Wikipedia:Reference desk/Archives/Science/2009 February 27

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February 27

can hydrostatic testing damage household pipes?

I understand that hydrostatic testing is a method for testing pipes for leaks. There are a number of plumbing companies that offer diagnostic services where they run water into the plumbing system via the sewer line and then monitor the pressure to see whether any leaks could exist underneath the house. My question is whether introducing pressure to a system of pipes (particularly those of an older, 1940's era house) could actually induce a rupture that would then be interpreted as an existing leak -- thus costing money to "repair" the defect. Does anyone have references on such an issue? —Preceding unsigned comment added by 64.91.177.4 (talk) 00:25, 27 February 2009 (UTC)

If there is already a weak spot in the pipes, then hydrostatic testing can convert the weak spot into a leak. However, if the pipes are already that weak, then ordinary events (fluctuations in supply pressure, or water hammer from closing a faucet too quickly) can also cause the weak spot to leak. --Carnildo (talk) 00:59, 27 February 2009 (UTC)

Applying higher than normal presssure to any system of pipes could certainly be the cause of them breaking. A stress test can cause the tested system to break. If if has a leak, the test might help locate it. If it is about to fail, the test could demonstrate that. But a pressure test is not a nondestructive test, since it can cause a marginal system to fail sooner than it would have. I could see hydrostatic testing as a useful acceptance test on a new system. Ask yourself if there is any way that applying high pressure to an aged system could improve it? Edison (talk) 01:55, 27 February 2009 (UTC)

Probably could damage the pipes; if someone wanted to sensibly check I can think of two ways offhand. Attach a pressure meter to an open tap, then close the valve to the mains. Wait and see if the pressure drops due to some leak somewhere. The other method is to close the valve to the mains and lower the pressure at an open tap with a pump, air will invade a leak and become obvious. Polypipe Wrangler (talk) 06:51, 3 March 2009 (UTC)

Macdonald 80 Shopping Center

Can anyone help me find references for Macdonald 80 Shopping Center ?, maybe in the East Bay Express, Contra Costa Times, West County Times, San Francisco Chronicle, Richmond Globe, Richmond Post, KTVU, KRON or any local affiliate of the broadcast channeles, NBC CBS FOX Univisión, etc. Richmond City Council minutes, the developer. Any help would be great!Troyster87 (talk) 02:25, 27 February 2009 (UTC)

Isn;t that a little backwards? Before deciding if the shopping center merited an article, shouldn't you have gathered your sources first? I mean, there is a very good chance that those sources don't exist at all... See WP:YFA for the proper way to build a new article, and notice that the first step, befre writing, is to gather references. Also, what is this doing at the Science Ref Desk???--Jayron32.talk.contribs 02:44, 27 February 2009 (UTC)

Engineering is a science, and this is an engineering project, and article about it, where should i have asked? and the sources exist, i have seen them. i just can't locate them, but it was reported in some of those newspapers and on websites. i am not questioning the notability, as it is a notable place, furthermore there is a precedent for this sort of article and nearly every other shopping center, district, and mall in the bay area has an article. some much smaller and far less notable!Troyster87 (talk) 00:25, 28 February 2009 (UTC)

I don't know about all that. I just know that, before I sit down to write a research-based document, I want to have the sources in front of me before I start writing. It seems a little bass-ackwards to create an article under the "I read this somewhere I think so I'll just go ahead and write all of this down." This has nothing to do with any of the other equally poorly thought out articles you may or may not find at Wikipedia. You wanted to know about your article. What you should have done before creating your article is to gather your sources first, and then used them to write your article. Just diving off the deep end and creating an article on the "maybe I can find something about this later" mentality is the cause of nearly every deleted article. People who do it the right way, by having their sources first, never get their articles deleted. If you contact the news sources you have listed, they likely have archives and concordances and things like that, and should be able to direct you to the right issues where the information is located. Just contact the newspaper and ask for the research department. Then explain that you are looking for articles about this shopping center. They can direct you to the right issues where you can find information. --Jayron32.talk.contribs 03:30, 28 February 2009 (UTC)

Psychological effects of norepinephrine

What are the psychological effects of norepinephrine? NeonMerlin 03:46, 27 February 2009 (UTC)

Did you read Norepinephrine? Or your textbook? --Shaggorama (talk) 04:14, 27 February 2009 (UTC)

I did read Norepinephrine, and it doesn't say anything about psychological effects. NeonMerlin 00:36, 2 March 2009 (UTC)

I hope this Q doesn't put you to sleep...

