Wikipedia:Reference desk/Archives/Science/2016 December 19

= December 19 =

glass turning cloudy
I have two sets of drinking glasses that have turned cloudy over the space of a few years. The cloudiness can't be cleaned. They have been on open shelves instead of in cabinets, so they are exposed to more light. Can exposure to light make glass turn cloudy? Bubba73 You talkin' to me? 05:46, 19 December 2016 (UTC)


 * Do you use a dishwasher? http://housekeeping.about.com/od/dishes/f/cloudydishes.htm  Rojomoke (talk) 06:10, 19 December 2016 (UTC)


 * Light does not turn real glass cloudy (although it can do this to polymer "glass" like plexiglass or lexan) -- what can turn glass cloudy is exposure to alkaline solutions (typically due to washing the glassware in a dishwasher and using too much detergent). 2601:646:8E01:7E0B:CA6:F242:4F2A:EC76 (talk) 08:08, 19 December 2016 (UTC)


 * Try rubbing them with lemon juice (or a cut lemon, or some similar acid).   D b f i r s   10:25, 19 December 2016 (UTC)


 * My favoured domestic acid for food utensils is malt vinegar, which is very cheap and already a byproduct of brewing ale: shame to waste the makings of a gin and tonic. {The poster formerly known as 87.81.230.196} 90.200.136.117 (talk) 11:05, 19 December 2016 (UTC)


 * If the glass has been etched by exposure to tiny amounts of chemicals like hydrogen fluoride in the air, then there's no cure, although they may look better when wet. My suggestion is to store wine glasses in a sealed container.  I kept the boxes my wine glasses came in, and I store them there.  Not completely airtight, but will certainly slow the exposure rate and thus damage. StuRat (talk) 17:20, 19 December 2016 (UTC)

Thanks for the replies. It is real glass, washed in a dishwasher. We tried vinegar but that didn't work. Bubba73 You talkin' to me? 21:14, 19 December 2016 (UTC)

Bubba73, It sounds like mineral deposits. Maybe try soaking the glasses in CLR. You can look that up. We get a different product with the same ingredient here. It works for me after trying unsuccessfully vinegar, lemon juice, and other acids. Anna Frodesiak (talk) 23:43, 19 December 2016 (UTC)


 * Thanks. Bubba73 You talkin' to me? 00:17, 20 December 2016 (UTC)

Static pile load
Is this what this is called? I would like to make an article about it.

http://freeimagehosting.net/upl.php

See also: Template:Geotechnical engineering

Anna Frodesiak (talk) 06:09, 19 December 2016 (UTC)


 * Is that supposed to be a link to a picture? Rojomoke (talk) 06:12, 19 December 2016 (UTC)


 * Ah, thanks Rojomoke. Sorry I got the wrong link. Here it is:


 * http://i.imgur.com/JjlQq2z.jpg


 * Cheers! Anna Frodesiak (talk) 08:13, 19 December 2016 (UTC)


 * Pile driver--Phil Holmes (talk) 08:54, 19 December 2016 (UTC)


 * Hi Phil. Those long things indicate that. However, there are those huge iron things that look like they are there to test if the ground sinks. Most constructions sites have them for half a year or so before building here in Haikou. Anna Frodesiak (talk) 10:07, 19 December 2016 (UTC)


 * They may not have a special name, just something generic like "vertical weights". StuRat (talk) 17:13, 19 December 2016 (UTC)


 * The answer to your question appears to be yes. Here are some useful sources
 * Handbook on Pile Load Testing - The Federation of Piling Specialists
 * Design and Construction of Driven Pile Foundations – Lessons Learned on The Central Artery/Tunnel Project
 * static pile load test manual - Department of Transportation - New York
 * SpinningSpark 18:19, 19 December 2016 (UTC)


 * You might also be interested that there is such a thing as pseudo static pile load testing, described in this book. SpinningSpark 18:24, 19 December 2016 (UTC)


 * Hi Spinningspark. Thank you! Yes, that seems to be it. And wow, those links sure do confuse me. I still can't quite figure out what they're doing. Anna Frodesiak (talk) 23:28, 19 December 2016 (UTC)

If anyone wants to start the article, those sources seem pretty good. I can upload some higher quality images, and maybe get right up to one to get detailed pics of instruments, etc. Anna Frodesiak (talk) 23:28, 19 December 2016 (UTC)


 * Wait a minute. I thought this thread began with you were going to start an article.... SpinningSpark 23:51, 19 December 2016 (UTC)
 * Hi, Spinningspark. I was, until I read those refs. I am interested in that giant thing, but to me it is like some sort of... How do I put this? Imagine a chimpanzee with a cuckoo clock. The cuckoo clock is the object with no article yet. I am the chimpanzee. :)


