Having said that, there's a lot of interesting biology about a dog. Today I want to talk about their tails and especially why they wag them.
Until a couple of weeks ago I had assumed that tail wagging was a mindless "I'm happy" thing. But its not, its much more cool, and a bit more complex than that. Firstly, its social. Wagging a tail is to say something. If a dog is secretely watched when it thinks its alone, it doesn't wag its tail, even if its doing something that you would expect to cause it to do so, eg when eating. So it seems likely that tail wagging is a form of social communication, but is it just telling us (or its canine friends) "I'm happy"? |
Tail wagging can mean "I'm happy" or it can mean "I'm scared"
A study in 2007 showed that dogs wag their tails assymetricaly, on average more to the left (from the point of view of the dog looking forward) or more to the right.
They wag more to the right when they see positive things they want to approach such as their owner or a cat and more to the left if they see something negative that they want to avoid such as an unknown, large and dominant dog.
Second bit of cool:
The right side of the body is controlled by the left side of the brain.
The left side of the body is controlled by the right side of the brain.
This happens in all vertebrates. BUT we also find in, many, many vertebrates, some actions are more right or left side associated depending on whether it is involved in approaching or avoinding something -
Birds look for food with their RIGHT EYE - LEFT BRAIN - APPROACH
Birds look out for predators with their LEFT EYE -RIGHT BRAIN - AVOID
Chimps scratch the LEFT SIDE of their body - RIGHT BRAIN - when upset AVOID
Dogs preferentially use their RIGHT EAR - LEFT BRAIN - to listen to other dogs barks APPROACH
but prefer to listen to the sound of thunder with their LEFT EAR - RIGHT BRAIN - AVOID.
And the list goes on - chameleons, toads all similar!
All this fits perfectly with the dog's tail
- wag to the right - left brain - happy/approach
- wag to the left - right brain - anxious/avoid
So there seems to be some hard-wired asymetrical connection between positive emotions/behaviours and the left side of the brain and between negative ones and the right side in a wide range of veribrates but why wag? Why wave your tail around if you're happy or worried? Remember I said that this seemed likely to be due to communication? But how can we tell? Third bit of cool: A couple of weeks ago scientists published a study showing that asymetrical tail wagging is noticed and responded to by other dogs. If a dog is shown a silhouette of another dog wagging its tail either to the left or right (or not at all) - to the right- it had a slow relaxed heart rate and relaxed behaviours. - to the left- it had an elevated heart rate and anxious behaviour patterns. So dogs do notice each others wags and respond appropriately! |
Disclaimer - Are humans similarly asymetrical in our emotional responses? I don't know. You could do an experiment - tell your teacher if you have not done your homework while either standing in their right or left visual fields and see if one of them makes them more annoyed!
Post disclaimer additional related factoid: Most aspects of vertebrate senses and motor responses are crossed over from one side of the brain to the other side of the body. HOWEVER smelling does not . This makes things confusing. But the emotion sidedness of the brain still seems to match up.
- signals from the right nostril are sent to the right side of the brain and from the left nostril to the left side of the brain.
Horses prefer to smell unknown stallions (which maybe dangerous) with the right nostril (right side of brain). Similarly, dogs check out novel scents with their right nostrils, but if after repeated exposures the smell is not connected to anything yucky then they switch to their non-anxious left side.
Human infants respond more positively to nice smells if place under the left nostril rather than the right!