Is there a device that can detect when a person is asleep ? My Dad seems to have narcolepsy, and falls asleep all the time during a conversation, then wakes up later and continues as if he never dropped off. The issue is with him trying to watch a movie. He is likely to fall asleep several times during the movie, but not realize when, or even that, he fell asleep. At the end he says "that movie was terrible, I couldn't follow the plot at all". It would be nice if there was a device that could detect when he falls asleep, hit the pause button, then unpause when he awakens (although he could do this last part himself, I suppose). He used to enjoy movies, and maybe he could again in this way. StuRat (talk) 04:24, 27 February 2009 (UTC)

I can't think of what it's called, but I remember once seeing a device that kind of hung off your ear and if your head fell to one side it would beep. I think it just had a motion sensor in it, simple, yet probably effective most of the time, as long as your head's not propped up. I don't know if waking him is what you're after, but this is a start at least. I'll post a link if I find it. -Pete5x5 (talk) 05:31, 27 February 2009 (UTC)

This is on the right track. Next I need a variant of this device that can send a signal to a robotic hand that can press a pause button. Any thoughts ? Could I open up the ear device and connect a wire from it to a robotic hand ? StuRat (talk) 14:26, 27 February 2009 (UTC)

Polysomnography --Mdwyer (talk) 06:34, 27 February 2009 (UTC)

Yes, an electroencephalogram (EEG). You probably should read "The Promise of Sleep" by William DeMent, ISBN 0440509017. It discusses the issues you're asking about extensively, mentions treatment options, etc. 207.241.239.70 (talk) 06:48, 27 February 2009 (UTC)

Does his doc know and is/was he taking any medication? Some meds like Zolpidem, Thalidomide, antidepressant (stopping those)etc. can have sleep disorders as side effects. His physician could then send him to a sleep center if necessary. I think this is what Pete was looking for [1]. They tested something similar on truck drivers at a shipping agency I had a project at. They ended up not using it because lots of drivers didn't like it. 76.97.245.5 (talk) 08:36, 27 February 2009 (UTC)

Narcolepsy is a rare cause of excessive daytime somnolence. There are several more likely reasons why your dad is falling asleep. If this is a problem for him, I recommend referral to a sleep specialist. Axl ¤ [Talk] 08:32, 27 February 2009 (UTC)

I thought narcolepsy WAS excessive daytime somnolence. That is, I thought it was a symptom, not a cause. It is most likely a side effect of one of his many medical problems (prostate cancer, kidney failure requiring hemodialysis, diabetes, etc.) and the meds he takes to fight them, but stopping those meds isn't an option in most cases, so we need to find a way to live with this condition, instead. StuRat (talk) 14:26, 27 February 2009 (UTC)

If you believe that your dad has a medical condition such as narcolepsy, you should advise him to seek information from qualified medical professionals, such as a doctor, and not random strangers on teh intrewebz. If he genuinely has a problem, then doctors can prescribe devices or medicine to help him. --Jayron32.talk.contribs 15:32, 27 February 2009 (UTC)

[To StuRat] Narcolepsy is a diagnosis of itself, with specific recommended treatment. It is only one of the causes of excessive daytime sleepiness. Axl ¤ [Talk] 15:40, 27 February 2009 (UTC)

Some cars have been shown (mostly a 'concept cars') with devices that detect when the driver is falling asleep at the wheel. I believe they have cameras that look at your eyes and check things like blink-rate and duration. I have yet to see one sold commercially though. This paper talks of using heart-rate changes to predict when someone is about to fall asleep while driving. Following the references from that paper might yield something useful. SteveBaker (talk) 16:32, 27 February 2009 (UTC)

Going back to the ear device, instead of getting it to activate a robotic arm you could instead get it to send an RF (radio frequency) signal to an RF repeater, changing the signal to IR, and pausing the DVD player. My dad designs and creates custom remote solutions, so I know this is possible, you'd just need to butcher an RF remote and somehow get the device to activate it. Getting the parts shouldn't be hard, but it will be moderately expensive (A good, reliable remote that's RF will run you $200, an RF repeater is about $60, and then the cost of the device (these costs in Canadian dollars)). It'd be really cool if you did it, but it would be a lot of trouble. -Pete5x5 (talk) 19:40, 27 February 2009 (UTC)

