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Q. Is it true that sugar makes you hyperactive? —Stella F., 13, Wisconsin A. No, it doesn't make me hyperactive—thanks for asking. And it probably doesn't make you hyperactive, either. Despite what parents say, sugar hardly ever makes anyone hyperactive. Scientists have found out that sugar is harmless as far as kids' behavior goes. (Teeth are a whole different story, though.) In one of the most convincing experiments exploring this provoking issue, scientists gave 24 kids special diets for nine weeks—three weeks of high sugar, three weeks of the artificial sweetener aspartame (NutraSweet), and three weeks of another artificial sweetener, saccharine. During the experiment no one knew which diet the kids were on. Was the jam sweetened with sugar? Or aspartame? No one knew. Meanwhile, the scientists studied the kids' behavior. When the nine weeks were up and the diets were revealed, the researchers found out that sugar didn't make kids hyper after all. And it didn't make them more impulsive, aggresive, or inattentive, either. But some parents couldn't believe the evidence. (What is it with parents?) They STILL believed that sugar made their kids nuts. I asked Professor Mark Wolraich,* who led the study, why parents hang on to the belief that sugar drives kids crazy. "The power of suggestion is a strong force," Mark says. "If parents believe that sugar makes behavior worse because of what other people or the media tell them, then they are more likely to see that expected behavior." He also points out that kids are most likely to get lots of sugar at times of excitement such as birthday parties or Halloween. So parents are just mixed up about what's giving their kids a buzz: It's the excitement in the air, not the sugar in the ice-cream sundae. —Rosanne *Mark Wolraich, M.D., is a developmental-behavioral pediatrician at the University of Oklahoma Health Sciences Center. Q. Why don't mammals have bellybuttons? I know they have umbilical cords. —Jennifer, Pennsylvania A. "Actually, they do, you're just not able to see them," says veterinarian James Richards*. The bellybutton is the little spot that's left by the umbilical cord—the tube that brought in your nourishment (and piped out your wastes) when you were growing in your mother's uterus. Since most mammals grow quite a while in a uterus, most have bellybuttons. It's just that some are hard to find. "Ours is particularly visible because of how it is shaped," Richards says. "Every aspect of mammals' bodies differs. Noses look different. So do bellybuttons." Veterinarian Michael Guinan** gives this advice for bellybutton detection on dogs: "If you run your finger over the belly where you see the hairs are swirling, you'll feel a little roughness, a little bit of a scar." That's the bellybutton. Cat bellybuttons are much harder to find. They're flat and usually covered with thick fur. Primates have bellybuttons that are more like ours. But dugongs, giraffes, mice, and whales have them, too. Some mammals don't have bellybuttons at all because they don't spend much time in a uterus. Kangaroos and other marsupial mammals live for just a few weeks in the uterus before crawling up into their mother's pouch. And don't bother trying to find a bellybutton on a duck-billed platypus or echidna. They hatch from eggs. —Rosanne *James Richards is the director of the Cornell Feline Health Center at Cornell University College of Veterinary Medicine in New York. Q. Who invented dark chocolate and who though of making it into weird shapes (like animals and stuff)? —Hannah R., 11, Alaska A. The factory-made dark-chocolate bars like the kind we buy today were invented in 1847 by J. S. Fry & Sons, a company in Bristol, England. But people have been making dark chocolate by hand for much longer. Mexico is where people first cultivated the plant used to make chocolate, Theobroma cacao. And way back in the early 1500s, Spanish nuns in Mexico were making a fortune selling dark-chocolate candies. I found this out by reading The True History of Chocolate by Sophie and Michael Coe. The Coes say it's likely that people in Mexico were eating dark chocolate even before the Spanish nuns arrived. To make chocolate into shapes—weird or otherwise—you need a mold. The first company to sell chocolate molds was La Maison Pinat, in Paris. In 1833 the company expanded its original cake-mold business to include chocolate molds. Chocolate maker Robert Steinberg, co-founder of Scharffen Berger chocolate company in Berkeley, California, dug this up for me in the book Le Moule à Chocolate (The Chocolate Mold) by Henry