Hit or Myth?
There's been a lot of talk about whether it's safe to drink out of plastic bottles. After a widely circulated, government-funded 2003 study linked chromosome damage in the eggs of female mice with bisphenol-A (BPA)a component in polycarbonate containers like those ubiquitous hard-plastic water bottles, baby bottles, and water-cooler jugsmore scientists entered the fray to argue over the health effects on humans. The debate remains open: A number of independent studies suggest cause for concern, but it will be years before any consensus emerges. According to the National Toxicology Program, both sides in this fierce debate have "credible" points. It would be premature to avoid polycarbonate, but for now, if you have older containers that are scratched or cracked, and thus mor...
Q) From how high up can a flying squirrel safely launch?
Jan Nesset, Durango, Colorado
A) As you probably know, flying squirrelsa subfamily of 43 species found in North America, Europe, and Asiadon't really fly. They glide, by taking off from a high perch, spreading a special membrane called a patagium, which resembles a bat wing, and soaring up to 150 feet to another tree. A split second before impact, they slam on the brakes by changing shape from that of a sleek F-16 to a bell-shaped parachute. John Scheibe, a biology professor at Southeast Missouri State University, says that because flying squirrels are so lightabout two ounces, whereas gray tree squirrels can reach a poundtheir only "flight" limitation is the height of the tree. (Thankfully, nobody's tried launching the fellas from airplanes.) But in theory, if you discounted atmospheric obstacles, a flying squirrel leaping from a 30,000-foot tree could make it down to earth in 45 minutes and expend only one-tenth of its daily metabolic output. For this Iron Squirrel event, it had better bring some nuts.
Q) How did early explorers find the North Pole, when faced with 24-hour sunshine and a magnetic pole that was far from the geographical pole they sought?
Chris Yeats, Tulsa, Oklahoma
A) You're correct to assume that a compass won't lead you to the top of the world, but you don't need constellations to guide you. T. H. Baughman, a polar historian at the University of Central Oklahoma, says that with just a sextant, a device called an artificial horizon, and astronomical tables, people 250 years ago had the requisite tools for tracking the sun to find latitude 90 north. But because polar conditions are tough on these sensitive instruments, the technique wasn't foolproof. In fact, it seems increasingly likely that American Robert Peary, long believed to be the first to the pole, in 1909, didn't make it: Small calculational errors probably had him off by a good 30 miles. It would be 1968 before American insurance salesman Ralph Plaisted finally became the first undisputed pole conqueroras confirmed by an Air Force flyover.
Q) Which plant can survive at the highest elevation?
Jason Schoener, Grand Blanc, Michigan
A) New species are discovered at higher sites every year, but the current altitude champ is a beige lichen found at 24,300 feet on Everest's neighbor Makalu. However, some people, explains biologist Stephan Halloy, of the New Zealand Institute for Crop & Food Research, don't count lichens as plantsthey're the result of a symbiotic relationship between a fungus and an alga. Among vascular plantswhich transport water to their leavesthe winner is Saussurea gnaphalodes, a low, hairy rosette that grows at up to 21,000 feet on Everest. It's no surprise the plant is runty: To survive at such heights, where CO2 is scarce, alpine flora have to develop more stomata (the leaf pores that enhance gas exchange), hunker down, and invest more biomass in their roots than their shoots. When they're successful, says Halloy, high-altitude plants can live up to 3,000 years, rivaling the oldest known specimens on earth. These plants are built to last.