Asymmetric tail-wagging responses by dogs to different emotive stimuli

Dontcha love the language academics use to title their papers?



The stuff inside this particular one is even better, though — as reported by the NY Times:

When dogs feel fundamentally positive about something or someone, their tails wag more to the right side of their rumps. When they have negative feelings, their tail wagging is biased to the left.

It happens just today I was thinking about symmetry and the human body — how there is apparent symmetry externally, but the internal organs are not symmetrical.

Which got me thinking specifically about the heart. Why is the heart on the left? Always on the left? Why aren’t there mirror people with right-sided hearts? Would a human with a heart exactly in the middle be . . . different? How? A different species? And I wonder what would it feel like, emotionally, to have a heart smack dab in the middle?

Don’t ask me why I was thinking all this btw. I have no idea. Now if I were a sci fi writer . . .

Anyway, I’m not, so back to the Times article — this biased whole tail wagging thing is because our brains (“our” meaning a whole lotta higher critters) aren’t symmetrical either. And of course the brain’s asymmetry casts a shadow visible on our external bodies, if you know where to look:

Research has shown that in most animals, including birds, fish and frogs, the left brain specializes in behaviors involving what the scientists call approach and energy enrichment. In humans, that means the left brain is associated with positive feelings, like love, a sense of attachment, a feeling of safety and calm. It is also associated with physiological markers, like a slow heart rate.

At a fundamental level, the right brain specializes in behaviors involving withdrawal and energy expenditure. In humans, these behaviors, like fleeing, are associated with feelings like fear and depression. Physiological signals include a rapid heart rate and the shutdown of the digestive system.

Because the left brain controls the right side of the body and the right brain controls the left side of the body, such asymmetries are usually manifest in opposite sides of the body. Thus many birds seek food with their right eye (left brain/nourishment) and watch for predators with their left eye (right brain/danger).

In humans, the muscles on the right side of the face tend to reflect happiness (left brain) whereas muscles on the left side of the face reflect unhappiness (right brain).

But that’s not all. Get this — one researcher speculates that the asymmetry of the brain evolved because of the assymetry of the internal organs:

The asymmetry [of the brain] may also arise from how major nerves in the body connect up to the brain, said Arthur D. Craig, a neuroanatomist at the Barrow Neurological Institute in Phoenix. Nerves that carry information from the skin, heart, liver, lungs and other internal organs are inherently asymmetrical, he said. Thus information from the body that prompts an animal to slow down, eat, relax and restore itself is biased toward the left brain. Information from the body that tells an animal to run, fight, breathe faster and look out for danger is biased toward the right brain.

My speculation about how a person with a heart in a different spot might feel different doesn’t sound quite so weird now, does it ;-)

(Humor me, please! LOL)

[tags] dogs, neuroscience [/tags]

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14 Responses to Asymmetric tail-wagging responses by dogs to different emotive stimuli

  1. Jeff says:

    Situs inversus, or reversed inner organs does happen. Donny Osmand apparently has it.

  2. Kirsten says:

    oh wow!!!!!!!!

    I knew there was something about that guy!!!!!!!!

    And now I have the title for a novel — Situs Inversus — maybe I’m a sci fi writer after all, Jeff, dear! Thanks!

  3. Bernita says:

    But what does it mean when dogs wag their tails in circles?

  4. Kirsten says:

    uh oh, Bernita, you may have found the hole in the theory!

  5. Roberta Liford says:

    What if your dog has a cropped tail that sticks straight up so that when he wags it it goes rapidly from side to side with no discernable difference.

  6. Kirsten says:

    I don’t know, Roberta!

    My dog’s a Pembroke Welsh Corgi so none of this theory helps us a whit. Too bad, maybe if she could emote a bit with her tail she’d be a little more, er, balanced.

  7. Wonder if this applies as well to when a dog give you their paw? Are all right pawed dogs, happy dogs? :)

  8. Kirsten says:

    Interesting question, Michelle.

    The “give a paw” behavior is shaped version of a more generalized behavior . . .

    It would be interesting to see if dogs have a tendency to paw with the right more than the left — i.e. to see if pawedness has a bias as well.

  9. Lilly says:

    My dog goes crazy – happy when she sences (she’s blind) my oldest son but more or less ignores my younger son. Wonder if it has anything to do with the fact that my older son has a dog.

  10. John Lacher says:

    When discussing canine behavior, one has to keep in mind the breed characteristics of the dog especially when discussing a mixed breed. Understanding canine body posture is extremely important, not to mention that of the human. Both have a direct correlation when it comes to training. Observation in the positioning of the dogs tail upon greeting another dog or a human will tell you a lot. A straight ridgid position of the tail will tell you that the dog is being cautious, almost to the point of being guarded. Human body position such as the arms folded at chest level sends un unfriendly message to the dog. A stare, or direct eye contact of the human toward the dog can often casue the dog to establish a defense posture. The ears and mouth immediately become less relaxed. The dog begins to move forward toward you or he will stand his ground.

  11. Jo, proud Dutch Shepherd owner says:

    that was an excellent question! My dog paws a bit…thought not as much as he used to(we did our best to nip it in the bud). That’s the last behavior he really has….and while i’ve never noticed which way his tail wags the most to, or which paw he paws with the most, i’m determined to conduct observations until next Saturday….

    peace out!

  12. Kirsten says:

    Hi, Lilly & Jo, sorry to take a bit to moderate your comments, I’ve been entertaining an out of town guest and so have been spending quite a bit less time recreating on the internet :-)

    John, letting your comment through until I check out your site & see if you’re only plugging yourself or if you’re graciously promoting Outwitting Dogs as well, heh heh heh.

    That said, regarding dog body language, verbal descriptions aren’t nearly as useful as pictures or, better yet, video. Of course Turid Rugass’ stuff is fricking excellent and here’s another book out by, is it Brenda Aloff? might have teh name/spelling wrong here, I’m off to play shuttle bus now so have to run . . .

  13. Jo, proud Dutch Shepherd owner says:

    Well, I’ve been making my observations. My dog really truely DOES wag his tail mostly to the right!! ….When he’s not frantically excited about something. And he seems to paw mostly with his right paw as well. Interesting…very interesting.

  14. Kirsten says:


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