CULTURAL QA 12-2023-04 Allthe BELOW QA are from Quora DIGEST to me on 05-12-2023.
QUORA ANSWERS NEED NOT BE100% CORRECT ANSWERS. Compiled and posted by R. Gopala Krishnan, 80, on 05-12-2023. Q1 Ifwild animals, both predators and prey adapted their appearance to be a camo intheir natural habitats, why are none of them green? A1 GaryMeaney, passionate fan of all things animal2y Our perception of colour is differentto that of other animals, and that’s important to keep in mind.Take placental mammals, for example. To a deer in a lush forest, a prowling tiger would not appear orange.If it did, it wouldn’t be very good at ambushing its prey. Rather, the deer would perceive thetiger as the same colour as the surrounding vegetation. Let’s take a closer look and explainwhy this is. Humans, of course, are primates, and to be more specific we arepart of the Old World monkeys, or catarrhines. Most catarrhines are trichromatic - in their eyes, theyhave three different types of cones, which are colour-receptive cells. These three cone cells detect red, blue and green. If red and green fire at once, the brain interprets thatas yellow. All other colours are some combination of the previous four. Becausewe can distinguish red/yellow (orange) from green, a human or a macaque couldsee the orange tiger in the green grass. There are a couple of possiblereasons why Old World monkeys became trichromats. It may have been to spotfruit in the trees, or perhaps to notice when one of their peers blushes.Subtle changes in skin tone are one of the many social cues which are importantfor cooperation in primates. Reptiles, including birds, are also trichromatic. This is why birds often have such vibrant, colourfulplumage, and indeed why there are many green reptiles. That brings me to asecond point, which is that there certainly are green animals. Some of you may now be wondering -given that our reptilian ancestors were trichromatic - why mammals lost one oftheir cone cells, only to re-evolve it with the OldWorld primates. The thing is, whiletrichromacy is obviously great for colour vision, it’s not the best for seeingin the dark. Old World monkeys are all diurnal, so we don’t have thisproblem. However, when the first placentalmammals evolved, the world was dominated by dinosaurs, which were far largerand hungrier than them. They could only come out during the night, when most ofthe trichromatic dinosaurs were inactive. They lost one of their three conecells in order to have improved night vision, and became dichromatic. This means that they use the samecolour receptor for red and green, and thus any kind of brownish or orangey huewill be more or less indistinguishable from the colour of foliage. This is, ofcourse, why most mammals are brown, and why primates are the most colourfulmammals: Now, some bonus fun facts. Marinemammals such as seals, sea lions, whales, dolphins and so on are in factmonochromatic - all their cone cells are the same,so instead of perceiving different colours, they simply detect the intensitylevel of light. Water, being dense, tends to scatter and absorb longerwavelengths of light, so there’s not much reason to have good colour vision. There are even mammals which arenaturally tetrachromatic, which have four different cones - reindeer. Up in the Arctic, the sun may stay in the sky for a verylong time, so objects end up absorbing a lot of ultraviolet radiation. Due totheir tetrachromacy, reindeer are very sensitive to UV light, and thus foodsources like lichen contrast starkly against white snow, which reflects theradiation. Anyway, to summarize my answer toyour question: whilethere are certainly many green animals, you don’t often see green mammalsbecause they (and their predators) usually struggle to distinguish brownishcolours from the colour of plants. This is because most mammals detectred and green using the same type of cone cell in their eyes. Q2 Howis helium a finite resource if we're constantly wasting it on things likeballoons? A2 GeoffreyWiddison, Been learning science since I was six, still getting started. Updated2y It’s a finite resource because we have no practical way to make more ofit, so when we exhaust the available supply, we’ll be out. Now,if you’re asking why we’re wasting it on balloons, the reason is simple: capitalism. The free market doesn’t care whethera resource is limited or crucial, it cares what people will pay for. Being limited means aresource will become more scarce over time, it doesn’t mean that the supply islimited right now. We’ve gotample helium for the time being. And as long as people are willing topay a buck or more for a cubic foot of gas in a balloon (and that gas is onlyabout half helium, nowadays), the market will sell it to them. Eventually, we can expect helium tobecome more scarce, which will drive the price up, and consumers will no longerbe able to afford balloons.But that will also mean that the price is higher for its more essentialfunctions. The only way to prevent this is tobypass capitalism. Wecould pass laws prohibiting frivolous uses, but such an action would be a veryhard sell in the US. The government did maintain a Strategic HeliumReserve for a long time (yes, I know it sounds fictional, but that’s a realthing), but it was privatized years ago, causing all that saved helium to besold on the private market. As a result, the government is taking really no measures to conservehelium, most of the public either doesn’t know enough or care enough to do so, and the market only responds to current supply anddemand. So we keep digging it up and selling it, and will do so until we can nolonger meet demand, and then the price will rise. EDIT: I've been getting a bunch ofcomments that seem to be laboring under the same misconception, so I'll addressit here. Helium that gets soldis not taken from the atmosphere. Helium in the atmosphere is far too low inconcentration to realistically extract in large quantities . The helium we use comes fromunderground deposits that took millions of years to accumulate. Every depositwe deplete is gone forever. Q3 Whatis the membrane of the heart? A3 Soniya,5h The heart's outer membrane is calledthe pericardium, consisting of two layers: the visceral (inner) pericardium andthe parietal (outer) pericardium. These layers enclose the pericardialcavity, which contains fluid, reducing friction as the heart beats. The visceral pericardium is closely attached to the heart's surface, while the parietal pericardium is further away and fusedwith