 * And I still do not know what the weights are for. (I'm assuming they're blocks of iron.) To see if the ground squishes? To make the platform heavy so they can push the cement polls into the ground? Anna Frodesiak (talk) 00:02, 20 December 2016 (UTC)
 * I usually start off as a chimpanzee when I start to write most of my articles. By the end of the process I often manage to convince at least one or two people that I actually know what I am talking about.  So I really didn't know anything before I dug up those sources, but I'll try to help.  That first pdf seems to explain everything.  Chapter 2 gives the reasons for doing the tests.  It's partly about the ground conditions, but mostly about the behaviour of the pile itself under load - making sure it is not going to break and bring the building down when they build it.  If it's a new design of pile, or unusual ground conditions, the testing is also validation of the pile system design.  The weights in your picture are the test loads on the pile.  Your picture seems to correspond most closely to the method the pdf call kentledge on page 16.  Hope that helps. SpinningSpark 00:27, 20 December 2016 (UTC)
 * Spinningspark, thank you for giving me faith in myself. Do you think I should just start a paragraph at Deep foundation? I am out of town for a day or two, but when I come back, I will read, eat a whole bunch of bananas, and type a paragraph or two with my feet. :) Anna Frodesiak (talk) 00:39, 20 December 2016 (UTC)
 * Nah, start a page. A couple of paragraphs is fine for a start class article.  I'm pretty sure you can get a DYK out of that as well.  What should go in the deep foundation article is just a mention and a link together with mentions of the other possible methods of testing drilled piles (the article currently only says there are various methods without saying what they are) <b style="background:#FAFAD2;color:#C08000">Spinning</b><b style="color:#4840A0">Spark</b> 12:35, 20 December 2016 (UTC)
 * Spinningspark, I did it: Static load testing. Don't laugh. I have no idea what I'm doing. Anna Frodesiak (talk) 01:14, 22 December 2016 (UTC)
 * Cool! <b style="background:#FAFAD2;color:#C08000">Spinning</b><b style="color:#4840A0">Spark</b> 01:26, 22 December 2016 (UTC)
 * Hi Spinningspark. And I started kentledge. It's not much more than a dict. def. but I've posted at project ships and hope to get pics of ship kentledge and show via diagrams where it fits into the ship and how much is used, etc. Cheers, Anna Frodesiak (talk) 03:07, 22 December 2016 (UTC)

Research for my book (nsfw)
!!Not Safe For Work warning!!

I'm writing a story where the heroine gets captured and tortured by a pervert who makes her eat nothing but human male ejaculate. I need to know how many men it would take to supply enough daily ejaculate to sustain an adult female. I'd also like to know the consequences of such a diet in the long term. Would the woman stay healthy or would it eventually result in protein poisoning? Thanks for your help!

Brokie22222 (talk) 15:44, 19 December 2016 (UTC)


 * The Straight Dope famously took this on and came up with a two calorie figure.  It doesn't look like top of the line science though.  Jezebel says just 0.7, Queerty agrees , Greatist says "5 to 25" , Go Ask Alice says five to seven.   So far I don't hear the Nobel Committee applauding.  It should be clear that semen does include sugars (the little swimmers require constant external nutrition, as they are in prime racing trim!).  I don't know what the effect of so much polyamine such as spermidine would have, etc.  You'd have to do the experiment; no other way in biology, not really.  I suppose Daoists in the pursuit of Jing (Chinese medicine) might have screened some ideas.  I am strongly suspicious gout could result but I haven't done the research to back that up with data. Wnt (talk) 17:03, 19 December 2016 (UTC)
 * There are only about six basic plots. Provide us with your plot summaries and we will write the book for you (and collect the royalties on your behave), thus saving you from doing all the hard and time consuming background research. To make it a page turner we can also add a montage of out of our own personal observations to hang upon the main story,  so the that the reader is itching to turn the page to discover what happens next. Waiting for your reply.--Aspro (talk) 17:08, 19 December 2016 (UTC)
 * Wnt, the Nobel committee will indeed likely not be applauding, BUT, any peer-reviewed research on this question may well win an Ig Nobel Prize. Perhaps the OP would consider asking those scientists who are the main contributors to this prize, the magazine Annals of Improbable Research, which, according to our article, "usually showcases at least one piece of scientific research being done on a strange or unexpected topic". Eliyohub (talk) 12:53, 20 December 2016 (UTC)

"Healthy food" vs. "Junk food"
Junk food is usually depicted as sweets, highly processed meats, and refined grains. But what happens if a person doesn't care about health and just looks for something on sale in the fresh produce section of the grocery store, in the egg department of the grocery store, and drinks from the grocery store's water fountain? The person may just want an extremely cheap, simple, efficient lifestyle; and prepared foods or convenience foods are just not cost-effective when one can pick up free packets of sugar in cafeterias. If that person eats raw fruits and vegetables (without washing for convenience), cooks eggs on his own car engine, and collects free water from water fountains, which may or may not be contaminated by industrial chemicals, then how can one assess whether such a lifestyle is "healthy" or not? What does "healthy" really mean? Is "healthy" really subjective and dependent on the individual's body's ability to adapt to the environment? 66.213.29.17 (talk) 17:22, 19 December 2016 (UTC)


 * The last Q is the one we can best address here. While a person's genetic makeup may make them more or less susceptible to things like heart disease, cancer, stroke, and diabetes, we don't currently have the technology to identify which people need to worry about them and which don't, and, in your example, it doesn't sound like this person would be able to afford such tests if we had them.  So, that leads us to a "one size fits all" diet that is only adjusted for age and gender, for the most part.  There are some exceptions, though.  For example, sodium sensitive hypertension runs in my family, so we need to avoid salt or our blood pressure skyrockets.  No test was needed for    us, as we can detect the effects for ourselves (hear our heartbeats in our ears, for example), after eating a salty meal.  StuRat (talk) 17:30, 19 December 2016 (UTC)


