Wikipedia:Reference desk/Archives/Science/2015 July 10

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July 10

where do pigeons get their magnetite from?

is it in their food? - https://en.wikipedia.org/wiki/Magnetoception

Adambrowne666 (talk) 00:06, 10 July 2015 (UTC)

• Magnetite is Fe3O4, see Magnetite#Biological_occurrences as a place to start looking. μηδείς (talk) 01:24, 10 July 2015 (UTC)
  • Thanks, Medeis, but we're going a bit circular; the article doesn't say where the magnetite originates, just that it occurs as crystals in some organisms - I guess it's not a huge mystery; other minerals are taken in in the diet - i was just interested in where Fe3O4 occurs naturally in the things that pigeons eat... Adambrowne666 (talk) 02:15, 10 July 2015 (UTC)
    • Why do you assume it is in their food? Obviously they have iron and they have oxygen, so maybe the cells just make it. --Trovatore (talk) 02:49, 10 July 2015 (UTC)

      Well, they would still need to eat something containing the iron at some point. StuRat (talk) 03:04, 10 July 2015 (UTC)

      I would certainly hope so. How else are they going to make hemoglobin? --Trovatore (talk) 03:43, 10 July 2015 (UTC)

      They would need to eat more iron than would be required for other biological reasons. StuRat (talk) 16:11, 11 July 2015 (UTC)

Not an answer, but note that some birds do intentionally swallow inedible things. Some birds swallow stones for their gizzards, and some parrots eat clay to help with indigestion. So, it's possible they could intentionally hunt down and eat magnetite crystals. StuRat (talk) 02:48, 10 July 2015 (UTC)

• A shred of reliable info, supporting Trovatore's guess - this [1] is about humans, but the abstract refers to "biogenic magnetite". SemanticMantis (talk) 14:05, 10 July 2015 (UTC)

• Here's a whole book "Magnetite Biomineralization and Magnetoreception in Organisms" - [2]. Of course I haven't read it but Table 1 seems to say that magnetite is biochemically precipitated in pigeon heads. SemanticMantis (talk) 14:09, 10 July 2015 (UTC)

• FWIW domestic chickens also have magnetite and we know exactly what they eat when they are kept in cages.DrChrissy ^(talk) 14:18, 10 July 2015 (UTC)

Iron is a part of a balanced diet for anything with hemoglobin (including pigeons and a more surprising variety of invertebrates than you might think). Though stranger things happen in biology, I'd guess it is highly unlikely that magnetite crystals would be allowed through the intestinal lining and circulated through the blood, so I'd expect magnetite in pigeons is assembled atom by atom from the same general reserve, which is held by iron-binding proteins (ferritin, lactoferrin, transferrin...) Wnt (talk) 14:21, 10 July 2015 (UTC)

• Magnetite#Biological_occurrences (already posted above by Medeis) clearly says, with reference "Biomagnetism is usually related to the presence of biogenic crystals of magnetite". Between this and the two refs I posted above, I think this is pretty clear - they make it (and so do we, and so do many, many organisms). SemanticMantis (talk) 15:02, 10 July 2015 (UTC)

Thanks everyone - yes, it does say biogenic, SemanticMantis and others - I overlooked that. Amazing what biology can do. Adambrowne666 (talk) 23:23, 10 July 2015 (UTC)

Sausage cover

I looked through the contents. People are asking questions about star evolution and I am barging in with my sausage :-)

This is the issue. I try to eat healthy food, vegetables, salads, no trans fats, etc. My wife reads all the labels. She is even more fanatical being in her skinny body. But occasionally we both get sick on eating dinosaur meat, (read chicken's), and a few days ago we went into our local supermarket which is definitely of high grade and bought two packs of sausages with pork and beef inside. I consumed my first sausage without giving it a second thought but my wife said: "look, the cover (sack) is plastic." I mean the cylinder where the meat has been squeezed in. No, I said, it cannot be, it is an intestine. But looking more carefully I agreed that it was not an intestine, it was too thick for it and too smooth. But it cannot be a plastic either which is not digestible in general case.

