Wikipedia:Reference desk/Archives/Science/2020 July 1

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July 1

A physical trait that most of the people born with it although it's considered a defect

Could you think of one physical trait that most of the people born with it although it's considered a defect in terms of medicine or evolution, and the minority who don't have this trait considered the normal genetically / historically? (N.b. before I'm going to be said that a tail is one of them, or blue eyes is one of them, I have to say that I'm looking for the opposite case, where the absence is considered more normal historically.) --ThePupil (talk) 02:09, 1 July 2020 (UTC)

Lactase persistence? Actually a minority trait worldwide, but a majority trait in particular regions, particularly Western Europe whose world-dominating culture assumed it was "normal". {The poster formerly known as 87.81.230.195} 2.122.56.20 (talk)

Although the absence of a tail is considered more normal historically in our timeline, Dr. Zaius might consider it a defect. But how could the same person consider something both "normal" and "defective"? That implies that having a fault is the norm, like, in some subcultures, being greedy. But then why call it a fault, instead of proclaiming, "Greed is good!"?

The only things I can think of that someone might consider a fault despite being normal would be things where for evolutionary reasons we have ended up with something less than ideal compared to what has evolved in other animals, or what we could have ended up with if evolution was guided or designed. E.g. the optic nerve passing in front of the retina (inferior to that of octopuses - although neither of those articles actually mention that), or skeletal problems relating to bipedalism. Iapetus (talk) 10:32, 1 July 2020 (UTC)

How do you justify your opinion that the Octopus' optic architecture is superior? That in the vertebrates the sensible parts of all retinal cells are precisely aligned on the internal surface of the eyeball instead of lying on the bumpy carpet of the nerve cells makes the optic nerve running outside of the retina a superior design that improves the focusing precision of the vertebrate eye. Positioning errors of more than 2 µm do spoil focusing in cephalopoda, whose visual acuity is possibly worse than that of vertebrates. 2003:F5:6F12:6900:B815:447B:8293:D661 (talk) 19:26, 1 July 2020 (UTC) Marco PB

Bad eyesight? many people need glasses to see clearly, you'd expect this to be something which is selected against in evolution.

also fits with the OP's name :P Rmvandijk (talk) 11:53, 1 July 2020 (UTC)

Yet another vision related one is trichromacy when tetrachromacy is possible for some. Graeme Bartlett (talk) 11:58, 1 July 2020 (UTC)

A good example, although in a sense most people aren't, strictly speaking, "born with" refractive error. Rather, they develop it over time because of the interplay between genes and environment. In particular, as noted in that article, lack of sunlight exposure appears to promote the development of myopia. There are other vision abnormalities like strabismus that often are either present at birth or develop soon after. --47.146.63.87 (talk) 17:51, 1 July 2020 (UTC)

Appendix? — Preceding unsigned comment added by 86.162.76.127 (talk) 12:21, 1 July 2020 (UTC)

It seems as if the appendix plays an important role as a reservoir of useful gut bacteria in cases of extreme diarrhoea (as e.g. caused by food poisoning). In situations where food or water is likely to be contaminated, this can provide a very real benefit. --Stephan Schulz (talk) 14:01, 1 July 2020 (UTC)

This is true, but it's hard to say whether this outweighs the cost of "it can randomly decide to try and kill you, which is often fatal without modern medicine". Said cost is presumably why selection pressure has reduced it to vestigality, and might eventually get rid of it altogether. --47.146.63.87 (talk) 17:51, 1 July 2020 (UTC)

Devolution (biology) seems relevant. Search the web for human devolution and similar. Yup, when (if) we lost gills we lost the ability to breathe under water. 85.76.78.189 (talk) 15:47, 1 July 2020 (UTC)

We did't really lose it, as we didn't ever have it: to get with gills from water the quantity of oxygen we take with lungs from the air we would need gills of more than sixty liters, which would be some kind of hindrance, wouldn't it? 2003:F5:6F12:6900:B815:447B:8293:D661 (talk) 19:49, 1 July 2020 (UTC) Marco PB

