Q) Are any animals immune to rattlesnake bites?
Alan Scott, Rural Valley, Pennsylvania
A) There are some 40 known rattler-proof North American mammals, including species of pack rats, ground squirrels, pocket mice, and other snakebite-size critters. They've developed proteins that neutralize metalloproteases, the components in rattler venom that destroy blood vessels and cause massive internal hemorrhaging. Some species are immune to only one type of rattler, while in other cases only certain geographic populations of a species are protected. And not all immune animals are runts—the Virginia opossum is shielded from 37 species of pit vipers, including all major North American rattlers. Of course, evolution never stops, so the defense can fade if enough generations of a species reproduce in an area with few rattlers. According to Jim Biardi, a postdoctoral fellow in chemistry at UC Davis, that's precisely what's happened to certain populations of California ground squirrels. Alas, some of the squirrels don't realize they've lost their protection, and display a genetic aggression toward snakes—attacking them, in some cases—despite their lost immunity. Says Biardi, "Those squirrels don't last too long."
| POP QUIZ |
| A footloose reader wants to know: What's the "FORBIDDEN DANCE"? The phrase, popularized during the late-eighties lambada craze, which spawned the should-have-been-banned film The Forbidden Dance, can actually apply to a number of dances that have been outlawed. The hula was barred in Hawaii for much of the 19th century by Christian missionaries because of its "pagan" religious associations; the tango went underground in Argentina in the mid–20th century when military dictators censored song lyrics and restricted public gatherings; even decidedly nonsensual Scottish and Irish dances have periodically been groovus non grata in the British Isles. This year, the Indian supreme court outlawed the aptly named Anger Dance, a ritual involving snakes, bones, and knives. In the U.S., some Protestant fundamentalist sects still ban any shaking of your money maker. And you can't always escape by ditching the dance floor: The Texas legislature recently attempted to restrict certain "sexually suggestive" cheerleading moves that would make Patrick Swayze blush. |
Q) How many acres of land are there on earth? How many is that per person?
Mark Shapiro, Portland, Oregon
A) you're looking for elbow room, how's 5.6 acres? That's what you get when the planet's 36.5 billion land acres are divided by 6.5 billion, the current population. Remove from the equation areas that the UN deems inhospitable, like Antarctica, the Sahara, and Terre Haute, Indiana, and your allotment drops to 4.7 acres. Now subtract one and a quarter acres for the crops that feed you (more if you enjoy an occasional burger). Feeling claustrophobic? You can still find breathing room if you know where to look. In the U.S., 83 percent of us are squeezed into metro areas, and 54 percent live on the coasts. So if you relocate now to Gackle, North Dakota, come 2050, when the planet's population will reach roughly 9.2 billion—leaving humans a measly 2.6 acres apiece—you'll still have that ice-fishing shack all to yourself.
Q) Is there a maximum speed a human can run?
Crystal Krueger, Madison, Wisconsin
A) Two physiological factors will likely prevent anyone from doing much better than 27 miles per hour, the record clip Canadian Donovan Bailey hit in the 100-meter finals at the 1996 Olympics. The first is our muscles' twitch time—how long it takes them to start contracting after being signaled by our nervous system. According to Peter Weyand, director of the Locomotion Lab at Rice University, in Houston, human twitch times are in the middle of the mammalian pack, limiting runners to about 2.2 to 2.5 contractions per second. Our other major shortcoming is our "swing time"—how long our foot is airborne during a running stride. For Homo sapiens, no matter if you're Marion Jones or Star Jones, swing times fall between 0.31 and 0.40 seconds. In addition, unlike many faster-running animals, we lack any remarkable anatomical tools, like the cheetah's elastic spine. That means even the world's fastest sprinters will probably never break 28 mph—as long as they remain human.
