I've heard that wearing wet cotton makes you lose body heat faster than wearing nothing at all. So if I'm caught in a freezing downpour while wearing just cotton, am I better off buck naked?
—William McNeill, Norwood, Massachusetts
I call cotton 'thermal-dynamic nudity,'" says William Forgey, president of the Wilderness Medical Society and author of Basic Essentials of Hypothermia. One pound of water absorbed in conventional cotton clothing can suck away 245 kilocalories of energy—roughly what you'd lose chopping firewood for an
hour—because water fills the air pockets that, when dry, give the fabric its insulating quality. (This is why synthetic fabrics work best for wet conditions: Because they wick water to the fabric's surface, the insulating air spaces stay intact.) So if cotton's all you've got, then yes, you're better off in the nude. But barely, since an average adult
male has six hours to survive when he's wet and has no insulation on a 20-degree-Fahrenheit day. If help isn't close at hand, follow Forgey's advice. Instead of stripping down,stuff your wet clothes with leaves and pine needles like a scarecrow and tie the cuffs of your pants and shirt with shoelaces, creating a foliage-filled parka packed with insulating
air spaces. Second, poke a hole in a plastic garbage bag if you've got one, and pull it over your bulky profile; this will halt evaporative heat loss. Lastly, cover your head with a makeshift hat, such as an empty backpack, or even some plastic trimmed from the garbage bag, to curb the whopping 50 percent heat loss from your head. It's hardly a fashion
statement, but it may well save your hide.
Which organism can survive the most hostile environment?
—Chris Knutsen, New York, New York
"Extremophiles" are what biologists call the tiny bacteria that subsist on iron, manganese, sulfur, and hydrogen three miles below the earth's surface in the 140-degree heat of South African mine shafts, as well as the pink microorganisms called Deinococcus that inhabit radioactive waste pools inWashington State's Hanford
Nuclear Reservation. As for creatures actually visible to the naked eye, there are tube worms so hardy, they cozy up to 700-degree-Fahrenheit hydrothermal vents 8,250 feet down in the Pacific Ocean, south of Mexico's Baja Peninsula. But perhaps the most masochistic of the lot is the amphipod, a shrimplike crustacean that thrives at the bottom of the western
Pacific's 36,000-foot-deep Mariana Trench, where water pressure is 1,100 atmospheres—equivalent to 16,170 pounds per square inch—and the temperature is a consistent 32 degrees Fahrenheit. If you're wondering how it's possible for an animal to survive there, you're not alone: "People have been studying deep-sea organisms for 40 years," says Art
Yayanos, a biophysics professor at Scripps Institution of Oceanography, "and we still don't have a clear answer about why some can live at extremely high or low temperatures and why some can't. It's a field that's ripe for a bright new idea."
Do bears in captivity hibernate?
—Bill Mayer, Bozeman, Montana
First, let us correct a common myth: Not all wild bears hibernate. Black bears living in the Southeastern United States, for example, rarely curl up and sleep for months on end, because meals of acorns and roots are available year-round. As for grizzly and black bears that inhabit the colder climes in, say, Alaska, nodding off and ceasing most bodily
functions (including urination and defecation) for five months in order to conserve 75 percent of their typical daily energy is a last-resort survival tactic for winter months when they run out of food. Likewise, the only reason captive bears would hibernate is if their zookeepers stopped feeding them bear chow (most often a mixture of corn, wheat, and
animal fat)—something most zookeepers are loath to do. "Nobody is trained to starve animals," says Charlie Robbins, a director of Washington State University's Bear Research Education and Conservation Program, who weans his black and brown bears off calories from early November through mid-March. By early August, Robbins notes, "a bear's brain throws
some kind of neurological switch that says, 'Give me all the food I can eat.'"
Why is ice slippery?
—J. Rypins, Chicago, Illinois
In addition to ice, water, and vapor, there is a fourth state of H2O, a quasiliquid film just a few molecules thick that sits atop frozen lakes and sidewalks, causing skates to glide and commuters to fall.According to Richard Armstrong, a physicist at the University of Colorado's National Snow and Ice Data Center, ice molecules form a rigid lattice
framework that is strongest at the core, where ice is coldest; move toward its surface (where the temperature approaches melting point), and the chemical bonds between molecules begin to break down. The warmer the air temperature, the looser the ice molecules, and the slipperier the surface. The converse is also true: The frigid midwinter air temperature at
a lake in the Yukon creates a surface that's less slick than any ice skating rink, because the bond between molecules on the surface of that lake is stronger in the cold air. As any polar adventurer or arctic skater will tell you, smooth ice does not necessarily mean that it's slippery. For cutting figure-eights, 22 degrees is the optimal air temperature,
creating perfectly slick ice; when the mercury dips to -40 degrees, the experience is akin to skating on cardboard.
Send your questions for The Wild File to Outside, 400 Market St., Santa Fe, NM 87501, or submit them here.