twins" as opposed to "a clerical error", but I don't see how gender identity comes into this at all.  This is a question of the genetics of twins, not gender perception.  S n o w  let's rap 03:23, 10 January 2016 (UTC)
 * There's a good chance I'm Klinefelters (also met one other Klinefelters' individual in my life). Intersex people are not as rare as you think -- they make up about 1% of the population. Of course, it's typical for members of the cishet patriarchy to underestimate the population frequency of queer people... and how would you define each "genetic sex"? Based on one sex having an active SRY gene and the other not? But what then there's the issue of epigenetic DNA methylation (due to environmental factors affecting the mothers, or childhood development of the mother) of sequences associated with sexual development, androgen insensitivity syndrome, SNPs which make regulatory sequences less effective at binding estrogen or SRY. Just because the two common chromosomal outcomes are 46,XX or 46,XY doesn't mean expression/regulation/transcription of sex-specific sequences are confined to two individual sharply-contrasting patterns.  Yanping Nora Soong (talk) 05:26, 10 January 2016 (UTC)
 * 1) Let's drop the "cishet patriarchy" stick. As a cognitive scientist, I can assure you am broadly supportive of the notion that transgender identities are an empirically verifiable consequence of human neurophysiology.  Even putting my understanding in this area aside, I'd not be inclined towards dismissive bias with regard to self-determination in this area.  Nobody is trying to minimize anyone's right to their perceived gender here.  2) Intersex people do not make up 1% of the population (I presume you are speaking global population), but even if they did, I would still consider 1% "rare", so that accounts for that apparent (but not actual) difference in perspective. 3) I'm not sure you are entitled to speak for all intersex people in classifying them (on their behalf) as part of queer culture, which is a social construct and not de-facto relevant to their physical make-up. I know you're not the first person to make that assessment, but to me it's an apples and oranges matter 4) No one said anything about "sharply contrasting"; clearly the genetic make-up of all individuals of our species (male and female) is such that we all share more in common with eachother than we do with any other organism.  But if you know of any serious research which supports the notion of a third physiological sex in the human race (or any sexual species), I'd be genuinely flush with fascination to hear about it.  5) In any event, I still fail to understand what in Graeme's proposed scenario relates to a transgendered issue.  He proposed a theoretical in which two identical twins are miscategorized solely on the basis of their physical sex organs, not their later gender identities, which would not be in evidence in a newborn that has neither concrete concepts of gender nor linguistic skills to share them if they did...   S n o w  let's rap 05:52, 10 January 2016 (UTC)


 * The problematic issue is your emphasis on a distinction between a "physiological sex" versus a "socially-constructed gender". But sex itself is also a social construction, and conflicts with gender identity frequently arise because of differences in genetic expression or neural structure compared to the archetypical members of their assigned sex. Would you assign all 47,XXY individuals to the male sex, based on this notion of "natalism" and physiological sex, even for individuals with a genetic transcription pattern and neurophysiological features very unlike 46,XY individuals? Sex is not a continuous variable, not a binary one. Yanping Nora Soong (talk) 06:20, 10 January 2016 (UTC)


 * Sorry, but while I agree with some of the points that you make at the periphery of your main argument, the fact of the matter is that your interpretation of "sex" as a socially constructed phenomena is pretty idiosyncratic. Sex is clearly a physical term linked to specific phenotypical traits and physiological structures, first and foremost. That's the entire reason the English language began, in the modern world, to reflect a difference between this notion and gender, and they are overwhelmingly used in that manner.  And most individuals in our species are generally (and non-controversially) regarded dichotomously in this manner.  Clearly you have different ideas of how blurred these lines are for people in general.  That's fine, but surely you recognize that the way you use some of these concepts and their associated terminology is non-congruent with the norm in established science in this area?  S n o w  let's rap 08:48, 10 January 2016 (UTC)


 * Btw, no one but members of the cis-patriarchy would use a word like "transgendered," honestly. Yanping Nora Soong (talk) 06:20, 10 January 2016 (UTC)


