A dog wagging its tail (gasp) to the right! via Wikimedia.
According to research reported in the New York Times article "If You Want to Know if Spot Loves You So, It's in His Tail," dogs show emotional asymmetry in their brains just as humans do.
In humans the left side of the brain is apparently associated with attachment, love, positive feelings, a slow heart rate, etc while the right side of the brain is associated with depression or fear. The cool thing is that this kind of emotional asymmetry has been shown to exist in a variety of different animals, now including dogs.
Dogs show emotional asymmetry by wagging their tails with a bias towards the right when they are pleased and by wagging their tails with a bias to the left when they're fearful. This would be the expected expression of emotional aymmetry because the left cortex of the brain is mostly associated with the control of skeletal muscles on the right side of the body (and vice versa).
I think that Darwin would be pretty impressed with these findings because of his interest in the expression of emotions in humans and animals. In Cyril Aydon's biography of Darwin (reviewed on Amazon), a few of my favorite sections included Darwin's thoughts about Jenny the Ape. Those few sections make me think that Darwin wouldn't be too surprised to find out that other animals exhibit the same kinds of brain asymmetry as we do.
Also cool (and I'm sure you all have seen this): it was recently discovered that one gene for the control of a single growth factor is responsible for dogs' size variation. A little of Darwin's artificial selection at work, eh?
2 comments:
I hadn't seen the article about the single growth factor before. Wow, that's pretty crazy! I wonder... If this gene is present in small dogs and absent in large dogs, what about medium sized dogs?
--Julie
I think it has to do with variability in binding affinity in the promoter region for this gene or its transcription factors or something like that. Fun!
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