Wikipedia:Reference desk/Archives/Miscellaneous/2015 July 31

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July 31

Urinating / defecating simultaneously?

Are humans the only species that can accomplish the same task at once? Obviously, I only speak for myself here but I've never witnesses any other common animal do the same thing, save for birds. — Preceding unsigned comment added by 42.114.5.58 (talk) 08:33, 31 July 2015 (UTC)

I've seen dogs do that. Adam Bishop (talk) 10:33, 31 July 2015 (UTC)

... and cows. You need more observations. Dbfirs 12:55, 31 July 2015 (UTC)

And birds and reptiles, who do not have separate exits in their lower abdomens, but rather have a single orifice called a cloaca which is used for all reproductive and excretory function. See Bird anatomy#Kidney which describes who urine moves from the kidneys to the cloaca, but rather then be excreted directly, migrates back into the colon where it mixes with bird feces before being eliminated together with them. --Jayron32 16:58, 31 July 2015 (UTC)

Double Digestion in humans

Does double digestion ever occur in humans? It seems odd that most of our primate relatives practise it and we do not. In fact, a lot of food seems to quite literally go down the toilet merely because it never had a chance to get absorbed the first time round. (Onions, sweet corn, seeds) Or, did humans naturally engage in behaviour and it simply being a case of modern culture deeming it inappropriate. — Preceding unsigned comment added by 76.106.33.151 (talk) 16:55, 31 July 2015 (UTC)

Humans don't do this because their digestive system is extremely efficient (although yours seems a bit sub-standard). Animals that do this generally have poor digestive systems and/or have a primary food source that is difficult to digest, such as rabbits and grass. Which primates do you think eat their own faeces?--Ykraps (talk) 17:42, 31 July 2015 (UTC)

It just says gorillas and chimps here Coprophagia--Ykraps (talk) 17:47, 31 July 2015 (UTC)

Okay, but given that those are our two closest relatives, it's reasonable to ask about why humans generally don't do it. I suspect that our guts aren't particularly more efficient than a chimp's (though, if so, that would serve as at least a provisional explanation). 64.235.97.146 (talk) 18:30, 31 July 2015 (UTC)

Eating faeces is done for a number of reasons and, despite what it says in the article, I'm not sure they do it for nutritional value although mountain gorillas eat a lot of green plant matter which is tough to digest. Lowland gorillas tend to mainly eat fruit which is easy to digest so I wouldn't imagine they re-ingest their food.--Ykraps (talk) 20:21, 31 July 2015 (UTC)

Humans tend to cook their food. Cooking food makes it easier to digest. It is very rare for animals to cook their food. 209.149.113.45 (talk) 19:15, 31 July 2015 (UTC)

Probably not on purpose, anyway. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:17, 31 July 2015 (UTC)

First of all, rabbits are not at all hard to digest, so I am not sure why they were mentioned above. Second, unlike chimps and gorillas, humans have teeth, hence we can chew stuff like corn thoroughly, rather than just randomly tossing it at our colon to see the outcome. Finally, as mentioned, most people have cooking degrees, while Spain has only recently begun admitting orangutans to its culinary institutes.

There are also traditional methods of preparing fermented drinks like chicha which involved chewing up and spitting out the starch to be fermented. This is also how baby food is prepared in primitive societies. μηδείς (talk) 20:01, 31 July 2015 (UTC)

Chimps and gorillas do have teeth. Robert McClenon (talk) 20:26, 31 July 2015 (UTC)

By which I meant, grass, which is the primary food source of rabbits, is hard to digest, and rabbits have a poor digestive system.--Ykraps (talk) 20:23, 31 July 2015 (UTC) (also I'm pretty sure chimps and gorillas do have teeth).

Why would Mother Nature have been so mean-minded as to give rabbits a poor digestive system? Are they aware they're deficient? What would be the biological purpose of having any anatomical system that's poor? Or are you speaking in relative terms here, and is the truth that what's poor for a rabbit when compared with the human system is actually just dandy for the rabbit in its own terms? Are you suggesting that if the rabbit digestive system were as good as that of humans, rabbits wouldn't have to spend all their time eating and could devote more of their time to studying the Lives of the Saints, doing good works, and generally being more productive members of animal society? ... wait, they're already notoriously productive ... -- Jack of Oz ^{[pleasantries]} 20:33, 31 July 2015 (UTC)

I think that what Ykraps meant in saying that rabbits have a relatively poor digestive system is that it is not as efficient in digesting cellulose as that of ruminants, which are foregut fermenters, or equids, which are hindgut fermenters. Rabbits probably made a different evolutionary investment than the development of an efficient herbivorous digestive system. Robert McClenon (talk) 20:45, 31 July 2015 (UTC)

I would use snakes as an example of an animal with a poor digestive system, although "slow" might be a better description than "poor". Since their jaws and teeth aren't designed for chewing and their digestive system is limited to the length of the snake, that decreases surface area and means it takes them days or weeks to digest what we could digest in a single day. Being cold-blooded also slows everything down, especially on cold days. StuRat (talk) 20:50, 31 July 2015 (UTC)

Perhaps I'm being a bit harsh about rabbits' digestive systems. They're perfectly adequate providing the food is passed through twice. As to why nature would do such a thing; well I'm afraid that contrary to popular belief, nature isn't perfect.--Ykraps (talk) 21:11, 31 July 2015 (UTC)

Stu, even "slow" is based on a comparison with other species of animal. That's really pointless, imo. Unless, of course, you're comparing species (and maybe that actually happens all the time without it being explicitly acknowledged). But when just describing some species in its own terms, comparative words would seem to have no place. (We really have to get out of the habit of calling giraffes "tall" and tortoises "slow" and whales "big". It's so discriminatory.) -- Jack of Oz ^{[pleasantries]} 21:15, 31 July 2015 (UTC)

Perhaps rabbits are not ruminants as they needed to stay small to not compete with large ruminants and fast to survive. 76.70.6.43 (talk) 01:41, 4 August 2015 (UTC)