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

= May 19 =

Human height data
Can someone tell me where to find data about the distribution of human heights? More specifically, for adults in North America, or the USA, or Canada?

Thanks, CBHA (talk) 04:39, 19 May 2016 (UTC)
 * Our article on Human height, has US specific age x growth and age x height graphs for males and females. Vespine (talk) 06:49, 19 May 2016 (UTC)

Why do women prefer tall men (besides these reasons)....
there are exceptions of course, but women on the whole prefer taller men as mates. If you asked a woman who feels this way why she feels this way, she might say something about tall men being stronger, making her feel safe, etc.. And while all height might be *loosely* correlated with physical strength, we all know plenty of short people who are strong as oxen as well as many tall, skinny weaklings. Also, if you asked a woman who she found more attractive: a competitive strongman who was five-foot-2 or a man of slightly  below average strength who was six foot two, and they were equal in all other ways, many woman would choose the tall guy.

So if we assume, for the sake of argument, that height is NOT a reliable proxy for physical strength, what are the other reasons for preferring tall partners? Is it considered a proxy for good physical health (related to strength, but not the same thing), or is it just some kind of inexplicable evolutionary behavior of which the woman herself is unconscious?--Captain Breakfast (talk) 07:15, 19 May 2016 (UTC)
 * There may be some opportunistic motivations such as you are describing ( if accurate however that there exists such thing as an homogeneous set of the "women" the way you are classifying them ). But if we are considering sets, there may be also a question of an image (resulting from the pattern and used in that hypothetical pattern of an element of one set considering those of an other set ). Selecting randomly one of the cloud links in the article image could lead you to the article microscope. If you were a woman you probably would not want to carry the device around, so there is some chance that too tall works too. My opinion is that the view you're exposing is probably accurate only as long as the market can absorb and afford to further increase the size of our SUV's, after this will become too expensive and the market crashes there is some chance we might come to observing the opposing trend. --Askedonty (talk) 07:51, 19 May 2016 (UTC)


 * There are lots of studies – this gives a good overview. When done properly, evolutionary psychology (and other evolutionary studies) doesn't say "This trait evolved because it had this advantage" but rather "This trait evolved because it improved survival or reproductive for this reason" (see misconceptions about evolution). Evolution doesn't have a plan - it doesn't know that tall men are stronger - it's just a process of random mutations that have no real goal. So - assuming it's evolved and not cultural - women didn't evolve to prefer tall men because they're stronger, but maybe because the children of women who preferred tall men were more likely to survive to adulthood, or perhaps because tall men were able to defend and care for the woman better so she lived longer and had more children. Smurrayinchester 08:54, 19 May 2016 (UTC)
 * (Jayron32's answer to the question below reminds me that sexual selection may also play a role here - in theory, if tall men dominate in the population, women who are attracted to tall men have an advantage since they have more partners to chose from.) Smurrayinchester 14:19, 19 May 2016 (UTC)
 * The "height is NOT a reliable proxy for physical strength" claim caught my eye. Assuming that this is an evolutionary trait (it may be cultural - it would be interesting to see any studies from Asian regions where humans are, on the average, shorter), evolutionary preferences do not have to be reliable. They just have to be right slightly more often than wrong. --Guy Macon (talk) 09:50, 19 May 2016 (UTC)
 * It exists at the least. I always wondered why my short Asian mom hoped I'd grow till 6 feet. Sheesh. That is not realistic when her husband's 5'8" and her family's way shorter than 5'9" (my actual height). Sagittarian Milky Way (talk) 14:49, 19 May 2016 (UTC)


 * A couple possibilities come to mind:


 * 1) Age marker. If a male is tall, there's was good chance they were an adult, or at least old enough to father and hopefully care for children.


 * 2) Health marker. Poor health, and in particular a protein-poor diet, can result in short height.  So, a tall man is more likely to be healthy and have access to good food. StuRat (talk) 16:02, 19 May 2016 (UTC)


 * Two words: Stiller... and Meara. ←Baseball Bugs What's up, Doc? carrots→ 19:34, 19 May 2016 (UTC)


 * Sexual dimorphism is correlated with polygyny in animals. Last I looked, I think the figure for humans was somewhere on the curve around where 1.4 females per male fall, though I should recheck that. Wnt (talk) 23:08, 20 May 2016 (UTC)

Evolutionary body hair reduction in females
Both female and male apes, including chimps who are regarded as the closest relatives of humans, are fairly hirsute. Human females, however, became less hirsute during evolution, losing facial and most of body hair, compared to males. Why is that?--93.174.25.12 (talk) 09:33, 19 May 2016 (UTC)