 * Really? Drat, I'll just have to tell that to those of the transgender men and women that I know who use the term regularly...they'll want to know they aren't conforming with the newest prescriptivist rules and neologisms, I'm sure. I just hate giving bad news...  S n o w  let's rap 08:48, 10 January 2016 (UTC)
 * "transgendered" is a slur. Better than some other words, but still an offensive misuse. see this article. Yanping Nora Soong (talk) 09:21, 10 January 2016 (UTC)
 * A slur, really? I can see now that you are speaking specifically about one variant--I previously thought you were objecting to "transgender" broadly--but still, a slur is a term intentionally used in a derogatory fashion (or which has a historical context for having been used in such an offensive manner). As that article you cited notes, even the trans community is divided about the use of "transgendered" as a construction, let alone broader society.  The supposedly "grammatical" arguments don't hold water for anyone who knows the first thing about English syntax/morphology, and the rest of the assertions for why it is improper are "just because", without any effort to explain the source of offense--just straight up linguistic prescriptivism.


 * Now, when it comes to things that make people feel belittled or just not generally respected, I actually do accept the "just because" argument, because what is the harm in making a reasonable effort to accept norms that allow people to feel they are being treated with dignity? But it is way too early in the evolution of this terminology to start saying that the word's usage is fixed down to the level of it's particular exception to certain affixes, and certainly way too early to expect everyone to be on the same page about these nuances (within the trans community, let alone broader culture).  There's surely room for reasonable people to feel strongly about this or that usage, and other reasonable people should make an effort to avoid those terms that give offense, but labeling that word a "slur" is a disservice to every person (trans or otherwise) who has had to face real, intentional and pervasive discrimination and hatespeech in their lifetimes: .  S n o w  let's rap 02:29, 11 January 2016 (UTC)


 * I am actually transgender, and you're not, I believe. Do you see the irony of a cishetero person lecturing a queer trans person on this issue? "transgendered" has always elicited a feeling of screechy disgust among my trans friends, especially when it refers to them or their friends. Yanping Nora Soong (talk) 23:52, 11 January 2016 (UTC)


 * A) You know exactly nothing about who I am or whether I'm female, male, cis, or trans, nothing about what my gender identity or how it informs my perspectives, though you are very long on making assumptions about those things on pretty much zero evidence.
 * B) You never will know those details, because, guess what, Wikipedia isn't for sharing our personal details or promoting ideological causes and I take the separation of those activity from my role as contributor here very seriously. It's not always easy, but it is essential, and if you give it a try, I think you'll find that it is immensely liberating when you begin to realize just how nice it is not to have what you say being filtered by others for your sex, gender, or any other superficial criteria.  What matters here are what you bring to the table in terms of contributions.  If you cannot reconcile yourself to this manner of discourse, and find you must personalize discussion in the way you have in this discussion, this project is probably not a good match for you.  Though, point in fact, I also consider some degree of ability to separate myself from a factual discussion to be an immensely important part of being an effective empiricist and humanitarian in many areas of my life.  To say nothing of how important it is to being an open-minded person in general...
 * C) Even taking Wikipedia out of the equation, you really do assume a level of authority that, forgive me, I must be blunt, is just plain narcissistic; being trans and knowing what your friends think (though frankly I wonder if you know that, given the leaps you've made here) doesn't empower you to speak for a vast global community. I don't recall any news of you being elected the trans godhead.  You feel you have a good bead on how the segment of that community that you are familiar with feels about certain nomenclature.  Well guess, what, I'm even more certain that most trans people would be horrified at your blind attacks on others and that you claim to be speaking in their name when making these assertions.
 * D) Even if you were entitled to speak for all trans people everywhere, the arguments you are making would still suffer from the serious flaw that they are a arguments from authority. If you really want your positions to stand on their merits, try to establish the facts, not your supposedly exulted position.
 * E) while we're on the subject of logical fallacies which undermine your argument, consider that strawman arguments don't do your position any favours either, least when you provide them in a space frequented by a number of scientists. My beliefs are not those that you have tried to paint on top of me. I've run out ways to say it and patience with doing so. Please stop it, take some time to read WP:NPA, WP:SOAPBOXING, WP:NOTAFORUM, WP:PROMOTION, WP:CIVILITY and WP:NEUTRALITY and then decide if you can conform to our community standards here and whether this is really the best place for you to contribute in the way you wish to.  S n o w  let's rap 04:52, 12 January 2016 (UTC)


