Why do dogs wag their tails?

[attackferret]

My roommate was just looking at my dog, wagging his tail, and asked me why they do that. I have no idea. So I'm going to pass the question on to you intelligent folks. What evolutionary advantage does tail wagging give to dogs? Why do they do that?

[GIltine]

As far as I have learnt it's a sign of emotion. Humans smile when they are happy, dogs wag their tail. Humans cry when they are sad, dogs put their tail between their legs.

I know with cats their tails are for balance, but I'm not sure if the balance theory works for dogs too.

[walrus]

Originally Posted by GIltine

I know with cats their tails are for balance, but I'm not sure if the balance theory works for dogs too.

balance??!! how come my cats don't fall over when their tails are waving back and forth??!

[Lacykitten]

Tails, ears, and the body in general are communication devices. Watch some doccumentary on wolves, wild dogs, etc. Their communication is heavy with body posturing in addition to vocalization.

Wagging tails in dogs is generally a positive sign, happiness and playfulness. But depending on the rest of the body language it can also be unease, uncertainty, etc.

In cats, it's usually a negative sign, a lashing tail when a cat is upset, but my one cat Dreyfuss wags her tail like a dog and it's really cute.

[grog]

Originally Posted by attackferret

My roommate was just looking at my dog, wagging his tail, and asked me why they do that.

To get to the other side

[bird]

Holy F*ck, grog! I thought the exact same thing when I saw this thread.

[jenzie]

Pretty much what Lacy said. They are dozens and dooozens of things a dog can be feeling when they wag their tail. There are some great books on it, maybe I'll stop being lazy and go look them up at some point.

[oldradical]

This reminds me of a comedy record I heard when I was young, about "Little Bo Beep," and when it came to the place about how the sheep would come wagging their tails behind them, the exasperated commentator exclaimed, "Pray tell me, what else could they wag!"

Does that help?

[grog]

Originally Posted by cymraegrrl

Holy F*ck, grog! I thought the exact same thing when I saw this thread.

Sarcastic minds think alike?

[trichaos]

My dog barely has a tail so she shakes her entire ass.

[attackferret]

You guys are cracking me up! oldradical, I love your story. Tri, my sister's dog does the exact same thing! For some unknown reason, the dog has half a tail, and apparenlty wagging that just doesn't get the job done. So he wags the entire back half of his body! It's hilarious.

As for the actual purpose of the tail wag, I agree that it definitely shows emotion. But then I started wonder why dogs have tails in the first place. Could it be for balance, as GIltine mentioned? I don't think I've ever seen my dog use his tail that way, but that doesn't really mean anything. Is it to wrap around their noses to keep their noses warm in the winter? I think I saw that on a documentary a long, long time ago. I may be making it up, though, my memory is crazy bad like that.

Speaking of foxes, do foxes wag their tails? I have no idea.

[zatoichi]

i wonder if dogs smile in the wild... my dog definitely smiles. she exhibits all her emotion with facial expressions. i wonder if some of these expressions are learned, being raised in a human environment, or if they're innate...

[herbi]

Tails are great for balance! Watch a dog (or wolf) in a high-speed chase after a rabbit (or a sight-hound in a lure-coursing event) and see how a long tail gets thrown out as a brake to check the hind end in a tight turn. A substantially hefty tail can also be thrown out stiffly behind when walking across a narrow object and twitched to one side or the other like a balance-bar. And of course they can be a stabilizing rudder in the water (ask any Lab). They don't much come into play just walking around on solid level ground, true, and humans have screwed around with breeds so much that a lot of tails are too stubby or curly or skinny to be much use balance-wise, but I think in the original "DOG" plans, that could be one function.

But yeah, the main thing is a social signal. Which is important enough to be the whole entire reason for a tail in and of itself, in an animal where social communication is SO important. Tails often have contrast-enhancing markings (light or dark tip, light fringe along the back) and dogs' eyes are very sensitive to motion (and contrast), so a moving high-contrast body part becomes a very noticeable and effective signal.

"Wagging" is kind of vague, though. There are so many different ways in which a dog can move his or her tail-- back and forth, yes, but also up, down, extended, curled, relaxed and loose, stiff and straight, and even in a circle. (I loves me some cute circle-wags! ) And that signal can be combined with so many other ear, face, body, and vocal signals that you can't get an accurate meaning from just tail-motion alone. I think the closest we can come to putting a word on JUST the wagging would be "excitement" or "nervous arousal". Some people use the word "happy", but like Lacy and Jenzie said, it can be so many more things. (Or like my old Behavior Prof. Katherine Haupt used to tell students who thought a tail-wagging dog was always safe to approach: "Maybe he's just 'happy' that he's about to get the chance to bite you!" )

Some old-skool guy (I wanna say Konrad Lorenz, but don't quote me on that because my books still aren't unpacked & I'm too lazy to look it up) theorized that tail-wagging always expressed internal conflict. Like, the back and forth motion of the tail was an external indicator that the dog's mind was moving back and forth between two options. So, a familiar dog wags because he is happy to see you because he likes you, but also a little scared because you are so dominant. He has an urge to approach and greet but also to retreat, hence the wagging. I've never been too satisfied with that myself. I think one can dispense with the "back and forth" symbolism and just say it expresses a level of nervous energy or excitement, and whether that excitement is a form of happiness to be hanging out with friends, or a form of anxiety about an enemy, the rest of the context can help you decode.

Another tidbit: puppies don't wag their tails at all before they're about 4-5 weeks old or so, and all pups in a litter won't be reliably wagging in a normal doggy way until about 7 weeks. Also, dogs only seem to wag at other life-forms with which they can have social interactions, so it's not just about expressing excitement, it's about expressing excitement TO somebody else. They will wag at other dogs, people, cats, and there's an anectdote floating around about a puppy wagging at a butterfly (awwww!), but they don't wag at their food bowl or chew-toy when nobody else is in the room. Cool, huh?

I always think it's sad to see a dog with no tail. Sure, there's still the cute butt-wagging and waggle-stubbing, but a LOT of nuance has been lost. Same with cropped ears, or certain shaped faces. A lot of breeds known for aggression have been either bred or surgically modified to be deliberately difficult for people (and other dogs!) to "read", thus stacking the deck in favor of conflict. People suck.

I don't know about ALL creatures with a common name of "fox", but I have seen red foxes (Vulpes vulpes) (on film-- in real life I've only ever seen one fox at a time, no social interactions) doing all the usual canine signaling-- play-bows, puppy submissive/food-begging mouth-licking, and greeting tail-wags.

(OK, whoever was silly enough to take the bet that I wasn't going to write a long-ass post in this thread, pay up! )

[seitanicvegan]

My dog wags her tail for the sole purpose of wacking my plants and knocking things off the furniture. If she breaks something, she expects brownie points.

[herbi]

Originally Posted by zatoichi

i wonder if dogs smile in the wild... my dog definitely smiles. she exhibits all her emotion with facial expressions. i wonder if some of these expressions are learned, being raised in a human environment, or if they're innate...

Yeah, they do. (Smile in "the wild", that is.) They have a relaxed happy smile, a goofy open-mouth silly play-face smile, a tight worried nervous smile, and some dogs even do a "submissive grin" where they show their teeth just like a human smile! (That can be scary to people who don't know about it and think it's a snarl, but it's adorable and hilarious when you recognize it.)