Wikipedia:Reference desk/Archives/Science/2015 June 11

= June 11 =

Why do some people claim to enjoy bitter flavours?
My understanding is that aversion to bitterness is an evolutionarily-conserved trait but adults purport to enjoy bitter coffee or beer or lager. Are they pretending to like it until their response changes or did something "go wrong" in their genetic combination and development into adults? --78.148.104.33 (talk) 01:43, 11 June 2015 (UTC)


 * Are you the same one that asked why other like jazz when you don't? ←Baseball Bugs What's up, Doc? carrots→ 01:46, 11 June 2015 (UTC)


 * No, I'm not but I don't see how this is related. I don't know how a person comes to like the music that they do but I'm talking about tastes in which I expect a similar response across many mammals that developed a sense of bitter taste. 78.148.104.33 (talk) 02:33, 11 June 2015 (UTC)


 * The enjoyment, or not, of the taste of anything surely has to have at least some genetic factor. In last month's interview with David Letterman, he said that he tried Scotch when he was about 11, and it was delicious - he couldn't get enough of it. In contrast, I don't like alcohol, never have. But there could be environmental factors too. ←Baseball Bugs What's up, Doc? carrots→ 05:07, 11 June 2015 (UTC)


 * De gustibus non est disputandum as they say. Gandalf61 (talk) 05:58, 11 June 2015 (UTC)
 * The untranslated Hebrew in that article is especially helpful. NOT (as they say). — Preceding unsigned comment added by Baseball Bugs (talk • contribs) 08:31, 11 June 2015 (UTC)


 * In case it isn't obvious, there are two common definitions for the worse "taste." The question is using the definition of a triggering specific taste buds on the tongue. Specific taste buds trigger the "bitter" taste. The rebuttal and quote use a completely different definition of what a person claims to enjoy. That is purely psychological. There is no relationship between something such as "taste in music" and "sensation of a bitter taste on the tongue." 209.149.113.240 (talk) 13:18, 11 June 2015 (UTC)


 * The evolution issue is that bitter foods may be poisonous, so are best to be avoided, unless you know they are safe, or are starving and willing to take the risk. So, initial avoidance makes sense, maybe with just a small taste.  Then, if there are no ill effects, it makes sense to try a bit more, etc., until it is established as safe.  This translates into "developing a taste" for initially unpleasant foods.   StuRat (talk) 03:26, 11 June 2015 (UTC)


 * Shockingly, the usual reason people claim to enjoy something is because they actually enjoy it. Why do you assume they must be lying, or that something must be 'wrong'? AlexTiefling (talk) 10:02, 11 June 2015 (UTC)


 * Perhaps the question is asking about peer pressure. Everyone at work says they love coffee. Do you say that you find it rather disgusting to ruin a good cup of hot water with ground up tree poop? Of course not. You lie and say you enjoy it also. What if everyone was telling a lie and everyone secretly disliked it? I believe that is what the question is asking. 209.149.113.240 (talk) 13:21, 11 June 2015 (UTC)
 * Where did you get the idea that a plant's fruits and seeds are excrement? ←Baseball Bugs What's up, Doc? carrots→ 17:17, 11 June 2015 (UTC)
 * Yes, technically I'm sipping hot water steeped with ground up shrub embryos and endosperm. OP would probably like this recent XKCD cartoon . SemanticMantis (talk) 20:42, 11 June 2015 (UTC)
 * Right. Those are not excrement. Technically, a plant's excrement would be oxygen, among other things. The cartoon is funny. But I know people who like beer, so it's not a myth. ←Baseball Bugs What's up, Doc? carrots→ 21:22, 11 June 2015 (UTC)