 * BTW, the food choices you listed are good, but maybe some grains, beans, and veggies would be a nice addition. I can get good quality multi-grain bread from my Dollar Tree for US$1 for a 1.5 pound loaf.  A can of beans is cheap enough, and can be eaten unheated, if need be.  Same for many cans of veggies, although fresh ones, like carrots, are healthier. StuRat (talk) 17:36, 19 December 2016 (UTC)


 * Liked the bit about cooking eggs on his own car engine - what about cooking perfect jackets potatoes on the exhaust manifold -yes, did that too.  There is so much b@** about a healthy diet that all I can  suggest   is that the OP reads Paleolithic diet. One may not be able to take it straight out of freezer and bung it it into a microwave like a TV dinner .. but ask you, what is cheaper in the long run and which provides a healthier diet without the need to take vitamin tablets, coenzyme Q 10 etc.? Healthy means attains retirement age without having to fill  out an expensive prescription  each and every month for medications, for complaints that  our forbears did not suffer from – and even grand children, now get these  drugs proscribed. Some editors may disagree and I say let them bring it on...  Type 2 diabetes and so many other common conditions are linked in with the introduction of HFCS etc.  Sure, association is no proof of  causation but those apologist have a lot of explaining to do to explain as why the US life expectancy is dropping, and  dropping in comparison to the rest of the world:  whist in denial of the wight of  temporal evidence. --Aspro (talk) 18:29, 19 December 2016 (UTC)


 * Drugs are prescribed, although perhaps it would be better if many were proscribed. :-) StuRat (talk) 18:49, 19 December 2016 (UTC)


 * Darn.. need a better speell chequer. Any sufgeestions?--Aspro (talk) 19:18, 19 December 2016 (UTC)


 * So you have complaints about your exchequer ? I see an audit in your future. :-) StuRat (talk) 21:44, 19 December 2016 (UTC)


 * More people take medications now because we can treat more things. A hundred years ago, we knew basically nothing about what caused cardiovascular disease, so someone would just get to their 60s or 70s and suddenly keel over from a heart attack or stroke. Today, their doctor will screen them and put them on a statin, antihypertensive drugs, and/or aspirin, if they are at high risk. Mental illness runs in my family. One of my great-grandfathers committed suicide. I have severe depression and am on an antidepressant. If it weren't for that I might have wound up like him. I mean, I guess in a sense you can say that "healthy" means "not having to take medications", but there are plenty of people like me who wouldn't be "healthy" without them. Now obviously I'm not denying poor diet can contribute to some illnesses. --47.138.163.230 (talk) 23:56, 19 December 2016 (UTC)
 * Not denying the value of psychotropic medication in some cases, but abuse and misuse is still rampant. The Rolling Stones realized something was wrong way back in 1965. Way ahead of their time, I'd say - psychiatry took a lot longer to get a grip on the problem. Eliyohub (talk) 13:02, 20 December 2016 (UTC)


 * Perhaps it would be helpful to look at the issue of what healthy food categories are too expensive for the poor. Nuts/seeds and berries come to mind, and perhaps healthy fish, like salmon.  Still, I managed to buy sunflower seeds for US$2 a pound, peanuts for US$1 a pound, blackberries and raspberries for US$1 for a 6 oz package, and salmon for US$1 for a 4 oz fillet.  Not as cheap as potatoes and onions, to be sure, but still within reach. StuRat (talk) 18:54, 19 December 2016 (UTC)


 * Avoiding salt sugar and fat goes a long way, but cheap foods are often loaded with salt sugar and fats. Count Iblis (talk) 22:24, 19 December 2016 (UTC)


 * In a fast food restaurant, yes, but not in the grocery store. The cheapest foods are often fruits and veggies, which are healthy. A bag of potato chips cost far more than the same weight in raw potatoes. StuRat (talk) 00:56, 20 December 2016 (UTC)


 * That's nice and all if you have a grocery store near you. Also you're not taking into account the time and labor cost of preparing a meal yourself. Ever prepared your dinner after working two full-time jobs for minimum wage? --47.138.163.230 (talk) 02:44, 20 December 2016 (UTC)


 * Boiling potatoes is no big deal, and fruit often requires little or no prep, and, if you consider the work that must be done to afford more expensive junk food, it's less work overall to buy healthy, raw produce. Also, I believe those food deserts to be largely a myth.  I live in an area (Detroit) that's often cited as one, but I have 3 grocery stores within a mile.  Compare this with a hundred and fifty years ago, when people had to go much farther, on average, by horseback, and would then get food that required a lot more cooking, like a big bag of whole wheat. StuRat (talk) 15:11, 20 December 2016 (UTC)


 * Agree with Stu about this myth. Before automobiles and supermarkets with their frozen foods. People bought food in bulk when it was cheap (i.e. harvest time) and stored it for the leaner times when fresh produce became expensive. The normal working day (was back then) 12 hours. How long does it take to prepare a nutritious meal? Answer: Less time than it takes one to go to and back-again  to a convenience store to buy something that one just bungs into the microwave. Think that the only way that one can be convinced of this is actually try it. Initially it may take time to learn how prepare and  to cook  raw unprocessed food. With experience though, it becomes faster as one learns how to chop and dice with a (sharp) knife and balance that with ones working life. Good example is the Lancashire hotpot. Just bung everything into the the pot and when one returns home Voilà – a ready, very cheap and tasty stew.--Aspro (talk) 16:04, 20 December 2016 (UTC)