That is getting pricey, and I have no problem with wires. Is there a cheaper way to do it with wires ? StuRat (talk) 22:15, 27 February 2009 (UTC)

Well, if you have some kind of device that'll reliably detect when he falls asleep - it should be very simply to modify a 'universal' TV remote to pause the TV. Presumably there is no need to automatically unpause it since when he wakes up - he'll see that the video has paused and realise. He can then un-pause it himself. The only issue is that most DVD/VCR's will drop out of pause and simply stop playing after a couple of minutes. But assuming that's not such a huge deal - you can usually 'train' a universal remote to produce any command on any button. Carefully dismantle the remote - remove all of the buttons - you'll see the two copper 'pads' beneath that the button will connect when you press it. You'd carefully solder a thin wire to each pad and connect them up to either a small relay or an opto-isolator (both parts you can get from RadioShack for a few bucks)...whatever signal comes out of your 'sleep detector' can be used (possibly via a transistor) to drive the relay or opto-isolator to 'connect' the two pads on the remote just like you'd pressed the button yourself. No robots required! However, the means of detecting sleep may be tricky. Does his head change position as he 'nods off'? If so, something as simple as a mercury tilt-switch would work (you find them in old air conditioner thermostats for example). Something like that could be connected directly to the remote's button pads with no other electronics whatever. SteveBaker (talk) 03:26, 28 February 2009 (UTC)

Before you shovel out money on parts for a modification you should first try and see if it works at all. Automatism would have him lose awareness, but the ordinary signs of sleep would not result. A device that reacts to him literally "nodding off" would be useless if his neck muscles didn't get the information that the consciousness was taking a break. I was by no means trying to imply above that he should stop taking his medication. (Some substances can cause sleep disorders when stopped rather than while taken, actually) You should inform his doctor, because he may need to know and apparently your dad's not aware of what's going on. There's an off chance that he could switch your dad from product A to product B, or add pill C to your dad's regimen and things might improve for a bit or at least be kept from deteriorating. Sounds like, in the longer term, you should cast around for things that keep your dad occupied and allow for him to be absent for a bit, or keep his acuity up for the duration. See if he likes puzzles or playing games. --76.97.245.5 (talk) 22:30, 27 February 2009 (UTC)

A doctor can prescribe a sleep study at a hospital. to see if someone has some condition such as Sleep apnea, which is sometimes treated by a CPAP. As for falling asleep during a movie, the proof of it is starting the movie from the beginning when the person is well rested and having him note where material appears that he does not remember from having watched it. One might also sometimes point out the red stain from where the glass of merlot spilled, depending on the cause of the somnolence. The mind is good at filling in when the person sleeps through part of a movie, just as the brain fills in the blind spot in a visual image, and does not see a hole. For people who fall asleep while sitting up, the dropping of the chin on the chest cold be a way to activate a switch which pauses the movie and administers a painful shock to the rear. A Snore detector might also be useful in operating the pause control. Edison (talk) 01:57, 28 February 2009 (UTC)

A cheaper modification to my way still includes the ear thing (as I think that's one of the few, and probably least expensive, reliable methods of detecting when he's asleep. You could just take apart a cheap, Wal Mart style universal remote ($30?), and take out the part that mimic's the IR signal of other remotes. Then 'program' your remote's pause button in (probably just hold it in front of the receiver and press the pause button). Then have an IR transmitter with a wire connected to it ($1.00?) connected to the ear piece and the other end glued to the front of the DVD player, where the sensor is. The wires on the transmitters (at least the ones I have) are 12 ft. long, so that should suffice, or it can be extended. It would be annoying having a thin, black, almost invisible wire going across the room, but other than that it's inexpensive, and overall more reliable than wireless. I'd really like to see you build this contraption, it'd be very cool. I have no doubt that it can be done, you just need to be very good at taking things apart, and have a lot of electrical tape! Alternatively, I just thought that you could tape down the pause button on your remote, then have your dad put his head in the way. If he falls asleep and his head falls, the signal will no longer be blocked and the movie will pause. You'd probably want to get a cheap universal remote for this method too, so that he doesn't have to move the constantly pausing one to un-pause it when he wakes and risk putting in back in the wrong spot. You'd also need rechargeable batteries, or it would get equally costly eventually. -Pete5x5 (talk) 07:22, 28 February 2009 (UTC)

Anybody is answering it?????