 * What I mean is that "sexing" a baby is inherently a subjective choice, based on the discretion of the sexer. Sex assignment is a phenomenon of oppressive social power -- it is not a scientific process to be "wrong" or "correct" on.
 * Anyway, the primary sequences of monozygotic twins may be identical but the endocrine exposure pattern, the DNA expression pattern, as well as the epigenetic methylation pattern may not be. In fact, there is a reported case of identical twins where one twin transitions and the other does not. A possible explanation would be that the fetuses were not subject to equal endocrine or signalling conditions in the womb. Yanping Nora Soong (talk) 06:26, 10 January 2016 (UTC)


 * Eh, sexing is really not that open to interpretation in a clinical environment. There's the occasional intersex newborn, as we've noted, but for unambiguous cases, physicians are not allowed to use their "subjective" assessments to label a child in a manner inconsistent with their sex organs.  Certainly, if you feel making note of a child's physical sex (which is deeply important to the manner and quality of medical care they receive) is a "phenomena of oppressive social power", you and I are not going to see eye to eye on this.  It's one thing to accept self-determination in an adult--it's quite another (very silly) thing to say that sex doesn't exist outside of our minds, or to treat it like an offensive notion, or to expect people who have to deal with it as a matter of clinical reality to tiptoe around necessary and practical medical and empirical terminology, lest they be accused of being a part of a system of "patriarchal injustice"...  But this is getting to drift far afield from the OP's question, so I will leave my impressions at that, per WP:NOTAFORUM.


 * As to your point about epigenetics, I find that much less controversial. It's going to be exceedingly rare that one twin has pronounced gender dysphoria and the other doesn't, but it's not altogether outside the realm of possibility and I'm not surprised at all that cases have surfaced, even if the present one is an impressionistic report.  S n o w  let's rap 08:48, 10 January 2016 (UTC)


 * Hmmmm. Isn't sex in a way a social construct when you sit down and class more than one karyotype as being one sex? Biological sex definition is that XX and XY are two different things.  But when you say XXY is "more or less XY because of how it looks and acts", that's a bit more of a cultural call.  Now of course, there's some biological basis in that XXY and XX often can produce offspring together - nonetheless, there is precedent for delineating multiple fertile or potentially fertile sexes in other species like naked mole rat, so it's not so so obvious we have to say XXY and XY are precisely the same sex.  In practice, I find it convenient, but I've noticed most methods of classifying people that seem convenient to me eventually seem annoying to someone being classified. :) Wnt (talk) 11:49, 10 January 2016 (UTC)


 * Yes, and clearly XXY (or any intersex) individuals require us to adopt a more nuanced approach, but most people are not intersex--and more to the point, neither the OP's question nor Graeme's hypothetical in any way suggest that they are discussing anything but a typical XX or XY scenario. Condemning a medical professional for noting that vital medical detail on a birth certificate (or in any clinical context) on the grounds that they are acting to further "patriarchal oppression" is, frankly, just asinine, quite regardless of your dedication to the equal rights and needs of those born intersex.  S n o w  let's rap 02:49, 11 January 2016 (UTC)
 * Did the question rule out intersex conditions? The OP just ruled out Turner syndrome. The whole issue of monozygotic twins having different sexes is "rare" to begin with. But then again, you see XX and XY individuals as "typical" and 47,XXY individuals as "not typical", and you don't think you're being cisnormative. There is also more to intersex conditions than just chromosomal presentations -- there's androgen insensitivity syndrome and various presentations of adrenal insufficiency. I'm not condemning medical professionals, I'm just saying there's a lot of cultural normativity to sexing such that it's not necessarily an issue of "incorrectness" for doctors to sex identical twins differently. Yanping Nora Soong (talk) 12:43, 11 January 2016 (UTC)


 * "But then again, you see XX and XY individuals as "typical" and 47,XXY individuals as 'not typical'"


 * Yes--"not typical", as in, statistically unlikely, relatively uncommon in a live birth; not "strange", "wrong", "abnormal", "unacceptable", "ewwwwww" or any of the other things you want to read into it without any indication on my part or that of anyone else participating in this thread. Typical≠normal; they have very different semantic values, especially in a scientific/empirical context. Pull out a dictionary or simply stop going out of your way to try to construct indication of chauvinism or outright bigotry that are not in any way in evidence in anything anyone has said here.  It's rude, obnoxious, and frankly (to the extent you take it) more than a little weird.  It's more a quality for an idealogue than a scientist, which, from your knowledge, it seems possible you might be.


 * "There is also more to intersex conditions than just chromosomal presentations"


 * Yes, that would be why I referenced other intersex conditions.


