Plans to build hydropower dams along small branches of Southeast Asia's longest river could have a devastating impact on millions of people who rely on the world's largest inland fishery, scientists said Monday.

Plenty of attention has focused on plans to develop 11 big dams along the main stem of the 4,600 kilometer (2,850 mile) Mekong River which passes through China, Myanmar, Laos, Thailand, Cambodia and Vietnam.

Paleontologists have traced the origins of humans and other vertebrates to a worm that swam in the oceans half a billion years ago, said a study published Monday.

A new analysis of fossils unearthed in the Canadian Rockies determined that the extinct Pikaia gracilens is the most primitive known member of the chordate family, which today includes fish, amphibians, birds, reptiles and mammals.

A year on from one of the biggest earthquakes in recorded history, Japanese scientists are warning anew that Tokyo could soon be hit by a quake that will kill thousands and cause untold damage.

Greater Tokyo, home to 35 million tightly packed people, has seen a three-fold increase in tectonic activity since the magnitude 9.0 undersea quake that unleashed a killer tsunami last March.

An ice dam at Argentina's Perito Moreno glacier collapsed early Sunday, creating an impressive spectacle not seen since July 2008, although few tourists were actually awake to experience the moment.

Several tons of ice fell off the 60-meter (200 foot) ice dam into Lago Argentina at the national park in southern Santa Cruz province.

Seven Asiatic black bears kept as pets in small cages will be prepared for a return to the wild in Vietnam after their owner decided they were too big for captivity, an official said Monday.

The animals, also known as moon bears owing to the distinctive yellow crescent-shaped mark on their chests, were given to the Wildlife Rescue Centre in Cat Tien National Park in southern Vietnam.

A pair of Swiss policemen cast a suspicious eye as a creature in a space helmet with a camera mounted on top and carrying an astronaut's backpack wanders around Basel's St. Johann Park.

But what appears to be a visiting extra-terrestrial turns out to be a maverick designer, Jan Torpus, who is pushing the boundary between the real world and fantasy in a project he calls "augmented reality."

The science journal Nature called on the Canadian government in an online editorial Friday to "set its scientists free" and allow them to speak about their research.

"It is time for the Canadian government to set its scientists free," Nature said in a rebuke of a "gradual tightening of media protocols for federal scientists" since Prime Minister Stephen Harper's Conservatives won power in 2006.

Radio waves that move like pasta spirals could help unclog the wireless world by boosting the power of radio communications, Italian and Swedish researchers said Friday.

The new way to make radio signals more potent without boosting bandwidth is described in the Institute of Physics and German Physical Society's New Journal of Physics edition of March 2.

The supreme court of Virginia on Friday ruled in favor of a prominent climate scientist, blocking a two-year attempt by state officials to get access to his university emails and grant materials.

The case was brought by state attorney general Ken Cuccinelli, a skeptic of global warming, against the University of Virginia where well known climate scientist Michael Mann taught from 1999 to 2005.

A stolen U.S. space agency laptop containing codes that control the International Space Station did not put the orbiting lab in peril, a NASA spokesman said on Friday.

The unencrypted notebook computer went missing in March 2011 and "resulted in the loss of the algorithms used to command and control the International Space Station," NASA Inspector General Paul Martin told lawmakers this week.