We looked at the package, nothing about the sack. This is my question. I am sure thousand of people have had similar experience. Is it possible to find a description of what stuff this sack is made of, à priori, based on my admittedly incomplete description? It started bothering me. Thanks. --AboutFace 22 (talk) 01:21, 10 July 2015 (UTC)

See sausage casing. Beef casings might look somewhat like plastic, but they do also actually use plastic ! Presumably, the plastic casing is like the wax on the outside of high-end cheeses, in that you are expected to discard it, not eat it. You'd expect that they would clearly label whether the casing is edible or not, but they don't seem to bother with cheeses, so may not with sausages either. StuRat (talk) 01:27, 10 July 2015 (UTC)

see http://www.fao.org/docrep/010/ai407e/ai407e20.htm , edible synthetic casings are made from collagen (scar tissue), cellulose (wood) or possibly plastic. Frankly if you are into healthy food the content of the sausage ought to frighten you more than the casing, my wife, the butcher' daughter, won't touch them even when she knows the butcher. Big clue, buy decent looking joints of meat, mince it yourself, make your own sausages. It'll cost a lot more than store bought sausages because it isn't made from floor sweepings and cheap filler. Better idea, forget sausages unless you need to use a whole animal up, make a beef stew instead. Greglocock (talk) 04:19, 10 July 2015 (UTC)

It's a terrible waste to use good cuts of meat to make sausages. Sausages are a tasty and economical way of using some of the stranger looking bits of a carcase. I would expect the ingredients list to say what the sausage skin is. DuncanHill (talk) 09:44, 10 July 2015 (UTC)

Oh guys, I am so glad I posted on the issue. I was very reluctant initially, waited for a few days but I got a wealth of knowledge. StuRat is always here to help and educate "ignorant" but Greglocock, an unexpected contributor, many thanks to you for your very informative and humorous response, my wife had a kick out of it. We do this sausage thing perhaps twice a year, but now it will be history. The sausage leftover will go to the garbage can. Yes, my sausages looked exactly like one of them shown at the link you provided. DuncanHill, the pack has no information whatsoever on the casing except the minimum required by the FDA: calories, sodium and cholesterol contents in the sausage itself. Thanks again. --AboutFace 22 (talk) 14:03, 10 July 2015 (UTC)

Is New horizons will be able to send any data to us if we somehow managed to make a contact with it after Pluto flyby?

What the New horizon will do after it successfully tranfers the data of Plutu flyby to earth.?Will it travel in forward direction or it can change its path and will aim for another subject?And if the distance is the problem then we can place any probe in between earth and the new horizon which will help to send any command or data from earth...?turbo 06:20, 10 July 2015 (UTC) — Preceding unsigned comment added by Sidsandyy (talk • contribs)

See New_Horizons#Future_mission_objectives. 196.213.35.146 (talk) 06:38, 10 July 2015 (UTC)

Distance is not the biggest problem. Voyager 1 is still in communication with Earth at a distance of 125 AU, almost 4 times as far away as New Horizons. And that is with 1970s technology. I think the limiting factor on a space probe's operational lifespan is probably reliability of electronic components rather than distance. Gandalf61 (talk) 11:04, 10 July 2015 (UTC)

(ec) Did you read my link? "Past 55 AU, the communications link will become too weak, and the RTG wattage will have decayed significantly enough to hinder observations." What is your source? 196.213.35.146 (talk) 11:51, 10 July 2015 (UTC)

No, I didn't. I was replying to the OP's comment "And if the distance is the problem ...". My point is that communication between space probes and Earth is technically possible well beyond Pluto so distance is not the limiting factor here. Although a full program of fly-by observations may not be feasible beyond 55 AU, that doesn't mean that New Horizons will cease to communicate at that distance either. Gandalf61 (talk) 12:28, 10 July 2015 (UTC)

Yes it is possible, but Voyager 1 has a 3.7m high gain dish antenna. New Horizons has a 2.1m dish. 196.213.35.146 (talk) 12:57, 10 July 2015 (UTC)

