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Why are humans the only animal who need to wipe their bottoms after elimination?

11 Answers
Do any of the other primates need to use external materials to cleanse themselves? If humans are the only species that do this, why? Is it diet or anatomical configuration? It seems strange to me that healthy dogs, cats, horses, etc. are able to eliminate without reaching for the Charmin. What's different about our own bodies that we must do so? Or are we eating such an unnatural diet that we do not have healthy / normal digestive tracts?
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This is a rather unique topic. I am uncertain of what or how much information you are seeking Boatal18 so forgive me if I don't provide enough or entirely too much information.

Nevertheless, it is true that animals do not leave a significant amount of residue on the themselves after defecating as compared to human beings. The most obvious external difference would be our anatomy. Humans have fleshy buttocks that would be more likely to be soiled while eliminating than animals. In addition, squatting is a natural posture for defecation but humans have "evolved" and now sit when they defecate, (which does not facilitate cleanliness.)

Most animals do not possess fleshy buttocks and their internal/external anal sphincter is often protruding somewhat during a bowel movement, (which would reduce the likelihood of soiling themselves.) Obviously animals with longer fur are more likely to have remaining residue and dangling materials.

Animals also have a more efficient digestive system. Herbivores have a relatively large cecum to digest cellulose plant fibers. The hind gut breaks down and ferments food/roughage, produces fat-soluble vitamins and extracts much of the moisture from ingesta. Manure is a mixture of feces and plant fibers and is typically dry. Lagomorphs produce dry fecal pellets and excrete cecotropes, (which is ingested.)

Almost all carnivores possess anal sacs just inside the anus. As the animal defecates, there is pressure upon the glands and a small amount of oil-based secretions are passed during a bowel movement. The stool of animals may also be coated with more mucous, resulting in less external contact with excrement.

Although healthy animals do tend to stay cleaner after elimination, occasionally they may have a hygiene issue. Some species are rather flexible and can self-groom. Obese animals often cannot reach their backside and have more issues with soiling due to rolls of fat. Some may scoot their bum across the floor or ground while others may rub against a vertical object. Non-human primates may simply remove the troublesome material manually. http://www.youtube.com/watch?v=v_IcH678AI0 However no species, other than human beings, uses bathroom tissue after elimination.

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You state that most animals will not go around with feces covered behinds, well you must not have ever been around very many animals. Most of them can and do get very dirty with excrement either their own or that of other animals. I have seen cows defecate all over a nursing calf and the calf will just continue nursing. Dogs love to eat and roll in cow manure and the droppings of other dogs to pick up the scent of it. Horses will roll in fresh manure piles and don't get me started on pigs, that will sleep in the stuff.

Animals that are flexible enough like cats and dogs will clean their anal and genital areas using their tongue, which is why I cringe when I see people letting dogs lick on their faces. As for animals like horses, deer, and cattle, while they can not lick themselves clean back there, they do not have the massive buildup of fat around their anal opening that we as humans do - ie our cheeks. Instead their anal opening is more or less on a flat surface so that much of their fecal matter falls straight down away from their body.

One thing these types of animals do have that we lack is a fly swatting tail to keep insects which are attracted to their dirty behinds, away. A nice warm fecal filled rectum is a good place for flies and their like to feed and breed so the area has to be protected. In our case, our two fatty cheeks do that job when we stand up and they close in over the anus to seal it away from invaders. They also make nice soft pads to sit on.

You can blame the need for tissue paper for cleaning our behinds on our anatomy and the invention of the modern flush toilet. The design of the modern flush toilet puts us in a totally unnatural position for defecating, a sitting position. The natural position for creatures such as ourselves to take when cleaning our bowels, is a squatting one. A squatting position would spread apart the cheeks, leaving them out of the flow so to speak. In parts of the world where toilets are not used and the population uses a squatting stance, there is little need for toilet paper.

I have also read that the practice of using a toilet and sitting while defecating, is the reason that up to 2/3rds of all adults in the western world will suffer from a hiatal hernia by the time they are over 50. We have to apply too much pressure on the organs in our abdomen when defecating while sitting. That pressure causes the opening in the diaphragm to be stretched or even torn, forcing part of the stomach up through it. Defecating in a squatting position relieves the need to strain while going.

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I think it has more to do with diet than anything else. Humans eat meat, which is what makes our waste toxic. The feces of cows and horses, as it probably is with most other animals, can be used as an organic mulch that produces healthy produce and green grass. The diet of most animals is strictly vegetarian.

If humans do not wipe, the toxicity of their waste will cause serious rash and other ill effects that leave us in pain and very uncomfortable. Other animals who eat mainly vegetables, fruits and grain excrete a healthier waste material and it usually is a clean cut, as it is not so pasty.

As mentioned in an above answer, most animals have the ability to lick themselves clean, humans do not.
Since I have cut most meat out of my diet, I find my own excretions much cleaner, although I still wipe out of habit.

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Most animals do have feces left after they use the bathroom, many people just aren't away of that because they don't interact with many animals. One of the main anatomical differences is obviously the fact that we are bipedal animals, and this results in a different way of both using the bathroom and living in general. Social factors do also play a role as most animals use the bathroom whenever they feel the urge, whereas humans wait and, in one way or another, force themselves to both go and finish. With all of these factors considered, you may notice more "left over," but there isn't really one exact factor that leads to this.

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Well there are a few reasons for this

When a human eats proper diet, they can excrete without even needing to wipe. In times before there was all sorts of nasty junk food that is hard to digest, there was probably less of a need to wipe.

Humans, as opposed to animals, have the inability to lick their anus clean. . .

Humans evolved to be eliminating in the squatting position. In this position, there is also less of a need to wipe. You should try it out sometime, for science!

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I was going to give a well thought out answer here but I see Facers22 beat me to it thinking along the exact same lines.

But when I scrolled down I re-read the actual question and the answer is very simple. Humans are NOT the only animals that need to wipe their bottoms after elimination. Other animals do have a need to wipe from time to time and they find a way to do so, the rest of time they apparently don't see the need.

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Ummm, no. Most animals don't go around with feces-covered posteriors unless they have a health issue (diarrhea, sacs are impacted, etc.) or have eaten something that has disagreed with them. Horses, for example, remain clean after eliminating. People do not. There is clearly an anatomical difference -- not just one of hygienic preferences. THAT is what I'm looking to learn. Not whether or not we prefer to smell clean.

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Okay, WHY do they not need to? It is obvious that cleaning ourselves is an act of hygiene. It is obvious that animals do not need to wipe themselves.

What is the PHYSIOLOGICAL difference that makes humans messy unless they opt to clean themselves?

I am looking for someone who understands human anatomy vs. that of other animals and can explain the difference in this area.

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I think we are he only ones who do it because we are the only ones who care whether or not we are clean and smell clean.
I know my dogs just sort of pinch off the BM, but sometimes they have a little left on them. They could care less.

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In my opinion, cleaning our selves is an act of hygene. Other animals do not need to wipe themselves after elimination because they don't need to.

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My dogs and my goats all rub their behinds on the ground after they defecate. I think if they had thumbs, they would probably use toilet paper too.

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