Wikipedia:Reference desk/Archives/Science/2013 January 25

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January 25

Cellular co-transport

I understand the basic idea of co-transport (the passive diffusion of a species, usually an H⁺, Na⁺, or K⁺ ion is coupled with the transport of another species, usu. which the membrane is impermeable to such as glucose, against its concentration gradient). What's confusing me is: a lot of resources I've consulted indicate the use of the energy "stored" in the ion's gradient. I'm not quite getting how this leads to any sort of energy being "stored", because as I understand it, were the membrane permeable, the concentration gradient would be balanced out through random motion of the particles, not some sort of attraction. So where does this idea of energy being built up by an electrochemical gradient come from? Second, if the membrane is impermeable, and transport proteins can change shape upon binding with an appropriate substrate, why is active transport even necessary, since in theory, even if the external concentration were lower than the internal concentration, the membrane and lack of active site on the interior would prevent outward diffusion, while random motion of the molecule outside would lead to it eventually entering the active site anyway (I guess this one is partially related to why is energy required to overcome this gradient, which I guess might be answered if the first question is answered) Brambleclawx 03:49, 25 January 2013 (UTC)

You're right, the ion concentration would even out due to Brownian motion if it were not actively maintained. I can see why you would question a vague concept of "energy storage", but instead think in terms of membrane potential (that's not a bad article by the way, the first figure caption has a nice simple explanation). It's also not quite right to treat a plasma membrane as either permeable or impermeable, they're selectively permeable. The combination of those two articles gives a more comprehensive answer than I could hope to give here, hope they help! Jebus989^✰ 13:31, 25 January 2013 (UTC)

I think it's the idea of "potential energy" messing me up here. I just had a look at chemical potential, where it's said that "Movement of molecules from higher chemical potential to lower chemical potential is accompanied by a release of free energy". Why? I can understand gravitational potential energy, in that elevating an object means it will have more kinetic energy going down, but I don't understand chemical potential energy, seeing as particles move randomly (as opposed to in a certain direction as would occur in gravity). And yes, I know the plasma membrane semi-permeable, but it is impermeable to ions unless they travel through a transport protein (either passively or actively). What I'm suggesting is that since ions cannot diffuse out, even if the interior had a higher concentration, wouldn't a randomly moving particle outside eventually enter the binding site of the transport protein, which could then change shape (as s result of the bonding of substrate, assuming that's how passive transport proteins (and I don't mean ion channels) work) to add the particle to the already high concentration? Since the particle is moving "randomly", there really isn't anything making it move away from the high concentration. Brambleclawx 03:33, 26 January 2013 (UTC)

Mathematically, the energy is accounted for by the entropy term in the equation. Since entropy is lower with a concentration gradient than when it's equalized, entropy increases; thus the -TS term becomes more negative, i.e. energy is released. It's statistical in nature. In the absence of an energy gradient for the operation of the transport protein, as with any other reaction it is reversible. Consider a badly designed revolving door, where people coming in go through the door clockwise, but people going out have to go through counterclockwise. Clearly, if the number of people on either side of the door is around equal, the door isn't going to do much turning. On the other hand, if there is a gradient, the door starts rotating, and energy can even be tapped off it to run the escalators (a brilliant old idea of mine) or something. The energy is obviously subtracted from the kinetic energy of the people (who then replenish it muscularly). In the concentration gradient model, the energy comes from the kinetic energy of the molecules, a function of temperature, thus the T which is multiplied by the S. S is analogous to the net number of people going through the revolving door (in minus out), T is analogous to the average velocity of the people passing through. Gzuckier (talk) 06:28, 26 January 2013 (UTC)

Oh... I was under the impression transport proteins only allow for movement in one direction? Brambleclawx 19:10, 26 January 2013 (UTC)

To begin with, consider the business of adding water to acid. You have a nice big container half full of concentrated sulfuric acid, you want to dilute it 50-50, so you just fill her up, right? Except, well... the acid gets angry. It turns out that a container half full of water and half full of acid has free energy to give away when they get mixed. I don't think I ever learned the physics of this one, but I assume that the Gibbs free energy remains constant, and G(p,T) = U + pV − TS ; if the entropy S goes up (due to mixing) then the Gibbs free energy goes down, so the solution has to give energy away somehow to meet conservation. So yes, an electrochemical potential contains energy - you can have a little hole in a membrane between acid and not-acid and get energy out of it in various ways, ranging from simple heat evolution in our example to the more sophisticated methods of extracting energy from the mitochondrial proton gradient in cellular respiration. Wnt (talk) 00:30, 27 January 2013 (UTC)

Different types of pepper

Excluding specific chemical testing, and assuming I'm not interested in the color of the resultant dish, is there any practical reason to add ground black pepper to a stew in which I put ground cayenne pepper? I mean to say, is the taste of the spiciness different enough that there's any real reason to add black pepper assuming I'm already going to be putting in cayenne because I find that black pepper alone doesn't provide a spicy enough taste. DRosenbach ^{(Talk | Contribs)} 03:53, 25 January 2013 (UTC)

