Wikipedia:Reference desk/Archives/Science/2015 December 21

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December 21

Vitiligo

In reference to the condition Vitiligo. My understanding is that it effects the pigmentation of the skin. Does this differ by race? More specifically, would the affected skin of a Caucasian person turn black, while that of an African American turn whiter?

Thank you for your assistance. I am new to Wikipedia and I hope that I am using this forum correctly.

David L Boca Raton, Florida — Preceding unsigned comment added by 99.10.176.177 (talk) 04:03, 21 December 2015 (UTC)

See our article Vitiligo. The condition is a partial lack of pigmentation. As such it results in a lightening of the skin. The article contains pictures of both black and white sufferers. Rojomoke (talk) 05:48, 21 December 2015 (UTC)

But note that the lighter the rest of the skin, the less noticeable it will be. StuRat (talk) 08:07, 21 December 2015 (UTC)

Does libration cause tidal effects ?

...such as tides in liquid, and tidal heating in rock ? StuRat (talk) 08:06, 21 December 2015 (UTC)

To use the terminology exactly: gravity is a first order effect; tides are a second order effect; any additional complication is a third-order effect at best. We use these terms precisely in physics to mean the size of the effect is an order of magnitude smaller - usually as an exponent in a polynomial expansion of the governing equation. In the case of the equation for the tidal force, we're specifically referring to the polynomial exponent on the radial distance between the two objects. After a certain point - usually, the third order - we're talking about very tiny perturbations. It would be nonsense to deny that such effects exist, but for nearly any practical purpose, your calculation cannot be made accurate enough for these effects to matter. For example even if you were flying a spacecraft to the moon, you would not use these perturbations as part of your gravity model to calculate spacecraft trajectory. You would instead probably use a gravity anomaly map, because effects of the nonhomogeneous large-scale mineral distribution inside Earth has a much more significant effect on the spacecraft orbit. Alternately, you might just use a specialized RADAR to navigate by way of closed-loop feedback control systems, as Project Apollo did. In other words, engineering considerations trump the pure physics - which is so commonplace in so many problem-domains that physicists have specific terminology to refer to "dropping the higher order effects."

Put another way: do you have a use-case where you are able to (or need to) accurately calculate the gravitational anomaly of the Earth-Moon system with sufficient precision that you can actually account for these perturbations in the Earth-Moon distance? Our computers are great and powerful; our equations can be made arbitrarily complex; but why should we do these calculations, except for the fun of them? And if you enjoy recreational mathematics - as many of us do - then maybe you would agree that high-order expansions of the n-body problem are less fun than other, more interesting areas of pure or applied mathematics?

Here is a free, web-based treatment of libration, without complicated equations, from NASA Goddard: Librations of the Moon. I don't have either of the books referenced by that website; but I do have many others; in Moon, (Wilkins and Moore, 1955) uses one significant figure only in describing the libration; and he bases his discussion of the librated areas surface on the 300 inch map. Point is, you're using false precision if you think you can calculate better than the most accurate studies ever made by Earth-based observers.

Here is A numerically integrated ephemeris of the moon and planets spanning forty-four centuries (1983), with full text available. In this paper, the authors (from JPL) discuss tidal deformations. They also show that their numerical error with respect to lunar range is about one meter in ten years - so their math worked great when compared against Apollo lunar laser ranging data over the ... ten years that it had been available.

Nimur (talk) 16:53, 21 December 2015 (UTC)

So you're essentially saying 'yes, libration of the moon influences tidal effects, but the impact is negligible for even very high precision applied engineering problems in space flight.' Is that right? SemanticMantis (talk) 17:56, 21 December 2015 (UTC)

Libration is an effect - it is a symptom of the imperfections of the simplistic model of the orbit as observed on Earth. These extra complications to model that effect are of negligible importance for most high-precision astrophysical tasks. For example, if you wanted to write an equation to calculate the differential tidal force due to the diurnal libration (in other words, the error in the tidal force equation caused by the rotation of the Earth) - that effect would be very small. The tidal force equation already accounts for the fact that Earth is not a point-particle; so you'd essentially be looking for the additional effect due to the fact that it is a non-point-particle whose axis of rotation is not identically parallel to the lunar orbital plane. The effect would be tiny, and the equation to model it would be significantly more awful than the standard form of the tidal force equation (which itself is already an approximation, using a truncated expansion of a higher-order equation). Nimur (talk) 18:25, 21 December 2015 (UTC)

So... 'Yes' is your answer to my question of clarification? SemanticMantis (talk) 19:23, 21 December 2015 (UTC)

I'm not trying to be obtuse; I want to answer you correctly, and a "yes/no" is not a great way to answer the question correctly. To directly answer your query, "is that right?" - I think I have to respond "no, that is not right." Perhaps I have not clearly explained my case.

