Wikipedia:Reference desk/Archives/Science/2019 November 9

= November 9 =

Micellar water?
What's micellar water? Cosmetic cleansers are all about it now. I can't find any article on it.196.52.93.43 (talk) 01:28, 9 November 2019 (UTC)


 * See . It's a type of emulsion. SinisterLefty (talk) 01:38, 9 November 2019 (UTC)


 * Soapy water? HiLo48 (talk) 02:02, 9 November 2019 (UTC)


 * Yes, it’s essentially soap water (or more precisely: surfactants) plus marketing bullshit. We also have an article on micelles, by the way. Cheers ⌘  hugarheimur  —Preceding undated comment added 02:22, 9 November 2019 (UTC)
 * This is basically dish soap, right? I have a big jug of that from Costco, so can I get the marketing bullshit separately packaged and blend it in at home for a similar end result?  Thanks. 67.164.113.165 (talk) 20:41, 12 November 2019 (UTC)

Are humans all one species?
In biology class, I learned that female bull dogs (or some kind of dog breed) require Caesarean sections, because the head is too big. Without human intervention, the puppy is doomed. Online, I learned that interracial marriages are rising in the USA, with the most common type being white male and Asian female. But this type of coupledom may involve more Caesarean sections, as Asian females may have smaller pelvises than European females. So, without human intervention, a woman who cannot deliver the baby will be doomed. A dark-skinned African may migrate to Northern Europe, but may suffer from rickets due to lack of sun exposure. A Northern European may migrate to somewhere near the equator and suffer from malaria because he or she does not have the sickle-cell trait. Humans are separated from each other geographically, and it seems, even biologically; however, with modern medicine, that can greatly reduce the selective pressures acting on humans. Human population A may be adverse to human population B, and this prevents intermarriage. Are they two species? Human population A may be favorable to human population B, and this promotes intermarriage and union of the two ethnicities as one, forming a new lineage. Are they one species? Neanderthals mated with Homo sapiens. Are they one species or two? Where do we draw the line? SSS (talk) 02:31, 9 November 2019 (UTC)


 * Modern humans are a single species. ←Baseball Bugs What's up, Doc? carrots→ 03:44, 9 November 2019 (UTC)


 * The usual line, for sexually reproducing organisms, is "Can they mate and produce fertile offspring ?". Not that it must always be successful, just that it sometimes is. I'm not aware of any combination of two races that can never breed to produce fertile offspring. Thus, we are a single species. SinisterLefty (talk) 03:59, 9 November 2019 (UTC)


 * You might have two distinct species if you have two distinct mating populations that experience hybrid incompatibility when mating with one another, or experience some other form of reproductive isolation. Human races fail this on both parts: A) There are indeed, as far as I can tell, no well documented claims of interracial couples having worse fertility than either race generally; and B) the human races do not constitute isolated populations to begin with, nor are they valid taxonomic subgroups. Someguy1221 (talk) 08:10, 9 November 2019 (UTC)
 * Well, isolated populations did exist. One of the reason of Spaniards success in America is, Natives had been isolated from Old World for so long, diseases wrought havoc. And much less time was required to create breed of dog or cattle. But human species actually lacks genetic diversity, evolution cannot tap on an already large pool to create distinctive human race, it has to wait for some random selective mutation to appear, and even when critical for survival, such like high-altitude adaptation in humans, this creates rather hard to see variation (that is, you would see the irrelevant blackness of an Ethiopian, not his very relevant specific adaptation). Gem fr (talk) 21:23, 9 November 2019 (UTC)


 * It's called dystocia. For dogs it seems there may be as many as ten. I've been out with some right dogs in my time, but I always draw the line with the Orientals. One can't be too careful, can one? Martinevans123 (talk) 08:31, 9 November 2019 (UTC)
 * All dogs are also a single species, Canis Canis aka canis lupus familiaris aka canis familiaris, actually rather one of the 36-38 subspecies of canis lupus, all of them being able to interbreed (even though, a male teckel will have some trouble mounting a doberman female). This to show how large variations can be observed within a single species, in which quite a number of breed are distinguished


 * See also racialism Gem fr (talk) 09:07, 9 November 2019 (UTC)


 * See On the Origin of Species (especially the first dozen or so pages) for what is still one of the most profound and insightful pieces discussing the concept of species. Robinh (talk) 19:27, 10 November 2019 (UTC)


 * Ah, yes. The species problem.  The biggest issue with defining any grouping of organisms a "species" is that for any given definition, there will always exist groups of organisms which don't fit well in the definition.  The existence of things like ring species adds some added kinks to definitions.  -- Jayron 32 12:13, 12 November 2019 (UTC)

But here's another problem. Aren't tigers and lions not considered to be the same species? But yet they can reproduce to forms tigons and ligers - 1 is a male tiger female lion, the other female tiger male lion. So clearly there is more of a definition to species. 67.175.224.138 (talk) 12:37, 13 November 2019 (UTC).
 * Some species that are "close enough" genetically can produce offspring. The mule is an obvious example. They are born male or female, like your typical mammal, but they can't reproduce, with rare exceptions - as with the Liger and the Tigon. ←Baseball Bugs What's up, Doc? carrots→ 14:27, 13 November 2019 (UTC)