To me the taste is rather different. A quick glance at the articles suggests that the heat is perceived by the same pathway, but there are other aspects of the flavor of these spices besides the heat alone. --Trovatore (talk) 03:56, 25 January 2013 (UTC)

Black pepper comes from the berries of the Piper nigrum plant, and the heat comes from piperine. Cayenne pepper is from the Capsicum annuum plant, and the heat comes from capsaicin. They have completely different tastes. That being said, in cooking anything that works is OK, so try it both ways and see which you prefer --Guy Macon (talk) 04:04, 25 January 2013 (UTC)

Absolutely the tastes are different, and they work differently and have different flavor profiles; black pepper has Piperine as its major flavor component, and the heat of black pepper is actually its secondary use; black pepper is (like salt) a flavor enhancer; when used properly it doesn't just add its own flavor to foods, it makes foods taste more, well, more. That is, when you add the right amount of salt and pepper to a steak, you don't taste it as salty and spicy, you taste it as more beefy. When you add it to chicken, it makes it more chickeny and so on. Of course, if you use too much of it, like with salt, it will start to provide too much of its own flavor. Sometimes, in some dishes (like Steak au poivre) the actual flavor of the pepper is what you are going for. But in general, black pepper is an indispensable ingredient in cooking. Watch a cooking show or two. You'll notice they add salt and pepper to like, every single thing. That isn't to make everything taste peppery and salty. It's to make it taste good. Now, Cayenne gets its heat from Capsaicin, which is a different substance, which tastes different and works in dishes differently. Capsaicin doesn't really enhance flavors like piperine does, it is mainly a source of piquancy (spiciness) and nothing else. So, if I'm cooking any dish at all, I add pepper before it is cooked. Not tons, but the right amount to everything doesn't make things taste spicy or peppery. Cayenne, on the other hand, is just about adding spiciness to food. So yes, you would add both as needed, because each serves a different purpose. But as guy says, cooking is about trial and error. Cook the dish multiple times, and tweak it each time. If you like the taste of one over the other (or those you are serving do), then go with that. --Jayron32 04:12, 25 January 2013 (UTC)

I love Jayrons' answer. But incidentally: Steak au poivre is supposed to be made with crushed raw, green peppercorns and not with the ground up remains of dried black peppercorns. That makes a big difference to the flavor - and also to the texture. SteveBaker (talk) 14:12, 25 January 2013 (UTC)

I think that's likely to be one of those "my grandma makes it different than your grandma" issues (of course, not many grandmas make steak au poivre, but I digress). There's likely no "official" stance on the type of peppercorns used, but I've not heard that the "true" steak-au-poivre requires green and not black peppercorns. Some variations maybe do, but others do not. I've googled a half dozen different recipes for it, and I can't find any that require that particular stricture. Most just call for fresh cracked black peppercorns. A few of the more snooty ones recommend mortar-and-pestle treatment, but that's about it. --Jayron32 14:19, 25 January 2013 (UTC)

You fancy-schmancy Wikipedia types with your "reliable sources" and your "looking it up". In my day we just pulled an answer out of a hat, and if anybody said we were wrong we called him a Nazi Pedophile Bed-wetter and made fun of his spelling. Young whippersnappers have no appreciation for the old ways -- now get off my lawn! --Guy Macon (talk) 18:35, 25 January 2013 (UTC)

Like. Best. Answer. Ever. --Jayron32 22:41, 25 January 2013 (UTC)

You had hats? You softies. Wait'll I tell you where we had to pull our answers out of. Gzuckier (talk)

Why do we cry?

Why do human shed tears when in distress? Do any other animals also do so? --Yashowardhani (talk) 06:26, 25 January 2013 (UTC)

Have you read the Wikipedia article titled Crying? --Jayron32 06:50, 25 January 2013 (UTC)

(Wow! That's a great read!) SteveBaker (talk) 14:05, 25 January 2013 (UTC)

See also, Crying, which can induce crying. μηδείς (talk) 19:46, 25 January 2013 (UTC)

My unWikipediable opinion is that the biochemical arguments (release of toxins or hormones or whatever) mentioned in the article aren't sustainable in the face of questions re evolution (why don't other animals need to get rid of their toxins and hormones) and physiology (there are plenty of more efficient ways in which the body gets rid of stuff without needing a few ml of not very concentrated tears). My guess would be a byproduct of our neoteny/paedomorphism; our retention of infantile characteristics into adulthood, a typical way in which mammals (at least, maybe other animals too) evolve reduced aggression and increased social cohesiveness past puberty, and a characteristic well documented in our particular species of ape. In that view, the crying and the attendant concern, assistance, and/or reduction in aggression from other humans is a retention of the similar reaction humans have to a crying baby, which is of obvious evolutionary value. Now that you've made me think about it, I'm going to have to see if there are any citable third party refs that have similar ideas that I can cite in the crying article..... Gzuckier (talk) 07:06, 26 January 2013 (UTC)

