How Do Dogs' Senses Compare to Our Own?
You shouldn’t exactly be surprised to hear that dogs have superior senses of sight, smell, and hearing to our own. This is common knowledge, but just how superior are those three senses are is probably incomprehensible to you.
Now, of course, many senses are either heightened or dulled based on breed, with certain genetic and evolutionary factors taking over to impact a breed’s ability to use a particular sense. For example, basset hounds, which are perfectly built and bred for sniffing out a trail, have an incredible sense of smell that serves them well. Even their floppy, unmistakable ears hang in a way that pushes scents toward their nose. But even within these variations and exceptions in certain breeds, dogs still have some astounding advantages over us as a species.
Dogs don’t rely heavily on their sense of sight in the same ways they do smelling and hearing. To be blunt, their sight is pretty average as far as their needs are concerned but it is still wildly different from our own. To us, perfect vision is 20:20, while a dog’s best vision is about 20:80. They also lack some of the necessary components to see colors in the same way we do, unable to even depict some colors altogether.
Next, our range of site (without moving our head and neck) is about 180 degrees, allowing us to see in front and to parallel sides (assuming vision is equal in both eyes). Meanwhile, dogs have a 250-degree-wide range of sight depending on where their eyes are positioned on their face. The further their eyes are out to the sides of their face, the wider their range of vision will be.
During the daytime, we actually can see better than dogs but their vision is superior once the sun sets (or the lights go out). Dogs have a tapetum lucidum, which is a reflective layer of cells that sit behind the retina. This structure of cells is actually what’s responsible for that sometimes creepy glow or reflection we see in a dog’s eyes when shining a light at them in the dark. Here, “rods and cones” are used when absorbing light or seeing at day and at night. Rods are used for seeing during the day while cones are used for seeing at night, and dogs simply have more cones than us, allowing them to see more clearly than we would comprehend.
While puppies are actually born deaf and don’t start hearing for 21 days, their ability to detect sound is definitely superior to ours once it’s developed. In fact, they can already hear four times the distance of a human with normal hearing abilities once that sense starts to develop.
First off, dogs have 18 muscles that are put to use by their ears, all with the purpose of moving their ears around so they can more or less point them at whatever sound they’re trying to detect. From a simple design perspective, our own ears are at the sides of our head, while dog ears tend to be positioned toward or on top of the head. Of course, we know this can vary by breed just by looking at dogs. A hound dog with floppy ears is going to be more reliant on his sense of smell and less reliant on hearing, while German Shepherds are possibly the first dog that comes to mind when we think of pointy-eared canines with acute hearing. Other factors like hair inside ears and the positioning on a breed’s head will also dictate how well they’re able to detect sounds.
The major difference in ability here is that dogs are able to detect a frequency range of 67-45,000 Hz, compared to a human range of 64-23,000 Hz. This means they are far more sensitive to lower and higher pitched sounds, which explains exactly why they can lose their minds over some sounds you might not even notice. Coupled with all those muscles in their ears, dogs have an ability to decipher where sounds are coming from in ways we can not. For humans, there is typically a general sense or approximation of where a given sound may come from. But all those muscles and such a wide range of frequencies picked up by dogs actually allows them to pinpoint more precise locations of those sounds.
This is the one where our canine friends have us beat real good. Dogs possess anywhere from 10,000 to 100,000-times as acute a sense of smell as humans. "Let's suppose they're just 10,000 times better," says James Walker, former director of the Sensory Research Institute at Florida State University. "If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well.”
That’s almost an apples to oranges analogy, though, considering we’re talking about smell and not sight here. Dogs have such a superior sense of smell because they have up to 300 million olfactory receptors in their noses, compared to about six million in our own noses. That’s as many as 50 million more receptors dedicated just to the ability to take in smells, while the part of their brain that actually processes those smells is actually 40-times larger than our own. What this translates to is a greater capacity for deciphering the most minute details of a given scent. For example, to equate that back to the “3,000-mile” analogy, dog-cognition researcher at Barnard College, Alexandra Horowitz, describes this heightened ability with the example of our own ability to smell something like sugar added to our morning cup of coffee. For us, maybe a teaspoon of sugar would create a recognizable smell in that cup of coffee. But to a dog, that same teaspoon of sugar could be detected in one million gallons of water. That’s the equivalent of two Olympic-sized swimming pools worth of water.