Nell Greenfieldboyce

Nell Greenfieldboyce is a NPR science correspondent.






NASA says the biggest moon in our solar system has a salty ocean below its surface.

Researchers had suspected since the 1970s that a moon of Jupiter called Ganymede had an ocean. Now they've confirmed it, scientists announced in a teleconference held by the space agency.

Scientists studying the difference between human and chimpanzee DNA have found one stretch of human DNA that can make the brains of mice grow significantly bigger.

"It's likely to be one of many DNA regions that's critical for controlling how the human brain develops," says Debra Silver, a neurobiologist at Duke University Medical School.

It could also help explain why human brains are so much bigger than chimp brains, says Silver, who notes that "there are estimates of anywhere from two to four times as big."

Before anyone tries to cool the Earth with technologies that could counteract global warming, there needs to be a lot more research into the benefits and risks. That's the conclusion announced Tuesday by a scientific panel convened by the prestigious National Research Council to assess "climate geoengineering" — deliberate attempts to alter the global climate.

Geoengineering has been seen as the potential last-ditch option to stave off the worst effects of climate change, given that agreements to reduce greenhouse gas emissions have been slow in coming.

On a mountaintop in Chile, excavators have just started work on a construction site. It will soon be home to a powerful new telescope that will have a good shot at finding the mysterious Planet X, if it exists.

"Planet X is kind of a catchall name given to any speculation about an unseen companion orbiting the sun," says Kevin Luhman, an astronomer at Penn State University.

When Amy Seitz got pregnant with her second child last year, she knew that being 35 years old meant there was an increased chance of chromosomal disorders like Down syndrome. She wanted to be screened, and she knew just what kind of screening she wanted — a test that's so new, some women and doctors don't quite realize what they've signed up for.

The special tool-wielding power of human hands may go back farther in evolutionary history than scientists have thought.

That's according to a new study of hand bones from an early relative of humans called Australopithecus africanus. Researchers used a powerful X-ray technique to scan the interior of the bones, and they detected a telltale structure that's associated with a forceful precision grip.

The bar-headed goose is famous for its long, annual migration from the Indian subcontinent to central Asia, a flight that takes it over snowcapped Himalaya Mountains so high and dangerous that human climbers struggle just to stay alive.

Most radio reporters, I think it's fair to say, think about their voices a lot, and work to sound powerful and authoritative. I know my voice has changed since my very first radio story 10 years ago:

Compare that with how I sound these days:

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When Jim McGuire and some colleagues recently cut open a frog that they'd collected and euthanized on an Indonesian island, they got quite a shock.

"Out came the tadpoles, and they were alive!" recalls McGuire, a herpetologist at the University of California, Berkeley.

The researchers had just found the first frog known to give birth to live tadpoles.

Compared with other primates and our early human ancestors, we modern humans have skeletons that are relatively lightweight — and scientists say that basically may be because we got lazy.

Some researchers who study the virus that causes Middle East respiratory syndrome got an early Christmas present: permission to resume experiments that the federal government abruptly halted in October.

Remember that worrisome new form of botulinum toxin we told you about in late 2013, the one that supposedly had to be kept secret out of fear it could be used as a bioweapon that would evade all of our medical defenses?

Well, as it turns out, it's not that scary after all. The antitoxin stored in the government's emergency stockpile works and would neutralize the toxin just fine.


Would that be OK?

Scientists have discovered enigmatic markings on an ancient shell that's been sitting in a museum for more than a century — and they believe this may be the oldest known example of a deliberate geometric engraving made by a human hand.

Learning to name the colors is a ritual of childhood. At first kids have no clue; often they'll just say everything is "boo." Pretty soon, though, they can rattle off Roy G. Biv with aplomb. Still, that doesn't mean they understand what color actually is.


As cases of a worrisome respiratory virus continue to pop up in the Middle East, scientists who study it in the U.S. are struggling to understand how they'll be affected by a government moratorium on certain kinds of experiments.

Vincent Racaniello, who studies viruses at Columbia University, says Ebola has recently become his obsession.

"I find myself reading incessantly about Ebola when I should be doing other things," says Racaniello, host of the online show This Week in Virology, which has devoted several recent programs to Ebola.

An unusual government moratorium aimed at controversial research with high-risk viruses has halted important public health research, scientists told an advisory committee to the federal government on Wednesday.

Here's a question about the fine line between a prudent response and worrisome overkill: Is the sight of a U.S. Coast Guard helicopter hovering over a cruise ship to pick up a blood sample (which is to be tested for Ebola) a sight that should inspire feelings of reassurance, or a nagging sense that something is not quite right?

The question is still in the air after the weekend's effort to airlift a few milliliters of blood from a passenger who was on board what is now being called the Ebola Cruise.

How many times do top officials have to say that the Ebola virus is not airborne?

A lot, apparently.

Here is President Obama Thursday: "This is not an airborne disease. It is not easy to catch."

And the day before: "It is not like the flu. It is not airborne."

And Friday, a reporter asked the inevitable question about airborne Ebola when Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, held a press briefing about nurse Nina Pham's transfer to the National Institute of Health.

The federal government will temporarily stop funding any new studies that could make three high-risk infectious diseases even more dangerous. The government is asking all scientists involved in this research now to voluntarily halt their current studies.

The unusual move comes after a long controversy over experiments with mutant forms of a bird flu virus.

Prehistoric cave paintings of animals and human hands in Indonesia are as ancient as similar paintings found in Western Europe, according to a new study that suggests humans may have carried this art tradition with them when they migrated out of Africa.

Hospitals have been on the lookout for the Ebola virus in the United States, and Texas Health Presbyterian in Dallas was no exception. A nurse there did ask about the travel history of the patient who later turned out to be infected with the virus. But some members of the medical team didn't hear that the man had recently been in West Africa. So he was initially sent home — even though he was experiencing symptoms of Ebola, and that meant he was contagious.


The new policy will take effect next year, and it's the latest effort by the U. S. government to come to grips with so called "dual-use" biological research—legitimate medical or public health studies that could reveal how to make already-worrisome germs or toxins even more destructive.

Back in August, scientists reported that the Ebola virus is mutating during this epidemic.

When a virus spreads between people and reproduces, it copies its genetic code in a sloppy way. So there can be unpredictable changes.

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One of the reasons Ebola is so terrifying is that there's no vaccine and no cure. But the World Health Organization hopes to change that, with plans to quickly test experimental products during this outbreak.

By November, two promising vaccines will have been tested on people to see if they're safe, says Marie-Paule Kieny, assistant director-general at WHO.

The latest numbers on the Ebola outbreak are grim: 2,473 people infected and 1,350 deaths.

That's the World Health Organization's official tally of confirmed, probable and suspect cases across Guinea, Liberia, Sierra Leone and Nigeria. But the WHO has previously warned that its official figures may "vastly underestimate the magnitude of the outbreak."

So how bad is it really?

While the Ebola outbreak continues to rage in West Africa, it is also unfolding — in a virtual sense — inside the computers of researchers who study the dynamics of epidemics.

Policymakers look to these simulations to get a sense of how the outbreak might spread. They also can use them to run experiments to see which public health measures should take priority.