And it will stop communicating - see Radioisotope_thermoelectric_generator 196.213.35.146 (talk) 13:14, 10 July 2015 (UTC)

See New_Horizons#Power This is a reference desk - not thumb suck. 196.213.35.146 (talk) 13:21, 10 July 2015 (UTC)

Not sure if you are aware of this, but you are being rude and Wikipedia has a lower tolerance for that sort of behavior than some other sites. If you plan to contribute to Wikipedia on a regular basis you should read and take note of our policy on civility. Gandalf61 (talk) 14:29, 10 July 2015 (UTC)

Link between eye colour and short-sightedness?

Most people in my immediate family (myself included) have brown eyes and are short-sighted. My brother has blue eyes and good eyesight (as did my grandfather when he was young, before becoming longsighted later in life). Is there any connection, or is this just coincidence? I found an abstract of a paper speculating on a link between eye colour and myopia, but the abstract doesn't actually give the conclusion and the paper is behind a pay wall. Iapetus (talk) 10:13, 10 July 2015 (UTC)

Here's [3] an accessible mata-analysis/review of iris color and various pathologies from 2013 (your ref is 2012). The conclusions in the abstract support several links, but not to myopia (I only read the abstract). (Weirdly enough, I don't have access to Meng et al. (2012), and I have institutional access to almost every journal I've tried for...my usual tricks of looking for reprints online are also coming up blank) SemanticMantis (talk) 13:55, 10 July 2015 (UTC)

If nobody can get the article within a few days, I recommend just contacting one of the authors and politely asking for a copy - that almost always works in my experience. One coauthor's email address is listed here [4] SemanticMantis (talk) 14:00, 10 July 2015 (UTC)

Keep in mind that Meng et al was published in Medical Hypotheses, a journal designed to publish outre/unconventional ideas not widely accepted by experts in the field. Abecedare (talk) 18:13, 10 July 2015 (UTC)

Eye color changing over time

Supposing that a peer-reviewed study is found, I wonder if could account for change in eye color. I was born with green eyes. They slowly became dark brown by the time I was a teenager. Then, as an adult, they turned silvery-blue. I don't know how quickly that happened. I didn't notice until I was arguing with the lady at the DMV that my eyes were brown and she insisted on saying they were blue. So, I had to check the mirror. So, if there is a correlation between eye color and any type of disease, will the disease come or go with a change in eye color? 199.15.144.250 (talk) 13:39, 11 July 2015 (UTC)

I broke your Q off as it's own Q, since it's unrelated to the previous Q. AFAIK changes in eye color aren't related to disease. (There are changes in the color of the whites of the eyes related to disease, so that might be what you are thinking of.) One possible cause of eye color changes might be if the individual is a chimera, possessing two sets of genes. You might expect the eye color to vary from eye to eye or even within an eye, in that case. Also, eye color may look different at the DMV because of those harsh fluorescent lights. See Eye_color#Changes_in_eye_color for more info. StuRat (talk) 15:57, 11 July 2015 (UTC)

Error in spelling of search item

Hi

There is an error in the term "synaptic button". It's actually a "synaptic bouton" but I don't know how to fix that.

We often make redirects for common misspellings, and this is a good thing- it helps people find a relevant article even if they don't know exactly what to call it. Is that what you're talking about here? Synaptic button goes to chemical synapse, though synaptic bouton goes to Axon terminal. I don't know enough neuroscience to be sure, but it does seem to me that bouton/button should go to the same place. My guess is axon terminal should be the target for both, but I'll leave it as-is until we hear from people who know more about this. (@Looie496: want to chime in?) SemanticMantis (talk) 15:08, 10 July 2015 (UTC)

Synaptic button was created in 2005 and last edited in 2006 while axon terminal in 2008 which probably explains the redirect. Nil Einne (talk) 15:20, 10 July 2015 (UTC)

I made them both redirects to axon terminal, the proper target. Logically it would be better for synaptic button to redirect to synaptic bouton, but that doesn't seem to work. Anyway, thanks for bringing this to my attention. Looie496 (talk) 18:17, 10 July 2015 (UTC)

Thanks! SemanticMantis (talk) 18:54, 10 July 2015 (UTC)

Have added {{Redirect from misspelling}} to Synaptic button to warn humans/bots looking at the page. Abecedare (talk) 05:47, 11 July 2015 (UTC)

What is the reason that KPC culture is sampled from the rectum?