Prenates and Being Alive

scientific answers have been addressed, and this has degenerated into debate
The following discussion has been closed. Please do not modify it.
Do prenates (zygotes, embryos, and fetuses) meet all of the seven characteristics of life? In regards to homeostasis, aren't embryos before implantation able to survive in a petri dish (without using anyone else's body to sustain themselves)? In regards to reproduction, can't zygotes reproduce asexually by division for 14 days or something like that? Thank you very much, and please provide sources if you are able to. Futurist110 (talk) 08:44, 25 January 2013 (UTC) Just a note that "able to reproduce" is a tricky one to apply. Neonates cannot reproduce, nor can infertile adults or woman past menopausal age, but we classify all of these as alive. 86.163.209.18 (talk) 10:24, 25 January 2013 (UTC) Life is not an absolute well defined thing any more than a table or the colour blue is. However by most definitions such cells are alive. I don't know what your particular list of seven features to look out for is but for any such lists you'll have people pointing out fairly obvious things that should be included and others which shouldn't - but they are normally for things like viruses or memes or cells that have been frozen. Try giving a good complete definition of a table first and see if you can do it in 100 words or less without finding exceptions. Dmcq (talk) 10:38, 25 January 2013 (UTC) Just because a zygote is able to survive in a petri dish dose not mean it's capable of homoeostatic regulation, as temperature, humidity and atmosphere are all controlled, or it would last very short indeed. As for asexual reproduction, the only thing that sort of comes close is the formation of monozygotic twins, which occurs at the fertilised oocyte stage, not later. And I second Dmcq, what is your particular list, and why is it better than anybody else's? Fgf10 (talk) 10:42, 25 January 2013 (UTC) By the same token, a neonate left in a bed by itself will not survive for very long, nor would any of your body cells even though they are alive. I imagine Futurist is working from the standard "seven signs of life" taught in schools, often summarised by "Mrs Gren", which I would expect anyone who has studied biology to have learnt and examined before learning its weaknesses and issues, just as Futurist is doing. 86.163.209.18 (talk) 12:59, 25 January 2013 (UTC) Do you mean the The Seven Pillars of Life? If so, it's a fairly recent conception. There are other seven signs of life I find out there, but from what I can tell, they aren't covered anywhere on wikipedia which IMO tells you how much significance they have to real world biology. I did biology in university, but never learnt any 'seven signs of life' that I recall (most of these 'seven signs of life' I find seem to be targeted as secondary school level biology which I also did but don't recall learning it there either). Nil Einne (talk) 13:11, 25 January 2013 (UTC) No, that appears to be about some recent author's invented terms and categorisation. "MRS GREN" has been taught in both primary and secondary schools for at least several decades, and unpicking it and uncovering its weaknesses is a common way of getting secondary school pupils to think analytically about categories and empirical evidence. 86.163.209.18 (talk) 14:54, 25 January 2013 (UTC) Some primary and secondary schools sure. It's definitely not a universal thing as your reply suggested. Nil Einne (talk) 17:45, 25 January 2013 (UTC) Likewise, I've never heard of this, and I'm a biomedical researcher. Probably an American thing that never made it across the pond. Don't assume everybody is taught the same thing as you are, especially not when it's something as meaningless as that. And use of a slightly less condescending tone would be appreciated. Now on the science front, I was not debating the definition of life, but of homoeostasis. A cell of my body is not able to maintain homoeostasis, not is a neonate capable of full homoeostasis, as it is limited in thermoregulation. Fgf10 (talk) 14:59, 25 January 2013 (UTC) Nope, not a speck of American. If you read condecension into my tone, it was probably my annoyance at your comment sounding quite hostile ("why is it better than anyone else's") to someone who was asking a typical question that fits with an extremely common list taught to children, indicating that you were probably being snippy to a teenager asking a scientifically curious question that was completely appropriate to their stage in education. If you had googled their terms, you would probably have found some likely looking lists, and the clues that this is something taught to children at a certain stage in their education. 86.163.209.18 (talk) 15:05, 25 January 2013 (UTC) I was meant calling it by some corny name like "The pillars of life", not of the phenomena themselves, which (although as flawed a definition as there are), are know quite widely indeed. Fgf10 (talk) 15:19, 25 January 2013 (UTC) There are some things in science that do not have precise definitions because they are inherently "fuzzy" - and "life" is one of them. "Planet" is another word like that - hence the arguments over whether Pluto is a planet - which has nothing whatever to do with Pluto - and everything to do with the effort to apply a sharp division to a continuous range of phenomena. At some age, if you remove a foetus from the womb, it'll die instantly without a lot of intervention. A little later and it'll survive for a few minutes, later still, a few hours. When a baby is born at term, it'll survive for maybe a day without food and attention. When you're 40 years old, you'll still die after a few days to a week without water and after a month or so without food. There is no hard line that defines when an organism is independently alive because we all need support systems of one kind or another. We know that a rock is definitely not alive - and that an adult human definitely is - but there are just so many grey areas in between that no one set of rules can possibly draw that sharp line that you're looking for here. These "seven signs" lists (and many, many other efforts to define "life") work reasonably well when applied to an entire class of objects. Take, for example "Reproduction": We know that humans (as a group) can reproduce - so humans are generally considered to be "alive". However, I know quite a few people who can't reproduce - they are too old, or have had irreversible surgery to prevent them from reproducing. These