We appear to use less oxygen underwater: people can dive for minutes on a single breath. Gills of a few liters in addition to lungs would probably help quite a bit with avoiding death by drowning, and wouldn't be a big hindrance on land (other than making us look ridiculous). 93.136.4.100 (talk) 00:34, 4 July 2020 (UTC)

"Devolution" though isn't really something modern scientists recognise. And when "we" (more accurately, our early tetrapod ancestors) lost their gills, that wasn't a defect so much as getting rid of something that was no longer necessary and would have been disadvantageous to retain. (As an analogy, my car isn't defective just because it doesn't have a starting handle or a manual choke control). Iapetus (talk) 16:48, 1 July 2020 (UTC)

Argument from poor design lists plenty of "defects" that are present in most people. (As an aside I would split those off into a list and have that article just focus on the theological argument.) --47.146.63.87 (talk) 17:51, 1 July 2020 (UTC)

Much of the world has historically considered the foreskin such an abomination that they cut it off the penises of baby boys without any kind of pain relief. And I'm on record here and elsewhere as describing menstruation in women as a serious design fault. -- Jack of Oz ^{[pleasantries]} 21:47, 1 July 2020 (UTC)

I was reading an article that I obviously didn't understand. At some point humans lost some sort of stuff on their cell walls which makes us less able to repair things but must have had some evolutionary advantage. In particular it makes us more vulnerable to arthritis. good luck finding that. 116.251.21.209 (talk) 04:03, 2 July 2020 (UTC)

Yet another feature is Human endogenous retroviruses, which you might consider that you could do without inherited viruses, but some are essential. Graeme Bartlett (talk) 11:52, 2 July 2020 (UTC)

I've over-indulged on alcohol on many occasions but never suffered from Delerium Tremens/Hangover, not so much as a dehydration-induced headache. Maybe everyone else has inherited Irritable Bowel Liver Syndrome, and my genes are the future? Ladies, form a queue... Bogger (talk) 20:56, 8 July 2020 (UTC)

Cobalt decacarbamide nitrate

Cobalt decacarbamide nitrate, Co(CON₂H₄)₁₀(NO₃)₂ is known: [1]. Please note that it is only ref for existence of this complex. What is the color of this compound? Thanks for much. (Sorry if you don't understand, because my English is not good). Ccv2020 (talk) 16:34, 1 July 2020 (UTC)

As we have asked you several times, why? Why do you want to know the color and what is your overall goal with these questions? What property are you hoping to get out of knowing the colors of these transition metal complexes? --OuroborosCobra (talk) 19:55, 1 July 2020 (UTC)

Just read note in my user page. Ccv2020 (talk) 23:42, 1 July 2020 (UTC)

I want to suggest to you, Ccv2020, that in some of the cases about which you have been asking, a meaningful answer is not possible. The colour (more generally the Optical properties) of a compound does (do) not depend solely on its chemical composition or formula – it (they) also depends (depend) on its physical structure, which may be different depending on how it was prepared and the physical conditions (temperature, pressure, surrounding atmospheric composition, humidity, etc.) in which it being kept.

On a separate note, given your interests, you may be interested in the contents or links in the article Qualitative inorganic analysis, which was once a more important discipline than in today's world of spetroscopic techniques. (I still have copies of R. M. Cavan's Quantitative Chemical Analysis and Inorganic Preparations revised by A. B. Crawford (Blackie & Son 1923, repr 1948) and E. T. Thompson's A Laboratory Manual of Semi-Micro Inorganic Qualitative Analysis (Edward Arnold 1957, repr. 1966) on my bookshelves.) {The poster formerly known as 87.81.230.195} 2.122.56.20 (talk) 06:39, 2 July 2020 (UTC)