 * Who says so? ←Baseball Bugs What's up, Doc? carrots→ 09:44, 19 May 2016 (UTC)


 * Excuse my learned colleague, he always answers a question with another one. There doesn't seem to be one accepted hypothesis, but Evolution and Prehistory: The Human Challenge by William A. Haviland, Dana Walrath et al (p. 158) presents the argument that the human body hair pattern is the result of a large brain and a bipedal gait; the "Wheeler" mentioned seems to be Professor Peter Wheeler. There's also the now largely discredited Aquatic ape hypothesis, which puts our hair pattern down to spending a lot of time up to our necks in water at an early stage of our evolution. Alansplodge (talk) 12:45, 19 May 2016 (UTC)


 * Not always, just when an OP's premise is based on facts not in evidence. ←Baseball Bugs What's up, Doc? carrots→ 19:33, 19 May 2016 (UTC)


 * What? Are you asking for a citation for the statement that most women don't have beards? CodeTalker (talk) 20:20, 19 May 2016 (UTC)


 * Many men have sparse facial hair and/or body hair. And many women have some facial hair and certainly leg and underarm hair. The OP's premise is flawed. ←Baseball Bugs What's up, Doc? carrots→ 21:51, 19 May 2016 (UTC)


 * There is also the general concept of sexual selection; traits desirable for mating get passed on to future generations. Those traits don't have to be "advantageous", they just need to make one's mate horny.  -- Jayron 32 13:02, 19 May 2016 (UTC)


 * Sexual selection is the only theory thus far that explains the sexual dimorphism seen in the hair patterns of men and women. Halting of hair development at the juvenile stage or Vellus hair is consistent with men preferring juvenile characteristics in a breeding partner, evident today in the near total removal of pubic hair in pornography for male consumption. A rationalisation that body hair might conceal the female's state of health can be related to medieval witch-hunts when an alleged witch would be shaved to discover the so-called Witches' mark on her body. AllBestFaith (talk) 13:18, 19 May 2016 (UTC)


 * A twist on the sexual selection theme is the suggestion in Evolution and Human Sexual Behavior by Peter B. Gray, that body hair is associated with sebaceous glands and apocrine glands which make men smell stronger than women; women also have a better sense of smell than men, which "fluctuates across the ovulatory cycle" making women "more aware of male scents at times when it may matter most". Alansplodge (talk) 16:08, 19 May 2016 (UTC)


 * Yes, not a better sense of smell, a differently selective one. Counting everything, they may have a number of sensitive advantages which, those amongst them using male distraction as a useful extension to their own set of camouflage, allows them to point smarter. --Askedonty (talk) 22:25, 19 May 2016 (UTC)


 * Clothing (wearing furs, initially) is likely a factor in both reduction of thickness in hair in males and females (and even more so in children). That is, one of the main advantages of a thick coat of hair, keeping warm when it's cold out, was no longer an issue.  The advantages of less hair include increased effectiveness in cooling by sweating, which would be important where humans first evolved, in Africa.  Other benefits include fewer skin parasites, like fleas and lice.  This doesn't directly address the Q of why there would be a differences between males and females, but once there was a mix of genes for "less hair" and "more hair", this allowed sexual selection to occur. StuRat (talk) 16:09, 19 May 2016 (UTC)


 * A reference for StuRat's post above. Alansplodge (talk) 16:13, 19 May 2016 (UTC)


 * Was the African savannah ever cold? Sagittarian Milky Way (talk) 16:47, 19 May 2016 (UTC)


 * Currently it's "consistently cool to cold at night" although that's relative - 15 degrees Celsius. Still a bit chilly if you're naked I should think. Alansplodge (talk) 17:27, 19 May 2016 (UTC)


 * I guess the savannah's pretty high and/or dry then. York, Nebraska is a grassland 41° from the equator, 0.5km above sea level, has hardly any heat island and averages 17.6°C lows in mid-summer. Singapore's record low is only 19.4°C! Sagittarian Milky Way (talk) 18:44, 19 May 2016 (UTC)


 * Naked and possibly wet, if it just rained, and children would be particularly vulnerable to losing body heat, especially when windy. But with some nice furs to wrap around the kids, they should stay warm even in a storm. StuRat (talk) 03:38, 20 May 2016 (UTC)

Where in a plasmid map is 0 bp?
Since a plasmid is circular, is there some convention for determining where it starts (like the origin of replication?) when producing a plasmid map with indicators regarding the map length (the ruler which marks every, say, 1000 bp)? --129.215.47.59 (talk) 12:38, 19 May 2016 (UTC)
 * See here. The covention is to start numbering base pairs at the point in the plasmid known as the ORI, or "Origin of Replication".  The Wikipedia article titled Origin of replication also has some discussion of plasmids.  -- Jayron 32 13:24, 19 May 2016 (UTC)

