For a long time, scientists thought that our fingers wrinkled underwater because of osmosis — meaning the skin's cells absorbed water, causing our fingertips to shrivel up. But new research suggests another explanation: The wrinkles help us to better grip objects underwater, in much the same way tire treads help cars stay on the road.
Scientists discovered that severed fingers didn't wrinkle underwater. This suggested the wrinkling mechanism was controlled by the nervous system, and was therefore some kind of evolutionary response.
A study in 2011 showed that the wrinkles indeed functioned like rain treads, in that the grooves helped divert water away from the fingertips. For this study, researcher Tom Smulder and his team at Newcastle University in the U.K. asked subjects to move wet and dry objects from one box to another with and without shriveled fingers. Unsurprisingly, people with wrinkled hands transferred objects 12 percent faster than those with smooth digits.
The number of U.S. teenagers who drink and drive dropped by more than half from 1991 to 2011, federal health officials said Tuesday.
Nine out of 10 high school students age 16 and over said they did not drink and drive in 2011, according to the U.S. Centers for Disease Control and Prevention (CDC). This represents a decline of 54 percent over two decades.
Still, one in 10 -- or nearly one million students a month -- reported driving after consuming alcohol.
"Drinking and driving is risky for any driver, but especially for young teens," CDC director Dr. Thomas Frieden said. "Young drivers are 17 times more likely to die in a crash when they have a blood alcohol concentration of 0.08 than when they have not been drinking."
Car crashes remain the leading cause of death for teens, Frieden said. "There are more than 2,000 teens aged 16 to 19 killed on the road each year, and many of those deaths are alcohol-related," he said. One in five teen drivers involved in a fatal crash in 2010 had alcohol in their system, he added.
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For generations, teenagers have been the most dangerous drivers on the road, crashing almost four times more often than older drivers. A study quantifies for the first time in a decade how their risk of a fatal crash multiplies when they have other teenagers in the car.
It increases by almost half when a 16- or 17-year-old driver has one teenage passenger; it doubles with two teen passengers; and it quadruples with three or more young passengers.
Using federal fatality statistics, the American Automobile Association Foundation for Traffic Safety provided that data that will support parents who have forbidden their teenage children from driving with other teenagers.
"We know that carrying young passengers is a huge risk, but it's also a preventable one," said AAA foundation President Peter Kissinger.
The AAA study is the latest of three recent reports to raise concerns about teenage drivers. The Governors Highway Safety Association reviewed preliminary data from the first six months of last year, finding a slight increase in the number of fatal crashes involving 16- and 17-year-old drivers. The governors' group said if the trend continued, 2011 would reverse a recent trend of declining teenage fatalities.
In another study, National Highway Traffic Safety Administration last month said its research found that drivers under the age of 24 were much more likely than more mature drivers to send and receive text messages while driving.
Read more from the Washington Post.