Another note on obscure chemical colours, if you cannot find the information in a published journal (in this case probably Russian), then other people here are very unlikely to know, or to be able to consult a journal with the answer. One approach is to contact the person who published on the topic. If they did the preparation recently, perhaps they remember, or might even have a picture. For some other things you might be able to make a guess based on similar ligands, eg for this substance, perhaps ethylene diamine complexes might have a similar colour. (yellow) Ot it may be like bis(diethylenetriamine)cobalt(II) which can be orange. Graeme Bartlett (talk) 07:05, 2 July 2020 (UTC)

Sorry, Graeme Bartlett, but I think yellow or orange is not suitable. I think that pink or red is more suitable than your recommendations. Ccv2020 (talk) 06:37, 3 July 2020 (UTC)

So why do you think pink is suitable? Perhaps this would apply if cobalt was in +3 oxidation state. (it would then be a trinitrate). The colours are just guesses based on similar ligands. I think for article use we cannot use such speculation or guesses, and if there is no reference, we have to leave out that information. The chemical you mention appears to have very little written about it, so it would not justify an article on English Wikipedia. Graeme Bartlett (talk) 09:48, 3 July 2020 (UTC)

Calculated for complex: urea 76.65%, cobalt(II) nitrate 23.35%. I'm considering to call DMacks here to prepare it. What is your opinion, Graeme Bartlett? Can this complex prepared by reaction of two compounds? Ccv2020 (talk) 06:26, 4 July 2020 (UTC)

Take a look at this reference: doi:10.1155/2007/51567 which is for the iodide (instead of nitrate). This substance is coloured orange. The clue to look for is that carbamide=urea. But getting 10 urea molecules to crystallise is not so easy. The complex looks as if it could be made in a simple lab, with reflux capability. You would need urea, ethanol, and cobalt(II) nitrate. Graeme Bartlett (talk) 11:52, 4 July 2020 (UTC)

What do you think about [2]? It is said that corresponding chloride was pink, and bromide was lilac-violet. I also read this article one month ago. Ccv2020 (talk) 12:14, 4 July 2020 (UTC)

Graeme Bartlett, please read it:

1. According to fizmathim ref, iodide compound was violet.
2. Nitrate compound can be formulated as like as iodide salt ([searching…])

→ I'm not so agree with you that complex will have orange in color. I don't sure that. Ccv2020 (talk) 14:29, 5 July 2020 (UTC)

The article you link seems to say (лило́вый) "lilac", but being a .png it's hard for me to translate much here! Graeme Bartlett (talk) 07:03, 6 July 2020 (UTC)

Sorry, Leiem, can you prepare this complex? Thank for much (Read note in my user page). Ccv2020 (talk) 06:03, 6 July 2020 (UTC)

Ccv2020, perhaps it is not so easy to prepare or characterize. I have searched it in SciFinder, the compound (CAS number: 38724-90-2) has a structure of [Co(urea)₆](NO₃)₂·4urea. Four references can be found in SciFinder (but all of them are in Russian).

1. Kurkutova, E. N.; Rau, T. F. Crystal structure of Co(NO₃)​₂.10CO(NH₂)​₂. Doklady Akademii Nauk SSSR. 1972, 204 (2). pp 342-345. ISSN: 0002-3264.
2. Rau, T. F.; Kurkutova, E. N. Cobalt hexaurea and decaurea nitrates. Uch. Zap., Vladimir. Gos. Pedagog. Inst., 1972. 40. pp 14-16.
3. Rau, T. F.; Kurkutova, E. N. Cobalt(II) nitrate hexa- and decaureides. Uchenye Zapiski - Vladimirskii Gosudarstvennyi Pedagogicheskii Institut imeni P. I. Lebedeva-Polyanskogi, Seriya Fizika, 1972. 40 (6). pp 14-16. ISSN: 0372-5227.
4. Kurkutova, E. N.; Rau, T. F. An x-​ray diffraction study of cobalt nitrate decaureate. Struktura I Svoistva Kristallov, 1974. 1. pp. 77-85.

