Wikipedia:Reference desk/Archives/Science/2016 February 24

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February 24

How does smoking affect cognitive abilities?

Nootropic#Stimulants is the only evidence of a positive effect of smoking on cognition I could find. I wonder whether long-term smoking has long-term negative effects on (any) cognitive abilities. Could it be that smokers perform better after smoking, but just because that reduces abstinence signs? --Scicurious (talk) 00:42, 24 February 2016 (UTC)

Well, smoking may lead to loss of concentration due to distraction. That is, smokers spend time thinking about where to get cigarettes, when they can get a smoke break, where they can go to smoke, if they stink of smoke, etc. Then, if they get a smoker's cough or a far worse medical problem, that's even more distraction. StuRat (talk) 01:11, 24 February 2016 (UTC)

DO you have any references for any of that, or are you just making it up as you go along, as usual? --Jayron32 01:17, 24 February 2016 (UTC)

If you would read the link I provided, you can see the well established link between smoking and COPD. Do you imagine that having COPD, lung cancer, etc., is not mentally distracting ? But then I suspect you don't really care about that and are just trying to make trouble, as usual. StuRat (talk) 02:26, 24 February 2016 (UTC)

Having worked with many smokers in my time, I fully agree with your assessment. Keep in mind that they are addicts, and addicts are always focused on the next fix. Even forgetting the physiological disasters connected with smoking, it means they are always looking for breaks to go outside to the smoking areas, thus undermining both their own and their colleagues' productivity. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:53, 24 February 2016 (UTC)

The OP did not ask about the effect of smoking on lungs, i.e. COPD. The OP asked about evidence regarding connection between smoking and cognition. --Jayron32 02:30, 24 February 2016 (UTC)

And I ask again: "Do you imagine that having COPD, lung cancer, etc., is not mentally distracting ?" StuRat (talk) 05:58, 24 February 2016 (UTC)

What I imagine is irrelevant to this desk. This is not the imagination desk. It is the reference desk. --Jayron32 11:22, 24 February 2016 (UTC)

You're just trying to make trouble again, and I'm not going to provide a source to prove that having lung cancer or COPD can be mentally distracting, any more than I would provide a source to prove that 1 + 1 = 2. StuRat (talk) 00:56, 25 February 2016 (UTC)

Let's put this a different way. If someone asks how does sexual intercourse affect cognitive abilities, it's fairly unlikely the answer they're looking for is you may get HIV and if you do, it's going to be mentally distracting. Nil Einne (talk) 06:16, 24 February 2016 (UTC)

Well, early sexual activity does correlate with poor academic performance, pregnancy, dropping out, lower average wage, etc. Then there is the risk of various diseases, too. Those would certainly be worth mentioning. Perhaps not the main intent of the Q, but related. StuRat (talk) 06:24, 24 February 2016 (UTC)

Sure and people could get so frustrated with dumb answers that they'll ban someone from the RD and that person will be so unable to stand not being able to give random junk answers that they'll take their own life. An unfortunate outcome, but it doesn't mean suicide is a good answer to the question, how does using the RD affect your life. Nil Einne (talk) 06:34, 24 February 2016 (UTC)

• There are several good references here the OP may be interested in. --Jayron32 01:19, 24 February 2016 (UTC)

I agree with Jayron32. Suggesting that someone with a smoking related illness has impaired cognitive ability due to being distracted is Sturat "making it up as he goes along. ;) Vespine (talk) 02:56, 24 February 2016 (UTC)

No, StuRat is right. The addict's primary mental focus is on their next fix. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:02, 24 February 2016 (UTC)

That's complete nonsense, I disagree entirely. I was a smoker for 15 years and very very rarely was i distracted by "where I'm going to get my next fix", maybe during times of unusual stress, and EVEN THEN i would dispute that my cognitive ability was impaired in any measurable way. Clearly personal anecdote is not a reliable reference, but then neither are any of the claims you've proposed. Vespine (talk) 03:36, 24 February 2016 (UTC)

The addict also is typically in denial. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:51, 24 February 2016 (UTC)

For every complex problem there is an answer that is clear, simple, and wrong. Vespine (talk) 04:15, 24 February 2016 (UTC)