and Laure Dorchy. In those days popular shapes included kings, boys, girls, and, of course, bunnies. —Rosanne *Mark Wolraich, M.D., is a developmental-behavioral pediatrician at the University of Oklahoma Health Sciences Center. Q. If you sprayed a whole can of Reddi-wip, would it fill a bathtub, closet, room, or house? —Patrick L., 8 A. When you press the nozzle on top of a Reddi-wip can, a canister of compressed nitrous-oxide gas inside the can fills a thick cream with bubbles, making it fluffy and bulky. How bulky? To find out, our fearless editor-in-chief emptied out a can of the stuff in her kitchen. "VERY disappointing," she reports. "One can (seven fluid ounces) doesn't fill a pie shell enough to make a good throwing pie. For that you need at least two cans, and for safety reasons probably three." The experts at ConAgra Foods, makers of Reddi-wip, walked me through some math. According to the label, a can holds about 40 two-tablespoon servings of whipped cream, for a total of 80 tablespoons. At 16 tablespoons per cup, that makes five cups. With a little more arithmetic, it's easy to figure out that Reddi-wip is 17.5 percent cream and 82.5 percent bubbles. —Robert Q. How did the heart come to symbolize love? Wasn't the original organ of love the liver? While we're on the heart thing, why is it drawn the way it is? It doesn't look anything like a human heart. —Dana M., 18, Washington A. The heart hasn't always symbolized love. For instance, in A.D. 200, the Alexandrian physician Galen thought the heart was the source of courage and that love came from, yep, that's right, the liver. The heart's link to love seems to have begun in Europe during the Middle Ages, where the heart symbol appeared on church stained-glass windows and other Christian religious artworks, representing Jesus' love for mankind. That "valentine" heart symbole has been around since the early 1300s. Pierre Vinken, author of The Shape of the Heart, says that the symbol is the result of early 14th-century Italian illustrators' efforts to draw a human heart without having seen one. Dissection of human corpses was outlawed by Greek and Roman law and throughout the Middle Ages, so almost no one really knew what a human heart looked like. Instead they relied on descriptions by Galen and the Greek philosopher Aristotle. And since their descriptions weren't exactly perfect, neither were the drawings. —Rosanne Q. Can mosquitoes pass any kind of virus, like flu, smallpox, or AIDS? —Bethany S., 11, California A. My friend Martin Enserink, who recently wrote a long article about mosquito-borne diseases for the journal Science, jumped at the chance to answer this question. Here's what he wrote: "Only a couple of virus diseases, such as West Nile and yellow fever, are transmitted by mosquitoes. That's because these viruses are very special: they have learned to survive inside a mosquito's gut and how to make their way to its saliva, where they can infect us when the mosquito bites us. Those tricks give mosquito-borne viruses the ability to spread even in places where people live far apart. If your neighbors live two kilometers away and you never visit them, they can't give you the flu; but they could still give you yellow fever, if a mosquito flew from their house to yours." —Robert Q. A friend of mine told me that wet firewood burns faster than dry wood. Is this true, and, if it is, how is it possible? —Senia S., 13 A. Drier wood burns faster, but sometimes wetter is better. Even if a log or branch doesn't feel damp, it still contains water in its sap. "A piece of very young pine—all sapwood—can be 40 percent wood and 60 percent water," John Walker* told me. When you burn moist wood like that, some of the heat from the fire gets used up in turning the water into steam. That makes the wood burn more slowly, and it also leaves less heat to warm your living room or toast your marshmallows. So does very dry wood, like the kind used for furniture, make a better fire? Not necessarily. As wood burns, John Gulland** explained, it releases gases and tiny specks of carbon into the air. To give the most heat, a fire has to burn them, too. the faster wood burns, the more gases and carbon it gives off. Very dry wood burns so fast that much of this secondary fuel escapes up the chimney or stovepipe before it has time to burn. (It's called "smoke.") So it's better to burn wood that contains a little moisture—about 20 percent for wood-burning stoves. That's why, after cutting wood, most people let it dry out for a few months before burning it. —Robert *John Walker is a forestry professor at the University of Canterbury in