Q: You often hear about lost animals, including dogs and cats, traveling extraordinary distances to find their way home. Is there any truth to this?
Craig Collins, Santa Rosa, California
A: According to Bonnie Beaver, a professor of small animal medicine at Texas A&M University, the vast majority of these Disneyesque stories "turn out to be either hoaxes or cases of mistaken identity in which an overly hopeful owner mistakes a similar animal for the real McCoy." As for the handful of verified cases, animals have a good basic sense of direction and might be capable of wandering in the general direction of home until they eventually stumble on familiar sights, sounds, and scentsthe latter of which dogs can detect from at least five miles away. "Picture your house at the middle of several concentric circles with your dog at the outer edge," Beaver says. "Each ring represents a different smell that the dog is familiar with. No matter how many wrong turns it makes, it's going to eventually find its way home." Scientists suspect that more impressive feats of navigation, such as migrations or uncanny "incredible journeys," would require a sort of biological compassone that has been found only in birds and fish. The topic clearly needs more scientific elbow grease. Who do we call to get funding for a recreation of Lassie Come Home?
Q: Why does campfire smoke always seem to drift toward me?
Dustin Rodgers, Payson, Arizona
A: You might say smoke follows beauty, butno offenseit's probably one of two more plausible explanations. Fire scientists believe this unpleasant natural phenomenon is just an illusion, created by swirling wind. "It's a roulette wheeland it just feels like you're always the loser no matter where you sit," postulates Stephen Pyne, author of ten books on fire, including Fire: A Brief History. BLM smoke management specialist Carl Gossard, on the other hand, attributes it to a crueler irony: Sit with your back to the wind to avoid the smoke, and you actually force the breeze to eddy around you, pick up those pernicious fumes, and blow them in your face. Whichever theory you subscribe to, be aware of diurnal changes in the wind. "During the day, canyon breezes blow uphill, but at night they blow downhill," says Gossard. And on the beach, wind tends to blow onshore during the day, and offshore at night. "So if you're sitting around the fire for a really long time, you're going to have to make an adjustment." Suck it up, switch seats, or try yelling, "I hate rabbits!" three times in a row. Even if it's not a permanent solution, screaming anything will blow the smoke away for a moment.
Q: My friend told me that giraffes can't make a sound because they don't have vocal cords. How sad! Is this true?
Nancy Jones, Long Branch, New Jersey
A: Breathe easy. Giraffes do have a set of vocal chords, aka a larynx. But they're unable to emit more than a low moo or wheeze, so the 18-foot-tall watchtowers of the savanna communicate instead by making the air in their eight-foot-long necks vibrate. "It's called Helmholtz resonance," says Elizabeth von Muggenthaler, a biologist who recently completed a three-and-a-half-year study of giraffe bioaccoustics at zoos in North and South Carolina. "It's kind of the same principal as when you blow air across the top of a Coke bottle: Air circulates inside the bottle and is then released through the top." Von Muggenthaler has identified two distinct head movements that, she believes, may create Helmholtz resonance. In a "neck stretch," the giraffe swings its head to its rear, and then rapidly sweeps it up and forward like a serpent; in the second, a "head throw," the giraffe lowers its chin and then quickly raises it skyward. In both cases, the calls produced are mostly infrasonic, too low in pitch to be heard by humans, but apparently audible to calves and the giraffe's mateeven through stands of baobab trees and herds of safarigoers.
Q: If the head is the body's number-one route of heat loss, what's number two?
Barbara Wagner, Lexington, Kentucky
A: Runner-up: the hands. According to Richard Gonzalez, chief of biophysics and biomedicine at the U.S. Army Research Institute of Environmental Medicine in Natick, Massachusetts, hands can't help but throw off heat on a cold day, thanks to the fact that they're cylindrical. Cylinders are terrible at retaining heat because they have more surface area per unit of volume than any other shape. Not only are your hands poorly designed, but, like your head, they're poorly insulated, too, comprising mainly bone, cartilage, and tendons, which don't retain heat as well as fat and muscle do. (The feet and ears, both modified cylinders, are numbers three and four on the heat-loss list, and the armpits and groin are also big losers, too, because they contain a profusion of blood vessels near the surface.) Gonzalez offers this simple test to determine if your hands are losing too much heat: Hold your fingers to your lips; if they feel icy, you'd better find some glovesand a hat. A toasty head frees up warm blood needed to rescue your extremities.