Can grape consumption kill true foxes?
--Romanophile (talk) 16:47, 19 May 2016 (UTC)


 * This PhD dissertation says, with further citation, that foxes eat grapes sometimes. Remember the dose makes the poison, and this evidence of foxes eating grapes does not contraindicate toxicity (i.e. LD50) at high doses.   SemanticMantis (talk) 17:24, 19 May 2016 (UTC)


 * I doubt anyone knows for sure. We don't really know what causes grape and raisin toxicity in dogs, and the phenomenon wasn't noticed until relatively recently.  As many dogs have eaten grapes/raisins without any apparent symptoms, there have been suggestions that it might not be the grapes directly but rather something associated with them such as a pesticide or fungus that is actually the toxic agent, but at the moment we don't know what it is about grapes that sometimes makes some dogs sick.  Out of an abundance of caution, vets generally advise both dogs and cats to avoid grapes (though cats are unlikely to eat grapes and have never been documented to have a bad reaction ).  For what it is worth, thepetfox.net says that most foods that are bad for dogs are also bad for foxes and that foxes should not be allowed to eat grapes and raisins .  Dragons flight (talk) 17:40, 19 May 2016 (UTC)

Light trajectory inside a rocket at uniform speed
Hi, I'm starting to study General relativity and there is something that I can´t understand. If we are in a place without gravity inside a rocket with no movement and we turn on a flash light we will see the light trajectory as a straight line, for example, horizontal. If we accelerate the rocket up, so will see the light doing a curved trajectory as parable with inclination proportional to acceleration. In this explanation sometimes books give us example that the rocket moves faster each time interval and so the trajectory inside behaves as a parable. So my question is "Whats happen if the rocket is moving up at uniform speed and we turn on a flash light ? The trajectory of light will be a straight line horizontal or a straight line inclined down and with inclination proportional to speed ?" Suppose that my flash light is placed horizontal at left side at middle height of rocket.

If I think that the rocket at uniform speed has the same behave as a rocket with no movement, I will conclude that light trajectory will be a straight lin horizontal with no inclination. But if I think of explanation that while light is moving from one side to another, and during this time the rocket it´s also moving, I will conclude that light trajectory it should be a straight line with down inclination.

How can I explain and solve that ? — Preceding unsigned comment added by Futurengineer (talk • contribs) 18:05, 19 May 2016 (UTC)
 * You question really concerns the special relativity not general relativity since the speed is constant. You can also read aberration of light article. Ruslik_ Zero 20:34, 19 May 2016 (UTC)


 * Since the motion is uniform, it's equivalent to view the rocket as moving past other objects, or as stationary while other objects move past it. In the frame of the rocket, it is stationary and the beam moves in a straight line horizontally.  In the frame of an object which the rocket is traveling past, the rocket is moving at a constant speed and the light beam is moving at an angle (no longer horizontal) slanted in the direction of the rocket's movement, but still a straight line.  CodeTalker (talk) 21:40, 19 May 2016 (UTC)

Chermetids
What are chermetids? Cave insect mentions these animals in the penultimate section of its intro, and unlike all other animals in that area, chermetids is a redlink. A Google search pointed me to, which says The false scorpions, Chermetidæ, may at once be recognized... (this is in the original printing, not an OCR error), but no such name appears at Pseudoscorpion, the target of the False scorpion redirect. Is this perhaps a typo for Chernetidae? Nyttend (talk) 19:06, 19 May 2016 (UTC)
 * It would seem also certainly to be a typo, since Chernetidae is a family of pseudoscorpions. Typing m for n would be easy to do.  -- Jayron 32 19:15, 19 May 2016 (UTC)
 * If it is a typo, then it is both very old and very persisent: 120 google books, spanning at least 1886-1999. Here are a few rather divergent bibliographic entries for the same work of Menge, who is the name authority for Chernetidae. It seems that he probably intended to give the family a name starting with "chern", but "Chernetiden" one spelling offered by google. Without seeing the original book (or perhaps  Chamberlin (1931) or Beier (1932) as per ), it's hard to say for sure what happened.
 * Anyway, I agree that the words "chermetid" and "chermeditae" will almost surely refer to a family of psuedoscorpions also known as Chernetidae. I don't know what WP policy is when we cite a source that seems to have a mistaken spelling. Probably some big argument about truth vs. verifiability... I see now that someone has redirected chermetid to chernetidae, which either fixes the problem or exacerbates it, depending on your viewpoint and the value you place on adherence to proper taxonomic names ;) SemanticMantis (talk) 20:13, 19 May 2016 (UTC)
 * Just remember, "verifiable" means "able to be shown to be true". Verifiability not truth does not mean we are bound to repeat errors merely because they were recorded.  -- Jayron 32 21:57, 19 May 2016 (UTC)
 * The distinction is apt, and relevant to WP in general as well as this matter in particular. In case it's not clear, I am well familiar with the dictionary definition of verifiability, and I thought I was making an obvious allusion to Verifiability,_not_truth. I honestly cannot tell what the truth of the history is, or if perhaps ICZN views the names as synonymous in the limited sense of Synonym_(taxonomy). In this case, the name of the family is verifiably Chermiditae. It is also verifiably Chernitidae. If anyone thinks that is impossible, then I encourage them to practice belief in impossible things. Sometimes I've believed as many as six impossible things before breakfast :)SemanticMantis (talk) 22:23, 19 May 2016 (UTC)