Christchurch, New Zealand. Q. Why do fingernails curve when they get longer? —Julie B., 12 A. Our answer takes us to the nail-matrix domain—that's the area that produces the cells that become our nails. If you take a look at your nails you'll see a white crescent peeking up from the cuticle. That's the visible portion of the nail-matrix domain. The rest is below the surface or hidden by skin. So why do nails curve? I asked Cindy Loomis*, who studies nail development in embryos. Cindy told me the generally accepted explanation, even though she's not sure she buys it. So she's working on figuring out the truth—and I'm biting my nails waiting to find out what she discovers. In the meantime (drumroll, please), here is what she has to say about the nail-curving question: "In essence the downward curvature develops because the deep cells are produced more slowly than the cells near the surface." She adds: "I personally do not think this is the whole story." —Rosanne * Cindy Loomis is an assistant professor of dermatology at New York University. Q. Why, when lightning strikes the ocean, do all the fish not die? —Jake, 12, Illinois A. When lightning strikes the ocean, it triggers electrical currents that can kill fish by messing up the signals that control their hearts and other organs. Fortunately for marine life, the currents spread out and weaken until they become too weak to do any harm. How far away do fish still die? I asked Ewen Thomson, an electrical engineer at the University of Florida who specializes in protecting books from lightning. The "lethal distance," he explained, depends on (1) how much current there is in a lightning bolt and (2) how much current it takes to electrocute a fish. Ichthyologists (fish biologists) sometimes catch fish to study by zapping them with electricity. After talking to one of them, Dr. T calculated that lightning bolts probably don't kill fish more than 20 feet away in salt water, or 200 feet away in fresh water. Currents travel much farther on the surface of the water, though, so surface swimmers—including people—should stay out during storms. —Robert Q. Do bugs sleep standing up, lying down, or not at all? —Elyse B., New York A. "We're stumped by the word 'sleep,'" bee specialist Sheryl Soucy-Lubell* told me, after conferring with the other insect researchers at the Bohart Museum of Entomology in Davis, California. "Bugs definitely rest," Sheryl said. "They have periods when they don't move and their metabolisms slow down. But do they sleep?" It's hard to tell with bugs. Since they don't have brains, you can't watch to see if their brainwaves fall into sleep patterns. (Instead of brains, they have clumps of nerve cells, called ganglia, in various places throughout their bodies.) Whether it sleeps or just rests, what's a bug's favorite position? Some stand. Some dangle upside down. And some even cuddle up with other bugs. For instance, the males of one bee species Sheryl studies are not welcome in the nest. "So they all aggregate on a flower and spend the night 'sleeping' together," she said. —Rosanne *Sheryl Soucy-Lubell is director of education and outreach at the Bohart Museum of Entomology at the University of California, Davis. Q. When a person is blind, does he "see" black or something? —Addie C., 12, Washington A. It all depends on which blind person you ask. I asked Jeff Harrington* what he sees. Jeff started losing his vision to glaucoma when he was 13 and became totally blind at 23. He said, "You know if a TV station isn't coming in and the screen is completely snowy? That's how I describe it." But he told me that's not what all blind people see. So then I talked to Creig Hoyt** to find out more. He told me that it's common for people who are blind to have visual hallucinations. "We used to think this was rare—but it's not. The brain makes up stuff that isn't there." Creig also told me that a blind person's view of the world depends on what part of the visual system is damaged. "If you ask 20 kids who are blind what they see, you'll get 20 different answers," Creig said. —Rosanne * Jeff Harrington is a technology specialist at the Earle Baum Center of the Blind in Santa Rosa, California. Q. One of the characteristics of gems is that they are nonorganic. If carbon is an organic material, why is a diamond—which is made of pure carbon—considered a gem? —Natalie P., 14, Minnesota A. "Organic" usually refers to substances that come from living organisms. Carbon is called an organic chemical because living creatures are full of it. Plenty of the carbon on Earth, however, has never been near anything alive. Most diamonds, for example, form