This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Your dog is adorable, but face it, she makes a mess around the water bowl. This week physicists have, thanks to high-speed video, explained that such slovenly behavior is actually a clever way around a dilemma caused by the evolution of the canine face: Dogs do not suck.
People do suck. We have small mouths and long cheeks, so we can form a seal on the surface of a liquid and vacuum it into our mouths. But dogs have big, long mouths--the better to bite things with, back in their ancestral days--and that means short cheeks that cannot extend all the way around the mouth. That also means no sucking, researchers from Virginia Tech and Purdue universities explained this week in San Francisco, at the American Physical Society's Division of Fluid Dynamics meeting.
So what is poor, thirsty, adorable Fido to do? Slam her tongue down on the water for a start, says Tech's Sunghwan Jung, and then pull it back very fast. Jung and colleagues videotaped several dogs doing this, and it is worth watching the video: Dogs drinking water in slow motion.
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The initial impact displaces a lot of water, which rises up underneath the dog's tongue--accelerating at roughly 5 times the force of gravity; the scientists measured all this by modelling the effect by plunging a rounded glass tube into a water dish. Just before the column loses momentum and falls back into the bowl, the dog closes her mouth, pinching it off. Swallow. Gulp. Repeat.
(Cats, which also have the same short cheek problem, have a different solution. They use their tongues to lever water into their dainty mouths. It would be unseemly to approach this problem like dogs do.)
And when you yell at your dog, "Hey! Stop making such a mess!" don't be surprised if your pet turns her head to the left. Dogs may process different types of language in different halves of the brain, somewhat like people, according to another dog study announced this week. This one was published in Current Biology.
Dog brains have left and right hemispheres, each one connected to the ear on the opposite side. Left ear to right hemisphere, and so on. Again, rather like us. The scientists, from the University of Sussex in England, say the right side of the brain deals with highly emotional tones. The left side interprets familiar information--trained commands. The evidence? Scientists played a series of sounds for a series of dogs, taking care that the sounds were just as loud on each side. Understandable commands like "Come on, then!" prompted the dogs to turn right, perhaps indicating left hemisphere dominance at that point.
Distorted syllables--think of Charlie Brown's teacher's voice, but with a rising, encouraging tone at the end--pulled the dog's head to the left, hinting at left hemisphere activity focused on the emotional content, since the actual syllables were incomprehensible.
The researchers did not, however, explain what is happening in the brain when your dog does not listen to you at all. Perhaps she is thinking about her next drink.