 * One thing that may spread the impression that healthy food is difficult and time-consuming to prepare is cooking shows. They often show many steps and ingredients for something that could be done much more simply.  Take beans.  They might start with dried beans, parboil them, then soak them overnight, then bring to a boil again, then simmer while adding all sorts of other ingredients.  I use canned red kidney beans, which tend to be too high in salt and/or sugar, so I mix them with a can of unsalted, diced tomatoes, and add some chili powder.  I microwave them in the bowl I will eat from, and I have chili in a minute or two, with only a bowl and a spoon to rinse, with nothing burnt on and no grease (requiring detergent) to remove. StuRat (talk) 17:27, 20 December 2016 (UTC)


 * Peeling potatoes is no fun though, especially if you need to eat 1 kg like I do and the potatoes you got are very small :( . Count Iblis (talk) 18:22, 20 December 2016 (UTC)


 * Why do you think you need to peel potatoes. Much of the flavour is in the skins. Peeling is just a tradition of the middle and upper classes that could afford domestic staff to do it. Sure, I peel if going to boil and mash them but small potatoes for salads and things, there is little point. Also you are pre deposing yourself to type two diabetes where you will have to eat loads of potatoes to balance the medication.--Aspro (talk) 19:11, 20 December 2016 (UTC)


 * Agreed. No need to peel potatoes.  If you don't want to eat the peel, just leave it on the plate after you eat the innards, as many do with baked potatoes. StuRat (talk) 19:37, 20 December 2016 (UTC)


 * It does taste well if you eat a few, but if you have to eat 1 kg you'll not find it that appetizing anymore. The skin is not cooked well enough compared to the potato, you'll notice that after a while and it probably won't digest well. And having to leave the peel on the plate for all these potatoes doesn't make for a pleasant eating experience. At least that's my experience some time ago when I was eating in a restaurant. Now, eating 1 kg of potatoes is not going to cause diabetes, as diabetes is caused by beta cells becoming dysfunctional due to eating too much fat. Also eating too much fat causes insulin resistance. Therefore it's best to get as much energy as possible from carbs, and whole grain carbs are the best. Potatoes that stay firm are also good sources of carbs. Count Iblis (talk) 05:59, 21 December 2016 (UTC)


 * If you don't find the potatoes skins palatable, then just fry them in a little coconut oil to crisp them up. Ah! I here you cry – but coconut oil is a saturated fat and is bad for one – certainly is very bad to the profits of the corn oil industry who want you consume their product. Yet, how comes the Caribbeans didn’t suffer CHD nor diabetes? Follow the ''money'! --Aspro (talk) 18:55, 21 December 2016 (UTC)


 * This is the first time I've heard that eating fat causes diabetes and eating carbs does not. Do you have a source ? StuRat (talk) 14:54, 21 December 2016 (UTC)


 * No natural foods contains high levels of fat AND sugar like (say) modern  ice cream.  Which (like heavily advertised 'low fat processed foods but which is high in sugar) which no  longer uses egg yokes as the emulsify and not real diary cream  (a source of mainly lactose). The body, feasting  on this modern diet often fails to keep insulin/blood sugar haemostasis – leading to type two. Inuits, have traditionally enjoyed a high fat, low sugar diet, without suffering diabetes nor CHD until they adopted modern, convenient, heavily promoted high sugar diets.  So no, fat does not cause diabetes (another myth), it is rather the high content of sugar types (which during  evolution we didn't have much of -in the normal diet) which causes  the beta cells  (which you refer to) to give up. When it comes to red kidney beans I am lucky that I live close to a large Asian community and large bags of may different types of pulses are very cheap (can also turn them into bean sprouts by just adding water and changing it a few times). Just bung a big bag  of those into the pressure cooker and after, divide up into small bags and bung those into freezer until needed.  But for small quantities, purchasing a can is probably more efficacious. Also, for those just starting out, even chilli can be grown in flower pots along with mint, sage, rosemary and thyme. That's another few dollars over the years that one can save. Don't like using the pressure cooker for cooking meat though, as it may be quick but the full flavour of meat does not develop. Serves very good, as a slow-cooker though. It also provides an easy way to sauté the onions before adding spices as you don't risk burning them -which gives onions  and garlic a bitter taste (to be pedantic, sauté actually means quick fry -but one has to watch over that processes-  but in an electric pressure cooker pot, ,just leave it on low heat -without pressure- and the result is the very same). So the pressure cooker  was one of my best investments. Go to a second-hand book shop and buy some good cookery book that one's Grandmother would have understood and then...  Enjoy!--Aspro (talk) 15:56, 21 December 2016 (UTC)


