50 fascinating facts about dogs
Dogs are all around us, so it's easy to take them for granted. We think we know everything we need to know just by living with them, and for many years, scientists weren't particularly interested in studying dogs compared to more exotic creatures. So most of what we knew about them was based on tradition and conventional wisdom. But recently, there's been an explosion of scientific interest in dogs, including their behavior, intelligence, and perception, and scientists are now more informed than ever about man's best friend.
Stacker scoured scientific journals, news articles, and expert blogs to present 50 interesting facts about dogs. Stacker's slideshow includes information revealing fascinating findings to questions we would have never thought to ask. For instance, did you know that when a dog licks its lips when there's no food around, it means something about how she is feeling? And do dogs actually like baby talk?
The slideshow presents the most up-to-date answers to questions you might have always wondered about, like whether dogs can see color and how a dog's age compares to humans. It also provides details that give a richer understanding of common knowledge: You probably know dogs are excellent smellers, but just how excellent is probably more impressive than you might have imagined. This slideshow also contains some surprising facts about history. For instance, did you know that the current concept of "purebred" only goes back to the late 19th century?
Click through Stacker's slideshow to better understand how dogs feel, think, and perceive the world.
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Dogs are built to smell
A dog's sense of smell is more sensitive than that of humans. A dog's nose contains around 800 different types of olfactory receptor cells, which is about twice as many as in humans. The olfactory bulb, the part of the brain that processes smells, makes up 1.95% of the volume of a dog brain but only 0.03% of a human brain.
Dogs can detect incredibly faint smells
With that sensitive equipment in their snouts and brains, dogs can detect odors even when they are unbelievably weak. Experiments have shown that dogs can detect a test chemical at a ratio of one part per trillion. In one experiment, dogs could identify the smell of ovarian cancer in a single drop of blood.
Dogs can detect slight differences in the same smell
Dogs know what direction a smell is coming from because they can tell that it's very slightly stronger say in the left nostril than in their right. Smells also change with age, and dogs can detect that: A tracking dog can tell which way someone went by the difference between the age of the smell of more recent footsteps.
Dogs have another chemical sense in addition to smell
Like many animals, dogs have the vomeronasal organ (VNO) in the roof of the mouth, which detects pheromones. This is one reason dogs may lick things we think are gross, including the urine of other dogs—to get it closer to that organ. Along with their sense of smell, this lets dogs know many things about other dogs by what they've left behind, such as their sex and how long ago they were there.
Dogs don't recognize themselves in a mirror but may have self-awareness
The mirror test is an experiment that's supposed to show if an animal has self-awareness. Put a mark on their body when they're unconscious, and if they touch themselves there when looking in a mirror, they know it's their reflection in the mirror. Dogs haven't been able to pass the mirror test. However, one researcher has argued that dogs do pass the test if you do it in a way that tests the sense that's important to them: they can distinguish their own urine from that of other dogs.
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Your dog can see better than you in dim light
A dog's retina contains mostly the kinds of receptors called rods, which require less intense light to function, and fewer cones, which are responsible for color vision. They have only about 3% cones, compared to a human's 5%, so they can see better than humans in the dark.
Dogs can see colors
It's often claimed that dogs can't see color, or that they can't tell the difference between red and green, but this is an oversimplification. Dogs have only two types of cones where humans have three; while research on how dogs' color vision works is still ongoing, experiments have shown they can distinguish colors. They can also use other cues, including brightness and intensity, so no need to throw away your red balls—they can find them on the green grass.
Dogs can hear much higher pitches than humans
The highest pitches discernible to the human ear are around 20 kilohertz, whereas dogs can hear up to 45 kilohertz. This ability probably evolved so they could hear the high-pitched sounds of small prey like mice. However, while dogs can hear those "silent" dog whistles that you can't, high-frequency sounds don't carry as far or pass through objects, so they're only useful in limited situations.
Dogs can pick their name out of background noise, but not as well as people can
Ever notice how your own name seems to jump out at you from the sounds of a crowd? Scientists call this the "cocktail party effect," and it's been tested in dogs. They can hear their name when it is the same loudness as the background noise—something human infants can't do. However, human adults can even hear their name when it's softer than the background, which dogs can't. So be patient with your dog in an extremely noisy place—he may not just be ignoring you.
Dog noses are still better than human technology
Despite years of research and billions of dollars of investment into artificial scent detection, dogs still beat technology. High-tech sensors built by the military to detect improvised explosive devices (IEDs) only detect about half, while dogs can find 80%. And while we now have systems that can detect a smaller amount of a chemical than a dog can, they're huge and complicated and can't be used in the field. You can bring a sample to the machine, sure, but it can't go out and hunt for it as a dog can.
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