Hope it helps. --Leiem (talk) 07:04, 6 July 2020 (UTC)

It seems that ref 2 and 3 are the same. --Leiem (talk) 07:06, 6 July 2020 (UTC)

I tried it in lab. Cobalt chloride, cobalt nitrate and cobalt perchlorate were dissolved in water, separately, followed by adding urea. Mole ratio was 1:10 (metal salt:urea). Pink solutions were obtained. After adding ethanol in these solutions, no precipitate was formed. --Leiem (talk) 10:01, 6 July 2020 (UTC)

Leiem, can you keep it for 24 hours or more? Ccv2020 (talk) 16:27, 6 July 2020 (UTC)

Wait, it seems that complex was so hard to obtained in the form of crystals. Ccv2020 (talk) 16:36, 6 July 2020 (UTC)

I didn't find any literature that describes the preparation of the compound. Russian references above are not accessible. Usually simple complexes containing many simple ligands such as water, ammonia, etc. require difficult conditions like low temperature to obtain. (btw: I can keep them.)--Leiem (talk) 16:45, 6 July 2020 (UTC)

Leiem, pink color you had obtained by this method is like tetrakis(urea)cobalt(II) nitrate ([3]), and tris(urea)cobalt(II) perchlorate is the same ([searching…]), so… keep it for > 24 hrs. Ccv2020 (talk) 17:25, 6 July 2020 (UTC)

The reference I linked to above did not use water, but everything dissolved in ethanol (refluxing) 0.72 g urea in 30 cm3 ethanol, then add cobalt compound. The solution went pink in that experiment too, but crystals were orange. Graeme Bartlett (talk) 23:42, 6 July 2020 (UTC)

OK, I agree with you that complex will have orange in color. Ccv2020 (talk) 06:52, 7 July 2020 (UTC)

I will try ethanol when I have free time. --Leiem (talk) 14:23, 7 July 2020 (UTC)

When you do it, Leiem? Ccv2020 (talk) 11:23, 8 July 2020 (UTC)

Within this month. Recently I have other lab work to do. I will do it as soon as I have free time. --Leiem (talk) 12:29, 8 July 2020 (UTC)

How would a successful revival from cryogenic preservation combined with a successful cure to aging actually work in practice?

Some people are undergoing cryogenic preservation in the hopes of eventually getting revived. However, if one is a believer in eventual physical revival as opposed to things such as mind uploading (which, IMHO, is contrary to the spirit of cryonics), how exactly does one visualize a successful revival from cryogenic preservation combined with a successful cure to aging actually occurring? For instance, if someone dies at age 115 (with no obvious cause of death except extreme old age/natural causes) and then gets cryogenically preserved, just how exactly would this person eventually be revived? Indeed, what is the logic here? Specifically, just how are this person's organs (including their brain) actually going to get reactivated?

I'm aware that if someone young dies from heart failure, then simply undoing the cryogenic preservation (if this will ever actually become possible without significant brain and bodily damage) and giving this person a new heart (perhaps through things such as 3D printing) might be enough. However, what if someone's entire body gives out due to extreme old age? Then one would need to--in addition to figuring out a way to undo the cryogenic preservation--also need to figure out how exactly to successfully undo the effects of numerous decades of aging on one's body and brain (while still bringing this patient back to life, of course). Futurist110 (talk) 20:24, 1 July 2020 (UTC)

Your question seems to me not to be answerable. "[H]ow exactly to successfully undo the effects of numerous decades of aging on one's body and brain". If we did know, they would not need to be frozen, as they could be healed and rejuvenated today. It is just because we don't know what to do and how to do it that they let freeze themselves, in the hope that sometimes, somewhere, someone finds out a way of doing it. And of course that the way exists in the first place. And it can be found out. And so on 2003:F5:6F12:6900:B815:447B:8293:D661 (talk) 21:22, 1 July 2020 (UTC) Marco PB

I guess that what I'm asking is whether it's possible to unfreeze someone and at the same time cure their aging. Else, such a person would simply die and their body would turn to mush. Futurist110 (talk) 23:32, 1 July 2020 (UTC)