Libration is not a cause of anything: it is a visible effect of the orbit. That effect is basically broken in to three sub-effects superimposed on top of each other (as explained in our article):

• longitudinal libration: this is an effect of the elliptical (rather than circular) orbit of the moon. The radial distance to the moon does affect the tidal force; the elliptical orbit causes a different radial distance. I would not phrase this to say libration causes tidal variation. Rather, I would say elliptical orbits cause visible effects, including a small contribution to the visible libration of the Moon. The difference in strength of tides between perigee and apogee is described in our main tide article, §lunar altitude; however, this effect is less relevant than the effect of the solar tide (§springs and neaps). The effect is also significantly less relevant than geographical resonances. In other words, if you want to account for this orbital effect, you must already be accounting for many other more significant non-orbital effects.
• latitudinal libration: this effect is due to the inclination of Moon's axis of rotation with respect to the plane of its orbit. It does not meaningfully change the strength of the tidal force, because the moon is a near-perfect sphere. Obviously, you can try to be more accurate, and model this effect; but it's pretty darned negligible.
• diurnal libration: this effect is one of parallax as you (riding on the surface of the Earth) move your position over the course of the day. This changes the tidal force you experience (because you are moving); but it doesn't change the equation that governs the tidal force in any meaningful way. But - because Earth is an imperfect sphere, and because our planet's rotation is not exactly mathematically purely perfectly at a constant angular velocity, there are minuscule perturbations related to this component of the motion. These effects are probably negligible.

Because the total libration is a superposition of these three different effects, and two of them have essentially no contribution to tidal force (per application of the standard equation), I think it is not generally accurate to say that lunar libration has a correspondence to lunar tides. In any of the books I pulled off my shelf to review, or in any of the websites I checked, libration is not discussed with any relation to the tides (these effects are always discussed as conceptually distinct things).

My thesis, then, can be paraphrased: libration is caused by an orbital complexity, and the effect of that complexity on the tides is negligible. Nimur (talk) 20:10, 21 December 2015 (UTC)

@StuRat: There's such a thing as a "perigean spring tide" that is a few inches greater, which occurs when the Moon is closest to Earth and also aligns with the Sun. [1] Since the libration of the Moon and its orbital eccentricity are deeply linked, perhaps this is a relevant answer. Wnt (talk) 22:43, 22 December 2015 (UTC)

Let me clarify the Q

I didn't mean to ask specifically about the Earth-Moon system, or specifically about spacecraft navigation. More generally, can a dual system where both bodies are approximately tidally locked to each other, but still undergo libration with respect to one another, undergo tidal effects such as such as tides in liquid, and tidal heating in rock ? (And here I mean tides created by the two bodies, not additional external bodies.) StuRat (talk) 20:51, 21 December 2015 (UTC)

There is always a tidal force between two bodies: it corresponds to the difference in the amount of gravitational attraction toward one body (say the Moon) experienced by different points on the other (say the Earth). Effects such as the tidal movement of the ocean, and tidal heating in rock, are caused by the change in tidal force over time. As mentioned above, third-order effects. The tidal force depends on the distance and direction of the other body (a vector). So if one body is librating then it will feel dynamic tidal effects due to the direction changing, even if the orbit is circular. If the orbit is not circular, that alone will cause some tidal effects in both bodies because the distance is changing. --76.69.45.64 (talk) 02:05, 22 December 2015 (UTC)

This sounds like a correct answer to me. If two bodies are mutually tidally locked and orbiting one another, they can still have eccentric orbits that bring them nearer and further to one another, and necessarily introducing libration to their relative orientation. As you can imagine though, the change of tidal force during a full rotation will be greater than if it shifts by ten degrees or by a few percent of its value. Even if the two planets joust past one another in a high eccentricity orbit, they still will have the same maximum tidal force as if they were in a tight circular orbit while at their closest approach in the same position; and it will still reduce to the same nothing at the furthest remove that it would be if it were simply rotated 90 degrees. I think... Wnt (talk) 22:48, 22 December 2015 (UTC)

force != energy (God grief - I wish I had a dollar ever time that confusion occurs). A static force (of any kind) does not cause a transfer of energy. So if two bodies are tidally locked, there is a tidal force - but no energy transfer - and hence no tidal heating. Only if there is some relative motion between the two bodies does the force change over time and result in a transfer of energy from orbital/rotational energy into repeated deformation of one of both of the two bodies, which in turn would turn into heat as a result of frictional forces.