 * Regardless of sourcing, Wikipedia is not supposed to be in the business of posting information that is demonstrably false. ←Baseball Bugs What's up, Doc? carrots→ 22:04, 19 May 2016 (UTC)
 * The presence of multiple printed sources with the same misspelling is easily sufficient for creating a redirect for the wrong spelling; see R from misspelling, which I didn't use when creating the chermetid redirect. It's not fundamentally different from pages such as Threshhold and Millenium, which exist for the sake of people who misspell it themselves or people who might find the spelling error in print without knowing how properly to spell it.  Nyttend (talk) 02:07, 20 May 2016 (UTC)

Lifeboats
Looking at http://www.usatoday.com/story/travel/cruises/2016/05/18/royal-caribbean-harmony-first-look/84437986/ ("Exclusive: Inside the largest cruise ship ever built") I am having a hard time believing that that many lifeboats could possibly hold "6,780 people, not including crew". Looking into it further, I found http://www.cruiselawnews.com/2013/01/articles/sinking/titanic-redux-can-royal-caribbean-safely-evacuate-8500-passengers-crew-from-the-oasis-of-the-seas/ ("Titanic Redux? Can Royal Caribbean Safely Evacuate 8,500 Passengers & Crew from the Oasis of the Seas?") But what if the ship lists before the evacuation starts? Will the lifeboats and rafts on the high side be usable? And how fast can that many people evacuate without trampling each other? --Guy Macon (talk) 21:11, 19 May 2016 (UTC)
 * There was "lifeboat sticking out technology" as early as the Britannic 1914. It would be stupid for the to regress. I believe they could even carry the lifeboat over the ship and launch from the other side if there was too much list. Not sure. Sagittarian Milky Way (talk) 21:55, 19 May 2016 (UTC)
 * "lifeboat sticking out technology". Davit. --Tagishsimon (talk) 21:57, 19 May 2016 (UTC)
 * That would not have helped Titanic, whose problem was the removal of lifeboats from the ship before it set sail. Which takes us back to the OP's question: Do these ginormous cruise ships have enough lifeboats, or are the operators gambling with their passengers' lives, as the operators of Titanic did? ←Baseball Bugs What's up, Doc? carrots→ 22:03, 19 May 2016 (UTC)
 * Our article MS Oasis of the Seas points to this short feature on the lifeboats, fwiw. --Tagishsimon (talk) 22:09, 19 May 2016 (UTC)
 * Nobody was gambling with passengers' lives. The British Board of Trade recognized a couple of decades before Titanic that the largest of ships were always travelling in shipping lanes and these lanes were now so heavily travelled that there would (or should) never be more than a few miles between ships. In an emergency, ships would be able to summon aid by firing rockets or signalling with semaphore light. The uptake of radio technology confirmed that aid could be summoned rapidly, and lifeboats were regarded as necessary only for transferring passengers to the rescue ship(s). Why go to the expense of providing lifeboats for everyone on board when the biggest and newest ships with watertight compartments could be expected to float for many hours and rescue would be close at hand. It was in fact a good decision, but everything went very wrong for the Titanic because the officers on the Californian failed to recognize her rockets as a sign of distress and their radio man was off duty, and more importantly, was not woken. Titanic actually carried four more lifeboats than required by the BOT. The findings by both the American and British inquiries that there had been not enough lifeboats was wrong and a cave-in to the desire to spread the blame as widely as possible so that no living person could be found to have been at fault. Captain Smith took part of the blame for travelling too fast, but the blame should almost entirely have gone to the officers and captain of the Californian. Justice is not just about the letter of the law. It's also about minimizing the guilt felt by those at fault who have to go on with their lives. Akld guy (talk) 04:49, 20 May 2016 (UTC)
 * Making the assumption that a nearby ship would rescue them is certainly a gamble. ←Baseball Bugs What's up, Doc? carrots→ 05:26, 20 May 2016 (UTC)
 * It would have been better if, when reducing the number of lifeboats, it had been made mandatory for ships' radios to be manned continuously.  Also, many of the Titanic's lifeboats moved off with only a few people on board. 78.145.24.30 (talk) 11:19, 20 May 2016 (UTC)
 * The number of lifeboats was not reduced; it was simply not increased as ships' tonnages grew greater. That was in the early 1890s, 10 years before the dawn of radio and 15 years or so before it became routine for ships to carry it. The lifeboats were not carrying their full capacity because in the early stages, passengers could not be convinced that the ship was sinking. It was only when the angle of the deck became alarming that the reality set in. Akld guy (talk) 23:45, 20 May 2016 (UTC)
 * Yes. For White Star to have blamed others for the negligence of the Titanic operators is really cynical. ←Baseball Bugs What's up, Doc? carrots→ 12:49, 20 May 2016 (UTC)
 * Wikipedia has articles about the Titanic radio operators Harold Bride "considered one of the heroes of the disaster" and his senior Jack Phillips who perished. AllBestFaith (talk) 23:17, 20 May 2016 (UTC)
 * Titanic's radio operators were employed by the Marconi company, not the shipping line. They had a conflict of interest, in that they were obliged to make money for Marconi by relaying passengers' revenue-earning messages and they naturally gave those messages priority over shipping movement messages and warnings. So there was the "Shut up, keep out, I am working Cape Race [with passengers' messages]" retort at one point. Akld guy (talk) 23:55, 20 May 2016 (UTC)
 * Anyhow, you may be interested in Mega Lifeboat: "Schat-Harding has developed a 370-person lifeboat and davit system. The Oasis of the Seas cruise ship was the first vessel to be fitted with these new mega lifeboats... Oasis of the Sea is fitted with 18 of the new mega lifeboats. A total of over 44 of the traditional 150 persons lifeboats would have to be fitted to accommodate the same number of passengers. Oasis of the Seas has an overall length of 360m. The typical length of a 150 person lifeboat would be approximately 9.6m. So if fitted at a single level they would take up a length of over 210m (noise-to-tail) on each side of the vessel." Alansplodge (talk) 17:24, 20 May 2016 (UTC)

