Nearly 1 in 20 Americans older than 50 have artificial knees, or more than 4 million people, according to the first national estimate showing how common these replacement joints have become in an aging population.

The ruins aren't particularly impressive, just some stone and clay footings for houses that probably supported walls of wood or clay wattle. And it's that very ordinariness that has experts excited.

For two centuries it rested a mile from shore, shrouded by a treacherous reef from the pleasure boaters and beachgoers who haunt New England's southern coast.

If scientists find microbes in a frigid lake two miles beneath the thick ice of Antarctica, it will illustrate once again that somehow life finds a way to survive in the strangest and harshest places.

Federal weather forecasters say the La Nina weather phenomenon that contributed to the southwestern U.S. drought is winding down.

An effort to free whales from SeaWorld by claiming they were enslaved made a splash in the news but flopped in court Wednesday.

Prime Minister Vladimir Putin on Friday praised the Russian scientists who have reached a gigantic freshwater lake in Antarctica hidden under more than two miles (3.2 kilometers) of ice, a pristine body of water that may hold life from the distant past.

An ocean experiment that was accidentally conducted amid the shipping silence after Sept. 11 has shown the first link between underwater noise and stress in whales, researchers reported Wednesday.

A federal grand jury has indicted a Romanian citizen on charges he hacked into 25 climate-research computers at NASA's Jet Propulsion Laboratory in Pasadena.

President Barack Obama called on Tuesday for millions of dollars in new funding to improve math and science education, an effort he said would be crucial to the nation's long-term success.

When 22 bird flu experts meet at the World Health Organization (WHO) this week, they will be tasked with deciding just how far scientists should go in creating lethal mutant viruses in the name of research.

President Barack Obama's proposed 2013 budget for NASA boosts spending at the Kennedy Space Center, which bore the brunt of job layoffs at the end of the space shuttle program last year, the center director said on Tuesday.

Europe's first Vega rocket blasted off from French Guiana Monday in a successful inaugural flight aimed at giving Europe a vehicle for scientific satellite missions.

The race is on to discover life in the most remote and extreme environment known on Earth.

NASA intends to cancel plans to join Europe on a Mars sampling mission that is considered important to learning if life appeared beyond Earth as the U.S. space agency balances out a virtually flat $17.7 billion budget for 2013, officials said on Monday.