people don't pass the "Reproduction" test - but we consider them to be "alive" because they belong to a general class of "alive" objects..."Humans". Doing the same thing for viruses is really tough - and so it's becoming for so-called "a-life" (artificial life made inside a computer) - or various efforts to make artificial cells in the laboratory. At these fuzzy grey boundaries, this word is utterly arbitrary and using it to drive some kind of hard binary decision is fraught with difficulties. Hence the abortion debate here in the US - which (from a scientific perspective) is a completely fatuous argument because it is entirely about the meaning of a word that has no meaning in this realm of existence. So there is no answer to the OP's question - nor should there be. The best response is to un-ask the question: "The word 'life' has no meaning at these levels of existence"...and I think that's the best answer you'll get here today. SteveBaker (talk) 13:58, 25 January 2013 (UTC) To take SteveBaker's excellent analysis of the situation and add to it a bit; at best we have a definition for LIFE, in the sense of the entire system; we have a good concept of what the entire living system is and how it works, even the "edge cases" that SteveBaker notes above clearly fit into the "Life" classification; viruses, for example, did not arise on earth via geologic processes; they are part of the "living system" and are integrated into it. Absent the same system that created you and me, viruses would not exist. The problems come with coming up with any sub-classification of life that doesn't apply to the whole system. Once you try to define what it means for some part of the system to be a "living thing" you run into all sorts of problems. Even groupings of life run into the Species problem, concepts like ring species throw what should be the simplest classification concept (what is a species?) into a tizzy. The virus problem is itself another definition issue (are viruses alive and are viruses life are different questions, and possibly get different answers), as is the "when is a fetus alive" question. The answer is there is no absolute meaningful line that can be drawn which is beyond dispute. Any definition will defy consistency. Which isn't to say that any moral, ethical, or legal questions which arise are somehow invalid, but it does mean that people need to look for somewhere other than the scientific answers for resolving the moral, ethical, or legal conundrums surrounding the issues of what life is. --Jayron32 14:15, 25 January 2013 (UTC) Woah woah woah, surely nobody argues that a foetus isn't alive. All the cells in your body are alive. A foetus is definitely alive, just as it is definitely human. The debate on a reasonable level is whether it is an independently living being, and whether it is a person. Nobody would dispute that the cells in your heart are both alive and human (barring an interspecies transplant), but obviously your heart is not an independent living thing, nor is it a person. A neonate is generally considered not only alive and human, but an independent living thing and a person. The debate is at what point between "egg and sperm" and "human being doing algebra" you consider the living cells to become a separate human person. The "is a foetus alive?" thing is very much just a "discover the limits of definitions of life" task. 86.163.209.18 (talk) 14:50, 25 January 2013 (UTC) That's pretty much what Steve and I both said in different words. When someone asks "is a fetus alive", or "is a virus alive" or something similar the double question implied, but unasked, is "what is alive". Even the notion of "independent life" depends on a given definition of "independent". Another unasked question inherent in these sorts of discussions is "when is it morally OK to end life", and people often try to skirt the tough answer by establishing thick black lines where they can carefully say "well, that's not really alive, so it's not even a moral question, it's a scientific one". On the contrary, there isn't a good black line we can draw for a fetus where we can say "at this point in time, it is worthy of the same treatment as an adult human, but before this moment, it isn't any different than a fingernail clipping or any other discardable living tissue" That line does not exist, and the moral dilemmas about what sorts of "life" is accorded what sorts of "rights" is simply not a question one can answer by looking for hard-and-fast "scientific" definitions. It's the sort of thing that individuals and societies need to constantly wrestle with, and you can't shortcut the hard moral problem by looking to "Science" to provide convenient easily definable boundaries. --Jayron32 14:58, 25 January 2013 (UTC) Right - and for the abortion debate, the rational science-based solution is to recognize that this is not a black and white situation with 'bright line' definitions - and instead say that the circumstances for allowing an abortion should narrow progressively starting from conception (when it should be ridiculously easy) to the last trimester or so (when it should obviously be illegal). A gradual scale where it would require more and more extenuating circumstances and increasing levels of oversight to allow it would permit a rational balance between the rights of the unborn and the needs of the mother - and a kind of infinitely adjustable scale that could be adapted as new science and the needs of society are updated over time. But here in the USA that kind of debate is impossible because both sides are in entrenched positions and dare not give up an inch of ground. If we had such a sliding scale, the stakes for each small update to it would be much smaller - so debate would be less partisan - and without the demand for an impossible "bright line" answer, science could provide rational input to the decision process. SteveBaker (talk) 16:35, 25 January 2013 (UTC) I don't think there should be any doubt that zygotes are alive, and if they don't meet every aspect of a definition, that casts doubt on the definition. Certainly anyone at an in vitro fertilization clinic would make a huge distinction between a live zygote and a dead zygote; put it that way. However, even a live human may not be alive in terms of consciousness, and thus in the legal sense, as evidenced by brain death. But people still are very careful to preserve the life of organs taken from a brain dead donor. I dislike these definitions of life for many reasons, not the least of which is that they seem to