No, it's not possible.--Shantavira|^{feed me} 05:32, 2 July 2020 (UTC)

Science Fictional suggestions have included scanning or processing the preserved brain in some way so as to preserve or replicate the memory, and then imprinting this somehow in a clone of the original body (which would lack its acquired defects) or the mind-blanked body of a future person such as an executed criminal. However, how these things could be done is simply not yet known, and they may never be possible. But as Larry Niven (who has written fiction around this subject) points out, you're going to die anyway, so spending some money (if you have it) on a long shot is a gamble worth taking. {The poster formerly known as 87.81.230.195} 2.122.56.20 (talk) 07:11, 2 July 2020 (UTC)

There's also the metaphysical question of if your consciousness and/or soul would be transferred to that body. If not, it would not be very useful to you. 93.136.4.100 (talk) 18:57, 4 July 2020 (UTC)

My copy will have my values and interests, and so will continue my projects. That is useful to me, regardless of questions of soul. —Tamfang (talk) 01:35, 5 July 2020 (UTC)

However, a copy of you is not you. Thus, every time Mr. Spock teleports somewhere, he is killed and a copy of him takes over. Now count the number of times you've seen Kirk die. - Nunh-huh 03:32, 5 July 2020 (UTC)

If such a thing ever were to be possible, and everyone could in some way live 'forever', then unless humans found other places where they can live (other than Earth), then people would at some point have to stop having children, in order to avoid overpopulation. And this restriction would have to be placed on young people (the old people being preserved forever will have already had their children), which would raise many difficult questions regarding ethics and the meaning of human life. PaleCloudedWhite (talk) 08:23, 5 July 2020 (UTC)

Unless this imaginary magic that allows us to live forever also keeps us fertile forever, you would need to keep some young breeding stock and replace them as they age. Otherwise you get a population that cannot reproduce getting smaller and smaller as accidents, suicides, murders, etc., kill some of the ageless ones off. --Guy Macon (talk) 04:06, 7 July 2020 (UTC)

If you have two corpses who have been dead and buried for decades, can you do a DNA test on them to see if they are biological brother and sister to each other?

If you have two corpses who have been dead and buried for decades, can you do a DNA test on them to see if they are biological brother and sister to each other? Futurist110 (talk) 23:32, 1 July 2020 (UTC)

It depends on the exact conditions of the burial, but after decades, probably yes. But it may not be perfect (parents/children and full siblings share the same amount of DNA, so the relationships may need to be disambiguated in some other way). --Stephan Schulz (talk) 01:36, 2 July 2020 (UTC)

You are (almost - X and Y are different sizes) 50% related to each parent because half of your DNA comes from each of them. You are only 50% related to your siblings on average. Siblings can theoretically be anywhere from 0 to 100% related.

To confuse things further, DNA testing typically tests just a small part of the DNA.

See [4] and [5]. --Guy Macon (talk) 01:58, 2 July 2020 (UTC)

The remains of Richard III were found and DNA-tested in 2012, more than 500 years after his death, so you certainly can get useful data from even long-decayed corpses. Tigraan^{Click here to contact me} 10:48, 2 July 2020 (UTC)

But we can beat that: Cheddar Man: DNA shows early Briton had dark skin: "A cutting-edge scientific analysis shows that a Briton from 10,000 years ago had dark brown skin and blue eyes... The Natural History Museum researchers extracted the DNA from part of the skull near the ear known as the petrous". See also Cheddar Man. Alansplodge (talk) 15:28, 2 July 2020 (UTC)

More related to the original question, we have the recent case of a 5000 years old burial where it could be stated from DNA analysis that the parents of a man buried there must have been "either siblings or parent and child." The tomb lies in the Brú na Bóinne cemetery complex in County Meath, north of Dublin, in eastern Ireland. [[6]] 2003:F5:6F12:6900:65E6:812D:B982:EFF1 (talk) 16:30, 3 July 2020 (UTC) Marco PB