 * Reading between the lines. We do Not give medical advice here. Sometimes, one can put 2 & 2 together and come up with 5. A editor here, may be a diagnosed diabetic, and should he see the sense, and thus  radically change  s/he's   diet... that may bring about a crisis though lack of the whole picture  – because the prescribe medication levels are  far more than is what needed on a proper healthy diet. Which may mean a rush to hospital and a telling off by  quacks doctors on the dangers of deviating from the pharmaceuticals companies profit making recommendations, as to how much carbohydrate one should eat each day. If any type two,  should wean  himself off expensive monthly prescriptions - that is also unlikely to please his general practitioner either, who looses out on raking in  the fees of his (life saving ) prescriptions which are no longer necessary after adopting a proper diet.  They ( the recovering  type 2's) often get grilled by their  quacks doctors about their responsibilities to the future of their children (a fear tactic), but without the inhibiting symptoms of diabetes they are able  return to being full time  bread winner who can once again, provide for their families. There are perhaps a few good doctors out there but many just look at it from the financial point of view.  As always Caveat emptor--Aspro (talk) 20:21, 21 December 2016 (UTC)


 * I've eaten just the skin before of a bake potato due to my mum having trouble chewing it and there was no problem. It didn't amount to 1 kg of potato worth of skin, but I have no reason to think it'll be significantly different especially when you're eating the potato as well. Nil Einne (talk) 01:05, 22 December 2016 (UTC)


 * Yes, the skins are nutritious, but there are some caveats:
 * 1) Remove the eyes (or just don't eat them).
 * 2) Restaurants often don't bother washing the skins, figuring nobody will eat them. So watch for sand and dirt.
 * 3) Some restaurants don't wrap them in foil when they bake them, resulting in burnt, inedible skins. StuRat (talk) 17:33, 22 December 2016 (UTC)


 * The potatoes I buy are completely covered in mud, just peeling them looks to me the most practical way to get dinner ready on time. About carbs vs. fat, note that I eat close to 4000 Kcal, my daily running for one hour burns about 1000 Kcal. So, 2000 Kcal from carbs in total (of which about 1000 Kcal from bread) is in my case just half of the total energy intake, and it's recommended that you get between 30% and 50% from fats, although some people have argued that we should only get about 10% from fats. Also, carbs contain more oxygen atoms than fats, for cardio exercise this difference matters; it makes carbs the analogue of high octane fuel. Count Iblis (talk) 22:18, 22 December 2016 (UTC)


 * Mud is water-soluable, so should rinse off easily. On the other hand, trying to peel muddy skin would make the peeler muddy, which would then transfer mud back onto the peeled potato.  So, you need to rinse the mud off first before peeling, too.


 * Also note that boiling potatoes has a cleaning effect. I often find bits of sand in the bottom of the pot which were on the potatoes, and would be unpleasant to eat, but were removed by boiling.  And it's not so important to remove any foreign contaminants if they are all sterilized by boiling. StuRat (talk) 15:40, 24 December 2016 (UTC)


 * About diabetes see here Count Iblis (talk) 22:14, 24 December 2016 (UTC).

Does early sexual maturation predict a shorter life expectancy?
In modern times, humans are becoming sexually mature at younger ages. Does this mean that human life expectancy will decrease or that childhood will shorten? Does this mean that children will live shorter lives than their parents, but because they can reproduce earlier, they can still replace the older generation? Does this mean education has to be squeezed into or reduced to only 5 years of learning time? 66.213.29.17 (talk) 17:41, 19 December 2016 (UTC)


 * Not when earlier sexual maturity is a result of a lack of starvation, versus earlier times (and in particular a lack of protein and fat). A demonstration of this is how long women live past menopause these days.  50 years or more is not uncommon. StuRat (talk) 17:58, 19 December 2016 (UTC)


 * Now if early sexual maturity is a result of a genetic tendency towards rapid aging, then that may be an example of what you meant, but that is not common. Those with progeria, however, do not experience early puberty, and it may even be late or absent. StuRat (talk) 18:01, 19 December 2016 (UTC)


 * We answered a very similar question a few weeks ago:  Dragons flight (talk) 18:32, 19 December 2016 (UTC)


 * Take a minor exception to the OP's comment that humans  now become sexually mature at younger ages.  Juliet (and many other maidens) was only thirteen. Fast-forward to the current age of contraception.  It is now permissible (with parents gritting there teeth) that is thought that teenagers can now enjoy safe sex. The age of sexual awakening though, is  exactly the same  and has remained so throughout recorded history.--Aspro (talk) 18:53, 19 December 2016 (UTC)


 * While certainly some historical people (e.g. Juliet) became sexually mature early, the science strongly indicates that the average age of sexual maturity (specifically menarche) has been falling, in part due to better nutrition. Dragons flight (talk) 20:43, 19 December 2016 (UTC)


 * Your second reference states: "It is not rare among Eskimo women that they have their first child at at the age of twelve, and children born before the mothers were eleven have been recorded." These data are "strictly in accord with the supposition that the hotter the environment, the earlier the maturity."  So, ask again : what has changed during recorded history? --Aspro (talk) 23:55, 19 December 2016 (UTC)


 * In the context of music history (where the voice break for males is the reason why this comes up) I heard it exactly as Dragons flight mentioned, and that the age when Joseph Haydn's (1732-1809) voice broke (seventeen) was perfectly normal for that time due to poor nutrition. But the OP's extrapolation seems to go too far; I don't think it could happen much earlier than it does today without serious biological changes. Double sharp (talk) 11:49, 20 December 2016 (UTC)


 * Injecting hormones would do it, if people thought it was good to have puberty earlier: "Mom, it's so embarrassing ! All the other girls in my class have boobs, and I want shots so I will get them too !". StuRat (talk) 14:51, 21 December 2016 (UTC)

