Q) If our body temperature is 98.6 degrees, why does it feel so hot when it's 98 degrees out?
Sue Walton, River Falls, Wisconsin
A) ACCORDING TO University of Kansas exercise physiologist John Thyfault, the temperature of your skin is always a few degrees colder than your internal body temperature. Therefore, air at 98.6 Fahrenheit is hotter than your skin. But more important, says Thyfault, a former college tight end who often practiced with his teammates on artificial turf sunbaked up to 120 degrees, is the role of your nervous system. Scientists believe your brain, nerve networks, and thousands of hot and cold receptors in the skin that gauge the ambient temperature are all prewired to make you feel hot well before the air temperature exceeds that of your skin. Why? Since your body continuously produces excess heat through basic metabolic functions, it's the nervous system's way of making sure you take appropriate action—both voluntary and involuntary—to cool off before you experience heatstroke. In addition to sweating, this means drinking water, throwing in the towel for the day, and—for football squads wanting their quarterback to pass, not pass out—getting off the scorching turf.
Q) How many feet would the oceans need to rise to cause a globally catastrophic event?
Jim Concklin, Chicago, Illinois
A) IT ALL HINGES on your definition of "catastrophic"—and which hotly contested estimates you choose to believe. Global warming is, after all, one of the world's most feverishly debated issues, so predictions range widely. According to EPA figures, U.S. coast levels could jump one foot over the next century, which could permanently alter fragile marine estuary ecosystems, like the Chesapeake Bay, and potentially deluge the Mississippi River's floodplain. Not catastrophic enough? Consider a surge of roughly three feet, the upper estimate that the UN predicts by 2100 if the global-warming trend continues. It would ruin 16 percent of Bangladesh's rice production, destroy 12 percent of Egypt's agricultural land, displace 72 million Chinese, and partially sink major low-lying areas, like the Mekong Delta. Too apocalyptic? Well, if you're envisioning the ocean-covered earth shown in Kevin Costner's 1995 flop, Waterworld, don't worry, there's not enough H2O on earth, including what's on the polar ice caps, to cover even half of the planet's dry land.
Q) What causes you to see stars after a hard blow to the head?
Kendra Harpster, New York, New York
A) THOUGH THEY usually don't see anything as distinct as the constellation that orbits Wile E. Coyote's head after he's been nailed in the noggin by the obligatory falling anvil, many people see scores of revolving lights, technically called phos-phenes, in front of their eyes following a forceful blow to the brainpan. Problem is, scientists still aren't certain what causes the hallucinations. James Kelly, a neurologist at the Chicago Neurological Institute, says they've narrowed down the source, suspecting that phosphenes occur when there is "biomechanical irritation" (i.e., a hard whack) to the visual cortex—the area in the rear region of the brain called the occipital lobe that controls your sight. When it's jarred, scientists posit that temporary physiological and electrical changes there produce the ephemeral celestial visions—sort of the reverse effect of what happens when you slap the television to get better reception.
Q) Why do so many different animals have tails?
Geoff Witt, Hickory, North Carolina
A) "THE BETTER question," says Philip Johns, an assistant professor of biology at Swarthmore College, "is, Why do so many animals not have tails? They're incredibly useful." Defined as any extension of the backbone beyond the trunk, tails first appeared several hundred million years ago as propulsion devices on the chordate ancestors of hagfish, eel-like swimmers living up to 16,000 feet below sea level. Over time, as fish evolved into amphibians and took to dry land, tails became pretty useless for propulsion, but the appendages remain nearly ubiquitous today because of myriad uses that developed through natural selection. New World monkeys, for example, have prehensile tails that let them swing among branches. Squirrels use the appendage for balance. Dogs' tails help them communicate (we all know wagging means happiness). And some lizards are blessed with detachable models: When nabbed by their tail, they simply release it and slither off from predators unharmed.