Libration is a kinda vague term - our article about it describes several different modes of libration. However, at it's heart, it refers to relative motion between two bodies. If they are both tidally locked - then relative rotation is not present - but they could still vary in relative distances due to an elliptical orbit...and that would cause varying tidal forces and heating of one or both bodies. However, a highly elliptical orbit would screw up tidal locking because the speed of the orbiting body would vary throughout the orbit and the other body would not be fully tidally locked. So I think that true tidal locking requires circular orbits...but I could be wrong about that. In the specific case of our moon, the orbit isn't perfectly circular - and the moon's tidal locking isn't perfect either - it wobbles from side to side by a small amount.

• So our moon does feel tidal forces from the Earth.
• And because it has libration (it still wobbles and traverses a slightly non-circular orbit), those forces vary slightly.
• And because of that, the moon does experience some tidal heating.
• But, those effects are tiny because the libration is quite small and the tidal lock is pretty close to perfect.

IMHO, if there is libration, then there isn't perfect tidal locking...by definition.

SteveBaker (talk) 17:20, 22 December 2015 (UTC)

So then what term is used to describe a moon that "wobbles", but never completes a complete rotation WRT it's planet, if it's not "tidally locked" ? StuRat (talk) 17:53, 22 December 2015 (UTC)

What is the reverse of being tidaly locked?

What is the reverse of being tidaly locked?201.79.58.12 (talk) 15:44, 21 December 2015 (UTC)

Not being tidally locked. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:04, 21 December 2015 (UTC)

Asynchronous rotation? Some scientific magazines use this term at least: [2] — Preceding unsigned comment added by Jubilujj 2015 (talk • contribs) 19:43, 21 December 2015 (UTC)

What do you mean by "reverse"? —Tamfang (talk) 10:36, 22 December 2015 (UTC)

The other extreme. 201.79.50.148 (talk) 18:45, 22 December 2015 (UTC)

How would you describe that "other extreme"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:31, 22 December 2015 (UTC)

• Well, the OP can look at tidal locking, and orbital resonance. There's the simnple case of the Earth and the sun where there is no tidal locking, but there is a pretty linear but non-whole-number relationship between the length of our day and year, and there is the chaos of the moons of the Pluto-Charon system which leaves the four moons, Nix, Styx, Kerberos and Hydra tumbling, with no predictable period. The OP might also want to look at the difference between logical contraries and opposites. μηδείς (talk) 19:47, 22 December 2015 (UTC)

DC railway traction power supply

Why are DC railway power systems generally not earthed whilst AC is? 2A02:C7D:B91D:8000:19ED:D547:32C:A37E (talk) 16:29, 21 December 2015 (UTC)

See Railway electrification system, but I'm not sure what you mean by "earthed". There are plenty of DC systems that use a single feed conductor (catenary or third rail) with the traction current return through the track. Tevildo (talk) 19:45, 21 December 2015 (UTC)

"Earthed" is just British usage for "grounded". When the return current is through the track, the issue is whether the railway allows it to leak into the ground or attempts to keep the track electrically isolated from the ground. One issue that's specific to non-isolated DC is galvanic corrosion; I don't know if that's a sufficient answer to the question. --76.69.45.64 (talk) 02:09, 22 December 2015 (UTC)

Engineering asset management to operational management

How easy is it to move from a job in engineering asset management and project management within a public service to operational Management of a public service whether it's an ambulance service or a railroad network or a highway network? 2A02:C7D:B91D:8000:19ED:D547:32C:A37E (talk) 17:10, 21 December 2015 (UTC)

