Dogs have associated with humans for approximately 14,000 years. During that time we have been your companions, hunting partners, protectors and assistants. If you have spent a lot of time with your dog, he will treat you as the pack leader and look to you for direction as to what he is to do. Since you are his leader, then you should understand exactly how he perceives the world around him. In that way, you will be better equipped to provide the direction he needs to satisfy your desires.
Just like you, dogs have five senses: smell, sight, hearing, taste and touch. However, your dog's senses are tuned differently than your senses. Because of this, our perception of the world is somewhat different than your perception. Let's explore this further, so that you can understand why your dog reacts the way he does.
SMELL
Smell is our greatest asset. This is why dogs are used at airports to detect drugs, explosives and other contraband. It is also why dogs are used in search and rescue. Have you ever wondered why dogs have such a superior sense of smell?
Both humans and dogs have an olfactory system which discerns smells. Part of that system is a centre located within the brain called the olfactory bulb. This centre receives signals from the olfactory nerves located within the nose and it filters these smell signals and passes them onto the brain. While a human's olfactory bulb weighs about 1.5 grams, our olfactory bulb weighs about 6 grams, with slight variations by breed. That is four times larger than a human's olfactory bulb. When you consider that our brain is about one-tenth the size of a human's brain, this means that the portion of our brain devoted to smell is about 40 times that of a human's brain. Given that comparison, it is no wonder that we have such a keen sense of smell. In view of the fact that smell is our greatest asset, you can see why our perception of the world revolves around what we smell.
SIGHT
A human's most vital sense is sight. What a person sees primarily creates their sense of the world. A human's eye is constructed so that it can detect the finest details. However, our eyes are constructed to detect movement. Their ability to detect fine details has been sacrificed in favour of the ability to track movement and to see in low light situations. This is why we can see things that are moving, in near darkness, when a human cannot see anything. Most humans have good depth perception, while we have poor depth perception. Our pupils are much larger, in proportion to the size of our eyes than a human's are. In addition, our pupils cannot constrict as well as a human's can. This feature lets in more light, sacrificing depth perception for the ability to discern things in low light conditions.
Have you ever noticed that our eyes shine when they are caught in a beam of light at night? This is caused by a reflecting mechanism located behind the retina which gives us an additional chance to see things in near darkness. Tests have determined that we can see things in one-quarter of the light that a human needs to see the same things. As a side note, cats only need one-seventh of the light that a human needs to see, which explains why cats can see at night.
HEARING
Along with our sense of smell, we have a much better sense of hearing than humans do. The difference is primarily in the upper frequency range. While a human can hear sounds with frequencies up to 20,000 Hertz, we are capable of hearing all the sounds a human hears plus we hear sounds with frequencies ranging as high as 47,000 to 65,000 Hertz, depending on our breed. To show this comparison in a simpler way, consider a piano keyboard. The last key on the right end of a piano keyboard vibrates at approximately 20,000 Hertz. If you add another 28 keys to the right of the current keyboard, then the last key of the addition would vibrate at approximately 65,000 Hertz. Humans would not be able to hear at least the last 20 of the new additions, and most wouldn't hear any of the new additions. This is why humans cannot hear dog whistles, but we can hear them fine. The frequency of these whistles is above the frequency that human ears are capable of hearing. Because we can hear things that humans cannot, we frequently bark at something that our owner is unaware of. This sometimes frustrates our owner because he or she cannot understand why we are barking.
TASTE
If you examine the dog food section of a major supermarket or a pet store, you will see a vast array of dog food with all sorts of flavours. However, according to my veterinarian, I gulp my food down so quickly that I don't have much chance to taste it and I seldom chew it either. This trait is probably linked to my instinct which dictates eat quickly or your competition will take it away from you. Possibly dogs in a one dog household eat a little slower, but I doubt it. As they say...it's in my genes. So why all the variety? Actually, the smell of the food is what attracts us most. Our sense of taste is limited by the fact that we only have about 1700 taste buds while humans have about 9000.
TOUCH
Dogs have different degrees of sensitivity on different parts of our bodies. Our nose and muzzle as well as the pads on our feet are quite sensitive to touch. Some dogs become upset when you rub around their nose or mouth or the pads of their feet. Others enjoy a rub on the nose or around the mouth. Mom and dad had a German Shepard cross that loved to have the pads on his feet rubbed gently. His brother did not like to have his feet touched at all. I don't mind it sometimes, but I'd sooner get a tummy rub.
Our whiskers are very touch sensitive, because they are deeply imbedded in the skin covering the area above our mouth. Because of this, our whiskers amplify the slightest touch. Studies have determined that 40% of our brain area devoted to touch is dedicated to this area of our body. Interestingly enough, most groomers shave this area of us which greatly diminishes our sense of touch. My whiskers are shaved every time I'm groomed, so I frequently have to rub my face fairly vigorously on something so I can get a sense of what it feels like. On the other hand, I don't get food all stuck on my whiskers because they are shaved off.
In conclusion, we both have five senses that we can use, but humans mainly rely on their vision for a sense of the world while we rely mostly on smell. The other four senses are used by both to varying degrees. The other difference between us is that humans just don't understand how much you can learn by licking and smelling each other.
Until next time,
Teia
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