Humans and nature
Other animals spend their days foraging for food. Humans don't spend their days foraging for food. They exchange labor for symbols and use symbols to obtain food. And food has to be prepared a certain way to be appetizing; otherwise, humans won't eat it. When not searching for food, other animals mate, but mating may be confined to a particular breeding ground or time of year or time of day. Humans don't have a mating season. Babies can be born during any time of the year and can be conceived at any time of the day. Furthermore, humans sometimes prevent themselves from reproducing. Other animals die and let their bodies decompose. Humans bury the dead or cremate the dead; they don't want the bodies to be recycled for the growth of new life or allow themselves to be eaten by scavengers. Why don't humans behave like other animals? 66.213.29.17 (talk) 18:46, 19 December 2016 (UTC)


 * We do:


 * Not all animals spend their days looking for food. That's mainly true of herbivores, which don't get much energy per bite.  Carnivores and omnivores (like us) can eat occasionally and then not need to worry about eating for a while.  In the case of some reptiles, it may even be months before they have to eat again.


 * Repeated mating is not unique to humans. Bonobos are a famous example, but bored dolphins will do the same, as will others.


 * Who knows what animals would do with the bodies of the dead if they had the understanding and capability. Maybe they would incinerate them, too.  The basic reason for current human death rituals is that decomposing bodies pose a health hazard, when you have to deal with millions a year.  StuRat (talk) 19:01, 19 December 2016 (UTC)


 * Some huge generalisations from the OP. Mayfly adults have non-functional mouthparts - they do not spend their hours/day/days foraging for food. DrChrissy (talk) 19:18, 19 December 2016 (UTC)


 * If you'd like some references to go along with Stu's claim about reptiles, "After a heavy meal, an individual [python] may fast for weeks", according to Python_molurus, more general info at Snake. What he says about carnivores only needing to eat occasionally is not true in general, though it is true for some species. This is why, at the reference desk, we should support our claims with references to reliable sources, or at least Wikipedia articles. The Mexican free-tailed bat provides a clear counter-example; they eat dozens to hundreds of meals per night, foraging nearly continuously. See Mexican_free-tailed_bat, or here  for a more detailed discussion of free-tailed bat feeding. SemanticMantis (talk) 19:31, 19 December 2016 (UTC)


 * "Why don't humans behave like other animals?" Because we have big brains, and those big brains are both a boon and a bane. ←Baseball Bugs What's up, Doc? carrots→ 19:56, 19 December 2016 (UTC)
 * I'm afraid the OP is also incorrect about the way humans treat their bodies. The Sky burial article describes how this is a funeral practice in which a human corpse is placed on a mountaintop to decompose while exposed to the elements or to be eaten by scavenging animals, especially carrion birds. DrChrissy (talk) 20:02, 19 December 2016 (UTC)


 * Humans do behave like other animals because we are animals. The possible observable deference is the greater brian power, which means that we have a more developed Culture. Some chimps have been observed to pass on to the next generations 'culture'. In humans it has evolved to honer our dead etc. Some, ancient tribes left their dead in open grave to decompose.  There are also arial graves for vultures to consume the flesh of the dead. This is down to local 'culture'.  The psychologist Eysenck showed that humans  do have breeding seasons. The peaks of birth rates occur  in Europe  during  different months from that of Australasia.  The reason that Humans don't have to spend their days foraging for food:  A  little technology ( in the form of hunting weapons, the fashioning of which was passed on to the next generation by passing on 'culture) meant that in a community of perhaps 140 to 160 individuals, those members which were the hunters could provide sufficient  meat for the whole community. Divide the time the hunters spend on hunting by the  total local community and that equates to just 2 days of the week.  Also we developed the means to preserve meat for the lean times of the year.  The women folk of coarse went gathering – but that was also seasonal. That left a lot  of time for our forbears to develop even more culture to make daily life more comfortable. Lastly: And food has to be prepared a certain way to be appetizing; otherwise, humans won't eat it. Have  you watch any documentaries of tribes that still live a hunter gather life? When they are lucky enough to capture a critter -it goes over the fire, fur an all. Not on spit or anything fancy like that. The only way I would bring myself to enjoy a meal with them is for the experience alone. --Aspro (talk) 20:24, 19 December 2016 (UTC)
 * Culture is not limited to humans and chimps. It depends a little on how "culture" is defined, but many animal species exhibit a culture.  see for example Laland, K. N., & Galef, B. G. (2009). The question of animal culture. Harvard University Press. DrChrissy (talk) 18:24, 20 December 2016 (UTC)


 * Good point. Our article on culture does not spell out my understanding which is something like: That which is learned from ones peers which is not an instinctive behavior and which would not  spontaneously come about unless the animal witnessed others perform such behaviour, which  in turn, they learnt from their peers. On that scale, it is a simple dichotomy between nature and nurture. --Aspro (talk) 19:47, 20 December 2016 (UTC)
 * What you are describing is more like cultural learning and you might also like to check out social learning. DrChrissy (talk) 20:06, 20 December 2016 (UTC)


 * See also human nature, human condition, human, and Homo sapiens. SemanticMantis (talk) 23:06, 19 December 2016 (UTC)