Please stop being so ridiculous, the CLAIM you are attempting to defend is that smokers are cognitively impaired due to their "addiction". If that was even REMOTELY true, it should be fairly easy for you to find some references supporting that claim, instead of attempting witty rejoinders. Vespine (talk) 04:29, 24 February 2016 (UTC)

Who should I believe? You? Or my own eyes? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:00, 24 February 2016 (UTC)

The plural of anecdote isn't data. Fgf10 (talk) 08:08, 24 February 2016 (UTC)

You do realize that is actually the whole point of science? Because you can't always believe your own eyes. From homeopathy to exorcism, countless people believe complete nonsense because they trust their own eyes over empirical evidence gathered by other people. Vespine (talk) 05:25, 24 February 2016 (UTC)

There are many types of addiction, Mr B Bugs. Such as, for example, the addiction to only ever making unreferenced, anecdotal comments on a reference desk. The "undermining of productivity" and other damage that those sorts of "contributions", and their aftermath, make, would be hard to overestimate. I take the charitable view and assume that such posts are usually not made maliciously, but under the influence of illicit substances (another addiction). -- Jack of Oz ^{[pleasantries]} 06:12, 24 February 2016 (UTC)

The loss of productivity by smokers is a frequent problem in the business world. How many smokers have you worked with in your career? ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:43, 24 February 2016 (UTC)

Do you have a reference for that? DuncanHill (talk) 09:45, 24 February 2016 (UTC)

Here's a survey from a few years ago,[1] discussing the loss of workplace productivity caused by smokers. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:46, 24 February 2016 (UTC)

Which manages to misname the journal Lundborg was published in. DuncanHill (talk) 09:59, 24 February 2016 (UTC)

Wow, a typo invalidate the whole thing, eh? Never mind that the report squares with what business colleagues have been saying for a long time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:01, 24 February 2016 (UTC)

• Let's actually use some references shall we? Rather than listen to Baseball Bugs spouting baseless nonsense as per usual. Let's start here, for instance (just the first sensible hit in a quick journal search): " In nonsmokers and nondeprived smokers, nicotine enhances finger tapping, focused and sustained attention, recognition memory, and reasoning." Fgf10 (talk) 08:08, 24 February 2016 (UTC)
  • Addicts often think their performance is enhanced by the drug. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:23, 24 February 2016 (UTC)

And their thoughts change metrics in objective tests? Save yourself the embarrassment and just stop posting on this question. Fgf10 (talk) 10:08, 24 February 2016 (UTC)

During those tests, how often did they take smoke breaks? Save yourself the embarrassment and concede that I'm right and you're wrong. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:13, 24 February 2016 (UTC)

• • • Do you have a reference for that? DuncanHill (talk) 09:45, 24 February 2016 (UTC)
      • You may find this[2] enlightening. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:49, 24 February 2016 (UTC)
        • Ideally not a commercial site trying to drum up business for itself. DuncanHill (talk) 09:51, 24 February 2016 (UTC)
          • Feel free to look for a source that would be acceptable to your exacting standards. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:53, 24 February 2016 (UTC)
            • You made the assertion, you are responsible for finding a reliable source. Try reading WP:RS. DuncanHill (talk) 10:01, 24 February 2016 (UTC)
              • The source is good enough, whether you believe its information or not. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:03, 24 February 2016 (UTC)
                • Bugs, an advert is not a reliable source. You know that perfectly well. DuncanHill (talk) 10:05, 24 February 2016 (UTC)
                • The source is absolute bullshit. Again, just stop it. Fgf10 (talk) 10:08, 24 February 2016 (UTC)
                  • It restates conventional wisdom, so it's good enough. FYI, as regards you two, I put up with a lot more personal attacks from the likes of you two than I should have to be expected to, but luckily I have too little regard for your vile and vulgar comments to bother doing anything about it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:11, 24 February 2016 (UTC)

It completely contradicts the numerous peer reviewed scientific papers cited here already. Do you really not understand the difference between scientific studies and adverts and hearsay? Shocker: sometimes conventional wisdom is wrong. Good thing we all don't have your attitude, or we'd still be rubbing two stick together. Fgf10 (talk) 10:15, 24 February 2016 (UTC)

Feel free to provide a source that asserts addiction improves job performance. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:17, 24 February 2016 (UTC)

