How Dogs Experience the World: Part 2
Yesterday, we talked about how dogs smell and see. Today we’ll touch upon their senses of hearing, taste, touch, and a sixth sense that people may or may not have.
Dogs hear very well. They are able to pick up sounds at much lower intensities than people can, which means they can hear things from much farther away. This may be part of the explanation for the uncanny ability of some dogs to know when a loved one will appear long before they actually arrive. Perhaps they are picking up on the unique sound of the family car or their favorite person’s footfalls at a much greater distance than we can even imagine. Dogs are also able to hear sounds at a much higher pitch than we do. In general, the upper threshold for human hearing is around 23,000 Hz, while it goes up to about 75,000 Hz for dogs.
Some breeds of dogs have a better ability to hear than do others. Large, erect ears that can be turned towards a noise act as funnels, focusing sounds down the ear canals. The floppy, pendulous ears of other breeds, like Cocker Spaniels, actually make it harder for them to hear.
Dogs have only about one-sixth the number of taste buds on their tongues in comparison to people, but they are still able to detect the four primary flavors: salty, sweet, sour, and bitter. While taste is actually a fairly limited sense, it is greatly enhanced by what an animal smells. Think back to the last time you tried to eat your favorite meal while suffering from a stuffy nose…disappointing, right? Therefore, even though dogs have a limited number of taste buds, their fantastic sense of smell probably allows them to "taste" what they eat very well.
If you’ve ever seen a dog enjoy a good belly rub or back scratch, you probably already know that they have an excellent sense of touch. Dogs have sensory nerve fibers throughout their skin. Some of these nerves are closely associated with hair follicles, which allow them to feel even the lightest touches to their fur. Specialized hairs called vibrissae around the eyes, under the chin, and on the muzzle (i.e., whiskers) increase a dog’s sensitivity in these areas.
A Sixth Sense
Dogs not only have what can be thought of as the five traditional senses — smell, sight, hearing, taste, and touch — but also the ability to detect pheromones produced by other dogs using a structure above the roof of the mouth called the vomeronasal, or Jacobson’s organ. Pheromones are special chemicals produced by the body that are usually associated with reproduction or social communication within a species.
The presence of a functional vomeronasal organ in people is somewhat controversial, but there is no doubt that dogs respond to their own species’ pheromones. One obvious instance is when a male dog smacks his lips and chatters his teeth after smelling a female’s urine. This is called the Flehmen response, and it probably helps him move any pheromones left behind by the female towards his vomeronasal organ.
I like to think of the canine and human senses as complimenting one another. Together, we make a pretty good team.
Dr. Jennifer Coates