the fibrous pericardium, a tough outer layer providing protection andanchoring the heart in the chest. This complex structure supports the heart's function by allowing it tomove within the pericardial sac while maintaining a lubricatedenvironment. Q4 Couldlife have sprouted in different parts of the world over millions of years, ordid it happen in one spot only and spread everywhere? A4 KenSaladin, Freelance author of jest 21h I think it’s quite certain that the first proto-biological organic molecules and first protocells did arise in manydifferent places. It’shighly improbable that it would happen only once, in one spot on the globe. Thebiochemical evidence, however, strongly suggests that all life today came froma single ancestor. It’s not hard to imagine a scenariofor this. Suppose one protocell in a hot little puddle reproduces itself andeventually a small colony or “soup” of them exists. As such colonies encountereach other—spreading until they merge—they will compete for the chemicalresources needed for their survival and replication. The most successful ofthem—the most likely to produce descendents—will be those with (1) the greatestchemical stability or resistance to disintegration; (2) the fastest rate ofreplication; (3) the greatest fidelity of replication; (4) the most efficientuptake and use of environmental matter and energy; and (5) the most viablevariants (proto-mutation, if you will), hence the ability to spread intoslightly different environments (differences in wetness or aridity, waterdepth, pH, solar radiation, etc.). SoI say yes to both parts of your question: I think “life” (broadly defined)probably did arise in many places, but that today’s living organisms arose from lifeforms that originated from one place and “spread everywhere,” while theless successful variants (by the five criteria above) could not compete andwent out of existence. In other words, natural selection probably existed evenbefore true cells and organisms did. Q5 Whycouldn't Feynman answer the question about why magnets repel each other? Heclaimed that he wouldn't be able to explain it in layman's terms. Is this trueor was he unprepared to give a good answer at the time? A5 BrandonRoss, contributor at ScienceGrok.com8h It’s mostly true. Hell, most peoplecan’t describe how magnets work. I went there. Let alone why theywork. The problem is that perceivedmagnetic forces don't have a very satisfying explanation in layman’s terms. Atleast, not beyond saying, they exist. How deep do you want to go? There are quantum properties and effects atplay. And too manythings occurring simultaneously to fairly describe the phenomenon that humansactually observe. Sure, you can describe this complicated how. You can analogize. But, theanalogy just isn’t very satisfying explanation. Italmost never answers the, “But why? And why in this case and not everywhereelse?” Well. Let's just listen to whatFeynman said during an interview: And note that very perceptive initialresponse: “What do you mean, ‘What is the feeling between two magnets’?” “Whatdoes [your question] mean?” “What isthat you want to know?” If you want to really answer somehard questions, it behooves you to first understand what you’re really tryingto answer. And—ironically—why. Q6 Whatis the most important invention of the past 200 years that we often take forgranted? A6 SilkRoad, AI Expert Sun I bet you have a lot of things inmind, like smartphones, cars, or internet. But what if I told you that there is something even more essential andlife-changing that we use every day without giving it much thought? IndoorPlumbing Ancientcivilizations like the Greeks and Romans had some pretty cool systems to bringwater to their cities and homes, using aqueducts and public baths. But they also had some nasty problems with sanitation, like dumping theirwaste into rivers or streets, which caused diseases and pollution. Things got even worse during themedieval and Renaissance periods, when people had to rely on wells, cisterns,or rain barrels for their water supply, and used chamber pots or outhouses fortheir toilet needs. Imagine having to fetch water from a well every time you wanted to drink,cook, or wash yourself. And imagine having to empty yourchamber pot into a cesspool or a ditch every morning. Gross! But things started to change in the 1800s,thanks to the Industrial Revolution and some brilliant inventors who came upwith new ways to improve water and sanitation systems. For example, in 1829, the TremontHotel in Boston was the first hotel in the U.S. to offer indoor plumbing to its guests. And in 1848, the Public Health Act in Britain required every new house tohave a drain connected to a sewer system. That was a huge step forward forpublic health and hygiene. But indoor plumbing was not just aboutconvenience and cleanliness. It was also about social justice and equality. You see, before indoor plumbing was widely available, poor people had tosuffer from lack of access to clean water and safe sanitation, which made themmore vulnerable to diseases and infections. But with indoor plumbing, billions could enjoy the benefits of havingwater and toilets in their homes, regardless of their income orstatus. That's what I call a game-changer. Unfortunately as of 2023, around 60 percent of the world's population or 4.5 billion people either have notoilet at home or one that doesn't safely manage human waste (Unicef). Q7 Howdid humans evolve in such a perfect design? A7 JohnTalbot,3h Speaking as a doctor of medicaleducation - let me assure you the human body is a total mess - had it been designed (rather than having evolved) thedesigner would have to be a moron. Some of the weirder “design flaws” are directly due to evolution - such as the left recurrent laryngeal nerve. It onlyneeds to be a few centimeters long - from the base of skull to the throat, butinstead… …it goes on a magical mystery touraround the main blood vessel in the chest. The reason? In our fish ancestors, this blood vessel was much closer to the base ofskull. Inhumans, due to evolution, it no longer is. In fact, it has the same route in all animals that evolved from fish.Imagine how long it is in a Giraffe. In a dinosaur, such as a Brontosaurus, itwould have been 30 meters longer than needed. Now - back to human “architecture”who would build the sewage works a centimeter away from the water works and thematernity unit? -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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