make it harder rather than easier to reason through simple exercises like this. Wnt (talk) 16:24, 25 January 2013 (UTC) The problem with these "fuzzy-reality/bright-line-words" problems ("Is a foetus alive?", "Is Pluto a planet?", "Is my cat intelligent?") is that they aren't matters of science. The science of these things can often be perfectly well understood - but we're stuck with problems that are purely linguistic in nature. That's often OK - there are branches of science where we only care about the 'aliveness' of rocks and of people - and the word "life" is perfectly well-defined and understood. But when it comes to asking "Is Pluto a planet?" - then we can't answer and we should not attempt to do so. The correct response to that question (and to to this one) is "Why do you care?" - and generally, the reply to that is what enables us to come up with a rational response. In the Pluto question - perhaps some university "Department of planetary studies" needs to know whether they are allowed to spend money studying that particular rock? Maybe a museum is putting together a model of the solar system to hang from the ceiling and needs to know whether to include Pluto or not? The answer to those questions shouldn't hinge on some bizarre and artificial description relating to circularity of orbits or Pluto's ability to clear other bodies from it's region of space! Those are ridiculous criteria for deciding those questions - yet, the "bright line" definition of "planet" that we now have has indeed been used to decide those two matters...and it's ridiculous! So the actual underlying reason for asking the question is what is important. So in this question - is the OP really asking about the appropriateness of abortion laws or something else? The answer to whether some arbitary definition of a word in the English language applies or not tells you nothing whatever about the answer to the actual scientific or moral problem that the OP is trying to resolve. So we should find out what is really being asked and - if it is a scientific matter - endeavor answer that question instead. SteveBaker (talk) 16:52, 25 January 2013 (UTC) This got me thinking: how many mothers who are contemplating abortion would go through with it after they watched a 20 min video of those new hd ultrasounds of their fetus? I'll bet the mom would say "that's alive" after watching it.165.212.189.187 (talk) 17:44, 25 January 2013 (UTC) Whether we consider this complex decision-making issue from the legal standpoint, or from the scientific standpoint, or from the moral standpoint; establishing "alive-ness" is neither necessary nor sufficient for basing a decision. Furthermore, watching a video of something doesn't even establish "alive-ness." (Did you read any of the discussion above about how subtle the definition is, and how difficult to pin down it can be in certain circumstances?) Nimur (talk) 18:50, 25 January 2013 (UTC) Tell that to every person who ever saw one of these videos.165.212.189.187 (talk) 19:22, 25 January 2013 (UTC) The emotion reactions of a person who is pumped full of mood-altering hormones when faced with an image with many parameters that were chosen by an engineer is a poor basis for making public policy decisions. And your use of the term "alive" just highlights the fuzziness everyone is talking about. I had a kidney removed a few years ago. I saw an ultrasound of it first. I would say that it was alive. I would also say that it was human (not a human, but definitely a human kidney). And, assuming a some reasonable advances in cloning technology, it had the definite potential to become an adult human being. And, of course, the elephant in the room is that some people, for religious reasons, believe that there is a bright line and no fuzziness at all. --Guy Macon (talk) 19:03, 25 January 2013 (UTC) You might want to investigate the more relevant concepts of person and organism next time you are bothered by the notion of murdering your kidney. Rather a bright line there. μηδείς (talk) 19:19, 25 January 2013 (UTC) I am not trying to load my question. I am simply adding to the thought process. If you can get the mother to watch that and still choose to do it she would not be fit to be a mother anyway, if she was swayed by it to have it, surely no one would make her get an abortion. Guy, you obviously never saw a video of what i described, or you surely would not compare it to a fetus, wow. should we feel sorry for your kidney that it didn't get a chance to be colonized into a baby?165.212.189.187 (talk) 19:16, 25 January 2013 (UTC) At this time, it is clear that 165.212.189.187 is not requesting a science reference, and is seeking to start a debate. Please feel free to find an alternative internet forum to discuss this issue, which is very nuanced. The Wikipedia Science Reference Desk is not the correct place to have that discussion. Nimur (talk) 19:37, 25 January 2013 (UTC) No, nimur, if you read my question I am asking it is purely scientific: how many mothers after watching the video would still get an abortion? Hypotheticals are asked all the time here. Anyone?165.212.189.187 (talk) 19:49, 25 January 2013 (UTC) Closed per Baker, Nimur, myself. μηδείς (talk) 20:15, 25 January 2013 (UTC) I disagree with closing this. Perhaps a few people veered slightly off topic, but the scientific question about the definition of life is perfectly valid. More sources (or at least wikilinks) per paragraph might help defuse things. Wnt (talk) 23:15, 25 January 2013 (UTC) Closure doesn't imply a problem with the responses, just with continuation of debate. Your position on medical issues is well known. If you want this re-opened, open a discussion at the talk page. μηδείς (talk) 23:23, 25 January 2013 (UTC) Agree fully with the closure. As soon as I saw the "not be fit to be a mother" comment I realized that this was not a science question. --Guy Macon (talk) 23:28, 25 January 2013 (UTC) The person who said that was 165.212.189.187. The OP was Futurist. Just saying. --140.180.242.224 (talk) 23:54, 25 January 2013 (UTC) like I said scientific — Preceding unsigned comment added by GeeBIGS (talk • contribs) 00:13, 26 January 2013 (UTC) and hereGeeBIGS (talk) 00:15, 26 January 2013 (UTC) the ultimate point of my argument is that the mother can be the compass for finding that thin line that everyone is talking about. It is such a delicate subject that who better than "where the rubber meets the road" to guide the less informed and ignorant nonpregnant talkers.GeeBIGS (talk) 00:23, 26 January 2013 (UTC)

