The U.S. space agency said Friday it is seeking fresh ideas for robotic missions to explore Mars, after budget cuts nixed a planned partnership with the European space agency.

"NASA is reformulating the Mars Exploration Program to be responsive to high-priority science goals and the president's challenge of sending humans to Mars in the 2030s," the agency said.

Baboons can recognize scores of written words, a feat that raises intriguing questions about how we learn to read, scientists reported on Thursday.

In a specially-made facility in France where they could come and go at will, monkeys learned to differentiate between a real word, such as KITE, and a nonsense word such as ZEVS.

Scientists sketched a vision on Friday of converting the world's cities into giant sunlight reflectors to help fight global warming but met with skepticism from fellow academics.

Gradually replacing traditional urban roofs and roads with white or lighter-colored materials would yield a cooling benefit that, over 50 years, would be the equivalent of a reduction of between 25 and 150 billion tons of carbon dioxide (CO2), researchers in Canada said.

Sea levels in the southwest Pacific started rising drastically in the 1880s, with a notable peak in the 1990s thought to be linked to human-induced climate change, according to a new study.

The research, which examined sediment core samples taken from salt marshes in southern Australia's Tasmania Island, used geochemistry to establish a chronology of sea level changes over the past 200 years.

The coelacanth, a "living fossil" fish that predates the dinosaurs, is some 17 million years older than previously thought, scientists have found.

The earliest known skull of a coelacanth, unearthed in Yunnan, China dates the fish in its current shape to about 400 million years ago, according to research by the Chinese Academy of Sciences published on Tuesday in Nature Communications.

Scientists have sent robot scouts into deep space and unraveled the genome, yet on Wednesday were forced to admit they were still baffled by how homing pigeons navigate.

Experts at Vienna's Institute of Molecular Pathology said they had overturned claims that the birds' feat is due to iron-rich nerve cells in the beak that are sensitive to Earth's magnetic field.

Scientists are blaming slightly higher levels of carbon dioxide in Pacific Ocean waters linked to global warming for the failure of oyster larvae to survive in an Oregon hatchery.

They say higher acidity of the water that comes with more carbon dioxide makes it harder for young oysters to form their shells, dooming them in a matter of days, even if they are moved to more favorable environments.

India's environment minister said Wednesday that a European Union scheme to tax airlines for carbon emissions was "a deal breaker" that could wreck global climate change talks.

"I shall stick my neck out and say, for the environment ministry, yes the unilateral measure by the EU... is a deal breaker for the talks," Jayanthi Natarajan said in New Delhi.

U.S. and Russian researchers this week will begin flights over Bering Sea ice to answer a basic question about four of the region's most important species: How many ice-dependent seals are out there?

Scientists will count ringed and bearded seals, which the National Oceanic and Atmospheric Administration has recommended for listing as threatened species due to climate warming.

Learning to work in teams may explain why humans evolved a bigger brain, according to a new study published on Wednesday.

Compared to his hominid predecessors, Homo sapiens is a cerebral giant, a riddle that scientists have long tried to solve.