You're the one that brought up job performance. My sources adequately answered the OPs question. Your unsourced assertions are irrelevant to the question. Fgf10 (talk) 10:21, 24 February 2016 (UTC)

Of course they're more focused - they're thinking about their next nicotine fix. Have you never worked with smokers before? ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:23, 24 February 2016 (UTC)

Neither of our personal experiences are reliable sources. Again, provide reliable sources for your assertions. Fgf10 (talk) 10:25, 24 February 2016 (UTC)

Answer the question. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:27, 24 February 2016 (UTC)

Say the magic word! Of course I have worked with smokers, and have never seen a problem in their job performance. Again, that is irrelevant. Provide reliable sources for your assertions, or accept that you are wrong. Fgf10 (talk) 10:28, 24 February 2016 (UTC)

In this writeup,[3] nicotine enhances cognitive skills, but deprivation of nicotine degrades performance. As you would expect for an addictive substance. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:36, 24 February 2016 (UTC)

There we go! That wasn't that hard now, was it? PNAS even, good source. Completely agree with you. See how easy life becomes when you actually have sources to back up your assumptions? Fgf10 (talk) 10:39, 24 February 2016 (UTC)

I went to PubMed and typed in smoking cognitive decline (seriously not rocket science!) and found this study, which says in its introduction "Epidemiological studies have been conducted to explore the associations between smoking and physical and cognitive capability in mid to later life, generally concluding that smoking is associated with worse capability outcomes.1–8" I didn't look at everything that came up, but this is how you get started answering this kind of question. Wnt (talk) 12:30, 24 February 2016 (UTC)

I am very certain that some weeks ago, I read and linked to an Army or Air Force Federal Aviation Administration research paper, hosted on Defense Technical Information Library, about the effects of oxygen deprivation on standardized testing performance; and one of the strongest factors in that specific experiment was whether the participants smoked tobacco cigarettes.

After just a few moments searching our archives: in January of this year, I wrote: "Here is a wonderful piece of quantitative psychometric research: Effects of Hypoxia... (1997), in which test subjects performed the MATB test battery with different oxygen levels. Amazingly, being a smoker has an incredible negative effect on your ability to focus - perhaps stronger than the effect of hypoxic hypoxia!"

Nimur (talk) 15:10, 24 February 2016 (UTC)

Flower from a film poster

• Hi. I'm currently writing a paper about symbolism in Indonesian film posters, but I'm having trouble ID-ing the flowers in this one (I've also seen this poster with the flower looking yellow). The image used was almost certainly taken in Indonesia, and my wife says she's familiar with the plant, but doesn't know its name. Does anyone have an idea as to what kind of plant it is? — Chris Woodrich (talk) 07:20, 24 February 2016 (UTC)

Hi Chris. Are you sure it is a flower in that poster? It looks more like the lady is holding a bunch of grain seed heads to me. Perhaps she is harvesting millet or some other cereal grain? SemanticMantis (talk) 14:34, 24 February 2016 (UTC)

• It's a possibility, yes. I'm far from a botanist (as evidenced by my frequent visits here). Isn't Dipsacus also possibility? — Chris Woodrich (talk) 16:11, 25 February 2016 (UTC)

I suppose so, though to me the heads of teasel look bigger and closer to spherical than those in the photo. I'm not sure that teasel would have been grown in any quantity in Indonesia, but I also don't know much about agriculture in Indonesia. That's where I'd start - forget the giant list of plants found in Indonesia, and focus on the plants grown at large scale in Indonesia. I could be wrong but I think this is a harvest photo, and so I'd try to make the most of that clue. SemanticMantis (talk) 15:13, 26 February 2016 (UTC)

How do epidemiologists track down the source of a sexually transmitted disease if clinics have anonymous testing?

What is actually anonymous in anonymous testing? And if it's really anonymous, does that mean epidemiologists won't be provided information about the patient's sexual history? 140.254.70.33 (talk) 12:48, 24 February 2016 (UTC)

Different jurisdictions have different rules regarding the confidentiality of Medical records. In the United States, who may have access to those records may be governed by various laws, for example the Health Insurance Portability and Accountability Act or HIPAA. --Jayron32 12:55, 24 February 2016 (UTC)

See: http://www.cdc.gov/amd/project-summaries/tracking-std-transmission.html where it says:

CDC scientists are using genetic information (sequence data, including next generation sequencing) for the viruses and bacteria that cause these diseases, together with demographic, geographic, and clinical data from infected persons—such as risk group, age, location, and health status—to understand more about how infected people are connected. Combined, this information helps scientists to identify more precisely how these diseases are spreading so that outbreaks can be stopped.

