Everyday Mysteries
Like all chili peppers, habaneros get their heat from a tasteless, odorless chemical called capsaicin, which irritates certain nerves in the nose and mouth. Scientists rate hotness in Scoville units, a measure of capsaicin concentration. Plain old bell peppers rate a zero; jalapenos, 2,500 to 5,000 units; habaneros zoom as high as 300,000; pure capsaicin is a skin-blistering (literally) 15 million Scoville units.
But why would people willingly submit themselves to that kind of pain? Other mammals don't. Botanists believe plants use capsaicin as a defense to keep rabbits and other small mammals from eating them. Birds, which may not feel the heat of chili peppers, feed on them and disperse seeds through their droppings. Paul Rozin, a University of Pennsylvania psychology professor, observed a Mexican village where people ate plentiful quantities of chilies, but dogs and other animals that fed on human garbage ate peppers "out of necessity only," he says.
An old standby explanation is that people in hot climes eat spicy foods to perspire, in essence turning on nature's air conditioning. But it doesn't take a habanero to get a sweat going. Another theory is that the burn of chilies causes the brain to produce endorphins, the powerful chemicals that block pain and create a sense of well-being. Hot peppers, in other words, are a habit-forming drug.
Rozin, who discounts the endorphin theory, believes eating hot peppers is actually a form of "benign masochism." A pepper's burn, he says, is like riding a roller coaster. "Your body is responding as if in trouble, but you know you're really safe, getting a pleasure that comes from knowing better than your body."
WHAT MAKES A GREAT VIOLIN The historic violins most sought after by today's players and collectors were crafted hundreds of years ago in Cremona, Italy, by three famous makers: Andrea Amati, Giuseppe Guarneri, and Antonio Stradivari. Performers like Marylou Speaker Churchill of the Boston Symphony Orchestra say the best Cremona violins have "a tone quality that grabs you and you can't put it down."
For centuries, the secrets of their magnificent tone have been a sort of Holy Grail for makers, scientists, and cranks. Just what mixture of four-centuries-old alchemy, art, and skill produced the Stradivarius and its kin? Some believe Cremonese violin makers used very dense wood from old trees, floated down river from the Alps to Venice's saltwater lagoons, where mold attacked the wood and opened microscopic holes. That may have made the wood less dense and more resonant. Some modern makers have tried various methods of reproducing this special property; they have baked wood to reduce its density, buried it in the sand, and even simulated salt exposure by saturating wood in a solution made by boiling shrimp shells in potassium hydroxide.
Then there's the centuries-old hunt for the "lost Cremona varnish." Joseph Nagyvary, a Texas A&M University biochemistry professor and violin maker, has removed minute samples of varnish from several Cremona instruments and studied them under a scanning electron microscope. The varnish, he claims, contains minerals, such as quartz, calcite, and gypsum, which may account for the surface luster of Strads--and, more important, may have penetrated the wood's surface, enhancing and amplifying sound.
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