Garnier's new "micellar technology" in their makeup remover / facial cleanser

Can someone tell me what is exactly "new" or novel about Garnier's new "micellar water"? [3] I saw it as an ad for Youtube and I was so confused. Don't normal surfactants and detergents already form micelles? What is really going on here? Are they modifying the micelle-forming behavior of surfactants, perhaps making the micelles smaller or controlling their surface tension or making the surfactants branched or perhaps optimizing the ionic strength of the solution? I am so puzzled, especially in the way their ad targets women. Yanping Nora Soong (talk) 18:11, 21 December 2015 (UTC)

"Micellar water" is a rather recent marketing gimmick. It isn't just Garnier. There are many companies passing off water with a little soap as "micellar water" and reaping the profits. Soon, one of them will be smart enough to say they've removed the water and replaced it with dihydrogen monoxide for an even deeper cleansing experience. 209.149.113.52 (talk) 18:32, 21 December 2015 (UTC)

How did humans cope with pain before widespread opiate use?

Hi all. So I read an article about a failed attempt to strongly regulate Rx's of certain oft-abused opioids - Percocet, Vicodin, Oxycontin: http://www.sfgate.com/nation/article/Effort-to-cut-painkiller-prescriptions-falters-6710218.php. Then I go and look up when all of these were introduced to the market and found that Vicodin was introduced in 1984, Oxycontin in 1995, and Percocet in 1999. The news article suggests a powerful pharmaceutical lobby that discourages any new mandates on prescription practices revolving around these drugs. But the fact is, many people die from these drugs every year.

So, my question is, were humans just basically miserable before the introduction of mainstream opiate drugs? I know there was heroin, morphine, etc, but they were most likely used at a much lesser level than the prescription drugs we have now. Are users of these drugs so weak-minded as compared to those who survived without them for so many years? Why is there SUCH a demand and necessity for these that seemed less significant 30-50-80 years ago? Can't these people be happy with other drugs such as ibuprofen, acetaminophen, or etodolac?

Thanks for any and all insight. Justin15w (talk) 19:36, 21 December 2015 (UTC)

Opium has been in use for (among other things) pain relief, for thousands of years. Contact Basemetal here 19:40, 21 December 2015 (UTC)

In times gone by before the hysteria about the war on drugs etc if you were in chronic pain you'd have a syringe and a prescription for morphine. I suppose the other thing is that we now live longer so more, affluent, people are running into chronic pain. And I'll be honest, morphine for breakfast isn't as much fun as it sounds. Greglocock (talk) 19:54, 21 December 2015 (UTC)

Heroin, a morphine derivative first synthesized in 1874, was marketed by Bayer as a "non-addictive" substitute for morphine. Bayer, its fortunes based on aspirin and heroin, could be considered largely an analgesia company. Of course, they were later involved with another more infamous compound. - Nunh-huh 22:43, 21 December 2015 (UTC)

Also, pain is relative. If you never feel any, then when you get a splinter you feel like you are going to die. But if you are in constant pain, you get used to it, even without meds. For example, I have back pain so severe I could barely get out of bed this morning, but I don't take powerful pain killers, as the risks outweigh the benefits, IMHO. (For example, the pain keeps me from doing stupid things which would further injure my back, like lifting heavy objects.) StuRat (talk) 20:41, 21 December 2015 (UTC)

Yes, having been on a morphine drip for six months due to an almost fatal abdominal illness and all the surgical procedures related to it, whenever I am asked by a doctor, "On a scale from one to ten, ten being the worst, how does your broken bone feel?" I respond "one". μηδείς (talk) 21:53, 21 December 2015 (UTC)

Let us hope the question does not arise often! - Nunh-huh 22:43, 21 December 2015 (UTC)

Thanks. There was the time when I slipped on black ice and broke my left radius, and had to drive myself 15 miles at 1am to the hospital. I got to the admissions desk, put my arm on the counter, said I had broken my arm (you could see the bone just under the skin) and was told that my amateur opinion was unwelcome, and that "We are the professionals, and we will determine whether your arm is broken." μηδείς (talk) 02:07, 22 December 2015 (UTC)

Good to know you got the customary customer service :) - Nunh-huh 05:34, 22 December 2015 (UTC)

I guess the appropriate answer is "1. How do you know I am not a doctor? Is it written on my forehead? 2. Now you check if I am wrong, and then you can repeat that to my face." --Lgriot (talk) 13:54, 22 December 2015 (UTC)