 * I believe that it has to do with accustomisation. In my younger years, I hated grapefruit, coffee, and brandy, and now I exceedingly enjoy all three. It is not a case of me liking the bitterness, so much as it doesn't bother me anymore. Initially I hated the bitterness in coffee, and took my coffee with almost as much milk as coffee drank. As my sense of taste matured, I started to phase out milk and sugar from my coffee. Before long, I noticed that I was adding so little that I might as well leave it out entirely. To my pleasant surprise, I was correct, and was no longer bothered by the bitterness. In fact, I now prefer a double Ristretto when visiting a barista. Not only that, but I found that my general tolerance has increased for other traditionally bitter consumables. However, I can only tolerate bitterness, if there is an accompanying taste reward. For instance, grapefruit are both bitter and sweet. I enjoy grapefruit not for their bitterness, but for the other taste. I suspect that it is the same for other people, how much bitterness are they willing to endure for a reward. I hate absinthe, not because it's bitter, but because the taste of wormwood and anise is not much of comparative reward in my books. I don't think anyone would like the taste of aloe sap, for the same reason. Plasmic Physics (talk) 11:34, 11 June 2015 (UTC)


 * Genetics can have something to do with it sometimes, because when I was younger I was definitely a Supertaster. Even today, I can not (no-way!) eat for example Momordica charantia.--Aspro (talk) 13:35, 11 June 2015 (UTC)


 * This basically comes down to the difference between a flavor and a taste. Virtually nobody enjoys a pure bitter taste, but a flavor is a combination of a taste with odor and other factors.  People can learn to like specific bitter flavors if they are associated with rewarding things.  Tonic water, for example, contains quite a large amount of sugar, which is intrinsically rewarding.  Coffee contains caffeine, a rewarding stimulant, as well as oils that give it a pleasant odor. Looie496 (talk) 13:48, 11 June 2015 (UTC)


 * Not only the difference between flavour and tatste, but also acquired "tastes". Most people dislike coffee, alcohol, and cigarettes the first time they try them, but they come to associate the taste with the ensuant rush. μηδείς (talk) 01:11, 12 June 2015 (UTC)


 * There are plenty of people (myself included) who clearly do enjoy these flavors. Sure, it's possible to suggest that these people are merely pretending to like them for some kind of bizarre social reason - but enough people consume foods and beverages with those flavors when there is nobody else around to impress that it's hard to claim that they don't really enjoy them.
 * In the case of coffee and beer, parents generally keep those things away from small children, so there is no ability to become accustomed to those flavors in early childhood. When they become teenagers, they might experiment with them - and probably will find them distasteful initially - but social pressure may force them to continue to try until a taste for them develops.
 * The question here is whether the 'learned response' that's clearly going on here is:
 * That the initial distaste was learned (in effect) by preventing the senses from learning that these flavors are OK to consume in early childhood, and that this is conditioning is overridden by social pressure in later life ("unlearned")...OR...
 * That there is an inborn instinctive/genetic bias against these flavors that we learn to override later in life.
 * It's not easy to tell which of those things it is. I recall a study (sorry, can't find the link) that showed that even in the womb, babies somehow learn the flavors present in local cuisines and are born with preferences for those kinds of foods.  Notably, children in India are happy to eat strong flavored curry from a very young age, where children born in Europe and America are most definitely NOT happy to do that.  This is true even if a child born in India is adopted into a western-culture before they start eating solid foods...but it is not true of children of those adoptees.  This says that the preference for those flavors is learned from the mother and is not genetic in nature.  However, since we now advice pregnant women not to consume coffee or alcohol, this might well result in a change in preferences in the following generations. SteveBaker (talk) 13:25, 12 June 2015 (UTC)
 * The argument might make sense if there were some bitter tasting substance (not a condiment) that people consumed on its own with no psychological effect. For example, I like horseradish, but only as an accompaniment to meat whose taste it compliments. Is there some drink like beer or coffee that people consume without ever having had alcoholic beer or caffeinated coffee first? μηδείς (talk) 18:53, 12 June 2015 (UTC)
 * The ristretto that I mentioned earlier, actually contains less caffeine than a cappuccino. Normally, caffeine content does not even factor at all for me. I just prefer caf over decaf, because the decaf process detracts from the flavour. Plasmic Physics (talk) 12:11, 13 June 2015 (UTC)


