Wikipedia:Reference desk/Archives/Science/2016 May 25

= May 25 =

Anti muscarinics
There are mACh receptors in the vomiting centre, so why don't antimuscarinics like hyoscine block all vomiting reflexes (instead of just motion sickness and gastric irritation, in the vestibular nuclei and nucleus of the solitary tract). Thanks if any can help; Le Sanglier des Ardennes (talk) 10:39, 25 May 2016 (UTC)


 * Based on my perusal of the relevant articles, it looks like hyoscine/scopolamine is selective for the M1 mACh receptor subtype, while it's M3 receptors that trigger vomiting when activated. So that would explain it, if accurate. — Preceding unsigned comment added by 71.110.8.102 (talk) 21:09, 25 May 2016 (UTC)


 * So, are there M1 receptors in the vestibular nuclei and the nucleus of the solitary tract? Le Sanglier des Ardennes (talk) 05:47, 26 May 2016 (UTC)

Dulbecco's Modified Eagle Medium - food source?
Hi, the lab where I work uses Dulbecco's Modified Eagle Medium with phenol red for cell culture. The safety data sheet says it's not harmful. We add L-Glutamine before culture. Out of idle curiosity, if I were in a famine situation, could a stockpile of this media sustain me (with or without the added L-Glutamine)? Would I be better off than other famine-sufferers roasting rats and pigeons (in terms of health, nutrition, energy, disease, etc)? Thanks! 162.134.88.1 (talk) 16:16, 25 May 2016 (UTC)


 * I don't see any fats, so you might eventually succumb to rabbit death. StuRat (talk) 16:28, 25 May 2016 (UTC)


 * No carbohydrates, fats or significant proteins. Not going to last long. Plus, it tastes disgusting (yes I've tried). Fgf10 (talk) 16:30, 25 May 2016 (UTC)


 * It has carbs (glucose is a sugar/simple carb) and amino acids are the building blocks from which our bodies can assemble proteins, which are a perfectly acceptable substitute, provided a complete mix of amino acids is present. There are no complex carbs (starches), but those aren't required (neither are sugars). The lack of any fat, on the other hand, is a problem.  StuRat (talk) 16:48, 25 May 2016 (UTC)

how can I disclose a carved mountain photo, with several figures carved on it.
I took this photo twenty years ago hiking with my kids. It shows several faces and figures carved from a 150 ft. mountain. The carvings are on a timeline showing the evolution of animal life on earth. I would love too share the photo for display on Wikipedia. Steve.


 * See Wikimedia Commons "Upload Wizard" and follow the instructions. By the way, I was curious to see if we already had an article that mentioned these carvings, but have drawn a blank - could you give us a clue as to their location please? Alansplodge (talk) 17:41, 25 May 2016 (UTC)

How do people know so much of ancient history?
I've come to wonder, how do people know so much of ancient history?

People have been able to pinpoint individual events on individual days in ancient Roman times. That was two millennia ago. Photography or sound recording didn't exist, in fact even literacy was a relatively new invention. Have people been able to reconstruct the history solely by surviving literary records?

And what's even more puzzling is how people know so much of dinosaurs. No one has ever seen a living dinosaur, but on top of that, no one has ever seen an intact carcass of one. All we have to go by is fossilised skeletons. How have people been able to reconstruct so much of history of animals of which so little survives? J I P &#124; Talk 18:42, 25 May 2016 (UTC)


 * A skeleton tells a heck of a lot about an animal:


 * 1) It's age (by carbon dating, etc.).


 * 2) It's size.


 * 3) Whether it has wings, fins, and/or legs.


 * 4) The teeth, along with possible fossilized stomach remains, tell what it ate.


 * 5) What it's most closely related to (similar bone structure).


 * 6) Finding eggs tell us a bit about reproduction.


