Science desk
< June 29	<< May \| June \| Jul >>	July 1 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 30

Does scientific consensus support the premises and one of the conclusions of this magazine article?

So, I recently read an online article titled "Why Birds Can Fly Over Mount Everest" from the science magazine Nautilus. Its claims are quite interesting to say the least but now I have some doubts over their factual foundation.

TLDR: So, one of the the main conclusions of this article is that the primary reason birds could fly at the altitudes of the death zone where the partial pressure of oxygen is only around a third of the pressure at sea level is the fact that they possess great and efficient lungs that differ significantly from those found in mammals. Birds inherit this unique respiratory system from their dinosaur ancestors and the reason dinosaurs have these adaptations to begin with go all the way back to when plants left the oceans and colonized the Earth's landmasses. At first, plants on land had to stick to the surfaces of the land due to gravity but then they evolved a way to produce organic polymers known as lignin that has allowed them to form cell walls and thus complex structures such as stems, leaves, roots, and branches. For millions of years during the Carboniferous period, fungi and microbes lacked the ability to decompose lignin and this caused the atmospheric oxygen content to rise to over 30%. As a result, many lifeforms especially insects and amphibians became dependent on this elevated oxygen level. Later, fungi and bacteria evolved a way to oxidize lignin and decay all the dead woods that were not fossilized causing the atmospheric oxygen level to plummet to around 12% thus causing the Permian-Triassic extinction event and wiping out 95% of all species on Earth in the process. As a result, due to this evolutionary pressure of low oxygen level, dinosaurs evolve a highly efficient respiratory system.

Some questions I have regarding this article:

Are the relevant facts present in this article supported by scientific consensus among evolutionary biologist and paleontologists?
Is there enough evidence to conclude that the Permian-Triassic extinction was caused by anoxia from fungi and bacteria being able to decompose dead woods? Did 95% of all life literally suffocate to death?
If dinosaurs really did evolve their super efficient respiratory system in response to the low oxygen level during the early Triassic, how come the surviving ancestors of mammals, the Therapsid, did not have to do the same to survive?
Apparently, atmospheric oxygen level rose back up to 30% during the Cretaceous period. Did this have any significant effects on evolution? Why not?

StellarHalo (talk) 12:29, 30 June 2020 (UTC)[reply]

Just as a side comment, it is definitely known that birds can fly higher than the top of Mt. Everest. The definitive proof came in 1973 when a Rüppell's vulture collided with an airliner at 37,000 feet. --76.71.5.208 (talk) 00:01, 1 July 2020 (UTC)[reply]

I have no problem with that conclusion. The explanations for why and how the ancestors of birds developed such an adaptation to begin with are the main subjects of my questions and doubt. StellarHalo (talk) 13:08, 1 July 2020 (UTC)[reply]

I mean, just going off our article, the cause or causes of the P–T extinction are still heavily debated. There is not at present a settled scientific consensus on that, as opposed to, say, the K–Pg extinction event, where it's now firmly accepted that the primary cause was the impact event, and continuing debate is mostly about timescales and relative contributions of secondary factors. So it sounds like they're going too far in their claims. The high oxygen level in the Cretaceous had the notable effect of allowing larger insects; insects have no lungs and rely on mostly-passive gas exchange through spiracles, which means their maximum possible size is limited by the amount of oxygen they require. --47.146.63.87 (talk) 03:54, 2 July 2020 (UTC)[reply]

Insects actually got huge again during the Cretaceous? Could you please provide evidences for this? StellarHalo (talk) 15:55, 2 July 2020 (UTC)[reply]

It didn't say huge. It did say larger, that can be still rather small. Just larger. 2003:F5:6F12:6900:114F:CA11:A303:740C (talk) 18:11, 2 July 2020 (UTC) Marco PB[reply]

Some starting points are evolution of insects and Mesozoic. Looks like there are some relevant sources in those. --47.146.63.87 (talk) 06:25, 3 July 2020 (UTC)[reply]

What is the most sensitive part of the human body - externally?

What is the most sensitive part of the human body - externally? Is it the tip of the finger or penis? --ThePupil (talk) 14:11, 30 June 2020 (UTC)[reply]

Well, for about half the humans it's certainly not the penis. --Stephan Schulz (talk) 15:17, 30 June 2020 (UTC)[reply]

Correct, although the penis and clitoris are (in placental mammals) more or less the same thing, or homologous to use the fancy science term. The glans clitoris is the same tissue as the glans penis. --47.146.63.87 (talk) 03:24, 2 July 2020 (UTC)[reply]

I have no idea what the answer could be, but I suppose it may depend on what kind of stimulus you consider - a perpendicular press? rubbing? heat? cold?

