Need more blood donors? Economists have a suggestion: Pay them.

For nearly 40 years, efforts to compensate people for donating blood have been discouraged by the World Health Organization. In the United States, the American Red Cross says “all blood collected for transfusion in the United States must be from volunteer donors.”

But the authors of an essaypublished in Friday’s edition of Science challenge the rationale for such policies, which presume that the highest-quality blood comes from altruistic donors. The types of people who would donate blood only if offered...

Federal wildlife officials on Friday for the first time agreed not to prosecute a developer if an endangered California condor is struck and killed by turbine blades at its proposed wind farm in the Tehachapi Mountains, about 100 miles north of Los Angeles.

In granting a right-of-way, the U.S. Bureau of Land Management, with approval of the U.S. Fish and Wildlife Service, will shield Alta Windpower Development from prosecution if a condor is fatally injured at its 2,300-acre site near the high-desert town of Mojave during the projected 30-year lifetime of the project.

The Fish and Wildlife...

At the beginning of this week, the wind's fury was unleashed on the Oklahoma city of Moore. As the extent of the devastation has unfolded over the past several days, it's a bit of an understatement to say that Moore has been unlucky.

The tornado was estimated to have followed a path nearly 20 miles long, remaining on the ground for about 50 minutes. Most tornadoes end within 10 minutes.

LIVE VIDEO DISCUSSION: Join us at 11 a.m. Pacific time

Meteorologists in the National Weather Service's forecast office in Norman upgraded Monday's storm to the highest severity a tornado can achieve on the...

NASA Administrator Charles Bolden dropped by JPL on Thursday to outline the agency's plans to capture an asteroid, and to look at a model of a powerful new ion thruster that has enough strength to drag a space rock into orbit around the moon.

NASA unveiled a multistep plan to rendezvous with a smallish asteroid, put it in what looks like a giant reflective garbage bag, and bring it into lunar orbit, earlier this year.

Once the space rock is in a stable orbit around the moon, astronauts could land on it and bring small chunks of it back to Earth.

"This is the first chance humanity has to...

The leading cause of death during Superstorm Sandy last fall was drowning, according to a new report released by the Centers for Disease Control and Prevention.

The report, which analyzed 117 storm-related deaths, comes amid a National Oceanic and Atmospheric Administration warning that this year's hurricane season stands a good chance of being more active than usual. In its annual Atlantic hurricane season outlook, NOAA forecasters said Thursday that there was a 70% likelihood of three to six major hurricanes occurring this year. The seasonal average for such major storms is three.

In its...

Scientists are gaining a better understanding of the H7N9 bird flu that has sickened more than 130 people -- and killed more than 30 -- in China and Taiwan since February.

The latest research into the virus, which before this year had never been detected in humans, was published Thursday (subscription required for full text) in the online edition of the journal Science. 

Working with ferrets, an animal that is often studied to gain insight into flu transmissibility in people, scientists in China, Canada and the U.S. found that H7N9 could spread from one ferret to another -- suggesting that it...

Three astronauts who recently returned to Earth after living aboard the International Space Station will answer questions from the public in a live Google Hangout on Thursday.

The online chat starts at noon PDT, and you can watch it live right here.

(The video stream above will switch to the hangout at noon.)

If you've been wondering what it feels like to sweat through a heated reentry to Earth in the Soyuz capsule, or how foreboding a normal flight of stairs looks after months spent in zero gravity, now is your chance to ask three men with first-hand experience.

T...

Scientists estimate that there are about 8.7 million species on Earth, give or take 1.3 million. (Some believe that the true figure is even higher.) Of these, perhaps 1.2 million to 2 million have been officially identified -- the rest are still out there, awaiting discovery.

To some taxonomists, the urgency to find these forms of life is greater than ever. The loss of biodiversity threatens to drive some species to extinction before their existence ever goes on record. Researchers have identified new species at a rate of about 18,000 a year, but that’s too slow to close the gap.

“...

It ain't exactly a match made in heaven, but it's a friendship forged in the steamy peat swamp forests of Borneo.

That's where the fanged pitcher plant, or Nepenthes bicalcarata, teams up with a plucky, fluid-diving ant that makes its home nowhere else in the world but on the stalks and leaves of the carnivorous plant. The ant, Camponotus schmitzi, even swims around in the plant's lethal pools of digestive fluid!

Ordinarily, N. bicalcaratais a deathtrap for ants and many other insects. The plant uses beguiling colors and sweet nectar to lure prey to the lips of its large, deadly pitchers....

A new anti-tobacco campaign is urging smokers to turn to their physicians for help in quitting.

The campaign – "Talk With Your Doctor" – also encourages clinicians to ask patients whether they smoke and to offer them assistance giving up cigarettes. The Centers for Disease Control and Prevention, in partnership with several national physicians' organizations, unveiled the initiative Wednesday.

Though 70% of smokers see doctors regularly, most try to quit smoking without professional help, said CDC Director Thomas Frieden, himself a physician.

A doctor’s advice and assistance...

An advisory panel to the Food & Drug Administration has recommended approval of a new sleep drug that targets the brain's wakefulness centers, but suggested the agency should consider a dose of the drug,  called suvorexant, lower  than that proposed by the medication's maker, Merck. In doing so, members of the FDA's advisory committee on peripheral and central nervous system drugs appeared to agree with concerns raised by FDA staff scientists that, at higher doses, the sleep medication may cause dangerous next-day drowsiness in some patients.

The panel voted 13-to-3 in favor of sending the FDA...