Wikipedia:Reference desk/Archives/Science/2014 June 3

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June 3

Skin colour

What is meant by by dark reddish complexion? How does it look like? Which people other than Red Indians can be said to have dark reddish complexion. — Preceding unsigned comment added by 117.194.228.68 (talk) 02:54, 3 June 2014 (UTC)

There's a chart a ways down the page in Human skin color which may help explain. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:11, 3 June 2014 (UTC)

A Caucasian with a sunburn might look like that, too, until it peels. StuRat (talk) 03:19, 3 June 2014 (UTC)

Would that be an Armenian, an Azeri, or a (post-Soviet) Georgian? --Trovatore (talk) 04:04, 4 June 2014 (UTC)

All of those and many more. StuRat (talk) 04:07, 4 June 2014 (UTC)

Not too many more. --Trovatore (talk) 04:08, 4 June 2014 (UTC)

Some of our Georgians might have such a complexion too, 'specially if they been pickin' cotton all day in the sun. And don't even get started on the Texans... 24.5.122.13 (talk) 08:24, 4 June 2014 (UTC)

But they aren't Caucasians. Well, I suppose a few of them are, but not many.

Sorry, the term just bugs me. It's one of those attempts to sound more precise, that just winds up being inaccurate.

You can say Caucasoid, if you know what it means, and that's really your intent — a category from a somewhat dated, but possibly not entirely obsoleted, system of racial classification. But not "Caucasian". A Caucasian comes from the Caucasus.

For StuRat's original comment, the best term is probably "light-skinned" (the lightest-skinned "blacks" may be lighter than the darkest "whites", and would equally be covered by the comment).

But you know, if what you really mean is "what the man in the street would call white", then just say "white". No need to look for a scientific name for a less-than-scientific (but still widely understood) concept. Just say what you mean. Anything else just feeds the euphemism treadmill, and that's not a good thing. --Trovatore (talk) 08:44, 4 June 2014 (UTC)

Which is why they call'em rednecks. 24.5.122.13 (talk) 03:30, 3 June 2014 (UTC)

Is that why they invented the mullet (haircut), to stop having red necks ? StuRat (talk) 03:40, 3 June 2014 (UTC)

Caucasians are whites how can they have dark reddish complexion — Preceding unsigned comment added by 117.194.235.146 (talk) 05:28, 3 June 2014 (UTC)

They can temporarily, as I said. Look at the pic at the top of the sunburn article to see what I mean. The skin of Caucasians is somewhat translucent, so you can see the blood beneath it, to some extent. While healing from a sunburn, more blood is pumped closer to the surface, and this explains the dark red color. StuRat (talk) 13:52, 3 June 2014 (UTC)

Read the Human skin color before asking any more questions. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:58, 3 June 2014 (UTC)

Note that a strawberry mark or port-wine stain may also make areas of the skin dark red, but normally not all of it. StuRat (talk) 13:59, 3 June 2014 (UTC)

Rosacea and similar conditions can also make the skin redder than normal. StuRat (talk) 04:06, 4 June 2014 (UTC)

Drinking

Has any research been done linking ALDH2 deficient drinkers and frequency of alcohol consumption rather than units per week? — Preceding unsigned comment added by 82.40.46.182 (talk) 03:58, 3 June 2014 (UTC)

Added a title Rojomoke (talk) 04:34, 3 June 2014 (UTC)

Miracles

If Jesus was an alien could the miracles he performed be explained scientifically with our current knowledge? — Preceding unsigned comment added by 188.116.25.10 (talk) 08:29, 3 June 2014 (UTC)

No, because science has provided us with no evidence that aliens exist. This question does not belong on the Science Ref Desk. HiLo48 (talk) 08:33, 3 June 2014 (UTC)

I find the idea that first-century Palestine was infiltrated by a space-alien who just happened to look exactly like a 30-year-old itinerant rabbi to be a lot less plausible than that an actual rabbi did some unusual things that his audience later reported in their own terms as miracles. AlexTiefling (talk) 08:42, 3 June 2014 (UTC)