I noticed that KPC is sampled from the rectum. Is it the only place that's possible for KPC cheaking? If so, what is the reason or what is the explanation? 192.116.66.22 (talk) 15:26, 10 July 2015 (UTC)

Are you asking about the Klebsiella pneumoniae Enterobacteria which produces the Beta-lactamase#KPC (K. pneumoniae carbapenemase) (Class A) enzyme? -- ToE 02:24, 11 July 2015 (UTC)

This paper says that, It is more convenient and practical to collect rectal swabs than stool specimens to study carriage of colon pathogens, but I assume your question is why it is specifically the intestinal carriage of these bacteria which monitored when our article says that they are found in the normal flora of the mouth, skin, and intestines. Hopefully someone more familiar with this field will be able to answer you here. -- ToE 02:32, 11 July 2015 (UTC)

Rove Beetle questions

There has been (for at least 3 years already, I can't remember exactly anymore) a rove beetle infestation in some of the jungles in Penang, Malaysia. I happen to live in an apartment that's right next to one of these hilly jungles.
I have to shut all windows and doors after 7pm or there will be many of them flying in. But sometimes, there will be a few that fly in earlier in the day.
I have seen a few of my family members suffer from the rove beetle blood/juice before, and it has made me so paranoid. I have some questions regarding these rove beetles:

1. Apparently, these rove beetles here are an alien species and so they have no natural predators. (I can see how most animals will suffer greatly from internal injuries if they consume a rove beetle.)
Where do they originally come from and how did they get here?
And what animals are their natural predators? What adaptations do these natural predators have so that they don't get injured/sick from eating the rove beetles?

2. How easily do these rove beetles "burst"? And can they suicide burst at will?
I don't think they have a poisonous bite or sting, it's just that if you're not careful when killing them or if you don't look at what you're doing carefully, you may accidentally crush one.

3. What colour is the rove beetle "juice/blood"? How many hours can this liquid last and still retain its potency on human skin?
I ask this because of a particular injury to 1 of my family members. He tried on an old pants he found in the store room, and didn't notice any rove beetle anywhere at all. One day later, and his buttock had that signature red sore due to rove beetle blood.
So far, I've only seen the effects of this poisonous liquid on the skins of my family members. It seems to eat and dissolve/corrode human skin. But I've not actually seen a live moving beetle die and "bleed" before.

4. If I kill a rove beetle on a plastic object, and if I wash that object in the kitchen sink using a sponge and dishwashing liquid, how do I make sure my sponge is still safe for future usage? (it's usually used to wash the dishes)
Also, what precautions should I take when washing an object that a rove beetle has died on (and thus has spread its juice on the object) so that I protect my skin from harm?

60.53.157.40 (talk) 17:09, 10 July 2015 (UTC)

We have an article on rove beetle, the genus causing you problems seems to be Paederus, in the Paederina tribe. We also have an article on the sub-family Paederinae. The irritation it causes is called Paederus_dermatitis, caused by the agent pederin. Here are a selection of government documents and academic research papers [5] [6] [7].

For 2 - my quick reading indicates you are correct - only their Hemolymph (which is basically insect blood) that is irritating, I see no info on irritating bites or stings.