What actually are the cyanides? —Preceding unsigned comment added by Achraz (talk • contribs) 05:02, 27 February 2009 (UTC)

Did you read our article on Cyanide? --Jayron32.talk.contribs 05:06, 27 February 2009 (UTC)

That's why I was always afraid to breathe the air in the CN Tower. :-) StuRat (talk) 05:09, 27 February 2009 (UTC)

Possible; his account was just made today and he's already made 3 ref desk posts (even though I don't know who you're talking about when you say Freewayguy). I think we have to assume good faith and try to help unless you KNOW this is someone evading a block. -Pete5x5 (talk) 05:22, 27 February 2009 (UTC)

In fact, the top of this page specifically says "Be polite and assume good faith, especially with users new to Wikipedia."  ;) -Pete5x5 (talk) 05:25, 27 February 2009 (UTC)

For those confused by the above conversation, note a post was removed by the poster [2] Nil Einne (talk) 09:39, 27 February 2009 (UTC)

Doesn't seem like Freewayguy to me. --Tango (talk) 12:20, 27 February 2009 (UTC)

wavefunction in quantum mechanics

we know that not all wave fanction are allowed wave fanction in quantum mechanics only those wave fanction that satisfy schrodinger equation and also they are wellbehaved.But if it is not wellbehaved then what difficultise arise?Supriyochowdhury (talk) 08:18, 27 February 2009 (UTC)

If you expect the wavefunction to be a probability amplitude, you'd hope that it is square integrable and therefore normalizable. Vespertine1215 (talk) 10:14, 27 February 2009 (UTC)

Rear Axle

Which is the most critical part in rear axle ? —Preceding unsigned comment added by 59.98.178.48 (talk) 11:31, 27 February 2009 (UTC)

This looks suspiciously like a homework question. In order to answer this question, we need all the information above the question: Is it a car, wagon, train...? It is a front wheel drive or rear wheel drive? Are there any modifications such as a limited slip differential? -- kainaw™ 14:02, 27 February 2009 (UTC)

If we're talking about rear-wheel drive vehicles - then the most complicated bit is undoubtedly the 'differential'. But the most 'critical' part? Well, I guess it's all pretty critical...you can't really do without any of it. On a front wheel drive vehicle, the rear axle is generally a rather simple affair - and in some there actually is no rear axle at all with the rear wheels mounted directly onto the frame with no connection between them...so in that sense, none of the rear axle is 'critical'. Perhaps you could explain in more detail what exactly it is that you want to know? SteveBaker (talk) 16:24, 27 February 2009 (UTC)

Rear Axle rework

In which section rework is allow ? —Preceding unsigned comment added by 59.98.178.48 (talk) 11:37, 27 February 2009 (UTC)

I'm afraid your question is not understandable. Specifically the word "rework" does not make sense in the context of your question. Your IP address is in India, so I am going to proceed on the assumption that English is not your native language and that you may speak Hindi. If by "rework" you mean गृहकार्य which (I hope) is "homework" in English, there is no section of the Wikipedia reference desk that will answer your homework questions for you. However, the respondents on the reference desk will be glad to help you:

• Interpret your homework questions if you do not understand their meaning
• Help you understand the ideas and concepts
• Attempt to point you to resources that may help you answer them

By the way, I used this Hindi-English dictionary to find the Hindi word for homework. I apologize if I was wrong in assuming you spoke Hindi. I know India has many different languages. Other refdeskers, if I used the wrong Hindi word for homework, please correct it inline. Sifaka ^talk 02:07, 28 February 2009 (UTC)

I think rework means repair, my advice is consult a mechanic.Stevej000 (talk) 17:07, 2 March 2009 (UTC)

Moth question

In the book Silence of the Lambs, a moth species that feeds solely on lachrymal fluid is mentioned. Does such a species of Lepidoptera (spelling?) actually exist? If so, what is its name? 65.167.146.130 (talk) 14:38, 27 February 2009 (UTC)