One might also have to distinguish an area affected (e.g. whether you touch with a palm, a finger tip or a needle) as well as whether we apply it fast or slow (we get alarmed by a sudden, say, milligram force by a spider web thread on our face, but we ignore a weight of sunglasses on our nose). --CiaPan (talk) 15:18, 30 June 2020 (UTC)[reply]

When you talk about sensitivity, you usually mean a minimum force recognition (or another kind of level of intensity, like temperature difference, light intensity, electric voltage, pH deviation, humidity, etc). But there is another aspect of sensitivity - a resolution. For the two example places I suspect the penis glans is more sensitive to a light touch (but not same at each point on it) than a finger, but it gives much less precise information to the owner about at which point it is touched or in which direction it is rubbed. That I expect as a result of evolutionary adaptation - penis sensitivity serves as an orgasm trigger to induce ejaculation, so it just needs to detect it is at the right place, whilst fingers are used for sophisticated manipulations on complicated objects (catching little insects, peeling fruits, crushing nuts, to mention just a few) under the vision control, so they need be more precise but not that delicate. --CiaPan (talk) 15:41, 30 June 2020 (UTC)[reply]

If you consider sensitivity to a direct touch, I suspect the winner would be an eyelid - but that's just my private guess. :) CiaPan (talk) 15:45, 30 June 2020 (UTC)[reply]

Of course it's not a controlled experiment, but if I close my eyes and bring my fingertips near to them, I can indeed feel the touch on the eyelids before I feel anything in the fingertips. Indeed, I think I can even feel the warmth from the finger tips before actual contact. Very cool, very interesting! --Stephan Schulz (talk) 16:09, 30 June 2020 (UTC)[reply]

The most sensitive part is probably the corneal epithelium.^[1] --Lambiam 22:01, 30 June 2020 (UTC)[reply]

You're probably right, Lambiam, but that depends on the exact meaning of the requirement 'externally'. --CiaPan (talk) 22:07, 30 June 2020 (UTC)[reply]

@Lambiam: Failed to ping. --CiaPan (talk) 22:07, 30 June 2020 (UTC)[reply]

In strict physiological terms, "external" would mean surface ectoderm, excluding the odd bit out that migrates to the pituitary. --47.146.63.87 (talk) 03:24, 2 July 2020 (UTC)[reply]

Thank you all for the answers. I have to elucidate my question: 1. I meant to human boday of males. 2. The sense that I asked about it is touching or feeling pain.--ThePupil (talk) 22:35, 30 June 2020 (UTC)[reply]

Going by density of nerve endings I think it's supposed to be the lips. See also sensory homunculus. 2601:648:8202:96B0:0:0:0:C4FC (talk) 05:04, 1 July 2020 (UTC)[reply]

I don't think this is factually true. The dense nerve endings in the lips are mainly mechanoreceptors, while the cornea has a much higher density of nerve endings, but specifically of nociceptors.^[2][3] --Lambiam 07:23, 1 July 2020 (UTC)[reply]

List of colleges in the USA with the Master's program for Data Science.

Hello, Can I get the list of colleges in the USA with the Master's program for Data Science? — Preceding unsigned comment added by Hariomtsingh (talk • contribs) 14:57, 30 June 2020 (UTC)[reply]

Asked and answered elsewhere. Nick Moyes (talk) 22:09, 30 June 2020 (UTC)[reply]

At least provide a link Nick. — Preceding unsigned comment added by 86.162.76.127 (talk) 11:48, 1 July 2020 (UTC)[reply]

Ping: Nick Moyes. --CiaPan (talk) 14:01, 1 July 2020 (UTC)[reply]

Guys: That was hastily put up purely to avoid a duplication of editor effort. You'll have to check the unsigned editor's contributions if you want to see more. They posted at the Teahouse and then at RefDesk/Computing where they got a reply. Over to you - I'm rather tied up right now, and don't plan to dig out and post a link myself, sorry. Nick Moyes (talk) 14:27, 1 July 2020 (UTC)[reply]

For those interested: Wikipedia:Reference desk/Computing#List of colleges in the USA with the Master's program for Data Science.. --CiaPan (talk) 14:56, 1 July 2020 (UTC)[reply]

Telluric iron

The following question was sent to OTRS and the user cannot edit for technical reasons. I'm posting this here on their behalf.

