posted October 19, 2006 09:26 AM
From sunday edition of Parade (nix the errors - okay?)
See The world As Your Pets Do
By Sarah Wilson & Brian Kilcommons
When your dog rushes up to greet you and takes a quick sniff, what does he learn about you? A lot more than you might think. He can tell if you hugged your kids earlier, if you took any medications or drank too much last night. (Aren't you glad he can't talk?) Research in the emerging field of animal perception reveals that what we see, hear and smell isn't necessarily the same as what our pets do. here are the latest scientific findings:
Do You See What I See?
If you dog could tell you what he sees, he'd probably describe a fuzzy world of blues and yellows in the daytime. In dim light, dogs can see more shades of grays than we can. Our eyes are better at discerning colorful details in daylight. We also can see things quite close up while dogs cannot. (anyone who has watched a dog hunt for a treat right in front of him can confirm this.) What makes the difference? Simply put, humans have more color receptors than dogs.
In contrast, your cat, a nighttime hunter, can see clearly in conditions six times darker than we can. Those vertical slit pupils allow a cat's eyes to take in more light at night. Given the type and number of their color receptors, cats probably view the world in a pastel palette and don't see some colors at all. An apple tree laden with red fuit, for example, would appear light-colored with dark apples to your cat.
Does this make humans the best at seeing in color? Nope. For the best sight, we need a bird's eye view. Some birds have at least four types of color receptors. "We can't possibly imagine how incredibly colorful the world is to birds' eyes,"says Scott Lanyon, professor of Ecology, Evolution and Behavior at the University of Minnesota in Minneapolis. "For every color that we perceive, birds can see multiple distinct colors. Relative to birds, we humans are all color-blind."
A bird also can see ultraviolet light, which appears to have evolutionary implications. For example, when a starling parent brings food back to its young, nested in a dark tree, those hungry babies reflect UV to the adult from their skin and gaping mouths. The healthiest and largest baby reflects the most light. Generally, that one gets fed first and most. So when a starling mom tells you hnow "bright' her child is, she really means it!
The Nose Knows
Your nose is like an old static-filled, black-and-white TV compared to a dog's high-definition, start-of-the-art set. If you laid out all our smell receptors (about 5 million),they would fill your average postage stample. A dog's receptors about 220 million) would cover an average handkerchief.
Humans have learned how to harness that smelling power and put the canine nose to work. Dogs are now trained to pinpoint gas leaks in underground pipes; locate people under water, snow or collapsed buildings; and sniff out illegal drugs, foods and plants entering the country. Criminals may try to hide their illegal cache in something strong-smelling, but dogs can find the contraband as easily as we can pick a rose out of a bunch of daisies.
With their extraordinary ability to detect some odors at as much as one part per trillion, canines are even becoming medical diagnosticians. Researchers at the Pine Street Foudnation, a cancer research organization in Sal Anselmo, California, trained five household dogs to detect cancer on a patient's breath. They found that the dogs detected lung cancer with 97% accuracy and breast cancer with 88% accuracy. Maybe some day, you'll get a dog scan instead of a CAT scan.
What about taste? Research suggests that both cats and dogs are relatively insensitive to salt. And scientists recently learned that cats lost their sweet tooth after a genetic mutation deactivated sugar detectors on their taste buds. Both dogs and cats do have taste receptors for amino acids found in meat. As many of us have learned the hard way, don't leave the Thanksgiving turkey unattended.
Did You Hear That?
Both cats and dogs can hear things you cannot, which is one reason most dogs make such terrific home alarm systems. Cats can hear sounds several times higher than we can, which is useful when they hunt. If your cat leaps up, hisses and scoots out of the room--seemingly unprovoked--he might have been startled by something you couldn't hear.
All this suggests that the inexplicable behaviors we may observe in our pets shouldn't be dismissed as simply nutty. The world they live in is different from ours--but we are growing closer and learning from each other every day.
Sarah Wilson and Brian Kilcommons are animal trainers and the authors of the new book "My Smart Puppy."