I don't have an answer to the question - but wanted to ask for a clarification: are you asking "Could Jesus have been a space alien" or are you asking "Do we have the technology to perform the equivalent of biblical miracles"? The latter seems a fairly reasonable question for this desk.Phoenixia1177 (talk) 08:45, 3 June 2014 (UTC)

Magician Uri Geller Teaches Much About Bible Miracles might answer your question. We don't need an alien charlatan to do the miracles, just a normal human charlatan. Or just some followers who exaggerated. Dmcq (talk) 09:03, 3 June 2014 (UTC)

From a similar perspective, The Sins of Jesus (a novel), attempts to imagine the story of Jesus as a teacher who used sleight-of-hand and similar tricks that would have been available to magicians of his day in order to capture the attention of the audiences he lectured to. Dragons flight (talk) 10:18, 3 June 2014 (UTC)

The trouble is that we don't have accurate reports of these "miracles". If you take something like the loaves and fishes story - a tiny amount of food somehow feeds a large crowd of people, and after everyone has eaten, there is considerably more food wasted than there was food to start with. On the face of it, that would be a clear violation of conservation of mass laws - so it's certainly not possible within the realms of known science - and because conservation laws seems to be rather fundamental to our universe, it doesn't seem likely that even a very advanced alien species could pull this one off as it is described in the Bible. So if this event happened at all, there must be some kind of a failure of description of what really happened. A much simpler, and far more likely, explanation is something similar to what happened was in an impromptu block-party we once had when we'd invited some friends over and we had made some snacks for us to share - but some of our neighbors heard the party and came over to join in - and pretty soon we were running out of food. So the neighbors popped back home and emptied their fridge of snack food and brought it along - cold pizza, a few beers, some bags of potato chips...and along the way they roped in some other people who lived in the same apartment block. By the end of the day, the party had spread out into a second apartment, about a hundred people were partying and everyone was bringing food and drink...and there is no question that by the time we came to clean up, the amount of party left-overs was far more than we'd started off with. The snowball effect of excited people bringing small amounts of food and drink and sharing it widely produced an event that nobody who went to it will ever forget. The way it brought the community together was quite stunning - and it had long-term repercussions in how everyone who lived there got along. This had the feel of something "miraculous" and seems to have the exact flavor that the descriptions of the "feeding of the 5,000" event seem to be trying to impart.

You could say that the party was fed by the tiny amount of food we kicked it off with...and that seems overwhelmingly likely to be what happened in the loaves and fishes story - there is some kind of a political/religious rally - everyone is kinda peckish - somebody donates a small amount of food, but it's clearly not enough - so people disappear for a while and come back with more food...this seems a little 'miraculous' and after the story has been re-told, written down, translated, interpreted, re-translated - and who-knows-what else...it becomes a magic trick.

So before you look for aliens and advanced science, it's better to look at more mundane explanations because the simpler the explanation, the more likely it is to be correct. SteveBaker (talk) 12:59, 3 June 2014 (UTC)

That's very much like the classic story stone soup. StuRat (talk) 13:42, 3 June 2014 (UTC)

People seem to have been far more naive then, due to a lack of training in critical thinking, skepticism, and science. Whereas now we can check on any magician's trick by asking how it's done on the Internet (several such Q's have been posted here), back then they had no way to check on something.