Poor eyesight and the black death

I remember reading somewhere on the internet that the reason there are so many short sighted people around, despite the obvious evolutionary disadvantage, is that whatever genes contribute to shortsightedness, also make one less likely to die from certain diseases (I thinkt he black death was referenced, not sure though). I can't remember where I came across this I can't find anything to support this idea in a google search now. Is there anything to this idea? — Preceding unsigned comment added by 89.101.203.150 (talk) 20:24, 25 January 2013 (UTC)

Shortsightedness has been attributed to the rise of farming (as opposed to hunting) and its prevalence in the Chinese with an old farming civilization been given as evidence. I've never heard anything about black death genes, but the plague did hit denser farming societies worse, so perhaps there's a correlation, if not a cause. μηδείς (talk) 20:33, 25 January 2013 (UTC)

Our article is surprisingly disappointing on the origin question, both about individual and population genetics. If anyone has some sourced info on this I'd be very interested as well. Shadowjams (talk) 05:24, 26 January 2013 (UTC)

Maybe if you're nearsighted you're more efficient at picking the infected fleas off your body.Gzuckier (talk) 07:11, 26 January 2013 (UTC)

I don't see how farming could give rise to shortsightedness; what I heard (though I don't have any references I'm afraid) was that it is a consequence of reading and writing and perhaps a generally indoor lifestyle.--Shantavira|^{feed me} 09:58, 26 January 2013 (UTC)

The argument was not that farming causes poor eyesight, but that it allows people who, if they would otherwise be poor hunter-gatherers, to survive by farming. μηδείς (talk) 18:55, 26 January 2013 (UTC)

Recent research would suggest that a lack of sunlight is a cause of myopia. However, reading the CNN article, I don't see much evidence that the correlation with sunlight exposure is stronger than with the amount of near work (reading). Specifically, they find more myopia in highly urbanized, academically focused regions, but they didn't find differences between Scandinavian and Southern Europe regions. If they find correlation with being "academically focused" and based on that assume a (reverse) correlation with the amount of time spent outside, yet they don't find a correlation with the amount of sunlight available, then why propose a relation with exposure to sunlight anyway?? Remarkable that we haven't got a more definite theory yet for such a widespread condition. Is it perhaps because any "cure" would likely have detrimental effects? Can't imagine a policy recommending allowable daily intake levels for books... Ssscienccce (talk) 11:15, 26 January 2013 (UTC)

Tidal locking planets

Why are there many tidally locked moons in our solar system, but no planets tidally locked to the sun? Tarcil (talk) 20:26, 25 January 2013 (UTC)

Have you read about Mercury's spin-orbit resonance? Nimur (talk) 20:28, 25 January 2013 (UTC)

Thanks ... But it looks like it is only Mercury, and only partially. Why so rare compared with moon tidal locking? Tarcil (talk) 21:54, 25 January 2013 (UTC)

I was going to speculate that the gravitational gradient is smaller in the case of the planets, because the planets are so much smaller than the sun, but then I thought about Deimos... --Guy Macon (talk) 22:03, 25 January 2013 (UTC)

how dare you speculateGeeBIGS (talk) 00:29, 26 January 2013 (UTC)

I would guess that it's because the planets are much farther away from the sun than moons are from their planets, so that the sun exerts a lower gravitational acceleration on the planets than the planets do on their moons. Taking orbital period as a measure of the gravitational acceleration seems to bear this out. In the List of gravitationally rounded objects of the Solar System, the planet with the shortest orbital period is Mercury, with ~88 days. The moon with the longest orbital period is Callisto, with ~17 days Iapetus, with ~79 days, and all the moons listed are tidally locked.--Wikimedes (talk) 03:54, 26 January 2013 (UTC)

Tidal_locking#Moons says about the same thing.--Wikimedes (talk) 05:18, 26 January 2013 (UTC)

Cool, thanks - Tarcil (talk) 03:35, 28 January 2013 (UTC)

The number that counts is the diameter of the satellite multiplied by the mass of the primary divided by the cube of the distance from the primary. —Tamfang (talk) 01:37, 22 September 2013 (UTC)

Can insects get angry?

