What is it about our arse that we are the only animals in the world that need to wipe it

No other animals needs to clean their anus after a shit. We do. So how was it evolutionarily significant?

Discount animals that scape their itchy arses. Does not count.

Some previous threads on the subject:

The consensus seems to be that since humans evolved large gluteal muscles to enable them to stand upright, this resulted in a deeper butt crack, shall we say, compared to other animals, with more surface area for feces to adhere to.

We walk upright, which requires large butt muscles. Look at the glutes of your pet dog, or even of our closer relatives like the apes. They are much smaller than ours. This allows us to walk upright all the time, but also has the sometimes inconvenient side-effect that things don’t pass through as easily as with most other animals.

  1. Not enough roughage / fiber in modern diet

  2. Humans wear underwear that they do not wish to mark. This coupled with the fact the buttocks are a huge muscle in humans because of our upright gait…this making a large crack that clothing can get in to /faeces needs to get out of.

  3. The seated toilet may be a poor design. I’ve had to use the squat method a number of times in recent months (I’m living in China) and as awkward as it is to squat if you’re not used to it, it’s a big advantage in terms of helping you make a rimless slam dunk. :slight_smile:

ETA: Dammit double ninja’d on #2
(appropriately enough)


I refute the premise that we are the “only” animal in the world that “need” to wipe our butts. Ever been on a farm? Ever seen the unwashed asscrack of a cow, goat or horse? Sometimes flies breed in there.

Dogs, cats & rodents have dirty butts too, but they have alternate ways of keeping them clean. Be thankful our species evolved a thumb and the intelligence to invent toilet paper.

Or not thankful - if we were physically able to clean back there the way dogs and cats do, we probably would, and therefore wouldn’t think it’s icky so there’d be one less thing in day to day life to be disgusted at.

Haven’t you even seen a dog dragging it’s ass on the ground? Or your carpet?

Isn’t that a symptom of worms?

If worms are clogging it’s ass!

Ha ha… when “Lucy” (the skeleton not Scarlett Johannsen) was big news, Ricahrd Leaky was visiting at a reception at the university where my dad worked. My dad pointed out to him that because of our upright posture and gluteal muscles, “humans are th only animals that have to wipe their arse”. Leaky said he had never heard that before, but my dad had - so obviously it’s been common wisdom for a while.

As for dogs, my understanding is that usually dogs drag their ass when they have an infection ( =itch) in the glands that squirt their signature perfume scent onto their fecal calling card. Quite often these glands clog and become infected, swell upand are uncomfortable. IIRC reading that one delightful job for vets is to squeeze and empty these glands for poodles and other small dogs. Many of these sorts of animals have these glands, most notably the skunk has put it to a better use.

Maybe, but it’s more often a symptom of having a dirty butt. Happens all the time.

A dog who needs a little extra butt wiping does not need anywhere near the volume wiped as a human. Just because dogs scoot sometimes it doesn’t mean they have to wipe their butts with TP like we do.


I think you have this exactly backwards.

I can say with 100% certainty that both cats and dogs may occasionally wind up with their own poop stuck to their furry butts and it can result in anything from the aforementioned ass-dragging to some nasty butt licking to a major freakout on the part of the animal.

I have had to clean pet poop off the floor/carpet/fur as a result. While the cat was long-haired, the dog is short-haired.

It’s because we wear clothes.

If our ass cracks were bare, things would dry up and flake off or whatever - no worries (except for whatever we sit on, but that’s another discussion I suppose).

But we wear pants or skirts, etc. over our asses - plus (usually) underwear under that. So the dingleberries stay wet, don’t dry. And wet dingleberries smear on our clothes. And we don’t want to wear clothes with shit on them. Plus the itchy crack factor - which, if we were bare, wouldn’t be nearly the issue it is with clothes. Still may need to scoot across the grass now and again, but with direct exposure to the outside air, rain, water, etc. it would greatly take care of itself.

I recall someone discussing some writing about Henry VII and the dissolution of the monasteries in England. The interesting line was that England for a while was a huge exporter of paper and parchment “to supply the jakes of Europe”. All those medieval libraries of hand-scribed books went to be used for toilet paper.

Human beings don’t ‘need’ to wipe their arses. Just like animals we could get by fine without cleaning them. We choose to wipe our arses for all sorts of reasons but the act isn’t essential for life.

'cause baby’s got back yo!

I suspect that " modern" in this context is relative to pre-agriculture diets.

I wish my cat would learn to wipe his butt.