If I remember correctly, the moth in question was the Death's-head Hawkmoth, which feeds on honey from beehives, according to our article. I am not sure if Thomas Harris conflated the Death's-head moth with another moth, or as is more likely, simply invented the idea out of whole cloth. --Jayron32.talk.contribs 14:59, 27 February 2009 (UTC)

The Asian moth Lobocraspis griseifusa feeds on the tears of water buffalo. Some moths slip their probosces under the eyelids of sleeping birds to feed. It's interesting to note that a character in a sequel drinks the tears of children. --Sean 15:23, 27 February 2009 (UTC)

I guess the question then is "How does the moth make the water buffalo sad?" I got a million like this...--Jayron32.talk.contribs 15:43, 27 February 2009 (UTC)

You need some gnu material. :-) StuRat (talk) 18:10, 27 February 2009 (UTC)

I think Jayron's material is pretty good, especially if the audience has never herd it before. :-) 10draftsdeep (talk) 20:47, 27 February 2009 (UTC)

My aunt never liked that punny sort of humor, but my ungulate it up. --Sean 21:15, 27 February 2009 (UTC)

I wanted to contribute my own bad buffalo pun, but I don't anoa good one to use. --98.217.14.211 (talk) 22:41, 27 February 2009 (UTC)

I suspect that poking the water buffalo in the eye would cause it to water. Thanks for the answer, hopefully an article get created on this moth at some point. 65.167.146.130 (talk) 15:53, 27 February 2009 (UTC)

Shouldn't this question be at the Moth desk :-) Fribbler (talk) 15:59, 27 February 2009 (UTC)

grooooaaannnnnn :) Livewireo (talk) 21:49, 27 February 2009 (UTC)

I strenuously oppose levity on the Ref Desk, and I will not be cowed by anyone. That's no bull. We should not give anyone a bum steer. Edison (talk) 01:49, 28 February 2009 (UTC)

You're just trying to buffalo buffalo off the Science Desk... Nimur (talk) 04:51, 28 February 2009 (UTC)

Glutathione

How can you do to increase glutathione in the cells? It is true that 500 grams of vitamin C increase the glutathione in the cells by 50%? Thank you very much. —Preceding unsigned comment added by 151.65.126.7 (talk) 16:39, 27 February 2009 (UTC)

Our article glutathione mentions methods of supplementation. A google search of Vitamin C and Glutathione turned up this paper which found that mean red blood cell glutathione rose nearly 50% when subjects took doses of 500 milligrams (not grams) for 2-3 weeks. The authors also found that increasing the vitamin C dosage to 2000 milligrams (i.e. 2 grams) did not have a significantly different effect on glutathione levels compared to 500 mg. Sifaka ^talk 00:57, 28 February 2009 (UTC)

How to compare more than 5 products at biocompare.com

I am trying to compare the available unconjugated antibodies to human beta-actin, of rabbit origin for use in Western blots. When I perform a search using these parameters, the results are many. When I attempt to 'select all' and click 'compare', I am confronted with the message 'You are trying to compare more than 5 products. Please log in to add these to your selected products or reduce the number of products selected", or something to that effect. I am signed in, but there is no indication as to how I should "add these to my selected products" nor how this would help me achieve my aim of discerning which source of antibodies is the cheapest. Thanks in advance to anyone who might collaborate with me in elucidating this function of BioCompare. :) --129.125.137.62 (talk) 16:40, 27 February 2009 (UTC)

This is a common problem I have with the Compare function on many consumer websites. Some approaches I've tried:

1) Eliminate some items prior to use of the Compare option. This can be done using those attributes that are listed outside of Compare. In some cases, it's possible to sort by those characteristics, such as price, so you can eliminate some.

2) If you still have too many left, Compare them 5 at a time (or how every many are allowed), and then eliminate all but the best from each batch. Then Compare the best from each previous Compare.

