Wild Gorillas Seen Using Tools

Biologists have for the first time observed gorillas using tools in the wild: two females that independently used branches to check the depth of a pool or cross a muddy patch of ground in Africa's Congo Republic.

"This is a truly astounding discovery," said Thomas Breuer of the Wildlife Conservation Society at the Bronx Zoo in New York, who led the team that made the observations. "Tool usage in wild apes provides us with valuable insights into the evolution of our own species and the abilities of other species."

Previously, scientists had documented tool use in the wild among chimpanzees and orangutans and gorillas in zoos, but never before in wild gorillas.

The researchers first observed a female gorilla named Leah in a marshy clearing in the Congo Republic's Nouabale-Ndoki National Park attempting to wade through a pool on Oct. 9, 2004. When she got about waist-deep, Leah climbed out of the water, yanked a branch off a nearby tree and used it to test the pool's depth as she ventured farther in, the researchers reported.

Then on Nov. 21, a female named Efi used the trunk of a dead shrub to support herself with one hand while digging for herbs with the other, and also as a makeshift bridge over a muddy patch of ground.

"Although there are reports of tool use by captive gorillas, including object throwing and use of tools in feeding, there has been to our knowledge no reported case of tool use by wild gorillas, despite decades of field research," the researchers wrote in a paper published online last week in the journal PLoS Biology.

"The observed tool use involved gorillas from two different groups and thus could indicate independent inventions, perhaps reflecting past negative experiences with deep water," the researchers wrote.

-- Rob Stein

A Quake on Mars?

Scientists using NASA's venerable Mars Global Surveyor satellite to monitor the Martian surface have found new evidence that the planet may still be geologically active enough to have had a "marsquake" in 2003 or 2004.

By examining Surveyor photographs of a Martian crater, researchers confirmed that a dozen boulders perched on the crater lip in November 2003 had bounced down to the bottom by December 2004.

"Something happened during that year to cause those boulders to fall," said Michael C. Malin, Surveyor's lead imaging scientist. "The primary view is that Mars is essentially inactive now . . . but this may be evidence of seismic activity."

In a recent telephone news conference to mark the eighth anniversary of the Global Surveyor's arrival at Mars on Sept. 11, 1997, Malin detailed the changes that the satellite had observed during its life. These included the appearance of new gullies on a Martian dune, perhaps caused by evaporating carbon dioxide below the surface, and shrinking carbon dioxide "dry ice" deposits at the poles, suggesting the planet may be undergoing some sort of "global warming."

Because of the satellite's long life, cameras on the Global Surveyor, whose original mission expired in 2001, are able to return to targets over a period of years, thus recording changes in surface features that one-time visitors cannot see.

The Global Surveyor is the oldest operating spacecraft at Mars, but it has company from NASA's two Mars rovers, which landed on the planet early in 2004, and the European Space Agency's Mars Express, orbiting since the end of 2003. The ESA has just extended the Express mission for two years.

-- Guy Gugliotta

Carbon Dioxide Threatens Coral

Increased carbon dioxide in the atmosphere will damage coral reefs, according to research published last month in the Journal of Geophysical Research: Oceans.

The two authors -- Chris Langdon, associate director of the National Center for Caribbean Coral Reef Research at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, and Marlin Atkinson at the Hawaii Institute of Marine Biology -- studied how doubling carbon dioxide affected two coral species critical to reefs in Kaneohe, Hawaii. They found that as the seawater became more acidic as a result of increased carbon dioxide levels, coral skeletal growth decreased by 50 percent.

"The ocean is known to absorb carbon dioxide, causing measurable changes in seawater chemistry of the surface ocean," Langdon said. "If this process continues at the current rate, we expect carbon dioxide levels, and consequently the acidity of the ocean, to increase 200 to 300 percent in the next 50 to a hundred years, so it is important to learn how these changes might affect marine ecosystems."

The two marine biologists did not test the impact of global warming on corals, which are vulnerable to warmer ocean temperatures.

"Because many species of coral are already growing very near their thermal threshold, any warming will reduce their growth," Langdon said. "The combined affects of global warming and ocean acidification on coral growth could be even worse than what we observed in our study."

-- Juliet Eilperin

A female gorilla known as Leah uses a stick to test the depth of a pool in Nouabale-Ndoki National Park.