For 3 - this paper [8] seems to indicate that insect predators aren't harmed that much by the hemolymph. It seems that it primarily deters other predators, especially spiders. (also perhasp birds or small mammals)

This is very interesting stuff, thanks for the question! SemanticMantis (talk) 17:33, 10 July 2015 (UTC)

It sounds like you don't have window screens. They are widespread in the US, to keep insects, birds, etc. out. You might invest in some, as they are quite effective against large insects, less so against gnats. From the description, it sounds like those rove beetles might be just large enough to be blocked by window screens. StuRat (talk) 03:25, 12 July 2015 (UTC)

Can window screens keep out bugs that can be less than 1cm in length? (that's about the rove beetle's length)

What are the hole sizes that these screens come in?

118.101.238.50 (talk) 13:41, 14 July 2015 (UTC)

I looked up at window screen but the sizes they list (unsourced) seem far too large - guesstimating from the nearest example I see, there must be something around 16 squares per inch, not 4! Ought to fix that. It really surprises me if just about anyone lacks access to screening nowadays, because while the fixed professional installations can be expensive, mosquito nets/bed nets etc. are widely available and can be improvised to fit a window with nothing more than a sharp blade and some thumbtacks. Somewhat more rigid flexible screening is also available by the roll quite cheaply. The only limitation I can think of is that it's necessary to screen a place fairly thoroughly - it seems like even a small gap can let in a surprising number of mosquitoes, if you're situated somewhere that they are prevalent. But I don't know if rove beetles are as determined. Wnt (talk) 15:20, 14 July 2015 (UTC)

I believe you were looking at the frame sizes, not the mesh sizes. They listed mesh sizes down to 20×20 per square inch. 1/20th of an inch is 0.127 cm, or 1.27 mm. At that size they should block all but the smallest species, and even those might not want to wriggle through the screen mesh to get inside.

But for some reason window screens just don't seem to have spread to much of the world. I watch shows where they sell mansions around the world, and they often seem to lack this basic necessity, although I suppose they might remove them for filming, as windows look better without them. StuRat (talk) 17:08, 14 July 2015 (UTC)

There's a 20×30 mesh per square inch for sale here: [9]. And a 30×30 mesh here: [10]. That's 0.85 mm. There's 105×105, 120×120, and even 180×180 mesh for sale here: [11]. However, that fine of a mesh blocks most of the light and is probably extremely fragile. StuRat (talk) 18:12, 14 July 2015 (UTC)

This source says to wash skin with soap and water: [12]. That implies that the same should work to wash it off other surfaces, although water and detergent are probably more convenient than water and soap, in most cases. In the case of clothes, running them through a washing machine might be wise. It's probably a good idea to wash such items alone, though, in case they deposit any residue on other clothes. StuRat (talk) 04:11, 12 July 2015 (UTC)

The source also says

"Pederin is known to be soluble in alcohol so be careful when handling alcohol that has been used to preserve Paederus beetle specimens."

Does it mean that alcohol can be used to clean skin that has come into contact with the rove beetle blood?

Could those hospital alcohol wipes or hand sanitizers be useful?

118.101.238.50 (talk) 13:41, 14 July 2015 (UTC)

Yes, sounds like that would work, too. StuRat (talk) 17:06, 14 July 2015 (UTC)

about Diabetics curing Hurbal Plant not clear information on wikipedia

how "decorative sweet potato plant" and scientific research paper named the same plant as ipomoea batatas(Caiapo), IS these two plant are same and HOW it is linked to diabetics  — Preceding unsigned comment added by 14.139.245.2 (talk) 17:41, 10 July 2015 (UTC)

Ipomoea batatas is the sweet potato, which some people do plant for decoration. I'm certain there is no scientific research papers about any cure for diabetes (yet), but I do not know if there are any papers about the plant being used to treat diabetes. This article discusses some researchers' findings as to how sweet potatoes could be good for diabetics, but it doesn't cure diabetes, however. According to that article, Caiapo is derived from the sweet potato peel, which has additional qualities that the rest of the sweet potato does not. Ian.thomson (talk) 17:56, 10 July 2015 (UTC)

Yes, it is the same species, but note that the decorative varieties are not usually eaten for food - there are many decorative cultivars out there, and my impression is that many of them don't produce much food. This resource [13] from NCSU says "They are likely to be bland and mealy." Not sure how their nutritional content may vary from culinary varieties. SemanticMantis (talk) 18:53, 10 July 2015 (UTC)