BTW, this would have been an excellent Q for the Computer Ref Desk. StuRat (talk) 18:00, 27 February 2009 (UTC)

Homo sapiens

I know that homo sapiens are the only species within the homo genus still living. I find this curious. How common is it to only have one species within a genus in the animal kingdom? A Quest For Knowledge (talk) 17:56, 27 February 2009 (UTC)

Species and genus is an invention of the people that categorize life based on their own crietria. It is actually mostly arbitrary, and you will not easily find much common agreement between taxonomists on what constitutes distinct species within one genus, subspecies of the same species, different genuses, etc. etc. There's only one "Homo" species because someone decieded there was. You will often hear that breeding compatibility defines a unique species, but there are clear examples of where this falls down; for example what about three animals, A, B and C. Lets say that Animal A & B can breed to produce viable offspring, and B & C can breed to produce viable offspring, but that A & C cannot breed to produce viable offspring. Well, under the standard definition of species, A & B are the same species, B & C are the same species, but A & C are NOT the same species. So how do you classify them??? Depending on whose classification system you use, you will likely find THOUSANDS of single-species genuses. Look at Tuatara for an extreme example. It is an order that consists entirely of two species. --Jayron32.talk.contribs 18:23, 27 February 2009 (UTC)

Yes, but there used to be at least another dozen species under the homo genus. All are extinct except for us. To put it in another and less scientific way, there are lots of dog breeds (Shih Tzu, Pit Bull, German Shephard, etc.) but only one 'breed' of human. How common is this in the animal kingdom? A Quest For Knowledge (talk) 18:49, 27 February 2009 (UTC)

Just to clarify a little bit more, I understand that species can be classified in many ways depending on who is doing the classifying. This has come up before. I guess what I'm getting at is that our closest living relatives are the chimps and they seem to be pretty distant cousins. I'm wondering how unique humans are in not having any other close relatives still alive. I mentioned genus because it seemed the most succinct way of asking it. A Quest For Knowledge (talk) 19:10, 27 February 2009 (UTC)

Weeeeeell, to go back to pedantry and anthropocentrism... :) But seriously, have you seen the discussions on whether chimpanzees and humans should really be in separate genera? 79.66.56.21 (talk) 19:02, 27 February 2009 (UTC)

No, do you have a link you can point me to? A Quest For Knowledge (talk) 19:12, 27 February 2009 (UTC)

Check out The Third Chimpanzee by Jared Diamond. It's been a while since I read it, so I don't recall how serious Diamond was in his assertion or whether it was more or less to make the point that chimps and humans are very closely related indeed. According to the book, the Pan genus was named first, and so would have precedence over Homo, should the two groups be merged. The second chimpanzee, for those not familiar with primates, is the bonobo or "pygmy chimp". Matt Deres (talk) 21:28, 27 February 2009 (UTC)

Also, take a look at the various articles on race.--Shantavira|^{feed me} 19:08, 27 February 2009 (UTC)

To my knowledge no reputable scientist today thinks that the races come from different species of any sort. --98.217.14.211 (talk) 01:38, 28 February 2009 (UTC)

Breeds of dog are different types of the varieties of the same species. They aren't unlike humans of different races, or even just different hair colours/heights/builds. There is more variation between breeds of dog than humans, at least visible variation, but that's only a difference of degree. --Tango (talk) 19:28, 27 February 2009 (UTC)

The question here isn't so much about the vexed question of "What is a species?" - which we've addressed at length many times before (Conclusion: It's a vague term...sorry 'bout that!). This question is "What is a Genus?". If humans are the only species in our genus - what defines that term in such a way as to prevent other species such as the chimpanzee from being a part of our genus - or conversely keeps us out of the same genus as the other great apes? I suspect the answer will boil down to not upsetting the religious nuts...but perhaps there is a better reason.

Our article Genus says:

The rules-of-thumb for delimiting a genus are outlined e.g. in Gill et al. (2005). According to these, a genus should fulfill 3 criteria to be descriptively useful:

• monophyly – all descendants of an ancestral taxon are grouped together;
• reasonable compactness – a genus should not be expanded needlessly; and
• distinctness – in regards of evolutionarily relevant criteria, i.e. ecology, morphology, or biogeography; note that DNA sequences are a consequence rather than a condition of diverging evolutionarily lineages except in cases where they directly inhibit gene flow (e.g. postzygotic barriers).

Sadly, my knowledge of biology fails me at this point. However, I understand there to be a strong case for renaming the Common chimpanzee and the Bonobo 'Homo pan' and 'Homo paniscus' - thereby making them be the second and third extant species in our genus. Then we can arm-wrestle the chimps to see who gets to be type species for the genus....hmmm - maybe we'd better make that 'speed chess' - they'd probably beat us at arm-wrestling.