 * "Did the question rule out intersex conditions?...I'm just saying there's a lot of cultural normativity to sexing such that it's not necessarily an issue of "incorrectness" for doctors to sex identical twins differently."


 * Graeme was clearly meaning to reference a clerical error; I think that's pretty obvious from context for anyone who's not looking (consciously or unconsciously) for an excuse to instigate a debate on another issue altogether, so they can express their strong views on that matter (and subsequently imply myopic bias and cultural oppression in anyone who disagrees with them, while posturing themselves as a champion of non-normative rights). And as I said before, of course some perceptual/cultural judgement becomes implicit in sexing intersex infants.  How on Earth could it not? But your suggestion that doctors are allowed to just go with their whims with children that have no intersex morphology to the anatomy (or genetic tests in the rare cases where they are conducted) is patently wrong.  Nor do I think it is fair to say they are engaging in "patriarchal oppression" in following these practices in making vital medical notation...


 * "I'm not condemning medical professionals"


 * That doesn't seem at all consistent with your hyperbole above, but I'll leave it to anyone else who might read this to draw their own conclusions from what has been said. This is WP:NOTAFORUM for you to indulge in broadly bemoaning what you perceive to be injustices of gender issues in society--nor indeed is it a place for me indulge in pointing out what I feel are logical or factual fallacies in your arguments.  None of this is anywhere near the OP's question anymore and we must drop this discussion.  If you feel there is more you absolutely must say, you are quite free to message me on my talk page or invite me to yours, but even there we will have keep discussion brief. S n o w  let's rap 21:30, 11 January 2016 (UTC)


 * But you have never felt oppressed by your doctor. You don't have conditions or systemic disadvantages in which the doctor wields so much power and almost seems to wield it callously. Nowhere did I assert that sexing is whimsical. Also, it was not obvious to me that GB meant a "clerical error" -- it was apparent to me that he meant an "error of judgment". That is the cause of our disagreement. Yanping Nora Soong (talk) 23:52, 11 January 2016 (UTC)
 * First, how can you possibly think you are in a position to know that about me? Second, it doesn't have any relevance here. A newborn isn't struggling with feelings of oppression over power dynamics.  And a doctor has an ethical obligation to approach documentation in a manner which he believes will best serve the medical needs of his patient. Which, in this instance, means a straight assessment as to the sex--and yes, that means a binary assessment for most non-intersex individuals, much as you view that as a dirty word.  With respect, I believe you are transferring your own feelings of oppression on to a scenario where it does not fit (at least not to the extent and in the manner you perceive it to.  Further, it seems as if you are viewing your own experience with medical practioners in this regard as an asset in your ability to assess this situation neutrally, whereas I submit, given your strong feelings on the matter, it may actually be functioning as a confusing bias.  S n o w  let's rap 05:18, 12 January 2016 (UTC)


 * The difficulty here is the part of our OP's question that says "Of different sexes". There is no way for "identical" twins to have different X and Y chromosomes at the time they split from a single egg - so they are always the same "sex" (in the sense of having the same set of X and Y chromosomes).   Sure, they may feel that they don't belong to some gender stereotype - or they might both be XXY or some other rare combination of sex chromosomes - but at the point where the egg splits - they are the same - that's what "identical twin" means, so it's true by definition.  So let's quietly put that aside.


 * That said, however, the glitch here is "Turners Syndrome" - which is an unusual condition in that it is undoubtedly genetic - yet it is not inherited. It comes about when a female has one good X chromosome and another that is either missing or very severely damaged.  A male with just one horribly damaged X chromosome would die long before being born.  So all Turner's sufferers have no Y chromosome - and they are generally considered female.  They are also unable to have children.  Also, you can't inherit Turners - it's impossible.


 * So sufferers are universally girls who are lacking one X chromosome (or have one that is severely damaged)...which is not an inherited condition but a result of a DNA copying or combining error either at conception - or very soon after. Girls with this problem can survive (albeit with serious problems of many kinds) because their other X chromosome is normal - and for many bodily functions, that's sufficient.


 * In the hypothetical case of identical twins (both girls) one of which has TS and the other does not - then we know that at the moment the egg was impregnated, there were sufficient good X chromosomes for one child to be normal. So for this situation to happen, something has to go wrong very soon after the egg is split to form the twins.  Our article says "The chromosomal abnormality may be present in just some cells in which case it is known as TS with mosaicism." - the girl winds up with some cells having just one functional X and the others with two.  The consequences of this depend on how soon during development the problem occurred - so maybe TS hits some organs and not others.