Sense of smell
Do women haved a better sense of smell than men? My gf is always complaining of my smelly feet but I cant smell them at all.--178.106.99.31 (talk) 23:47, 19 May 2016 (UTC)


 * I've known women who had no sense of smell at all, and others whose sense of smell was very acute. It could also be that you're used to your own scents, so you don't notice. ←Baseball Bugs What's up, Doc? carrots→ 23:56, 19 May 2016 (UTC)


 * Here is a good start for your research. -- Jayron 32 03:04, 20 May 2016 (UTC)


 * To avoid smelly feet, take your shoes off when not walking. This lets heat and moisture out, and air in, which keeps the microbes from growing out of control.  Shoes that allow for airflow are also a good idea, but I've never found any shoes, short of sandals, to provide sufficient airflow. StuRat (talk) 03:31, 20 May 2016 (UTC)


 * BB hit on two key points. Your sample size is apparently 2. You could just as well ask do people with red hair have a better sense of smell? Or, do people with green eyes have a better sense of smell? Or, do people from Irish descent have a better sense of smell? (I don't know if your girlfriend has red hair, green eyes or Irish descent and you don't, but you get the idea.) In other words, while any of these may or may not be true, there's no particular reason to think of them based on the data you've provided. We're only talking averages here and your girlfriend's suggested better sense of smell may just be because she's different from you and not any particular characteristic. Also olfactory fatigue or other factors related to the fact that it's your own odour may reduce your sensitivity to it. (Although I admit I couldn't actually find good sources discussion olfactory fatigue relating to body odour. There was only where a group testing female responses to male body odour included a break due to the risk of olfactory fatigue/adaptation.) Nil Einne (talk) 12:43, 20 May 2016 (UTC)
 * Yes they do! "...women's superiority in episodic odor memory is largely mediated by their higher proficiency in odor identification." DrChrissy (talk) 17:13, 20 May 2016 (UTC)
 * Not unequivocally. The source cited also states "No sex differences were observed in the tasks tapping primarily sensory acuity (i.e., odor sensitivity, intensity discrimination, and quality discrimination) or in episodic memory for unfamiliar odors." AllBestFaith (talk) 23:05, 20 May 2016 (UTC)