Topic says it all. ScienceApe (talk) 20:48, 25 January 2013 (UTC)

"Anger" describes an emotion, but it seems all that we can observe from insects is behavior, especially since their manner of communication and expression is so different from our own that it's hard to draw parallels. However, here is an article describing attempts to detect emotions in bees. Insects can certainly become aggressive, but that doesn't necessarily imply anger, like we can't deduce from a bee's 'dance' that she is happy. - Lindert (talk) 21:04, 25 January 2013 (UTC)

What's the practical difference between emotion and behavior? Doesn't emotion just promote a certain kind of behavior? ScienceApe (talk) 00:41, 26 January 2013 (UTC)

There's a huge difference. You can have an internal emotional sensation, but that internal process is not required to cause a specific course of action. A person may get angry and yell, or punch someone, or may in fact do nothing; but their actions are not directly tied to that emotion. A person may show no outward signs of an emotional response, but it doesn't mean they didn't have it. --Jayron32 01:20, 26 January 2013 (UTC)

That's the basic difference between a feeling and an emotion. Feelings that are expressed are emotions. Feelings that are unexpressed are just feelings. (I always laugh when I'm told someone was "visibly emotional"). There's one school of thought that it's impossible not to express a feeling, even if it's virtually entirely internalised. Highly skilled observers say they can always detect a feeling, because the energy required to suppress its expression is apparent in other ways, however minuscule. Then it's down to the visual acuity of the observer, and their knowing what to look for. -- Jack of Oz ^[Talk] 22:15, 26 January 2013 (UTC)

I am not aware of this distinction. Could it be an Australian thing? I'm fairly certain there is no such distinction in American English, and the Wiktionary entry doesn't mention it. --Trovatore (talk) 22:22, 26 January 2013 (UTC)

Think of it this way: If you're talking on the phone to someone who's describing their emotional state, all you know is what they say and the tone of voice they use. They might say "I feel angry that abc happened"; they'll never talk in terms of "emotions". Now, observe someone who's clearly angry; you know this by the lack of calmness in their actions. This exhibition is the emotion, and that's why people say someone was "visibly emotional" (all they really need say is they're "emotional"); observers never report on the "feelings" of emotionally distressed people, only on what they can see, i.e. their emotions. What they're feeling internally is the feeling that caused them to act this way. If you want a reference, this is as good as any.-- Jack of Oz ^[Talk] 06:49, 27 January 2013 (UTC)

Well, honestly I don't find any coherent assertion in that reference, but whatever distinction they're making, it does not appear to be the same as yours. Yours at least makes sense, though I don't agree with it. Theirs, as far as I can tell, doesn't.

In any case, our article does not use the word in your sense. It says explicitly that emotion is a subjective experience. --Trovatore (talk) 10:34, 27 January 2013 (UTC)

can chimps get angry? Can humans get angry?GeeBIGS (talk) 01:00, 26 January 2013 (UTC)

I think the key word you should check out is "Anthropomorphism". ~:74.60.29.141 (talk) 03:00, 26 January 2013 (UTC)

If you check out emotion which mentions non human animals a few times, you'll find we also have an article on Emotion in animals which doesn't mention insects but primates. Nil Einne (talk) 03:32, 26 January 2013 (UTC)

I think we can answer this with a definite "No!", I don't think it's possible that they could have an exactly comparable emotion. Our article on anger says that the defining characteristics of anger in humans is raised blood pressure and the release of adrenaline and noradrenaline. Insects don't have blood (they have hemolymph) and their circulatory system is wildly different from ours - so it's extremely unlikely that they'd get higher pressure in those systems for similar reasons - or that it would feel the same to them as high blood pressure does to us if they did. Worse still, as far as I can tell from cursory research, insects produce neither adrenaline or noradrenaline - and they don't seem to have any analogous hormones. So really, they can't possibly feel what we do. Obviously there may be some analogous "fight or flight" reflex - but it would be a massive stretch to assume that they'd feel it the same way we do when it happens because all of the responses in humans cannot possibly happen in insects. SteveBaker (talk) 05:35, 26 January 2013 (UTC)

Whilst agreeing with the accuracy of answers by Steve and others above, anyone who has disturbed a nest of bees, wasps, hornets (etc) cannot help but observe that the aggressive defensive behaviour of these insects certainly makes humans feel that the insects are angry! Dbfirs 08:32, 26 January 2013 (UTC)

It has been established for considerable time that the emotions, especially anger, arise from and are behavior modes set by a part of the brain that arose early in evolutionary terms. According to my dictionary, anger means hot dipleasure; often invoving a desire for relaliation; inflamed; irritated; excited with anger; of threatening aspect. That certainly describes those bees etc Dfiers mentioned. There's nothing in this definition that requires self awareness or behaviour that is not instinctive. It also describes exactly a species of ants that live in my back yard, when I poke at stick into their nest entrance. Being ants, I'm certain that they don't have self-awareness like higher mammals and humans, but they certainly do get angry. They normally don't bite if you stand gently within 100 mm of the nest entrance, but if you poke a stick in their nest entrance, they'll search outwards 500 mm or more and they will bite. Further, W Grey Walter (British neuroscientist - see http://en.wikipedia.org/wiki/Grey_Walter) showed 60 years ago that a robot brain showing stimulus-triggered emotions can be constructed with nothing more than two radio valves and a handfull of basic electronic parts. So, insects have well and truely sufficient neurons to do the job. Of course they get angry. Ratbone 124.182.17.177 (talk) 10:54, 26 January 2013 (UTC)