SteveBaker (talk) 19:50, 27 February 2009 (UTC)

The problem with that definition of Genus is that it is still open to interpretation. What makes two extinct individuals or groups part of the same ancestral taxon? What if new discoveries lead us to want to split a taxon into two new taxons? What happens to the genera below that? What kind of expansion does a genus need? What needless means to one person is different than another. What makes a criteria "evolutionarily relevent" with regards to saying "these two examples are from different genera or from the same genus?" Ultimately, we justinvent these "rules" for classification (which still are themselves open to the subjective interpretation of the individual).

Its not much less arbitrary than how I decide to organize my CD collection. Do I organize it by genre or alphabetically by artist? Do I intermingle Jefferson Starship with Jefferson Airplane or are they seperate? Is Jane's Addiction funk-metal, or alternative-rock? Ultimately, the whole concept of taxonomy is a human invention, created for the convenience of organizing our knowledge of living things. Insofar as it helps us find commonalities and difference among all life, it is a useful thing to classify; but as with ALL classification systems, no set of rules will cover every eventuality, and there will always be a level of arbitrariness to it. Ultimately, "because someone just decided it would be this way" ends up being the biggest justification for deciding how to classify one animal or another into one taxon or another. --Jayron32.talk.contribs 20:47, 27 February 2009 (UTC)

A similar case to humans might be the horseshoe crab, which, despite it's name, is only distantly related to crabs. There are 4 known species of horseshoe crab, but those may be the only species left in their genus, family, or even order. Similarly, the coelacanth, of which there are 2 known remaining species, are the only known survivors of their genus, family, order, and even sub-class. The bowfin appears to be an example where only one species is known to exist in the genus. See living fossil for more examples. StuRat (talk) 21:52, 27 February 2009 (UTC)

Articles more specific to the reduction in the number of Homos walking around at the same time: Neanderthal#Neanderthal_extinction, vs. Multiregional origin of modern humans. Personally I would not have been surprised if Sapiens killed off any others. Our species appears to have never been good with strangers, much less ones who would pose a much more severe threat than many of the animals of the time. --98.217.14.211 (talk) 01:38, 28 February 2009 (UTC)

You also have to be VERY careful if you try to use dogs as an example in any discussion of this sort. Dogs are quite unique in that they are thought to be the oldest domesticated animals and humans have been selectively breeding them for thousands of years, that's why they're called "breeds" of dog. The thing is tho, unlike natural selection, human selection relies purely on traits that we can see, which turn out to be only a superficial fraction of the genetic material that actually "makes" a species. So selective dog breeding has created an incredibly diverse number of physically distinct breeds, much more so then you would find anywhere in nature, especially in the relatively short time, however, genetically the dog "breeds" are still practically identical. Vespine (talk) 12:12, 28 February 2009 (UTC)

Yes, I was afraid my dog breed comparison might derail things a bit. I was just trying to understand how rare it is in the animal kingdom for a species not to have any living close relatives. Koala bears appear to be in similar situation. Part of what was driving my question was me wondering whether homo sapiens intentionally killed off rival homo species. A Quest For Knowledge (talk) 01:41, 1 March 2009 (UTC)

I read a hilarious article a few years ago on how eager people generally are to attribute the Neanderthal extinction to us killing them off, rather than them just not making it. Wish I could find it again :) 79.66.56.21 (talk) 02:01, 1 March 2009 (UTC)