tens or hundreds of kilometers underground out of carbon from the mantle, where the temperature and pressure are too high to support life. In a few cases, diamonds turn up in rocks called eclogites, which started out as seafloor that got pushed down deep below Earth's crust. Some of their carbon may have come from ancient sea creatures. Even those diamonds, however, are very different from anything found in living organisms and are considered inorganic. Gems don't have to be inorganic, though. Pearls, which grow inside oysters, are considered organic gems. —Robert Jillian Banfield, a geochemist at the University of California, Berkeley, and Grahame Brown, editor of The Australian Gemmologist, helped answer this question. There wasn't room to give them credit in the issue, so I'd like to thank them here. Q. What happens when you pop your fingers or your back? What makes the popping noise? —Andrea M., 11, Arizona A. Your question remains one of life's great mysteries. Not many people have done experiments to find out for sure what's going on in popping knuckles. This much is clear: when you pop your knuckles, the sound comes from a joint. So let's take a look at the joint. Surrounding the bones' meeting place, there's a covering, called a capsule. It holds watery fluid that prevents the bones from scraping when they move. Pulling on a joint expands the joint's capsule. Tony Unsworth*, one of the few people who have actually studied knuckle popping, explains it this way. He tells me that when you pull on a joint, the pressure drops so much that the fluid vaporizes and forms gas bubbles. (Weird but true: reducing the pressure on liquids allows them to vaporize at lower temperatures.) But as soon as the bubbles form, bluid streams in from around the edges of the joint. That makes the pressure go back up, which makes the gas turn back into liquid. The bubbles collapse—and POP. Tony came to this conclusion more than 20 years ago, when he took x-ray movies that showed bubbles forming in human knuckles as they cracked. He explains this, complete with stills from his movies, in an article he published in the medical journal Annals of the Rheumatic Diseases in 1971. Still, it's hard for me to believe that little tiny bubbles in my knuckles make such loud cracks. But Paul Doherty**, another scientist, says it's possible. He did an experiment that proves it. Paul's Experiment: Fill a syringe 1/3 full of water. Get rid of all air bubles Observation: Grand Finale: —Rosanne * Tony Unsworth is the director of the Centre for Biomedical Engineering at the University of Durham, England. Q. How come natural gas can burn underwater? —Alex M., 10, Georgia A. Any fuel can burn anywhere, as long as it gets enough heat and oxygen, Mike Wilson told me. Mike is an expert in underwater pyrotechnics (burning, explosions, and fireworks) for a company called Pains Wessex Australia. Among many other things, he once helped invent an underwater torch that a scuba diver carried during the 2000 Olympics. To keep water from cooling down the flame, Mike explained, you need to surround the "burning zone" with a bubble, usually from a compressed-air tank. That's the idea behind the torches divers use to weld things underwater. Natural gas ought to work the same way, Mike thinks. "But the flame might hardly be visible,a nd it would likely be rather dangerous in the development stage," he said. "It's not something I would lightly undertake without the proper safeguards." —Robert Q. How many helium-filled balloons would it take to lift someone off the gorund? —Annika B., Oregon A. In 1982 a truckdriver named Larry Walters tied 42 helium balloons to an aluminum lawn chair, climbed aboard, and took a high-altitude joy ride over Long Beach, California. He drifted downwind at 16,000 feet and finally returned to earth by popping balloons with a BB gun. His homemade aircraft used big weather balloons, though—not the kind they sell at your local card-and-gift shop. To figure out how many normal balloons it would take, you need to know how much weight one balloon can lift. To find out, I bought a helium-filled rubber party balloon and dangled chains of paperclips from it to see how many the balloon could carry. Weighing the chains on a little household postal scale, I found that the balloon could lift about 3/8 of an ounce. A little arithmetic shows that it would take about 43 balloons to lift a pound (16 ounces). So if you weigh 80 pounds, you'd need 80 x 43 balloons = 3440 balloons to lift you. If you're itching to fly, it would be cheaper to buy a plane ticket. —Robert copyright © 2004 Robert Coontz and Rosanne Spector |