While dogs and humans are both mammals, and that makes us quite biologically similar, there are a few important differences which- while slight- do stand out.
One noticeable difference you might have spotted is the fact that dogs don’t have to wipe their rear ends after going number two. You may have wondered why this is the case. Well, there are several reasons for it, some behavioral, some dietary, and some evolutionary.
So, for those of you who have wondered why dogs don’t have to wipe their bums after going doody, here’s your answer.
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Why Dogs Don’t Have to Wipe: The Internet’s Most Complete Answer to the World’s Least Asked Question
Exterior Biology
This is where we get into giggle territory, somewhat- but that’s okay. Possibly the biggest reason that dogs don’t need to wipe after pooping is the fact that their bodily waste does not smear on their rear.
Human beings have prominent gluteus muscles. This is due to the fact that we stand upright, which makes it necessary for our glutes to be positioned in such a way so as to be able to draw our legs far backward during ambulation.
With a dog, the hind legs do not drawback as far, and therefore, their glutes do not need to protrude in the same way ours do. If a dog’s glutes were shaped like ours, they would be pointing toward the sky and would look quite strange indeed.
At this point, you might be thinking that horses have a similar posterior arrangement to humans, and yes they do. But, once again, because they are not upright, they do not need to draw their legs nearly as far back as we do.
For this reason, the prominent booty cheeks of a horse to not cover their anus. That is the primary reason why humans need to wipe after going number two- because our glutes and the fatty tissue that surrounds them cover our anuses.
Not to be unnecessarily graphic, but when sitting down on the toilet to go poo, some people will- let’s say- use their hands to open the bomb bay doors. The purpose of this is to get those glutes out of the way. This makes for less smearing, (sorry, that’s quite graphic), which allows for less wiping.
And that, in a nutshell, is the exterior, mechanical reason that dogs don’t need to wipe. But it is not the complete answer, as we shall see.
Interior Digestive Biology
Now, it may have occurred to you that even if humans had rear ends that looked like a dog’s it might still be possible for the waste matter to eject in a form and in a manner that would make wiping necessary. That is true. However, as it happens, there are a few differences between the digestive tracts of dogs and humans which affect the way waste material comes out.
First, consider the fact that different types of animals have differently shaped leavings. Rabbits tend to leave lots of little pellets. Cows leave enormous pancakes. Dogs tend to leave behind curly worm-shaped droppings, and humans leave… well, you know what we leave. These dropping shapes are partly adaptive for the types of behavior the type of animal exhibits as well as their general needs.
A rabbit’s droppings, for example, are relatively solid. It could be supposed that the reason for this is so that the droppings are less odoriferous. This would make the rabbit harder to track by scent, although there is room for argument there. But the point is that different animals leave droppings in different shapes and different consistencies for good reason. But the question is how do animals have differently shaped leavings?
Once again, our friend the horse can shed some light on this topic.
You have probably noticed that human leavings are usually made up of a lot of little nuggets that are not unlike those of a horse or a rabbit. The difference is that the nuggets left by people are usually all smooshed together. The reason for this is the human digestive tract is quite long and we have different fluids and enzymes at work.
The intestinal tracts of humans and dogs are shaped differently, are different lengths, contract and compress in different ways, and use different digestive chemicals to deal with and process fecal matter. At the end of the day, we have different Play-Doh factories turning out differently shaped ploppies.
And that is the interior, mechanical reason why humans need to wipe and dogs do not.
Dietary Reasons
It has long been known and accepted that human bodily waste is among the most unpleasant in the animal kingdom. In fact, many tribal civilizations both currently in existence and bygone would sometimes poison their weapons of war with human fecal matter.
Most cuts with a weapon so treated would spell the slow and agonizing death. We don’t need to go into much detail to understand the ugly peculiarities of warfare, be it modern or primitive, to reason that this alone is proof positive that human feces is especially unpleasant.
Because our leavings are so toxic, any amount of it left on the skin can result in a rash, hemorrhoids, and infections. Also, because humans tend to rest directly on their rear ends, this would also mean that we would be spreading this unpleasant, toxic material if we did not take great care to wipe after going number two.
Humans are omnivores, as you know. That is to say that we can eat meat, vegetables, fruit, grains, and just about anything that can be eaten. As a result, our digestive biology has to be especially robust with lots of different types of digestive enzymes and bacteria. In short, the human digestive tract is a kind of an all-purpose wrecking machine- and that means what comes out the other is can be a bit of a crapshoot. (I promise I’ll stop).
Now, by contrast, a dog’s diet is pretty simple. Sure, we do put grains and such things in their food- though we probably shouldn’t. But nevertheless, they more or less eat the same things or the same kinds of things almost all the time.
If you experiment with your diet, going carnivore or eating only vegetables, for example, you will find that your leavings also become rather- let’s say- not quite so mosaic.
What’s more, many popular dog food products are designed to make the dog’s leavings easier to deal with. Interestingly, this is not so much the case with cats. You see, cat owners have their pet use clumping sand and dog owners tend to have to pick up their pet’s fecal matter. The pet food manufacturing industry has recognized these realities and has developed dog and cat foods accordingly.
That might come as a bit of a shock since Alpo does not advertise the fact that they make food that helps make dog poops easier to deal with. But they do. Brands that don’t might be healthier- or they might not. But dog owners do not want their best friends making leavings that can’t be cleaned up without the use of an industrial-grade pressure washer, and we can’t argue with them.
Behavioral Evolutionary Reasons
Finally, we have the evolutionary and behavioral reasons for why dogs have evolved in such a way so as to not have to wipe after pooping. Keep in mind that arguments like this are always a bit subjective, but there may be a good bit of sense to them.
It is well known that predators often track their prey by following fecal scent trails. Because the primary survival adaptation of humans is a large and complex brain, it stands to reason that we have developed a number of behaviors that make it hard for predators to find our dwelling places by tracking our feces.
Dogs and cats are not entirely different in this regard since they bury their leavings- or try to. But humans are much much better at it. We have entire infrastructures dedicated to putting great distance between ourselves and our waste matter.
The extreme complexity of our toileting behavior makes it inevitable that we would have the ability to clean ourselves much better than a dog can. Yes, they can get their tongues back there, but they are not moving significant amounts of matter that way. It would be quite hideous if they did.
Humans use toilet paper- that is when it’s not all sold out. We do this because we can, and we’ve been doing it for so long that we can’t really imagine an alternative. Dogs, by contrast, are quite a bit more devil-may-care in their toileting behavior, and hopefully, now, we have a better understanding of why.