 * In Why We Get Sick, the authors suggest that aversion to bitterness is a straightforward evolutionary adaptation to avoid bitter poisons. However, that avoidance wears out with age because young children are the most susceptible to overcome by toxins and are therefore the most sensitive to the taste. I suppose that, as people get older (and larger), the benefits of ingesting potentially nutritious bitter foods outweighs the (reduced) risks of getting sick off them. Enjoying things we're not supposed to like is one of humanity's defining features. Matt Deres (talk) 13:31, 14 June 2015 (UTC)


 * I suspect there is a subtle genetic factor at work here. A friend of mine detests celery. I don't much care for it, but I don't hate it either. Other people seems to like it. Women in my family seem to like vegetables. That could be because of their requirements for iron, but why don't they go for red meat? Well, that could be cultural. Taste (as in flavor) is intimately tied to smell, and while there be small variation in people's taste buds, I suspect the variation in the ability to smell is much greater, which gives rise to widely varying food preferences.50.43.33.62 (talk) 14:23, 14 June 2015 (UTC)


 * Veggies provide lots of nutrients, such as StuRat (talk) 15:20, 14 June 2015 (UTC)

Flying in Mars
Could a plane of some kind fly on Mars? Or a zeppelin float?

The atmosphere is much thinner there, but so is the gravitational force. And the atmospheric pressure you would have to deal with in the case of the zeppelin is much lower lower. Hydrogen is less dense than the CO2 that makes the Atmosphere of Mars.--Abaget (talk) 17:30, 11 June 2015 (UTC)
 * NASA Langley's ARES program designed an aircraft for use on Mars. You can read our article, Aerial Regional-scale Environmental Survey, for an overview of the aerodynamic challenges.  In 2013, the mission was cancelled in favor of MAVEN, an orbital spacecraft.  Evidently, NASA's upper management does not believe that the scientific benefits of an aerodynamic flying platform on Mars are worth the costs and risks at this time.  However, perhaps at some time in the future, new technology or new scientific research objectives will reopen this avenue of exploration.  Nimur (talk) 17:53, 11 June 2015 (UTC)
 * For a more humours but still serious discussion on the subject, see xkcd "What if?" on Interplanetary Cessna. WegianWarrior (talk) 18:04, 11 June 2015 (UTC)
 * An enlightening aspect of that source was the statement that Titan has "surface pressure only 50% higher than Earth’s with air four times as dense." This is because its atmosphere (largely nitrogen like ours) is at only 1/3 the Kelvin temperature!  (Ideal gas law)  This would also be a factor in favor of Mars flight, but not to the same degree.  I'm guessing that air resistance should depend on the pressure and mass, but lift should depend only on mass?  No, wait... I better not spout off on this one, Nimur might put me in the stocks. Wnt (talk) 19:29, 11 June 2015 (UTC)
 * Lift also depends on air temperature and air pressure. Because the atmosphere of Mars is so different than Earth, if you want to accurately estimate lift generation, you also need to account for the fact that the air pressure is produced by different species of gas molecules.  To engineer an aircraft for such an atmosphere is deep into the territory of poorly explored aerospace engineering: there have not many empirical studies of airfoil performance characteristics in any atmosphere that is anywhere remotely near to Mars' near-surface environment.  The ARES team published Mars Airplane Airfoil Design with Application to ARES (2003) summarizing their research to that time.
 * For most purposes, aircraft performance is "equivalent" when density altitude is "equivalent." Density Altitude (on Earth) accounts for pressure, temperature, humidity, sea level pressure, and true altitude above sea level.  On other planets, one could construct a "density altitude equivalent".  To complicate matters, we do not have great weather prediction capability for other planets: we don't have dense networks of ground- and satellite- weather observations; nor do we have centuries of meteorological experience and theory.  Local atmospheric weather variations on Mars are known to deviate up to 20% (nominally) from our "best" Mars weather models: so we would need to over-design the aircraft performance to handle worst-case pressure, wind, and so on.
 * It's a fascinating topic; it's worthy of many years of study and depends on a lot of prior understanding about spaceflight and aeronautics. One of the key troubles with the Project Apollo Lunar Roving Vehicle was the persistent belief by many outsiders that it would be a "simple" engineering challenge analogous to building an (electric) automobile on Earth.  Boeing spent considerable advertising effort to remind everyone involved that this vehicle was actually a manned spacecraft, not a mere golf cart: it had to be built on Earth, transported through space, and survive with all its functionality intact, and then to operate on another world.  (I'm thinking of a specific and very memorable color brochure/pamphlet published by either GM or Boeing, but I can't find it at ALSJ's Lunar Rover document archive). So, when we talk about operating an aircraft on Mars on in the atmosphere of some other planet, it's very easy to overlook how very complicated the process is.  Not only does the aircraft need significant engineering for the unique conditions at Mars - it also must survive the journey to Mars, within the realistic constraints of dollar budget, fuel budget, mass budget, energy budget, and the risk/reliability envelope!
 * I don't think we can adequately summarize all of the engineering challenges except to point any interested reader towards the massive amount of available information from NASA's planetary sciences programs. The ARES mission is a good starting place, as it is the most recent major serious effort to design an aircraft for extraterrestrial operation.
 * Nimur (talk) 19:53, 11 June 2015 (UTC)
 * I agree that the ARES study is the "go-to" place to find the latest research. Winged or rotor-driven flying machines are be tricky but not impossible on Mars.  A "sufficiently large" balloon should work - but it might need to be huge to have any useful payload.  Most of Mars' atmosphere is CO2, which is really heavy - even a balloon filled with normal Earthlike air should be able to float.  The problem is with "sufficiently large" because Mars' atmosphere is pretty thin - so you'd need a lot of volume to displace enough atmosphere to counteract the weight of the balloon itself.  The problem is that with the air being so thin, and yet have fairly large wind speeds is that you really need rockets rather than jets or propellers to get thrust and to keep control of the thing - the need to provide reaction mass means that you're unlikely to be able to build something that is solar powered or electrical in nature - and then you're back to chemical rockets that aren't sustainable for a long duration exploratory flight.  One of the weirder ideas is a gas filled balloon that moves around by hopping and bouncing (possibly to impressive heights) which could use this occasional contact with the ground to provide thrust and some kind of steering.  Gyroscopes could provide orientation control while up in the air. SteveBaker (talk) 13:06, 12 June 2015 (UTC)