The OP should look at the etymologies of opium, poppy, soma, wine and hemp, all of which are quite old terms, with Grimm's Law having affected hemp (compare cannabis from the same root) and wine, which is found in the Semitic and Kartvelian language families, as well as Greek and Latin. The provenance of these words shows they were probably Wanderwörter for prehistoric trade goods. μηδείς (talk) 02:07, 22 December 2015 (UTC)

Alcoholic beverages have been used for pain relief for millenia. Here's a 75 year old article from Time magazine. Cullen³²⁸ Let's discuss it 21:36, 21 December 2015 (UTC)

In the Hebrew scriptures (Proverbs 31:6 KJV) it says: "Give strong drink unto him that is ready to perish, and wine unto those that be of heavy hearts." Cullen³²⁸ Let's discuss it 21:44, 21 December 2015 (UTC)

Here's an abstract of a 1988 article in the medical journal Pain. Cullen³²⁸ Let's discuss it 22:26, 21 December 2015 (UTC)

People have natural opioid receptors and produce their own analgesic. The problem of addiction is similar to what happens with hormones. A male that takes testosterone artificially will stop producing it naturally. A person that takes opiates regularly will stop producing natural analgesics. My own personal experience is that using pain medication for 2-3 weeks and then stopping results in a backache. The backache isn't an injury, it's just that my body didn't need to suppress it. It lasts for a few days and the body eventually overcomes it. Serious physical addictions are quite a bit worse as actual metabolic processes are affected and "cold turkey" leads to death.. The backache is more like the psychological addictions. It only takes a few times to realize it's temporary and psychological and not really physical. An analogy is the feeling of "hunger." people that are regularly fed, even if obese, still feel compelled by hunger. However, the body is not quite as cruel as presenting the unrelenting feeling of hunger if no food is present. The feeling of hunger subsides if no food is available, the stomach shrinks and as longer as water is available the body stops pestering for food. This information is available from accounts of people that are castaways or faced with situations where food isn't as readily available. An obese person can feel hunger pangs that far exceed the hunger pangs of an undernourished person in an impoverished country. The body pesters the brain for what it can attain but it's not masochistic enough to make the person more miserable than what they can attain over time. (note: these are long term scenarios and not short term where pain can be excruciating vis a vis torture). --DHeyward (talk) 04:21, 22 December 2015 (UTC)

P.S. I would add that most opiate addictions from medical use is psychological. I read how "horrible" withdrawal is and how it can "fatal" and it's usually related to heroin users. A month ago I was admitted to hospital after a fall that tore tendons in my elbow and caused swelling diagnosed as compartment syndrome. I thought I broke my arm. The X-rays came back negative but my blood tests indicated the muscle damage was causing a condition called Rhabdomyolysis. Basically kidney failure because the kidneys couldn't keep up with dying muscle tissue. My arm hurt a lot, my kidneys didn't hurt at all but that was the real reason I was in hospital. I had choice of oxycodone every 4-6 hours or the morphine drip as part of the IV. I chose oxycodone since I knew how it affect me having taken it before. After a few weeks, oxycodone feels like "normal" and the time for a new dose feels "abnormal." My arm still hurt but after 3 weeks, natural analgesics for everything stops 9arm hurts, back hurts, knee hurts). Increasing thre dose makes those pains go away. Stopping makes those pains worse. Stopping for a week defeats the psych desire for pain relief and "normal" returns without medication. Understanding that the feeling goes away makes stopping more manageable. In my experience, theres's no such thing as long term pain management" with a constant dose of pain medication. Either the patient stops taking meds for a time to get to "mormal" with no psych addiction or physical, or the patient seeks more and more pain medication because "normal" becomes whatever they take. A person taking 60mg of oxycodone a day for a year most likely has the same pain if they detoxed and took no meds for 4-6 weeks. Day 1 through 21 sucks as everything will cause pain but at some point their body recovers and 5mg of oxycodone does just as much as 60mg. --DHeyward (talk) 04:46, 22 December 2015 (UTC)

The mechanism of action of opiates is to activate the μ-opioid receptor, rather than directly interacting with some other chemical in the body. So far as I know, that means the mechanism of addiction is always (roughly) the same. The joke is that every 20 years, a patent expires, which means that the old opiate needs to be demonized as an addictive substance, while a new "non-addictive" version is marketed. So opiates gave way to morphine; then the heroic alternative of heroin was introduced; after that it was meperidine with the same sort of claims; [I forget what's next, sorry]; then it was oxycodone. There's been a bit of evergreening with "improved" formulations for that drug, but I think we're about due for the next wonder opiate. Wnt (talk) 12:29, 22 December 2015 (UTC)