I'm surprised this has not been mentioned yet but we need to remember one of the reasons why there are no seperate humans species is because our migration patterns and high interbreeding has meant few what we can classify as seperate species have been able to develop. In terms of the comment on 12 difference species, what you've missed is that most of these predate Homo sapiens sapiens. In other words, many of them may be just our ancestors. I'm not sure how many are not (Homo neanderthalensis is one) but for example Homo rhodesiensis says it is "it is probable that Homo rhodesiensis was the ancestor of Homo sapiens idaltu (Herto Man), which would be itself at the origin of Homo sapiens sapiens" which is what I would expect for a number of them. Even those which aren't one of our ancestors if they died before we even came into existance, you can't really say 'we' had anything them with their demise per se. And this leads me to my second point, the biggest problem is beyond the already inherent problems in taxonomy, labelling extinct species is even more problematic. While there is still debate over things like punctuated equilibrium I think basically every evolutionary biologist and taxonomist will agree that there is no clear cut line between Homo sapiens sapiens and whatever ancestor we care to name that predated it say Homo sapiens idaltu, the same for idaltu vs Homo rhodesiensis. Given the problems in taxonomic classification that already exist, combined with the problem classifying ancestorial species, you can hopefully easily see why saying that there are other Homo species simply because we have ancestors which we can choose to classify as different species is meaningless. (Some biologists suggest we shouldn't bother to classify historically extinct species or at least we should only view any classification as having any degree of meaning when we are comparing species at a fixed point in time). Leading back to the tuatara, since Sphenodontia once had many different species and this was likely at a distinct point in time (The two species of tuatara are the only surviving members of its order, which flourished around 200 million years ago) and "Although tuatara are sometimes called "living fossils", recent taxonomic and molecular work has shown that they have changed significantly since the Mesozoic era" do you see why the idea that Homo sapiens sapiens is unique because we've classified some of our ancestors as difference species is meaningless? Nil Einne (talk) 03:02, 1 March 2009 (UTC)

It's undoubtedly true that there was never a distinct 'break' between the ancestors of modern man and us. If we had always had one decent male and female, adult hominid fossil from every (say) 1000 years from a few million years ago until today - all set out in a neat line - we'd probably never consider an effort to draw a line to distinguish Homo sapiens idaltu from us. However, it is in the nature of archeology that we only find good examples that are widely separated in time - often they are just fragments of bone and we may be uncertain of the age, health or sex of the individual that this represents. These scattered snapshots are clearly and dramatically distinct from each other (although you can still lay them out in a row and see a progression of change). This leads us to want to attach labels to each one - because they ARE quite different and distinct. Identifying them as separate species seems the natural way to do that. However, this tendancy to name things like that in no way alters what we believed happened along the way. SteveBaker (talk) 16:50, 1 March 2009 (UTC)

Maybe this is a fringe theory, but there are people who believe that some cryptids exist, and, in effect, that some of these cryptids are actually other species in the homo genus that had not gone extinct. However, since this is categorised as an "extraordinary claim", scientists will usually reject the possibility. ~AH1^(TCU) 01:36, 2 March 2009 (UTC)

If Homo floresiensis (the "Hobbit") turns out to be a true species then since they were around as recently as 18,000 years ago (and possibly as recently as 12,000 years ago - and according to some reports as recently as the 1800's!) - they would certainly have been an example of a second member of the Homo genus - and one from which modern humans could not have been descended. But the jury still appears to be out on that one. SteveBaker (talk) 05:15, 2 March 2009 (UTC)

Bornholms Disease

Request for medical advice removed

Please note that the Wikipedia Reference Desk cannot provide medical advice. You should speak to a health care provider. - Eron^Talk 22:38, 27 February 2009 (UTC)

We can't but we could at least help the user find related information on wikipedia. (Going with our library analogy, your librarian would also not send you to your doctor if you asked where they have a book on condition XYZ.) The quality and relevance of that information is up to the reader to determine.:

The page you linked has a link to Coxsackie B virus on it. That has a bit more on treatment and a reference to a report on homeopathic treatment. The latter is also only symptom relief, though. A bit on using wikipedia: If you click on a blue word it will get you to a page that is related. To link to a wikipedia page here copy the page name and enclose it in two angled square brackets [[]].76.97.245.5 (talk) 23:01, 27 February 2009 (UTC)

I believe this was incorrectly removed as a request for medical advice (see discussion here: Wikipedia_talk:Reference_desk#.28Possible.29_Medical_advice_question_removed_-_Bornholms_disease) when it's simply a request to improve our article on Bornholm disease. As such, I have added your request to the talk page for that article: Talk:Bornholm disease#Article Improvements Needed. StuRat (talk) 17:55, 28 February 2009 (UTC)

I have done a little work on the Bornholm disease article, more input from others would be welcome. --Scray (talk) 12:07, 2 March 2009 (UTC)

Thanks. It's starting to look a bit better. StuRat (talk) 15:00, 2 March 2009 (UTC)