|What will a dog notice when standing here?
(a) path; (b) bushes; (c) grass; (d) brick wall
Fig. A: wagging to the right; Fig. B: wagging to the left
dogs’ tails wagged a statistically significant amount more to the right when the dogs saw their owners or (to a lesser degree) the cat, while their tails wagged more to the left when the dogs saw the unknown dominant dog. Conclusion: a right-wag means happy (“Approach!”); a left-wag means unhappy (“Retreat!”)
I thought this was really cool, first of all just because people are actually setting up labratory studies with dogs wagging their tails in them (labs with labs)? But also for the implications about understanding dog body-language. Anyone who works with aggressive or temperamental dogs knows that wagging can’t always be interpreted in the naive way it often is by the general population: wagging means excitement, or stimulation, not just happiness; so a dog wagging its tail isn’t necessarily any more friendly and approachable than a dog that isn’t wagging. So if these studies can really be trusted – if I can in general feel more comfortable with a dog who’s wagging more to the right than to the left, and if I should in general be cautious around a dog who’s wagging more to the left than to the right – that’s really helpful info. (Caveat, though: I’d hate to be the cat who makes that generalization when it sees my greyhound approaching while wagging mightily rightily.)
I had a few questions about the study, though, and when I started to try to answer the questions on my own I quickly realized how difficult science really is. The interpretation of the study was presented as being based on a combination of two assumptions about the “lateralization” of the brain:
1. the left side of the brain controls the right side of the body, and the right side of the brain controls the left side of the body; and
2. the left side of the brain processes more “positive” emotions, while the right side processes more “negative” ones.
Combine those two assumptions and you get the conclusion that the right side of the body should be more involved in expressing negative emotions, while the left side of the body is more involved in expressing positive ones. This is what was supposedly supported in dogs by the results of the directional wagging test.
What I wanted to know is: when a dog wags to the right, does that mean it is using the right side of its body? This is a physiological question: to wag its tail, does a dog “pull” the tail to one side (e.g. to the left with its lefthand tail muscles, whatever those are) or does it “push” it (to the left with its righthand muscles)? Or does it do both equally, simultaneously? If a righthand wag doesn’t mean more righthand musculature is being used, then I don’t see how the results of the directional wagging test can be seen as having anything like the meaning that’s being ascribed to them.
Again, this is a physiological question, to be answered by biologists who know canine musculature; so I thought I’d read a little bit about it. Well, I started to find things like this:
As to the cross-over of descending motor pathways, in dogs the rubrospinal tract is the predominantly volitional pathway from the brain to the spinal cord; the pathway decussates just caudal on the red nucleus and descends in the controlateral lateral funiculus; fibres of the rubrospinal tract terminate on interneurons at all levels of the spinal cord. (See Buxton, D.F., and Goodman, D.C. (1967). Motor function and the corticospinal tracts in the dog and raccoon. J. Comp. Neurol. 129, 341–360.)
Oops. I ain’t get gotten what duz bein sedded.
So I’ll just leave it at this: there’s some really cool research being done on how dogs communicate; and tail-wagging may be more complex and expressive than we’ve previously thought.
Oh yeah – and science is cool. 🙂