In almost every region, there are many plants which have analgesic properties - even the birch tree was used in Asia and North America long before its cousin, aspirin, was made. Collect (talk) 12:58, 22 December 2015 (UTC)

The OP might like to look at Zoopharmacognosy - self medication by animals.DrChrissy ^(talk) 13:08, 22 December 2015 (UTC)

Didn't they just "bite the bullet" (literally) in the old days? 2602:252:D13:6D70:DD24:7700:74C1:76C6 (talk) 15:36, 23 December 2015 (UTC)

That was more of a method for coping with pain during surgery (without anesthetics) than for coping with long-term pain. StuRat (talk) 15:54, 23 December 2015 (UTC)

Surgery without anaesthetics can occur in any era, but is a sign of extreme backwardness. Even in ancient times surgeons knew to use opium and nightshade, hashish, aconite, etc. to manage pain. My impression is that the demonization of "witches" harmed European medicine, as did the collapse of trade with the Near East; nonetheless, as opium was brought back by Paracelsus, there wasn't that long a period when bullets would truly need to be bitten. For example, despite common misconception of surgery without anaesthesia, the American Civil War left huge numbers of soldiers addicted to opium... Wnt (talk) 02:24, 25 December 2015 (UTC)

Are the sizes of noses becoming smaller in recent generations?

I'm aware that our ears become proportionally larger, in relation to our head, as we get older, and I assume the same is true for noses as well as it's largely cartilage.

Recently I've noticed that a lot of young people (early twenties and upwards, girls in particular) have very small noses! Yes, it's a silly question, and I suspect it's confirmation bias on my part once I started noticing. But have noses become smaller in recent years or is it just because I'm getting older and the people I know well have bigger noses because of age?

Thanks 95.146.213.181 (talk) 19:57, 21 December 2015 (UTC)

You might well be seeing the results of plastic surgery, which in some places is quite common, even for girls. See nose job. StuRat (talk) 20:36, 21 December 2015 (UTC)

WAG: Maybe they just seem smaller because people are getting fatter? Clarityfiend (talk) 03:42, 22 December 2015 (UTC)

It may also be a result of a shrinking world. Ethnic and racial features may be blending away in the area you live. A long time ago, they did studies when computer photo composites first became available. When respondents were asked to rate attractiveness, the mythical blend of a thousand faces was considered the most attractive by the sample. Another studt involving purebred dogs that were let loose in the street produced a "mutt" that was similar regardless of where the phenomenon happened. Don't know what that means but I would think that it's not odd that features would lose diversification and trend toward the "mutt" nose - whether that's larger or smaller for your particular group - I'd suggest the change is both a blend and more attractive than what you are used to. Weird, huh? --DHeyward (talk) 03:58, 22 December 2015 (UTC)

If there is indeed a change at the OP's locality. The possibility that he stipulates of confirmation bias is vastly more likely here. With respect, your response seems to suggest a lack of familiarity with the phenotypic genetics involved here. The timescale upon which phenotypes change is constrained by many factors, not the least of which is the length of a generation in the species in question, and phenotypes which are governed by sexual selection can be especially slow to change. And in this case we're not even talking about multiple generation but just the years in which the OP has been a casual observer of the relevant trends. In other words, the degree of globalization and increased mobility for certain ethnic groups is not sufficient to explain such a change according to the mechanisms you propose. Furthermore, your answer presupposes that the average global nose size is smaller than average traditional nose size in the OP's immediate vicinity (or even not in the immediate vicinity, since we can assume from the fact that the OP is using the internet to communicate with us that he has access to global media and that his observations extend to well beyond his immediate environs), and we can't possibly know what any of the actual figures are for any of those values other than (to some limited extent) the global average.

Now, if the OP were an elderly member of a very isolated community with an insular genetic population that had just in the last generation received a huge influx of outsiders from populations with notably smaller average nose morphologies, then yes, that could lead to the kind of situation you suggest. Outside that, there are much more likely explanations. But note that on the global or even national scales that "blending" alone is unlikely to account for smaller features, since, all things being equal, the global average would still stay the same. Significant changes in the size of any feature are instead determined by how likely people with features of a given size are likely to attract mates (sexual selection), how likely people with a given size of a given feature are to survive to procreate (natural selection, and this factor is clearly not a significant one in this context since big or small noses don't confer a significant advantage or disadvantage outside sexual selection) and all of the various anthropic factors that converge with these forces.