In your introduction about telluric iron, the content is "Telluric iron, also called native iron, is iron that originated on Earth"
I consulted a lot of volcanologists, and they told me that there can be no metallic iron in volcanic lava, because volcanic magma is too oxidizing, and iron is an active metal, and iron will be oxidized first. Among them, a professor from a world-renowned university replied to me as follows: "Magmas are too oxidizing to have free iron — it combines with S (e.g., pyrite) or O (e.g., magnetite)."
We know that all rocks on the earth are derived from volcanic lava. Since there is no metallic iron in volcanic lava, how does Telluric iron come from the earth? This is obviously very contradictory. To this end, I asked the US Geological Survey again, and the reply they gave me was as follows: "To the best of my knowledge, the only metallic iron that's found in the Earth's crust comes from meteorites. All other iron is combined with other elements. There's a great deal of information here (https://en.wikipedia.org/wiki/Iron). I hope that helps."
I followed his guidelines and found that the description of metallic iron on your website is this: "In its metallic state, iron is rare in the Earth's crust, limited to deposition by meteorites."
It seems that the description based on your website is also contradictory, so I urge you to answer me, which one is correct?

(OTRS agents: ticket:2020062710003031) Thanks, ‑‑ElHef (Meep?) 16:41, 30 June 2020 (UTC)[reply]

Native iron is found in lavas, generally basalts, which have interacted with sedimentary rocks with a high carbon content. Under these conditions, the oxygen fugacity is reduced sufficiently for iron to crystallise. This paper describes this process and lists three localities where native iron is found: in West Greenland on Disko Island associated with Paleocene basalts, in Russia at Yakutia in Permo-Triassic basaltic Siberian traps and in Germany at Bühl associated with basalts of the Miocene Central European Magmatic Province. These are very rare occurrences, requiring geologically unusual conditions. So the volcanologists, the professor and the USGS are describing what happens in virtually all magmas, but in amongst the vast volumes of basalts in the world we know that it can happen. Mikenorton (talk) 19:23, 30 June 2020 (UTC)[reply]

To add to the above, one must be careful when consulting scientists to give them enough information and context to understand and best answer the question. If you simply ask a volcanologist about the presence of metallic iron in igneous rock, they will give you an answer that is correct in 99.9% of cases. They may not bother with that 0.1% exception of cases in their simplified answer, as they aren't writing you a thesis on the topic. However, if you ask specifically about the rare cases of metallic iron in basalts, they likely will know and be able to explain that. This is a similar problem to when creationists give scientists a 10 million year old sample to carbon date, and get surprised when the scientist gives an answer that isn't 10 million years old. Radiocarbon dating doesn't work on 10 million year old samples. If you had told them the expected age range before dating, they would have told you to use another dating method. --OuroborosCobra (talk) 19:32, 30 June 2020 (UTC)[reply]

Although not an example of actual metallic iron, Bog iron may be of interest, originating as it does from non-geological, biological concentration processes. {The poster formerly known as 87.81.230.195} 2.122.56.20 (talk) 06:55, 1 July 2020 (UTC)[reply]

I've updated the iron article to include telluric iron, using the source that I mentioned above. Mikenorton (talk) 15:42, 2 July 2020 (UTC)[reply]

Plasma treatment vs vaccine

What additional elemente has a (future) vaccine against the current infection in comparison to plasma donation from cured invividuals? Does a vaccine require plasma fractionation to separate antibodies?--37.251.221.37 (talk) 23:57, 30 June 2020 (UTC)[reply]

Vaccines do not normally directly contain antibodies, but rather work to "train" the immune system to produce antibodies itself by presenting them with some form of antigen to recognize in a non-infectious form. The plasma donations directly contain antibodies. --OuroborosCobra (talk) 05:13, 1 July 2020 (UTC)[reply]

...which is why vaccines are useless if you already have the disease; your immune system is already gearing up to fight the invader as fast as it can. You want to start producing antibodies before you get sick, and vaccines basically trick you into thinking that you are infected. --Guy Macon (talk) 04:00, 7 July 2020 (UTC)[reply]