Richerman (talk) 15:02, 24 February 2016 (UTC)

How does glucagon avoid peristaltic?

As a preparation for ERCP test, the patient is given glucagon in order to avoid the peristaltic action. I would like to understand how an hormone that its function is to save on glucose level in the blood (by secreting glucose from the liver), also avoid peristaltic? ThePupil17 (talk) 14:11, 24 February 2016 (UTC)

See Glucagon#Endoscopic_retrograde_cholangiopancreatography. Ruslik_Zero 19:33, 24 February 2016 (UTC)

Distinguishing Human Blood from Pig Blood by taste/other easy characteristics...

This is sparked by the most recent episode of Lucifer (TV series). How difficult would it be to identify Human Blood vs. Pig Blood (or other mammalian species) by either taste or another human sense (Touch(?), Sight(?)). Also given that Lucifer was able to identify it as not only not Human but specifically as Pig, how easy would it be to tell enough species apart to specifically identify it as Pig? I'm guessing this would essentially be a Supernatural power since my guess is that even with a standard visible light microscope telling the species of blood simply identified as Mammalian would be difficult. Ideas?Naraht (talk) 14:21, 24 February 2016 (UTC)

Forensic use of genome profiling method to differentiate human blood samples from rat, squirrel, cat, dog, cow, and antelope. AllBestFaith (talk) 15:03, 24 February 2016 (UTC)

Interesting. This indicates to me that my guess as to the level of science to be *sure* is about right. I'm assuming that the pig is approximately the same genetic distance from humans as the animals mentioned in the article. Still doesn't answer the original question. :)Naraht (talk) 16:27, 24 February 2016 (UTC)

Pigs can have type A or type O blood; organs from pigs identified as blood group O cause less immune rejection when transplanted to humans.[4] AllBestFaith (talk) 16:40, 24 February 2016 (UTC)

Less rather than none, I would presume that if a pig with type O was able to donate to humans that blood donation today would be vastly different.Naraht (talk) 18:45, 24 February 2016 (UTC)

Here's some person [5] sharing their opinions on the tastes of different bloods. I don't think it's too crazy to think that some experienced people could easily tell e.g. pig blood from cow blood by taste alone. Keep in mind people regularly claim to detect differences in the same grapes grown in different places (Terroir), and I think most all of us can distinguish pig meat from cow meat by taste alone. SemanticMantis (talk) 17:30, 24 February 2016 (UTC)

Also, the character in Lucifer is the devil himself, and thus may be assumed to have abilities that humans lack. --Guy Macon (talk) 18:20, 24 February 2016 (UTC)

Not surprised the Chicken is different, which is why I specified Mammalia. Yeah, I can see someone with a wine taster's palate possibly able to do this. And yes, he's the Devil, but there is a difference between truly Supernatural abilities and those which simply come with a lot of experience (elsewhere in the episode, he comments on what bone is being broken *just by sound* in an attack of another character on the members of a gang. Supernatural or just what a Connoisseur of torture would learn over a few millenia, unclear.)Naraht (talk) 18:45, 24 February 2016 (UTC)

In forensic science, they generally use the Kastle–Meyer test to confirm that there is hemoglobin present - and if there is, they do an Ouchterlony double immunodiffusion to prove that it's human in origin. That second test takes 48 hours and relies on antibody/antigen bonding. Since those kinds of determination at crime scenes are typically kinda urgent, I'd guess that if there was an easier way to identify blood as human, they'd probably be using it. SteveBaker (talk) 21:40, 24 February 2016 (UTC)

To be fair, it's possible that "just taste it!" never actually occurred to them. --Trovatore (talk) 21:43, 24 February 2016 (UTC)

