Wikipedia:Reference desk/Archives/Science/2020 September 6

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September 6

Brown bear vs. human

I read that brown bear species (Ursus arctos) is divided into sixteen subspecies, due to morphological/genetical differences and habitat. My question is: from a strict biological perspective, would be ncecessary to divide humans (Homo sapiens) into subspecies, again due to morphological/genetical differences? Notice that I reject the social construct of "race", any kind of racial discrimination, the concept of one "race" being "superior" or "inferior", racial laws and historical definitions such as "Nordic race", Mediterranean race" and so on. I know that dividing humans into three or five or seven "subspecies" is not the same of brown bears, but I read biological differences exist and that's what I ask. Thanks in advance.--Carnby (talk) 07:51, 6 September 2020 (UTC)

Looking at Subspecies, I don't think it applies to humans. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:36, 6 September 2020 (UTC)

[Edit Conflict] The current consensus is that all living humans are members either of the species Homo sapiens which has no recognised subspecies, or of the single subspecies Homo sapiens sapiens, most often contrasted with the now extinct sister subspecies Homo sapiens idaltu.

Neanderthals have sometimes been classified as the subspecies H. sapiens neanderthalensis and sometimes as the species H. neanderthalensis: Denisovans have not yet been given a formal taxonomic status to my knowledge (which may well be outdated), as too little physical material representing them has been identified: one could argue for them being part of H.Neanderthalensis, a subspecies "H. neanderthalensis denisova", "H. sapiens denisova", or something else. The problem is that in biology there is no objective agreement on exact definitions of and distinctions between species and subspecies: different definitions (over 30 for "species") are used in different contexts. At least one prominent paleoanthropologist has expressed the opinion that there has never been more than one human species extant at any one time, given the evident willingness of various named 'varieties' of humans to interbreed when the opportunity arose.

There is also a model currently emerging within paleoanthropology of African Homo sapiens being an amalgam of several African regional populations somewhat physically and genetically differentiated through temporary geographical isolation prior to their subsequent re-merging, before their subsequent interbreeding outside of Africa with Neanderthals, Denisovans and possibly other groups as yet unknown.

Given the potentially fraught outcomes that might result from defining any living human population as a different subspecies from the rest of humanity, I suspect that all responsible scientists are very unlikely to discuss even the theoretical possibility of doing so. {The poster formerly known as 87.81.230.195} 2.122.2.158 (talk) 08:59, 6 September 2020 (UTC)

I echo the explanation by I.P above. Also you might find our article on Homo floresiensis interesting, who were described as the 'hobbit' people. Populations in the Nazca region and beyond (Easter Island) may have possibly been influenced by the Paracas culture; who are theorized as having naturally elongated skulls that predated and influenced Artificial cranial deformation. That's all a bit fringe though, and isn't well-covered on Wikipedia. Zindor (talk) 09:38, 6 September 2020 (UTC)

Correct me if I'm wrong but didn't I read somewhere that human races are more genetically similar to each other than different parts of an animal subspecies' range? Cause genetic mixing caused by humans exploring and falling in love or lust. Presumably in low tech eras the skin colors and nose shapes wouldn't mix quite as much as other genes as they were slowly selected by the sunlight and temperature of where they originated. So the races have mixed more than racists think. Also they like to show that Equatorial Guinea has the lowest IQ and don't say it was a small country where the crazy dictator killed anyone who might be smart and even anyone with glasses and they were the Dachau of Africa for awhile with massive population loss and brain drain from purges and people braving the minefields and boat ban to flee. Sagittarian Milky Way (talk) 13:53, 6 September 2020 (UTC)

Squirrels are able to produce subspecies. Potatoes are able to produce cultivars. Is H. Sapiens indeed the only magical life form totally unable to produce subspecies? I strongly suspect this is a very dangerous question to utter. People have been cancelled for far lesser crimes than asking this question. Tread carefully, as you are walking on politically correct eggshells here. 85.76.78.82 (talk) 16:57, 6 September 2020 (UTC)

Read what it is that causes subspecies, and it should become clear why humans don't qualify. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:29, 6 September 2020 (UTC)

We're all awfully closely related for a species with our numbers. Probably mostly due to recent bottlenecks, only a few thousand generations, in evolutionary times. There's a concept in population biology which I can't remember the name of - being the size of the population you would guess from a given amount of genetic variation. Well, humans have the genetic variability you would expect in a species of 100,000 or so, not billions. If that's missing from our relevant articles, it is probably because they were written by humans. :-)John Z (talk) 06:20, 7 September 2020 (UTC)

I think the answer to my question is this (from subspecies): "The variation among individuals is noticeable and follows a pattern, but there are no clear dividing lines among separate groups: they fade imperceptibly into one another. Such clinal variation always indicates substantial gene flow among the apparently separate groups that make up the population(s). Populations that have a steady, substantial gene flow among them are likely to represent a monotypic species, even when a fair degree of genetic variation is obvious."--Carnby (talk) 11:25, 7 September 2020 (UTC)

If a convenient asteroid is modeled as x% gold and platinum atoms and the rest rubbish how high does x need to be to mine it soon?