 * The treatment of the dead seems like an obvious racket, whether we're talking about the priests of ancient Egypt or the veterinarians who lobby to have it made illegal to put down your own dog with a gun. So I think that ties into the 'trading in symbols', or to be more conventional, money is the root of all evil.  Though of course it can be said that letting dead people rot in the street is bad public health, this doesn't explain the elaborate and inevitably costly rites as opposed to simply having a designated pit.  (cf. recreation in Brave New World, perhaps) Wnt (talk) 01:15, 20 December 2016 (UTC)
 * Cemeteries are memorials to the dead, and are much more useful in history and genealogy than a mass grave would be. ←Baseball Bugs What's up, Doc? carrots→ 01:56, 20 December 2016 (UTC)
 * Common graves were once common, but it was for the poor; social status demanded that you care for you deceased relatives to have a proper tomb. (That could still be the case nowadays.)
 * I would have thought most people from any culture wish to have a burial place, so I looked around a bit. This episode is certainly telling of Liberia's mentality on the subject. On the other hand, to my surprise, lots of Britons are ok with cremation AND ash scattering; presumably few of those wish for a memorial tomb. While one can speculate that people asking for cremation still want a formal ceremony and hence are still attached to a symbol although a different one, there is no attachment to a physical memorial anymore. Tigraan <span title="Send me a silicium letter!" style="color:">Click here to contact me 17:40, 20 December 2016 (UTC)
 * Not sure what you mean by burial place. The preference for cremation among many adherents to several Indian religions in many circumstances is surely very well known, as is the popularity of disposing the cremated remains in the Ganges among many Hindus. There are often specific holy places involved, but it's weird to call these burial places when there's no real burial involved. Nil Einne (talk) 04:10, 21 December 2016 (UTC)
 * Animals do have cultural orientations. See Animal-made art. Also see Henry, The Feline Fiber Artist. Bus stop (talk) 04:11, 21 December 2016 (UTC)
 * From something this it sounds like there are still ways to make dying expensive, even on the Ganges. From this it sounds like firewood at the Ganges is a big part of it.  Honestly I have no idea, nor the patience to research this sufficiently... I just assume that if someone is telling you to go off and get buried at a sacred river, they probably control some kind of concession on the river. Wnt (talk) 07:21, 21 December 2016 (UTC)
 * For the avoidance of doubt, I wasn't commenting on expenses involved, but simply that the assumption that "most people from any culture wish to have a burial place" considering one very well known practice doesn't involve something which would resonably be called a burial place. Nil Einne (talk) 01:10, 22 December 2016 (UTC)

cold and salt killing harmful bacteria
Is water sometimes so cold that it kills all harmful bacteria? Has seawater sometimes so much salt that it kills all harmful bacteria? — Preceding unsigned comment added by 89.7.33.34 (talk) 20:20, 19 December 2016 (UTC)


 * No to both points. Pathogenic bacteria and especially their spores can survive very high levels of salt. Even if the water is very, ever so cold, and frozen to liquid nitrogen temperatures. The nasties are still there and are viable.--Aspro (talk) 20:35, 19 December 2016 (UTC)


 * Further info at Bacterial spore and Dead Sea. ←Baseball Bugs What's up, Doc? carrots→ 20:40, 19 December 2016 (UTC)


 * It is possible to kill all bacteria with salt. For example, salting (food) involves deliberately adding dry salt as a preservative.  However, a dissolved solution of salt has to be much higher in concentration than natural sea water to kill all halotolerant microbes.  Haloquadratum, the most salt tolerant microbe, survives at concentrations 7 times higher than sea water.  Dragons flight (talk) 21:03, 19 December 2016 (UTC)


 * I was going to say something about brine and endospores, but then I ran across this (first here:, suggesting it was still treated as credible in 2014) from Nature in 2000: : "Here we report the isolation and growth of a previously unrecognized spore-forming bacterium (Bacillus species, designated 2-9-3) from a brine inclusion within a 250 million-year-old salt crystal from the Permian Salado Formation. Complete gene sequences of the 16S ribosomal DNA show that the organism is part of the lineage of Bacillus marismortui and Virgibacillus pantothenticus. Delicate crystal structures and sedimentary features indicate the salt has not recrystallized since formation."  I don't know if I missed this or if my mind simply refused to accept it.  I'm going to pause here for opinions, and to try to repair damage to my bullshitometer.  In any case I remain skeptical about the ability of salt to kill all bacteria. Wnt (talk) 01:08, 20 December 2016 (UTC)
 * Even MASSIVE doses of radiation cannot kill certain bacteria. Ever encountered Conan the bacterium? He's a true beast. Eliyohub (talk) 12:00, 20 December 2016 (UTC)
 * Well, that's easier to understand -- it just has mechanisms that resist radiation damage. It uses those to withstand 1000 times the radiation that would kill a human - not taking into account that it has less genome to preserve and it's less important that all cells live.  But 250 million is ... 1000 times 250,000.  Which is 1000 times 250.  And for a bacterium to live 250 years would be really freaking impressive to me. Wnt (talk) 19:39, 20 December 2016 (UTC)
 * Oh my god 250mya, that's hilarious. I'll have to select that paper for my next journal club. DNA's half life is so short that the genome of this critter shouldn't have lasted a tenth of that time period . Between degradation of the backbone and deamination of nitrogen bases, it's generally assumed that most claims of sequencable DNA isolation from samples over 1 million years old are extremely suspect, and over 10 million is impossible. Live organism isolation from beyond even that is simply ridiculous. I'll have to look into this bacterium in the future and see if anyone has specifically rebutted that nature paper. Someguy1221 (talk) 04:41, 21 December 2016 (UTC)
 * Hmm, people are still publishing papers like this . Must look deeper. Someguy1221 (talk) 05:35, 21 December 2016 (UTC)
 * Until proven otherwise, my personal wild guess is going to be that highly halophilic bacteria have worked out a way to swim through solid salt, dissolving then perfectly repairing the crystal behind them as they move, and thus bringing the relevant enzymes along their path with high efficiency in an inclusion. Thus, they would be more prone to be found in these studies because they create inclusions, and they are closely related to each other because they are related modern microbes.  It seems like this would be very easy to test this: take an optically smooth plate of salt like you might have ruined in your undergraduate chemistry days, dip it in a saturated salt solution in which these organisms are suspended, take it out after a while... then wait, and wait, and then look for inclusions. Wnt (talk) 18:12, 21 December 2016 (UTC)