Rather than looking at this from a forensics standpoint, I wonder if consulting a farmer or butcher would be more helpful. Most of the material that leaks from meat by the time it gets to the butcher will be protein rich liquid rather than actual "blood", but it would make for an interesting data point. The guy at the slaughterhouse would nominally be more informed about differences in blood, but I'm not sure how common it is for slaughterhouses to regularly manage more than one kind of animal. Just a thought. Matt Deres (talk) 15:25, 25 February 2016 (UTC)

In this particular case, it was at a "Crime scene" where the pig had been killed on the other side of a screen, and Lucifer was tasting the blood that had run under the screen. So Blood, not "meat juices".Naraht (talk) 15:32, 25 February 2016 (UTC)

Comparing the taste of my own blood from a cut finger to the blood from a really rather good rare steak last night...I can't tell the difference. (OK - cow not pig - and anecdote != evidence) SteveBaker (talk) 15:35, 25 February 2016 (UTC)

The Ouchterlony test is indeed a method, but it's a very old method. I was expecting there'd be something comparable to a pregnancy test that could do it, and found this (in case the links die, this brand is the "ABACard Hematrace") (see photo here). Wnt (talk) 13:39, 26 February 2016 (UTC)

See Lowenstein et al, Forensic Sci Int. 2006. Identification of animal species by protein radioimmunoassay of bone fragments and bloodstained stone tools. PMID 16191470. --NorwegianBlue ^talk

Is there a source for the number of the types cells organalles in human cell?

I'm looking for a source that site the exactly number of the cell organelle and the number of the cell parts. Yes, I know that there are many types of cells, but there are a basic number of general organelle that found in all human cells.ThePupil17 (talk) 14:36, 24 February 2016 (UTC)

"There are a basic number of general organelle that found in all human cells." -- Really? I don't see any information about organelles inside human red blood cells. Our article says "They lack a cell nucleus and most organelles", and "In mammals, erythrocytes also lose all other cellular organelles."

Now, I think it probably is true that there is a list of organelles that most types of human cells have. But then you have to get careful about which types of cells count in order to get a precise answer. Our article at organelle gives just seven organelles as the "major" organelles of eukaryotes. If you're interested in organelles, I'll also recommend symbiogenesis. SemanticMantis (talk) 15:12, 24 February 2016 (UTC)

Thank you for your comment. I knew that RBC are exception (and originally they do have). Do you know another type of human cell like RBC? ThePupil17 (talk) 16:07, 24 February 2016 (UTC)

Also worth noting is that the exact classification scheme is somewhat arbitrary and will vary depending on agreed upon conventions. Defining what makes a bit of a cell an organelle, or a part of an organelle, and how to classify all those bits, is not a universal truth given by God. These are human created schemes created by humans for our own purposes, and given the arbitrary nature of all such schemes, there are going to be differences. --Jayron32 16:19, 24 February 2016 (UTC)

It turns out mature Lens_(anatomy)#Lens_fibers also have no nucleus or organelles [6]. Also "Corneocytes are keratinocytes that have completed their differentiation program and have lost their nucleus and cytoplasmic organelles." So by mass we have a decent amount of non-nucleated cells, but only a few types. Gut flora have lots of cells without nucleus or membrane-bound organelles, but we don't usually consider those cells "human". SemanticMantis (talk) 17:01, 24 February 2016 (UTC)

Also, the definition of organelle is a bit fuzzy. Our article states that organelles usually are separated by a lipid bilayer, but lists "organelles" that are not. Both the nucleus and the cytoplasm contain many subcompartments which separate biochemical processes into confined spaces. The organelle article lists the proteasome among the organelles, the Cajal body is classified as a sub-organelle in its article. Where to draw the line is rather arbitrary, IMO. --NorwegianBlue ^talk 22:34, 27 February 2016 (UTC)

Is there any nervous system in the heart?