If the DNA can be sequenced, differences in their mitochondrial DNA will tell you that they do not share a mother, and differences in their Y chromosome will tell you that they do not share a father. But the converse is not true since, for instance, the offspring of full sisters will share their mitocondrial DNA sequence just as the sisters themselves do. The 50% figure for full siblings (and parent-offspring) is not as straightforward to establish as one might naively expect because much of our DNA shows no variation: we share more than 99% of our DNA sequences with each other. So one has to consider only genes that are variable in the population, and there is the added complication that past inbreeding within a family (e.g. cousin-cousin marriage) will elevate the chances that non-sibs share such a sequence. Distinguishing sibs from parent-offspring seems much more difficult to me. Jmchutchinson (talk) 08:43, 5 July 2020 (UTC)

Using mitochondrial DNA and sex chromosomes (and assuming no in-breeding or other pre-existing relationship between the parents, or other non-classical inheritance ideas), here are the combinations of matches I think we have:

Relationship	Michondrial match	X match	Y match
sister vs sister	yes	one yes, one 50% chance	neither has it
sister vs brother	yes	50% chance	only one has it
brother vs brother	yes	50% chance	yes
father vs son	no	no	yes
father vs daughter	no	father matches one of daughter's	only one has it
mother vs son	yes	son matches one of mother's	only one has it
mother vs daughter	yes	one yes, one no	neither has it

So this can only sometimes distinguish sister–sister from mother–daughter and can only sometimes distinguish sister–brother from mother–son. DMacks (talk) 09:35, 5 July 2020 (UTC)

Shouldn't the above chart specify that for most of the DNA (ignoring X and Y) there is an exact 50% match for parent-child and an on average 50% match for siblings?

Relationship	Michondrial match	X match	Y match	Other DNA match
sister vs sister	yes	one yes, one 50% chance	neither has it	anywhere from 0% to 100% match
sister vs brother	yes	50% chance	only one has it	anywhere from 0% to 100% match
brother vs brother	yes	50% chance	yes	anywhere from 0% to 100% match
Identical twins	yes	yes	yes	100% match
father vs son	no	no	yes	exactly 50% matches
father vs daughter	no	father matches one of daughter's	only one has it	exactly 50% matches
mother vs son	yes	son matches one of mother's	only one has it	exactly 50% matches
mother vs daughter	yes	one yes, one no	neither has it	exactly 50% matches

--Guy Macon (talk) 11:39, 5 July 2020 (UTC)

The theoretical probabilities that you calculate overlook three problems. (1) There are a variable number of crossovers between a parent's pair of homologous chromosomes before the gametes are generated. So it is unlikely that a child inherits a whole chromosome from either parent (except for an X chromosome from a father). Hence table entries such as "son matches one of mother's" and "one yes, one no" are nonsense. (2) Your "50% chance" only applies if the parents differ in that gene. Practically they often won't because of the limited variation in the population, which may be exacerbated by inbreeding. That is not a problem if you know the genotypes of the parents, as we typically do know in breeding experiments, etc.; you then can just ignore genes that are uninformative for this family. But in the scenario asked about, we have no information about the parents' genotypes. The best that you can do is look at genes that you know are highly variable (e.g. microsatellites); the proportion of genetic loci that differ will then be an upper limit on the figures for relatedness that you have calculated. (3) I see no way to distinguish your cases of exactly 50% and 50% on average. All that you can measure is the proportion of loci that differ, so you are averaging over many loci; the more loci that you consider, the closer you will get to 50% regardless of whether they are parent and child or sibs (assuming all parental genes differ). Jmchutchinson (talk) 13:49, 5 July 2020 (UTC)

Indeed, crossover is a really annoying "real" confounding situation and why the probabililites and looking for certain markers is a whole field of study. I had to phrase my intro carefully to exclude "non-classical inheritance"--it's the same way we teach standard genetics at the really intro level. In reality, the presence/absence is sure or son matching mom not dad X "however we define matching on a chromosome". , but the "match" is only at best a lineage in general. DMacks (talk) 15:26, 5 July 2020 (UTC)