Wikipedia:Reference desk/Archives/Science/2024 June 19

= June 19 =

Carnivore diet
(Disclaimer: I don't want to put my cat on any kind of diet, in fact I don't have a cat, so this is purely a science question). I was surprised to find a ton of online search hits about putting cats on vegan diets This one mentions that you at minimum have to include some supplements like taurine that come only from animal sources. Thus, the diet is not 100% vegan.

My question is whether there are at least potential workarounds such as protein synthesis, that would allow putting obligate carnivores like cats on purely plant diets and keeping them healthy? Question is inspired by a discussion elsewhere about "impossible burgers", which supposedly give meat-like nutrition to humans. There must be something missing though, that humans can do without but cats cannot. Thanks. 2601:644:8501:AAF0:0:0:0:78AE (talk) 09:28, 19 June 2024 (UTC)


 * Most mammals, including humans, can biosynthesize taurine. Felids lack this ability. Taurine can be synthesized in a chemical production process not involving animal sources; see . --Lambiam 06:09, 21 June 2024 (UTC)

Buoyancy question
What's the minimum concentration of an aqueous table salt solution which will ensure that a human being will float regardless of his/her body type, even with all his/her muscles fully contracted (assuming standard temperature and pressure)? Disclaimer: this is not a homework question. 2601:646:8082:BA0:649B:7753:3C84:C70D (talk) 10:28, 19 June 2024 (UTC)


 * 0%. Since water is 997kg per cubic meter and the average density of the human body is 985kg per cubic meter. 41.23.55.195 (talk) 11:37, 19 June 2024 (UTC)
 * Obviously you haven't been to the Dead Sea or the Great Salt Lake. Clarityfiend (talk) 13:53, 19 June 2024 (UTC)
 * If you are in a swimming pool you can descend to the bottom by contracting your muscles, which I guess decreases your body's volume. I guess that is what OP was referring to.  Question is how much salt it takes to make this impossible.  I can say 3.5% or so is not enough, since you can also do that in the ocean.  2601:644:8501:AAF0:0:0:0:78AE (talk) 16:45, 19 June 2024 (UTC)
 * I have never been able to float. --User:Khajidha (talk) (contributions) 17:58, 19 June 2024 (UTC)
 * Assume the "Jesus position" with an arched back. It works for me, and I'm no swimmer. ←Baseball Bugs What's up, Doc? carrots→ 18:55, 19 June 2024 (UTC)
 * That's not what I was asking -- the context here is a panic attack causing a person to sink (think something similar to the floundering in the water scene in Titanic, but minus the hypothermia), so obviously voluntary techniques won't work in this context. 2601:646:8082:BA0:649B:7753:3C84:C70D (talk) 23:05, 19 June 2024 (UTC)
 * Sure. I was talking to Khajidha. But knowing the technique can help conquer a panic situation. ←Baseball Bugs What's up, Doc? carrots→ 02:01, 20 June 2024 (UTC)
 * I don't have panic attacks in water (my one and only severe phobia has to do with something else entirely) -- I was asking this simply out of curiosity. So, at what salinity level would a person not sink even if he/she panics and suffers a muscular spasm all over his/her body? 2601:646:8082:BA0:649B:7753:3C84:C70D (talk) 02:30, 20 June 2024 (UTC)
 * According to this, the Dead Sea has the highest salinity in the world, at 34 percent, making it virtually impossible to sink. So that at least puts a frame on your question. And this suggests an experiment you could do. ←Baseball Bugs What's up, Doc? carrots→ 04:26, 20 June 2024 (UTC)
 * I'm aware of the Dead Sea -- however, my question was about the lowest salinity level at which a person would float under all circumstances, which is probably quite a bit lower than that in the Dead Sea. And does an egg have the same maximum density as a person with all his/her (I'd go with his, since a woman's body probably has a lower density than a man's) muscles fully clenched? 2601:646:8082:BA0:649B:7753:3C84:C70D (talk) 05:57, 20 June 2024 (UTC)
 * Well if you want this to apply to all people you will need to know the density of the most dense human body. That is probably one with deflated lungs, no gas in the intestines and a very low proportion of fat. And do we allow someone who at a barium meal? Graeme Bartlett (talk) 07:04, 20 June 2024 (UTC)