There are a number of papers studying the use of sweet potatoes to modulate blood sugar in diabetes. A meta-analysis published in 2011 (PMID 21843614) found an overall significant effect, though not very large in magnitude. Looie496 (talk) 18:25, 10 July 2015 (UTC)

Caiapo are an indigenous people, but apparently the word is also the trade name for a product made from skins of the white-skinned sweet potato Ipomoea batatas, according to a paper published in Diabetes Care by researchers funded by the company that makes the extract, Fuji Sanyo. Such company funded research typically should be taken with some skepticism (the way Cochrane puts it is "the risk of bias of these trials was unclear or high"), and no mechanistic basis for the effect is offered. In other papers it looks like it is stimulates GLP-1, sort of like barberry leaves AFAIR. Oddly, white sweet potatoes are probably low in flavonoids, which typically seem to be of relevance via adiponectin; but I see something else in PubMed about these being investigated by some other group. There are a very large number of plausible positive results for herbal remedies in type 2 diabetes; indeed there are better known herbs with longstanding use for the purpose such as cinnamon and cassia in Chinese usage. (For cinnamon see [14], which argues that the effects though real are small and 'clinically irrelevant'; they don't have a very thorough set of substances to evaluate though) To guess, and this is a massive generalization/speculation, I'd say that in general sweet foods carry a lot of signals that can sort of warn the body to brace itself for a sugar burden, and when we refine them down to pure chemical starch and sugar and make concoctions out of them, we leave ourselves more biochemically off-guard to what we're being hit with. Wnt (talk) 17:26, 12 July 2015 (UTC)

Age of Alpha Draconis

Does anyone have a source that lists the age of Alpha Draconis (AKA Thuban)? Partly because I'm noticing a neat trend that most of the stars that UFOs are supposedly from (e.g. Pleiades, Sirius, Zeta Reticuli) are younger than life on Earth (looks like we'll be abducting them!), and partly because the article on this star does not list its age. Ian.thomson (talk) 21:22, 10 July 2015 (UTC)

Thuban is clearly younger than the Sun. It is a giant star that has left the main sequence, and, being a giant star, has a shorter lifespan than a main-sequence G-type star. Can someone compute or look up the lifespan of the star based on its mass? On the one hand, if aliens are coming from Thuban, it is because their planet has been destroyed as Thuban goes giant. On the other hand, if aliens are coming from Thuban, life evolved more quickly than it did here. Robert McClenon (talk) 00:11, 11 July 2015 (UTC)

I figured. Everything else I can get a date on in Draco (not the best measure, but not the worst) is definitely younger - 550 to 10 million years old or so. Was just wondering if anyone's nailed down Thuban's date to anything so close. Ian.thomson (talk) 00:59, 11 July 2015 (UTC)

(edit conflict) The situation is complicated by Thuban’s being a close binary system; I don’t know how precisely the primary’s mass has been determined. But using the figure of 2.8 suns from the above-linked article, and given that stellar lifetime scales at about the –5/2 power* of mass, its main-sequence lifetime (which appears to have just ended) can be calculated as .076 of the Sun’s, something like three-quarters of a billion years. (* Our table at the top of Stellar evolution appears to use a power of −3: the best-fit exponent has a considerable range in various populations of stars, so for general purposes can only be a rough guide.)—Odysseus1479 01:29, 11 July 2015 (UTC)

Awesome. Possibly too WP:OR for the article, but totally works for the chart I'm writing up for other reasons. Ian.thomson (talk) 03:17, 11 July 2015 (UTC)

I think the OP's suggestion makes sense. UFOs often are said to come from famous stars. Famous stars tend to be bright stars. Bright stars tend to be giant stars. Giant stars tend to be short-lived. Wnt (talk) 17:04, 12 July 2015 (UTC)