 * Martian surface gravity is ⅜ of Earth standard, but the air pressure is far less than ⅜ of Earth's. —Tamfang (talk) 05:30, 13 June 2015 (UTC)

Dr. Charles Drew car accident
Who are the 3 doctors that were in the car when Dr. Charles Drew had his accident? What are their bios? Are there any articles on these other 3 doctors? I believe one of them was Dr. Walter R. Johnson, from Washington D.C. — Preceding unsigned comment added by 172.56.10.47 (talk) 23:47, 11 June 2015 (UTC)


 * See Charles R. Drew for our article. According to this article from  NCBI, which goes into quite a bit of detail about the accident, the other passengers in the car were Walter Johnson, Sam Bullock (the owner of the car, although Drew was driving),  and John Ford.  Tevildo (talk) 01:14, 12 June 2015 (UTC)


 * This is Dr Bullock's obituary. The best information I can find so far on Dr Ford is in the NCBI article.  Research is continuing. Tevildo (talk) 01:47, 12 June 2015 (UTC)


 * Does anyone else notice that Charles Drew is supposed to be black, but doesn't appear to be so in the pics in our article ? StuRat (talk) 17:49, 13 June 2015 (UTC)
 * This page has several photos of him that, shall we say, indicate his heritage more definitely (in particular, this one - high resolution). See also one-drop rule.  [No joy yet on Dr Johnson, I'm afraid - he doesn't seem to have had a sufficiently prominent career to be recorded on the internet]. Tevildo (talk) 18:44, 13 June 2015 (UTC)