 * Google has various opinions. Here's one: ←Baseball Bugs What's up, Doc? carrots→ 08:03, 20 June 2024 (UTC)
 * IP editor: you may be interested in this calculator which provides the density of saline solutions. Note that the answer you seek depends on the temperature of the water. By setting various concentrations of salt, you can find out the density of the resulting solution. You still have to decide what "floating in all circumstances" means to you. Mike Turnbull (talk) 10:12, 20 June 2024 (UTC)
 * Most of the short-term volume variation in humans comes from the lungs. Depending on which muscles exactly contract, the volume of the lungs may increase or decrease. Most people have a reflex to fill their lungs when they unexpectedly enter the water, making them positively buoyant.
 * Also, people who unexpectedly enter the water usually wear clothes. Clothes tend to be negatively buoyant when wet, but can trap a lot of air. When panicking, you can quickly squeeze that air out or your clothes, making you sink. And some clothes wake it very difficult to swim. That's why we teach our children in basic swimming lessons to swim with light clothes on, but also to get their clothes off if too heavy. Panicking people might forget to get their clothes off. PiusImpavidus (talk) 12:39, 20 June 2024 (UTC)
 * OK, User:Baseball Bugs FTW with the most helpful answer this time around -- thanks! 2601:646:8082:BA0:649B:7753:3C84:C70D (talk) 03:48, 21 June 2024 (UTC)
 * If it's any help I can sink and lie flat on the bottom of a swimming pool by just letting some air out but I can't do that in the sea. NadVolum (talk) 10:26, 21 June 2024 (UTC)
 * See isolation tank. 2A00:23A8:1:D801:1484:1471:392F:9B25 (talk) 15:43, 23 June 2024 (UTC)

How can DHA be a primary structural component of the brain, cerebral cortex, skin & retina?
Antioxidants? Do brain lipids ever go rancid while someone's still alive? Sagittarian Milky Way (talk) 23:52, 19 June 2024 (UTC)


 * Fats may go rancid, usually by exposure to air and light. Fats are esters. DHA is not an ester, it is a (fatty) acid. --Lambiam 04:55, 20 June 2024 (UTC)
 * How would brains be a delicacy if the fat was free acids? 12% lipids. And even if it was free acid the main problem's double bonds oxidizing probably eventually making it gum like oil paints' triglyceride molecules tangling and polymerizing. Sagittarian Milky Way (talk) 11:33, 20 June 2024 (UTC)
 * Whose brains are you eating? ←Baseball Bugs What's up, Doc? carrots→ 12:02, 20 June 2024 (UTC)
 * I don't eat any flesh but I've heard you can even buy brains 'n' beans in a can in the South (I've seen a pint or quart of pig blood in a container in a NYC grocery store so could doesn't necessarily mean common). Brains 'n' beans is calorie-dense, if you wolf it down cause it's delicious it becomes junk food. Sagittarian Milky Way (talk) 12:26, 20 June 2024 (UTC)
 * Rose brand pork brains in milk gravy are readily available at grocery stores 'round my neck of the woods (Hickory, NC). Oh! WHAAOE! eggs and brains. I also see sites selling them fresh or freeze dried.-- User:Khajidha (talk) (contributions) 14:42, 20 June 2024 (UTC)
 * Sounds about as appetizing as the Beverly Hillbillies' staple: possum innards. ←Baseball Bugs What's up, Doc? carrots→ 17:03, 20 June 2024 (UTC)
 * That's probably it, eggs 'n' brains, not beans. Sagittarian Milky Way (talk) 17:58, 20 June 2024 (UTC)
 * Is the question about DHA or about lipids? --Lambiam 19:08, 20 June 2024 (UTC)