All mixed together homogenously.Sagittarian Milky Way (talk) 13:18, 6 September 2020 (UTC)

Gold and platinum are native metals so i would imagine they'd be available fairly easily in their elemental form. I'm assuming the 'rubbish' would be carbonaceous chondrite such as found in a C-type asteroid. How to deal with that chemically i don't know, it might be easier to physically mine it. Zindor (talk) 13:34, 6 September 2020 (UTC)

So when I hear of people mining rocks with invisible gold content it just means the easy stuff is gone and they're scraping the bottom of barrel. So I might find gold nuggets walking around (jetpacking around?) a NEO and just pick them up? Sagittarian Milky Way (talk) 14:04, 6 September 2020 (UTC)

I doubt they'd exist alone as a sizeable nugget, as space debris would be constantly wearing away at them. As far as i'm aware, these companies mining precious metals out of low% sediment do turn over a profit. I'd suggest that panning in a river for nuggets might be a more viable option that jetpacking around an NEO. Zindor (talk) 14:24, 6 September 2020 (UTC)

Of course they make profit or they wouldn't do it, I'm wondering how many percent you'd need to scoop up the regolith or whatever and choose which atoms you want to take (maybe vibrating the grains in a centrifuge and taking the dense ones?) and still make profit. No one can be sure an asteroid is profitable without going there probably so it'd be a very expensive risk. Maybe one of our tech billionaires will try one day lol. And one wonders who gets to mine where if other billionaire(s) suddenly want to try the same asteroid if the first one makes high profit. Sagittarian Milky Way (talk) 15:37, 6 September 2020 (UTC)

Mineral/precious metal deposit speculation is a real business and sometimes money gets thrown at non-profitable mining projects, keeping it afloat, in the hope that they 'strike gold/the motherload' so-to-speak. The key is to invest early, let uninformed investors pile in and raise the share price, then sell your shares just before the project goes bust. It'll be a free-for-all once humanity gets into space; the UN Space Treaty that currently exists will just be ignored for sure. Zindor (talk) 20:19, 6 September 2020 (UTC)

Per Outer Space Treaty#Key points there is apparently some ambiguity about whether the treaty prohibits space mining, and many space-faring nations have decided it does not. Tigraan^{Click here to contact me} 09:13, 9 September 2020 (UTC)

• Our page asteroid mining cites [1] which does more or less that calculation. It assumes 150ppm platinum (0.015%) and would be deemed too unprofitable for the amount of risk taken. It also assumes between 700 and 70,000 tonnes of platinum are hauled back to Earth; the lower figure is already four times the yearly Earthly production (see [2], table 4) so it seems probable that the market price of platinum would decrease significantly if such a project happened (whereas the article assumes a fixed price). Tigraan^{Click here to contact me} 09:38, 7 September 2020 (UTC)

All these figures and calculations seem to me to be deeply futile and objectless: The launch alone from the Earth per Atlas V of a one ton vehicle costs at least $110.000 per kilogram, that is already 1.7 times the price of gold and 3.7 times the price of platinum. To bring something back from Mars to Earth would be many many times as expensive per kilogram than that, and the asteroids are on average twice as distant as Mars. So all together to bring one ton of gold or platinum back to Earth will easily cost tens to hundreds times the gold or platinum price here on Earth. So regardless of the content in precious metal of an asteroid, there is no profit in it and there will be predictabily no reason or possibility to mine any asteroid at all (let alone soon). 2003:F5:6F0A:5A00:11D3:AC15:98F8:D5F1 (talk) 10:34, 10 September 2020 (UTC) Marco PB

It would be much easier (if slower) to mine a distant asteroid than close-by Mars, because said asteroid would requires less delta-v in the return trip, which is the key parameter for the cost of spaceflight (see rocket equation etc.). But yeah, it would still be awfully expensive. Tigraan^{Click here to contact me} 13:18, 10 September 2020 (UTC)

Some asteroids with similar orbits to Earth need less delta-v than a Moon rock return mission and not that much more than a space shuttle. Still buttloads of fuel of course, but not asteroid belt level buttloads. Sagittarian Milky Way (talk) 01:16, 11 September 2020 (UTC)

A genetic cause for sex height differences?

Is there a genetic cause for height differences between men and women? Futurist110 (talk) 21:33, 6 September 2020 (UTC)

See Sexual dimorphism in primates, Sexual dimorphism in non-human primates. Zindor (talk) 21:59, 6 September 2020 (UTC)

Puberty covers it. The pubertal "growth spurt" is both initiated and terminated by rising estradiol levels. After the onset of puberty, males have lower levels than females, so they generally start the "growth spurt" later, and it lasts longer, resulting in greater average adult height. --47.146.63.87 (talk) 04:47, 8 September 2020 (UTC)