 * If the screwup happens at the first cell division stage - or as the sperm and egg combine - then both twins would have full-on TS.  It is remotely possible that TS "with mosaicism" could happen just before the egg splits to form the twins - and for one twin to have the bad luck to get all of the cells with the damaged X chromosome and for the other twin to get all of the good cells - in which case, one would be OK and the other would have full-on TS.  It's also possible for the transcription error to happen soon after the split in just one twin.  In that case she'd have TS with mosaicism (some good cells and some bad) and her twin would be OK.  In those highly unlikely cases, then yes - you'd have twins who are technically identical but which actually differ genetically because of that copying error either right before or right after the split.


 * I suppose it's mathematically possible for this to happen - but it seems astronomically unlikely just because you'd need:
 * A rare condition.
 * Coincidentally with having identical twins - which is a relatively rare condition.
 * For the chromosomal screw-up event to have happened late enough to save one twin - yet early enough to profoundly affect the other.
 * Multiplying those chances together, it seems very, very unlikely for there to be identical twins with TS present in just one of them.
 * SteveBaker (talk) 14:56, 11 January 2016 (UTC)


 * I suppose that any significant damage to SRY could have a similar effect, though it would require a mutation event even more unlikely than chromosome loss during mitosis.
 * I suppose there could also be variations in timing in guevedoces. (I suspect this article may exaggerate the case, but I don't actually know that) Wnt (talk) 15:23, 11 January 2016 (UTC)


 * SteveBaker, you're assuming the chances of all those events are probabilistically independent. But the hereditary factors that might predispose one to having identical twins might also predispose the mother (and her offspring) to other rare events. Yanping Nora Soong (talk) 23:52, 11 January 2016 (UTC)

Sex / gender distinction
We're talking in multiple places, but the whole idea of "sex is biological but gender is performed / socially-constructed," though historically important, has become frequently challenged. In fact, these challenges are well-sourced. See Sex and gender distinction. Challenging this distinction is not violating NPOV or soapboxing, especially when it is directly relevant to the question at hand.

From the above article I cited:


 * However, the sex/gender distinction, also known as the Standard Model of Sex/Gender, is criticized by feminists who believe that there is undue emphasis placed on sex being a biological aspect, something that is fixed, natural, unchanging, and consisting of a male/female dichotomy... In order to prove that sex is not only limited to two categories Anne Fausto-Sterling's Sexing the Body addresses the birth of children who are intersex. In this case, the standard model (sex/gender distinction) is seen as incorrect with regard to its notion that there are only two sexes, male and female. This is because "complete maleness and complete femaleness represent the extreme ends of a spectrum of possible body types."[44] In other words, Fausto-Sterling argues that there are multitudes of sexes in between the two extremes of male and female.


 * [different section]


 * Diane Halpern, in her book Sex Differences in Cognitive Abilities, argued problems with sex vs. gender terminology: "I cannot argue (in this book) that nature and nurture are inseparable and then... use different terms to refer to each class of variables. The ...biological manifestations of sex are confounded with psychosocial variables.... The use of different terms to label these two types of contributions to human existence seemed inappropriate in light of the biopsychosocial position I have taken.


 * [...]


 * Judith Butler also criticizes the sex/gender distinction. Gender, according to Butler, causes sex to appear natural and politically neutral. However, she argues that "the ostensibly natural facts of sex [are] discursively produced in the service of other political and social interests." Butler concludes, "If the immutable character of sex is contested, perhaps this construct called 'sex' is as culturally constructed as gender; indeed, perhaps it was always already gender, with the consequence that the distinction between sex and gender turns out to be no distinction at all." (ref: Butler, Judith (1999). Gender Trouble: Feminism and the Subversion of Identity (2nd ed.). New York: Routledge. pp. 9–11.)