So Jesus could have had a table with a hole cut in in, and somebody underneath reaching up through the hole to replace the food whenever it ran low and the cover was put back on, then plugging the hole back up again. Note that such tricks were common at the time from religious leaders. Much as absurd costumes go with Mexican wrestling now, back then any religious leader was expected to "perform miracles". Now, all this doesn't mean that Jesus was a total fraud, he may have just wanted to "save" as many people as possible that day and considered a little trickery acceptable in working towards that goal. StuRat (talk) 13:50, 3 June 2014 (UTC)

The explanation for that story is that Jesus opened His satchel and shared His food, which encouraged everyone else in the crowd to do likewise, to the point where there was food left over which could be donated to others. It's a good metaphor for what Christian love is supposed to be able to accomplish. In modern terms, it would be called "pay it forward". ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:44, 3 June 2014 (UTC)

I want to add upon Steve Baker's answer (Which I liked very much!): I don't think that even the first interpretation must contradict the Conservation of mass Law, because, I think, you could philosophize and say that the particles that have made the "Miraculously appearing new food" where brought by god into this time and place, directly from another dimension of the existing physical universe; If one seems fit to believe such an interpretation - Go ahead. Ben-Natan (talk) 04:42, 4 June 2014 (UTC)

If there is a God, conservation of mass is something it, assumedly, could circumvent (thus, not absolute); if there is no God, then it conforms to known science. My point being: if you can assume God, you don't need to assume physics gets in its way - at least, on traditional accounts - thus, you don't, then, need to provide an explanation for how God managed it.Phoenixia1177 (talk) 06:53, 4 June 2014 (UTC)

Indeed - if "God did it" is the explanation, then since he's supposed to be both omnipotent and omniscient, he could have either just magic'ed the food into existence - or rerouted the wiring of everyone's brains an hour after there wasn't enough food to implant the memory that they'd eaten well. If you can do absolutely anything, without recourse to the limitations of the laws of physics - then there is probably an infinite number of ways to pull off this trick. If God is limited by the laws of physics - then whatever he does can be done by a sufficiently advanced alien civilization. Right now, finding a way to pull mass from a parallel universe is rather more unlikely than finding a way to violate the conservation laws...so I'm not sure that this suggestion adds any explanatory power. SteveBaker (talk) 13:49, 5 June 2014 (UTC)

Why can't mercury get removed from fish somehow?

See http://science.howstuffworks.com/science-vs-myth/everyday-myths/10-absolutely-worst-foods-to-eat.htm#page=4

What brings mercury into the fish in the first place, and when they're caught, why can't there be any sort of method to remove mercury from these fish?

Are there methods being developed that will help remove mercury from the fish? What can you link about them? Thanks. --2602:30A:2EE6:8600:5C4B:9AF8:59B:4212 (talk) 08:59, 3 June 2014 (UTC)

We could stop polluting the sea with mercury. That would eventually get rid of practically all of the problem. Mercury in fish discusses the whole business. Dmcq (talk) 09:07, 3 June 2014 (UTC)

Since it's in the muscle I assume you would have to pulp the fish to be able to extract the mercury, which wouldn't be economical.--Shantavira|^{feed me} 11:50, 3 June 2014 (UTC)

An approach to lead poisoning that was known to Aulus Cornelius Celsus was to use "walnut juice"; the insoluble fraction of walnuts tends to soak up lead ([1], though this isn't the source I was looking for). If our medicine could catch up with the ancient Romans, well-chosen sources of natural fiber could be taken as routine supplements with meals to absorb some of the heavy metals. The fiber, more than harmless, would simply be excreted. Wnt (talk) 17:41, 3 June 2014 (UTC)

• The mercury is obviously not found in a concentrated chunk in the fish, it is spread throughout the tissues, and a s mentioned above, addressing that would require pulping and huge expense. The standard treatment for mercury poisoning is chelation therapy, you might read there. μηδείς (talk) 18:09, 3 June 2014 (UTC)

Human genetics

My understanding is that there are certain genes where every human shares the same allele, and other genes where there are many alleles in the human genome. What percentage of genes fall into the first category? 38.108.87.20 (talk) 12:57, 3 June 2014 (UTC)

I know that you can find out whether there are no known SNPs associated with a gene by [2]. That site has a good set of APIs, so you could program a script to run through and count up how many still have no SNPs associated, but it would be a significant amount of work. I bet someone has done it though, if you can just think of the right way to search... Wnt (talk) 17:27, 3 June 2014 (UTC)