 * The OP's question was : “Is water sometimes so cold that it kills all harmful bacteria? Has seawater sometimes so much salt that it kills all harmful bacteria?” Think it would be better to focus on the biochemistry, that explains how food preservation methods enable food to be kept for long periods without causing food poisoning.--Aspro (talk) 18:33, 21 December 2016 (UTC)
 * You have to remember that food preservation techniques don't require the bacteria or other microbes to die. It's sufficient to arrest their growth. Someguy1221 (talk) 00:20, 22 December 2016 (UTC)

Has any land animal evolved to become a sea animal?
Saw the first episode of Planet Earth II and a lizard has evolved to hold its breath for 30 minutes at a time because there's no food on the island. Any other animals do anything similar or more so? 2.102.185.190 (talk) 23:11, 19 December 2016 (UTC)


 * Evolution of cetaceans. Count Iblis (talk) 23:15, 19 December 2016 (UTC)


 * I think the OP is discussing the marine iguana. Unfortunately, the information they provide is not totally correct.  Our own article states "The marine iguana forages exclusively on inter- and subtidal algae,.... only 5% of marine iguanas dive for algae offshore, and these individuals are the large males." So, this behaviour happens, but is not as common as we might think.  Keep watching the series - it is fabulous! DrChrissy (talk) 23:56, 19 December 2016 (UTC)


 * Polar bears are classified as marine mammals. DrChrissy (talk) 00:03, 20 December 2016 (UTC)


 * Besides cetaceans and polar bears, we could give sea snakes and ichthyosaurs and turtles... looks like list of marine reptiles, marine reptile, marine mammal are useful here. Wnt (talk) 00:49, 20 December 2016 (UTC)


 * Penguins ? StuRat (talk) 01:41, 20 December 2016 (UTC)


 * That's actually "Pengwings" (see 4:05, but the Smaug bit before that is worth the entire video). μηδείς (talk) 03:00, 22 December 2016 (UTC)


 * Not only has a land animal evolved into a sea one, but it made the journey back again, at least according to the Aquatic ape hypothesis. Carbon Caryatid (talk) 01:36, 20 December 2016 (UTC)


 * Whales are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates) and some can hold their breath for up to 90 minutes.  Pinnipeds (seals etc.) are probably decended from bears or musteloids and, according to, elephant seals can hold their breath for up to 2 hours.  Richerman    (talk) 11:28, 20 December 2016 (UTC)


 * Since it's pretty obvious some land animals evolved to live in the water, perhaps the OP was referring more specifically to breathing. That is, has any kind of animal evolved from air-breathing to water-breathing? I'm not aware of any that have, though I wonder if some amphibians might qualify. Matt Deres (talk) 18:11, 20 December 2016 (UTC)
 * I'm not sure that was the intent of the OP. I believe they were talking about the marine iguana which holds its breath - it does not breathe underwater. DrChrissy (talk) 18:15, 20 December 2016 (UTC)


 * The giant salamander fits the bill. embryonically it has gills, which it loses.  Highly vascularized flaps of skin take over the function of oxygen absorption in the adults, allowing them to be fully aquatic. μηδείς (talk) 03:06, 22 December 2016 (UTC)

Any explanation for the Richat Structure?
Read the Wikipedia page but it's a little confusing. Do they know how it came about or not? 2.102.185.190 (talk) 23:13, 19 December 2016 (UTC)
 * What the article says is that "geologists now regard it to be a highly symmetrical and deeply eroded geologic dome". That's clear enough, though the fact that most of the paragraph discusses the evidence against another theory might be confusing. --69.159.60.150 (talk) 23:30, 19 December 2016 (UTC)
 * The most up to date publication on the structure is here, which explains the unusual features of this outcrop. Mikenorton (talk) 14:46, 20 December 2016 (UTC)
 * User:Mikenorton Thanks, however that link won't work for me. If readers go here, they should be able to then click on the academia.edu pdf link to access the "The 'eye of Africa' (Richat dome, Mauritania): An isolated Cretaceous alkaline–hydrothermal complex", Guillaume Matton, Michel Jébrak, 2014. SemanticMantis (talk) 20:32, 20 December 2016 (UTC)