You maybe don't need self-awareness to have emotions, but you do at least need phenomenal consciousness, aka qualia. Attributing "emotions" to a couple of vacuum tubes strikes me as a deliberately reductive redefinition of the word. --Trovatore (talk) 22:04, 26 January 2013 (UTC)

Bees (like most creatures) are programmed to defend themselves and their groups. We can't ever know what's in the mind of a creature so far removed from the human creature. We associate their buzzing with "anger" - but their buzz is simply caused by their wings. Likewise, we talk about storms as if they were living things: "angry" clouds, etc. This is how folk religions arose - anthropomorphism, as noted earlier. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:45, 26 January 2013 (UTC)

I don't agree that "We can't ever know what's in the mind of a creature so far removed". If we do brain scans on angry people, and see what parts of the brain are active, then do a scan of "angry" bees, and see the same spots are active, this is a good indication of a similar process. StuRat (talk) 17:58, 26 January 2013 (UTC)

Um, "brain scans" of bees and "same spots active" as in people makes no sense. Bees don't have a central nervous system that has any major analogous parts to humans in any way. You might as well try to figure out if humans can fly by examining the structure of human wings, or try to figure our how humans use their antennae. --Jayron32 18:08, 26 January 2013 (UTC)

Don't they have brain stem, at least ? They must have visual, audio, and smell/taste/touch processing areas, too. StuRat (talk) 23:09, 26 January 2013 (UTC)

See http://insects.about.com/od/morphology/f/Do-Insects-Have-Brains.htm Richerman (talk) 23:35, 26 January 2013 (UTC)

For study of insect brains, it can be more convenient to observe activity in visible wavelengths using a dye for calcium imaging. See [1]. For a comparison of insect and vertebrate CNS development, see [2]. (For that matter, anything in [3] is bound to make good reading!) Wnt (talk) 00:14, 27 January 2013 (UTC)

This is a pretty interesting topic. The spinal cord and a bit of the brainstem can be matched between insects and vertebrates on the basis of gene expression patterns. For higher brain areas the picture is more complicated. Recently, though, there has been a plausible claim that a structure in the insect brain called the mushroom bodies is homologous to the cerebral cortex of mammals. But none of this would be helpful in assigning emotional states to insects. Looie496 (talk) 01:20, 27 January 2013 (UTC)

Tracking the limbic system among vertebrates was apparently no simple task.[4] I'm having quite some difficulty finding a paper willing to mark the spot on the bee brain that corresponds. My gut feeling is that there is such a spot... Wnt (talk) 19:12, 27 January 2013 (UTC)

Danceable pulsars

Where can I find information on individual pulsars with a period between 0.45 and 0.55 seconds? Better would be audio recording of clicks from such a pulsar. Really awesome would be a live feed of those clicks. Thank you! Rotcaeroib (talk) 22:35, 25 January 2013 (UTC)

The nearest I can find for you is PSR J0357+3205 which pulses with a period of 444.10 ms (ref). You won't get a live feed, because someone would have to be pointing a radio telescope right at one just when you need it, and they'd surely want to be pointing their radio telescope at other things instead. To get an idea of the actual signal that comes from such a pulsar, see the plot on p24 of this paper. That's not a playable audio waveform in itself - you'd need either to use it to modulate a tone or, with a level trigger, as a MIDI event gate. To get the actual raw signal received from a given pulsar, you may have to contact the research groups using an instrument like Fermi Gamma-ray Space Telescope and see what they have. -- Finlay McWalterჷTalk 01:00, 26 January 2013 (UTC)

Some pulsars outside of your chosen rangfe seem danceable...

http://www.youtube.com/watch?v=uHEVo-LkDrQ

http://www.youtube.com/watch?v=gb0P6x_xDEU

http://www.youtube.com/watch?v=ZHv_eE2bvSs

http://www.youtube.com/watch?v=HSyRMotOhoM

http://www.astrosurf.com/luxorion/audiofiles-pulsar.htm

http://www.astro.cornell.edu/~deneva/psr_sounds/pulsars_sounds.htm

http://www.radiosky.com/rspplsr.html

--Guy Macon (talk) 08:49, 26 January 2013 (UTC)

If you're interested in danceable astronomy, you may want to check out this. A fascinating lecture which I was lucky enough to attend "live" (one of the few benefits of living in Waterloo is the close proximity of the Perimeter Institute). Matt Deres (talk) 15:54, 26 January 2013 (UTC)

This is a pulsar catalog, and is as complete as you're likely to get. You can filter by period (p0 > 0.45 && p0 < 0.55), and see exactly what data is available for each pulsar. There seems to be around 200 pulsars that fit your criteria. --140.180.242.224 (talk) 19:10, 26 January 2013 (UTC)

Wonderful answers. Thank you! Rotcaeroib (talk) 17:20, 28 January 2013 (UTC)