 * Some things the bones don't tell us are skin thickness, texture, and color, along with fur/hair/feather placement and location. Also whether it was warm blooded and what sounds and behaviors it exhibited.  In the case of intact DNA in the bones, we can potentially find out far more about those animals. StuRat (talk) 18:53, 25 May 2016 (UTC)


 * As for ancient history, writing in the key. All ancient civilizations with writing wrote down everything important to them.  They used different calendars, but once we sync to something we can accurately date, like an eclipse, we know the dates precisely. StuRat (talk) 18:58, 25 May 2016 (UTC)


 * " All ancient civilizations with writing wrote down everything important to them." That's not even remotely true, and I don't even know much about history. Unlike you, I have the good sense to not bloviate about the topics I know little about. I've spent a whole eight minutes trying to get a good answer together, and it's quite annoying when I can't post due to edit conflicts with your unsubstantiated opinions.
 * Also, you're also wrong about carbon dating, in two different ways. 1) fossils aren't skeletons, and so won't have the delta C ratios of their original organisms. 2) Radiocarbon dating is only effective up to about 50k years before present , which is long after the dinosaurs. We use radiocarbon dating for archeology and recent past, not for paleontology. There are other forms of Radiometric_dating that are used by paleontologists, but first pass aging of fossils is usually done via stratigraphy. Please, next time wait at least a few minutes before typing up your unreferenced and incorrect first thoughts on a topic. SemanticMantis (talk) 19:11, 25 May 2016 (UTC)


 * I added an "etc" after "carbon dating". I can do without the attitude, though.  And what's your problem with saying that people wrote down what was important to them ?  Of course they wrote down unimportant things, too, but that doesn't make what I said any less true. StuRat (talk) 22:13, 29 May 2016 (UTC)


 * (EC)Study of life in the distant past usually is considered paleontology, as distinct from history. If you think it's impressive to reconstruct what a dinosaur looked like, consider paleoecology and paleoclimatology, where scientists reconstruct entire ecosystems and synoptic climate patterns, sometimes starting with nothing but pollen recovered from an ice core. See e.g. these for a feel of how that works . Suffice it to say, pollen travels far and preserves well. It contains a record of both type and relative density of plants. Reconstructed plant communities then give information on the animal community as well as the climate. It's probably beyond the scope of this desk to give a complete rundown of methods used in paleobiology, but if you can specify and narrow you're interest, we can probably give you more specific references.
 * You might get better answers for methods in history at the Humanities desk. In the mean time, check out historical method, philosophy of history, Recorded history, Archaeological_record, and oral tradition. SemanticMantis (talk) 19:11, 25 May 2016 (UTC)

Of course some things are still not known for certain. For instance - there has been fairly recent controversy as to whether or not dinosaurs had feathers - see:  and. Richerman   (talk) 19:44, 25 May 2016 (UTC)


 * And to be pedantic, it's now accepted in science that birds are dinosaurs. So you've probably seen a lot of dinosaurs. As to how we know about prehistoric creatures, fossils are certainly great, but there are more sources of information than fossils. Genetic sequencing has been a huge boon; by comparing the genes of living organisms, we can trace out their shared evolutionary history based on similarities and differences. For one neat example, see L-gulonolactone oxidase. For learning more, good starting points include evolutionary biology and evidence of common descent. --71.110.8.102 (talk) 21:19, 25 May 2016 (UTC)


 * For Roman historical techniques, which you asked about, see Roman historiography. Regarding pinpointing dates.  Since the invention of standardized calendars pegged to astronomical events (like solstices and equinoxes) we can fairly easily count on calendars.  The modern Gregorian calendar is functionally close enough to the Roman calendar that we know how to connect dates between one and the other, so long as we have dates recorded by contemporary sources.  History can be reconstructed by historical writings from past historians, though such records tend to record mostly the history of the ruling classes only; other kinds of records, like censuses, tax rolls, shipping manifests, warehouse inventories, still exist from the past, and we can learn a lot about society from a combination of such mundane records as well as archaeology.  Heck, some of the oldest writing we have is from such boring stuff; much of what we have of cuneiform is boring stuff like "John Doe owes the government 21 pounds of millet in taxes" and "this pot contains olive oil".  -- Jayron 32 21:53, 25 May 2016 (UTC)


 * I asked a similar question a couple months ago. See Accuracy of ancient dates. Llaanngg (talk) 18:02, 28 May 2016 (UTC)

Bum zits
What causes them?--178.106.99.31 (talk) 23:27, 25 May 2016 (UTC)


 * The same thing that causes all acne. You can read that article and links from it to learn more.  -- Jayron 32 23:34, 25 May 2016 (UTC)


 * Miliaria can be mistaken for acne, and occurs in areas kept warm and moist. Most people in developed nations wear at least 2 layers of clothing over their rears, and sitting on them can also limit ventilation.  This is more of a problem when the weather is hot and humid.  Walking around, to aid ventilation, and changing clothes, when they get sweaty, might help to prevent this. StuRat (talk) 22:19, 29 May 2016 (UTC)