Yanping Nora Soong (talk) 06:13, 12 January 2016 (UTC)


 * YNS, these can be very mercurial issues, there's no question. I personally think that this issue comes down to certain academics using the same term differently, depending on the needs of their field and outlook.  Social theorists might very well regard "sex" as quasi-synonymous with "gender", while those operating in the hard sciences have need of a term that references rather less ephemeral principles of the biophysics of sexual organisms.  Personally, I think the reason the distinction evolved in the first place was to give different handles that allowed for more nuanced concepts in both fields and that social scientists who do no make an effort to predicate their refutation of that distinction in physical terms are not on solid ground in making a refutation of the nomenclature of biology.  Butler's notions on sex (which are not supported by any kind of biophysical data or evidence broadly) are by no means the standard adopted by most genetic or biomedical researchers; indeed, they are controversial even in gender studies.


 * Sexual organisms are not an illusion, clearly. It's true that the issue is complex and certain situations betray that our intuitions of strict dichotomies do not always hold up.  Nevertheless, it's broadly true that all sexual species reproduce by combining their DNA and, with regard to animals (humans included), this is achieved through the mechanism of male and female gametes.  Those are just biological facts.  The sexes exist as a consequence of them, but those mechanics do not by themselves define our perception of ourselves as sexual or social beings, which is why "gender" exists as a concept.  I don't see how trying to obliterate one collection of concepts serves the purposes of either field, and usually I think anyone who is trying to do so is operating under a kind of occupational blindness and an unwarranted step into areas they don't entirely understand. (Meaning this with regard to theorists broadly, not parties participating in this discussion).  S n o w  let's rap 07:43, 12 January 2016 (UTC)


 * while those operating in the hard sciences have need of a term that references rather less ephemeral principles of the biophysics of sexual organisms -- but don't you see, the fact that you're calling these principles "less ephemeral" or more "set in stone", biologically-determined, etc. is actually addressed and critiqued by sources in the sex and gender distinction article. Let's look at the following theses being asserted that a) there are only two possible human sexes, male and female b) it is impossible or "incorrect" for identical twins to be assigned to separate sexes.
 * In this case, you might wish to define the sexes as reproductive categories. How do we define them? Perhaps by the type of gametes they produce: you belong to the male sex if you produce male gametes, and you belong to the female sex if you produce female gametes. But what if you are infertile (for either chromosomal or endocrine reasons) and cannot produce any gametes at all? Or what if you can produce both types of gametes? Simply by turning certain transcription factors on or off, stem cells can be made to produce both types of gametes. In fact this is now being exploited to help queer couples reproduce. You would like to call these situations "rare" or "atypical" but, to assign one's sex purely based on conventional reproductive compatibility or the functionality of their gametes would disenfranchise a lot of people, and it is clear it has problems as a rigorous, generalized definition, since remember you are asserting a) there are only two sexes b) every member of the human race can be assigned to one or the other.
 * In that case, we might be compelled to use a neurobiological or psychosocial model of sex to define sex membership. But that kind of classification would be even more nuanced.
 * If you truly aren't cis, I apologize, but the kind of absolutism you espouse with regards to the number of sexual categories and sexual membership (every human can be assigned to either of two sexes, and one sex only) would be the kind of sexual absolutism a trans or nonbinary person who has experienced oppression from cisnormativity would never assert. Yanping Nora Soong (talk) 09:17, 12 January 2016 (UTC)
 * You should avoid this kind of generalization. On one hand, it does the "cishet" people an injustice to tar them as inherently prone to be the standard-bearers of an idea you view as wrong; on the other, it is actually more insulting, I think, to say a trans person could "never" have a certain idea.  I mean, remember, Jewish officers were awarded the Iron Cross during World War II, and attended functioning synagogues - and it actually made a kind of sense at the time, because war makes for very, very strange bedfellows.  So I feel sure there are trans people who hold the ideas you say they can't, and that they have their reasons to; here on Wikipedia we very much want people to focus on the idea and not our guesses about the person who holds it. Wnt (talk) 14:38, 12 January 2016 (UTC)


 * Also, I would like to add (and pardon the swearing -- I mean it in the most germane terms) -- SRY is a fucking signalling molecule. It activates transcriptional factors and signal transduction pathways that in turn, turn on / repress more transcriptional factors and signalling pathways. All members of the human race, have the genetic code and latent ability to produce male and female gametes, ovaries or testes, and even the neurobiological structures that make us attracted to masculine or feminine people. (While before HRT I was 35%/65% androphilic/gynephilic to begin with, hormone therapy made the ratio more 50%/50%.) It's only a matter of time before we fully decode what these switches are. Yanping Nora Soong (talk) 09:27, 12 January 2016 (UTC)