In short, I think the OP's guess of confirmation bias is probably at work here. That, or possibly he is picking up on a changing trend in media towards certain standards of beauty--an entirely different kind of selection bias. Certainly it seems to me that a larger-than-average feature is often seen as more likely to stand out as "unattractive" than a smaller-than-average value for the same feature, but that's pure impressionistic speculation on my part. What I can tell you is that there is a great body of research in measuring these features (which actually goes back a great distance due (ironically enough) to obtuse notions of racial superiority which some tried to validate through such measurements, but also extending into modern (and less racially driven) research. But again, at the risk of sounding like a broken record, the timeframe we are talking about here argues highly against the notion of a significant change as a result of natural or even sexual selection; to the extent the global average has shifted, it would be controlled more by the fact that relative population growth has risen in certain areas of the world, fallen in some, and remained steady in still others. But I'd rather trust the research in this area than speculate as to whether the new average is smaller (in concordance with the OP's observations) or larger (in contrast to those observations). But I will say I doubt the shift is significant in just the last generation, whichever the direction of the trend. Snow ^{let's rap} 07:38, 22 December 2015 (UTC)

Blending doesn't necessarily require genetic blending. Simple migration changes the "average" and 10 random faces from ten years ago might be markedly different than 10 random faces today. At least where I live, ethnic and racial integration is from a world populace and no longer simply regional migrations from historical enclaves. It's worldwide and it's more rapid than at any previous time. It's even different as previous migration was often displacement, not integration. Colonialism changed the average east coast face in the U.S. without much genetic change. The picture morphing experiment didn't create any genetic replicant, just produced an "average." I agree that it's just a bias and somewhere there would be people talking about larger noses but it would not be surprising to me to learn the average has changed due to multi-cultural integration. The census (at least in the U.S) shows some of it as part of the worldwide economy. Marin County is vastly different than a generation ago. --DHeyward (talk) 09:27, 22 December 2015 (UTC)

OP here, thanks for the replies. I'd considered that it might be 'blending' but thought the time frame was too short for that, but certainly it could be one of the factors. I live in an area that was famous for deep coal mining and shipbuilding. When those industries died out between 1960-1980 (I was born in 1974) the population probably changed rapidly, although I haven't any figures to back that up. Some families moving away for new employment, some moving in with new skills or for university education.

Confirmation bias does seem the most prominent reason though. Snow Rise, could you post links to the research measuring body parts if you have them (it doesn't have to be research specifically on noses!), I'd be interested in reading up on that. As for the media portrayal of beauty, I can't say that I've particularly noticed short noses, but now I will be watching out for them :-) 95.146.213.181 (talk) 17:43, 22 December 2015 (UTC)

Surely--I assume you are looking primarily for anthropometrics with regard to facial features still? In the distant past of psuedo-science meant to validate racist assumptions, this was a heavy field of inquiry (for a great read on this historical context, I can strongly recommend Stephen Jay Gould's The Mismeasure of Man. Modern anthropometric data collection is a broader affair, but data collection continues in the areas of facial features because it intersects with a number of different areas of research, including genetics/epigenetics, pathophysiology, guidelines for reconstructive surgery, biometrics, social and cognitive psychology, and many others. But I've tried to keep the selections here broad and concerned mostly with the proportions themselves rather than their applications. Many of these will be behind a paywall though, I fear.

To begin with, here is a systematic review of the literature in this area--it of course has a great many additional useful references within it: [4]. And here are some other studies along the same lines that you may find interesting: [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18]. Snow ^{let's rap} 20:59, 22 December 2015 (UTC)

Thanks. I'm not particularly looking for research on facial features, that was just what my initial question was about, which I think has been answered, but if your links have relevant info that would be great. I'll enjoy reading up on why scientists conducted the research on measuring body parts, whatever their reasons (I don't think racism exists so much now in general and certainly not in research, excepting a certain ignorant minority of people). I appreciate the effort you've put into all the links. 95.146.213.181 (talk) 21:38, 22 December 2015 (UTC)

You're most welcome; that's what we're here for! :) Snow ^{let's rap} 22:13, 22 December 2015 (UTC)