Science notes: Bacteria found under the ice of Antarctica

For the first time, scientists report, they have found bacteria living in the cold and dark deep under the Antarctic ice, a discovery that might advance knowledge of how life could survive on other planets or moons and that offers the first glimpse of a vast ecosystem of microscopic life in underground lakes in Antarctica.

"It transforms the way we view the Antarctic continent," said expedition leader John Priscu of Montana State University.

After drilling through a half-mile of ice into the 23-square-mile, 5-foot-deep Lake Whillans, (see the borehole, below) the expedition scientists recovered water and sediment samples that showed clear signs of life, Priscu said. They saw cells under a microscope, and chemical tests showed that the cells were alive and metabolizing energy. Much more study, including DNA analysis, is needed to determine what kind of bacteria have been found and how they live, he said.

There is no sunlight, so the bacteria must depend on organic material that has drifted into the lake from other sources -- for instance, decaying microbes from melting glaciers -- or on minerals in the rock of the Antarctic continent.

"Our stateside DNA sequence work will tell us who they are," Priscu said, "and, together with other experiments, tell us how they make a living."

But he said he was confident that the researchers had achieved the first glimpse of an ecosystem that had been completely unknown. He said, "It's the world's largest wetland."

Scientists at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said last week that an "Earth-like" planet -- that is, a small, rocky planet warm enough to have liquid water on its surface and potentially capable of hosting life -- could be as close as 13 light-years away.

Concentrating on stars in a sample of small red dwarfs -- about a quarter the mass of our sun and about 0.2 percent as bright -- Dressing calculated that 60 percent had planets smaller than Neptune orbiting them and that 6 percent had planets that could be considered Earth-like because of their size and their distance from their host star. Since red dwarfs are about 10 times more common than sun-like stars, the discovery suggests that there should be many, many Earth-like planets lurking within telescopes' reach.

A close encounter of the rocky kind is set for Friday when an office building-size asteroid will speed past Earth. It will be the nearest recorded brush with a space rock so large, NASA scientists said. Even at its closest, asteroid 2012 DA14 will be 17,000 miles away. But a million other potentially dangerous space rocks are out there, and one of them could be on a collision course with Earth. Critics say NASA is not doing enough to scan for these threats. "It's like Mother Nature sending a warning shot across our bow," said Don Yeomans of the Jet Propulsion Laboratory in Pasadena, Calif.

Ladies and gentlemen, good citizens everywhere, please listen to reason: The shark has been framed.

A new study said there's no basis for believing that sharks have a taste for human flesh. Human swimmers, often dressed in black wet suits and looking like seals, are mistaken for sharks' usual prey. The study offers a solution: Stop using "attack" as a term for every encounter. Stop describing animals that rarely kill humans as "man-eaters."

"Shark sightings" should be called just that, the study argues. A brush, bump, surfboard bite or close call is a "shark encounter." A bite that results in injury should be identified as a "shark bite," and a bite that leads to death should be called a "fatal shark bite."

A Ohio State University study shows that playing violent video games can make people more aggressive, but the co-author said it is impossible to link such games to violent criminal behavior. Brad Bushman, a professor of communication and psychology, said people who played a violent video game for three consecutive days showed increases in aggressive behavior and hostile expectations each day they played. He said it provides the first experimental evidence that the effects of playing violent video games can accumulate.