Just to clarify: my understanding is that the lack of known SNP is a very poor proxy for "every human shares this allele" - right? I mean, the human genome project only had 5 individuals in the private portion and 40 (?) in the public portion. So it stands to reason there are many unknown alleles out there, especially for non-famous loci... Also, turning the question around: are you aware of any specific loci in the human genome which have been thoroughly sampled, and found that there is no variation in allele? Is there a specific name for such a thing that I could use for searching? SemanticMantis (talk) 19:43, 3 June 2014 (UTC)

For those not familiar with the term (such as me, until just now), presumably the SNPs being referred to here are single-nucleotide polymorphisms. (My default expansion of the abbreviation would be this one) AndrewWTaylor (talk) 22:11, 3 June 2014 (UTC)

The HapMap data is also at NCBI, so as far as I know it should be up-to-date for those individuals also when searching Gene, but I will admit I haven't gone hunting for SNPs in a gene lately to be sure. Wnt (talk) 02:09, 4 June 2014 (UTC)

• I don't know whether the current database rules this out, but in a probabilistic sense it is impossible for it to be true. Because of the way the genetic code works, a substantial fraction of single-nucleotide mutations are "neutral", meaning that they have essentially no functional effect. The probability of any gene having nobody in the world with even a single neutral mutation is vanishingly small. Looie496 (talk) 15:16, 4 June 2014 (UTC)

Thanks, @Looie496: and @Wnt: - that's what I thought too, but I wasn't really confident. I appreciate the probabilistic reasoning, and agree with it. However, I'm not sure how rule out something like this: there might be some very primitive allele and locus that admits no neutral variation. Something that incorporates none of the normal redundancies or error correction. It seems possible that, if the allele is exactly "right" then e.g. some structural protein is correctly produced. But if there are any changes to that allele, it becomes lethal to a developing fetus. That's a very strained and slightly ignorant example, but it's the only way I can think of that a locus would have no variation across the extant human population. (overlinking for benefit of the group, thanks to Andrew for the reminder :)SemanticMantis (talk) 16:00, 4 June 2014 (UTC)

Well, now we're getting into a tricky area concerning what the word "gene" means. Most of the time nowadays when a scientist uses the word "gene", the intended meaning is the portion of a chromosome that encodes a single protein or some other product such as an RNA. That's the meaning I had in mind when I answered the question. A gene, in that sense, is generally a few hundred nucleotides in length. But there are other possible ways of using the word, which may yield a different answer. Rather than write out a long explanation, let me point to a blog post I wrote recently about this problem, "There is no such thing as a gene". Looie496 (talk) 18:05, 4 June 2014 (UTC)

Thanks, User:Looie496, for linking to that post, although seeing "Die Selfish Gene" made me fear it was in Tscherman. The only flaw is that your treatment wasn't booklength. Non-biologists (and too many supposed Biologists) are absolutely convinced Dawkins is the shit and his concept is both meaningful and irrefutable. I prefer SJG'sand especially Ernst Mayr's telling criticisms. μηδείς (talk) 18:26, 4 June 2014 (UTC)

Right, that's why I was careful to talk in terms of loci and alleles. I don't think we really need the word "gene" much anymore. I read your blog post, and found it interesting, but I don't see what it has to do with my hypothetical allele that must be identical across all viable individuals. I guess you mean the bit about recombination? In my hypothetical example, recombination would still preserved the allele, because there is only one version of it that "works" -- But, until I hear otherwise, I'll assume that the correct answer is that there are no loci for which there is no variation in alleles across the human species. SemanticMantis (talk) 19:00, 4 June 2014 (UTC)

What about the genes for having mass, or winglessness? I think we all share identical versions of those. μηδείς (talk) 02:09, 5 June 2014 (UTC)

I just noticed no one pointed you at Ultra-conserved element. I really ought to look up what is known for SNPs in some of these. Wnt (talk) 01:22, 7 June 2014 (UTC)