Wikipedia:Reference desk/Archives/Science/2021 April 4

= April 4 =

Why is the scientific literature so ambiguous as to whether intersex humans (chimeric or otherwise) have ever self-impregnated?
Is it simply unknown or just difficult to prove? Viriditas (talk) 02:24, 4 April 2021 (UTC)
 * Perhaps because such people are relatively rare, instances of their becoming pregnant are rare within that initial rarity, circumstances in which those doubly rare cases were not presumtively impregnated by someone else (and thus the idea of their having self-impregnated has even arisen) are triply rare, and known cases in which there is scientifically plausible evidence that they could not have been impregnated by someone else is, to coin a term, rare4.
 * I suspect the number of cases corresponding to that succession of criteria is likely to be less than one, but I confess that, not recalling any reference to such an occurrence (despite a long-standing interest in Forteana), I don't feel inclined to dig for one without some prior evidence, particularly given the emotionally sensitive nature of the matter for some. Others may be willing to, but perhaps you can start by pointing to your sources suggesting that it may have happened at all? {The poster formerly known as 87.81.230.195} 2.219.35.136 (talk) 17:37, 4 April 2021 (UTC)
 * It's in the article on true hermaphroditism:


 * There is a hypothetical scenario, though, in which it could be possible for a human to self fertilize. If a human chimera is formed from a male and female zygote fusing into a single embryo, giving an individual functional gonadal tissue of both types, such a self-fertilization is feasible. Indeed, it is known to occur in non-human species where hermaphroditic animals are common, including some mammals. However, no such case of functional self-fertilization has ever been documented in humans.


 * It's all incredibly ambiguous, including the supporting references in the aforementioned article. Just because something hasn't been documented, doesn't mean it hasn't occurred. Viriditas (talk) 21:41, 4 April 2021 (UTC)
 * I agree, and it may have done, but part of the point of my analysis above is that, even if it did occur, it's likely that nobody would realise that it had. The vast majority of the human population in the past and present were/are not closely monitored by reproductive biologists.
 * [Edited to add] The same considerations apply to the possibility of full human parthenogenesis. Perhaps a few Virgin births really have happened, but since most women of fertile age throughout history have either been in an ongoing sexual relationship, or had at least one sexual encounter (voluntarily or not), or would not have been believed if they said they hadn't had sex, such instances would not have been noticed or countenanced. {The poster formerly known as 87.81.230.195} 2.219.35.136 (talk) 22:06, 4 April 2021 (UTC)
 * I just discovered that virign births are claimed by 1% of U.S. moms. Viriditas (talk) 04:58, 6 April 2021 (UTC)
 * "US moms" is the newspapers' interpretation of what is actually "US teen moms"(link to the actual study), which might color any sociological conclusion you want to form.
 * More importantly: does it prove that 1% of US teen moms are (liars/idiots/religious fanatics/other), or does it prove that any poll option will get about 1% by entry error alone? Per the article, the "virgin moms" are n=45, but (emphasis added).  Tigraan Click here to contact me 16:48, 7 April 2021 (UTC)
 * A poll is not a controlled study. -- Jayron 32 17:06, 7 April 2021 (UTC)


 * Would that be a known unknown or an unknown unknown? Alansplodge (talk) 21:52, 4 April 2021 (UTC)


 * No case of human self-fertilization case has been reported in the medical literature. In the absence of reported cases, it is very4 hard to prove that such cases have occurred. Clearly, if they occur, they are rare indeed. What is ambiguous about this? --Lambiam 22:03, 4 April 2021 (UTC)


 * Agree with User:Lambiam: there's nothing ambiguous here; you're just disappointed. Matt Deres (talk) 20:03, 5 April 2021 (UTC)

Sulfur hexafluoride bed
Would enough sulfur hexafluoride in an open container (possibly more concentration rather than volume) support human body for floating? I've seen only light objects floating on it. Thanks. 212.180.235.46 (talk) 13:16, 4 April 2021 (UTC)
 * No. Sulfur hexafluoride is a gas at normal temperature and pressure (so-called "STP"). Its molar mass (calculated from its molecular formula) is 146 g/mol. One mol of an ideal gas occupies 22.4 litres, so its density (roughly, as it may not quite behave ideally) is 146/22.4 = 6.52 g/L, as at Gas. We know you can float people on water, which is 1000 g/L, so you're about a factor of 150 out (even if it were a liquid, which it isn't). I suppose that you could cool the container of SF6 to just below its boiling point of -50.8 C and try to float someone on the liquid but I suggest not trying that at home. Mike Turnbull (talk) 13:38, 4 April 2021 (UTC)
 * Our article about Ultralight materials might be a starting point to see what the least dense solid (or at material that could be made into a solid object) is to pair with various extremely dense gases. DMacks (talk) 14:59, 4 April 2021 (UTC)
 * Some nitpicks: first, per our article at sulfur hexafluoride, the density (at STP - standard temperature and pressure) of SF6 is 6.17g/L, which is quite a bit below your estimate (as you write, the 22.4L/mol figure only applies to ideal gases).
 * Second, whether it is liquid or gaseous is irrelevant for buoyancy effects. In practice, all gases as STP are less dense than all liquids at STP (I expect someone can find a creative counterexample but that is a good rule of thumb), so liquids are better for floating objects; yet, it is possible to float solids with large enough voids in SF6 (do not do that at home, unless you are trained against apshxia risks). Tigraan Click here to contact me 16:34, 7 April 2021 (UTC)
 * Yes, as I finished my edit and pressed "publish changes" I suddenly thought about helium balloons floating upwards in air and remembered that the science is buoyancy so gases could work if dense enough. In fact that made me wonder if the OP had intended to use uranium hexafluoride as the example, remembering its isotope separation in a gas centrifuge. Checking the article, it needs to be above 57 C (it has no liquid phase under normal conditions, only solid subliming to gas). So you would have (again, roughly) 352/22.4 = still far too small. Nice to see we have pedants in our midst,, and thanks for the photo which shows the effect nicely! Mike Turnbull (talk) 08:01, 8 April 2021 (UTC)
 * Tungsten(VI) fluoride is the densest gas at standard conditions. Molecular weight is 294 about double sulfur hexafluoride. Graeme Bartlett (talk) 08:23, 8 April 2021 (UTC)