Purkinje fibers

From Wikipedia, the free encyclopedia Is there any nervous system in the heart? For example, if we can to reach to the heart of creature while it alive and awake (without anesthesia or analgesia) and make a incision, is it supposed to heart it? ThePupil17 (talk) 17:26, 24 February 2016 (UTC)

See Angina pectoris. Key quote: "This is explained by the concept of referred pain, and is due to the fact that the spinal level that receives visceral sensation from the heart simultaneously receives cutaneous sensation from parts of the skin specified by that spinal nerve's dermatome, without an ability to discriminate the two." --Guy Macon (talk) 18:28, 24 February 2016 (UTC)

The question being asked here is actually whether heart tissue contains pain receptors, and the answer, as Guy says, is that it does. (Brain tissue, as you might know, does not.) Looie496 (talk) 18:33, 24 February 2016 (UTC)

What does it mean "pain receptors"? ThePupil17 (talk) 00:31, 25 February 2016 (UTC)

See pain receptor. StuRat (talk) 23:38, 27 February 2016 (UTC)

I didn't quite understand the example of the question. Anyway, there are motor nerves and sensory nerves, and the answers so far have only dealt with the latter. The heart does not have motor nerves in the conventional sense, but it has nerves which influence its motor activity. See Sinoatrial node and next Heart rate. Note the figure which shows innervation from the vagus nerve and the sympathetic nerves. Then read about the electrical conduction system of the heart, which is made up of specialized muscle cells which function in a similar way to nerve cells. A denervated heart does not stop to beat, but it has a limited ability to respond to the physiological needs of the body by changing its pulse rate, responding only to soluble mediators in the blood stream. --NorwegianBlue ^talk 22:11, 27 February 2016 (UTC)

• I am surprised no one has mentioned the Purkinje fibers, ThePupil17. μηδείς (talk) 22:15, 28 February 2016 (UTC)

Koala is a marsupial

When was it first revealed that the koala is a marsupial?? I know that the koala was initially thought to be a bear species when it was discovered by Europeans in 1788. Georgia guy (talk) 22:56, 24 February 2016 (UTC)

According to our article (see: Koala#History) "English naturalist George Robert Waterhouse, curator of the Zoological Society of London, was the first to correctly classify the koala as a marsupial in the 1840s. He identified similarities between it and its fossil relatives Diprotodon and Nototherium, which had been discovered just a few years before". Richerman (talk) 23:05, 24 February 2016 (UTC)

Also interesting to note: "The first published image of the koala appeared in George Perry's (1810) natural history work Arcana. Perry called it the "New Holland Sloth" on account of its perceived similarities to the Central and South American tree-living mammals of genus Bradypus" Richerman (talk) 23:15, 24 February 2016 (UTC)

It is now known that there are no truly native species of placental mammals in Australia. At the time of the so-called discovery of Australia by Europeans, there were two species of placental mammal in Australia, a canid, and a hominid. The dingo is sometimes referred to as a "wild dog of Australia". He is not that. How did he get there? No one has suggested that the dingo swam across Wallace's Line. How did the hominid get there? Boats. If the dingo came in boats, he is not a wild dog of Australia. He is a feral dog of Australia. He came in the boats of the Australians. Robert McClenon (talk) 03:51, 25 February 2016 (UTC)

If you read Dingo#Origin and genetic status we still don't really know how or when the dingo got to Australia. If it has been there for over 20,000 years, as is indicated by Aboriginal rock art, I think it would be fair to call it wild rather than feral. Richerman (talk) 08:18, 25 February 2016 (UTC)

Aren't you forgetting that bats and rodents are also native to Australia? See Mammals of Australia#Placental mammals. - Lindert (talk) 09:50, 25 February 2016 (UTC)

An interesting but only marginally related comment has to do with the taxonomic status of the opossum, in particular the Virginia opossum. Linnaeus didn't know what to do with it, because, prior to the exploration of Australia, he didn't know what is was. At the time, it was not only ordinis sui, but subclassis sui. When Australia was explored, it was then discovered that the opossum belonged to a previously unknown subclass. It took a long strange journey from Africa to North America, and the ship on which it took its journey was nothing less than South America itself, which took a long strange journey from Africa to North America. Robert McClenon (talk) 03:51, 25 February 2016 (UTC)

Africa had nothing to do with it. Marsupalia originated in South America, when Australia and South America were still attached to Antarctica. Africa was separate by then. The marsupials of Australia got there from South America via Antarctica, according to current theories. It is logically possible marsupials originated in Antarctica, but we have no such evidence, and the cladistic (if not physical) diversity of and most primitive forms of marsupials are found in the Americas. See monito del monte. μηδείς (talk) 02:14, 27 February 2016 (UTC)