Yes, but Thuban isn't a famous star for being a bright star. It isn't a bright star. It is famous only for having been the pole star in the past. Robert McClenon (talk) 17:11, 12 July 2015 (UTC)

Also, one of the stars mentioned above is a famous star because it is a bright star, but isn't a giant star in the usual sense. Sirius is a bright near-by main-sequence star with a white-dwarf companion. Robert McClenon (talk) 17:13, 12 July 2015 (UTC)

@Robert McClenon: I was arguing general trend, but I should note that Thuban calls its subject "a white giant star, being 250 times more luminous than our Sun". Even Sirius, with just twice the Sun's mass, shouldn't be as long-lived - according to [15], the main sequence lifetime of stars is inversely proportional to the 2.5th power of their mass, so just double the size of the Sun reduces 10 billion years by a factor of 5.6, to under two billion years. Even though it's one of our nearest neighbors its life is still shortened sufficiently by fame that it must be younger than the Earth. Wnt (talk) 23:24, 12 July 2015 (UTC)

I agree that Sirius, although not a giant star as usually defined, is a star that is considerably more massive than our Sun and so has a shorter lifetime than our Sun. What we don't know is how much time really is required for intelligent life to develop that is capable of interstellar travel. We only have one data point, one planet that is 4.6 billion years old, on which life will probably be capable of interstellar travel in about a century, which is still 4.6 billion years due to imprecision, and we don't know how much of the 4.6 billion was spent in the advanced development of life. (We know when the oxygen catastrophe and the Cambrian explosion were, but those are just data points again.) Robert McClenon (talk) 23:32, 12 July 2015 (UTC)

Indeed, according to the anthropic principle and such, it's possible life takes quadrillions and quadrillions of years to develop, and Earth was just a one-in-a-kind fluke - hence we evaluate from here. But I am skeptical of that; abiogenesis seems plausible enough that the somewhat more morose view that the sky is littered with immense numbers of long-dead civilizations, all of which destroyed themselves, seems like the more believable option. But I digress. Wnt (talk) 00:17, 13 July 2015 (UTC)

Giant stars as usually defined are short-lived because they have already exhausted their hydrogen, and the process of stellar death is itself relatively short. There are also short-lived extremely bright main-sequence stars that may be called giant stars because of their high mass. So, yes, famous and bright stars are likely to be short-lived. Robert McClenon (talk) 17:16, 12 July 2015 (UTC)

I only arrived at the trend developing a history chart for a tabletop role-playing game that includes (among other things) UFO mythology. According to the standard lore, the Grey aliens are supposed to be from Zeta Reticuli (which doesn't have any exosolar planets), the Nordic types from the Pleiades, whoever "contacted" the Dogon people are from Sirius, and the Reptilians from Alpha Draconis. Though instead of simply abandoning those star systems, I'm letting the "real world history" column point out that any life from those systems probably wouldn't have advanced enough to bang the rocks together, if they're even multicellular. Ian.thomson (talk) 19:23, 12 July 2015 (UTC)

Plejaren and Pleiades

The article on the Plejaren does not indicate that they are said to come from the Pleiades, although they were once called Pleiadeans. The Pleiades, being a large star cluster, would be an unlikely location for a life-bearing planet, according to some theories, because planets in a star cluster might not have stable orbits around a single star. Robert McClenon (talk) 20:33, 13 July 2015 (UTC)

We don't have them cited on here (mostly because they go against WP:PRIMARY or WP:RS), but I've also got some other sources that identify the Nordic aliens (of which the Plejarens are an example) as being "Pleiadeans" (though I'll try to sort through and see if any would be appropriate to add to the article on Nordic aliens). Plus, UFO mythology is pseudoscientific at best, and this fits the general trend of "stars too young and not enough habitable planets." Ian.thomson (talk) 20:51, 13 July 2015 (UTC)

Ok, found one quicker than I thought. Didn't realize Infobase Publishing was that open to printing fringe material (if for kids, but still meets WP:RS). Ian.thomson (talk) 20:56, 13 July 2015 (UTC)