Nell Greenfieldboyce

Nell Greenfieldboyce is a NPR science correspondent.

With reporting focused on general science, NASA, and the intersection between technology and society, Greenfieldboyce has been on the science desk's technology beat since she joined NPR in 2005.

In that time Greenfieldboyce has reported on topics including the narwhals in Greenland, the ending of the space shuttle program, and the reasons why independent truckers don't want electronic tracking in their cabs.

Much of Greenfieldboyce's reporting reflects an interest in discovering how applied science and technology connects with people and culture. She has worked on stories spanning issues such as pet cloning, gene therapy, ballistics, and federal regulation of new technology.

Prior to NPR, Greenfieldboyce spent a decade working in print, mostly magazines including U.S. News & World Report and New Scientist.

A graduate of Johns Hopkins, earning her Bachelor's of Arts degree in social sciences and a Master's of Arts degree in science writing, Greenfieldboyce taught science writing for four years at the university. She was honored for her talents with the Evert Clark/Seth Payne Award for Young Science Journalists.

With recent news headlines proclaiming that dozens of people have been selected as finalists for a Martian astronaut corps, it might seem like a trip to this alien world might finally be close at hand.

But let's have a little reality check. What are the chances that we really will see people on the Red Planet in the next couple of decades?

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 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.

Imagine that scientists wanted to take Ebola virus and see if it could ever become airborne by deliberately causing mutations in the lab and then searching through those new viruses to see if any spread easily through the air.

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.

Mark Fairchild, who studies color and vision science at the Rochester Institute of Technology, says that even physicists get it wrong when they confidently assert that color is just a wavelength of light.

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.

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.

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.

A smoldering debate about whether researchers should ever deliberately create superflu strains and other risky germs in the interest of science has flared once again.

No one likes it when a new drug in people's medicine cabinets turns out to have problems — just remember the Vioxx debacle a decade ago, when the painkiller was removed from the market over concerns that it increased the risk of heart attack and stroke.

To do a better job of spotting unforeseen risks and side effects, the Food and Drug Administration is trying something new — and there's a decent chance that it involves your medical records.

The electric eel's powerful ability to deliver deadly shocks — up to 600 volts — makes it the most famous electric fish, but hundreds of other species produce weaker electric fields. Now, a new genetic study of electric fish has revealed the surprising way they got electrified.

Scientists have long puzzled over the origin and evolution of our closest relative, the Neanderthal. Now, researchers say Neanderthals seem to have developed their distinctive jaws and other facial features first, before they evolved to have big brains.

That's according to an analysis of 17 skulls, all taken from one excavation site in a mountain cave in Atapuerca, Spain, known as the Sima de los Huesos — the "pit of bones."

Octopus arms keep from getting all tangled up in part because some kind of chemical in octopus skin prevents the tentacles' suckers from grabbing on.

That was the surprise discovery of scientists who were trying to understand how octopuses manage to move all their weird appendages without getting tied in knots.

Unlike humans, octopuses don't have a constant awareness of their arms' locations. It's kind of like the eight arms have minds of their own. And as an octopus arm travels through the water, its neighboring arms are constantly in reach.

For the first time, scientists have expanded life's genetic alphabet, by inserting two unnatural, man-made "letters" into a bacterium's DNA, and by showing that the cell's machinery can copy them.

The advance means that scientists have a new tool for exploring how life encodes information, which could help them understand life's origins.

What's more, this is a step towards giving living cells new abilities, like being able to make more and better medicines, cheaper and faster.

Questions are swirling around a science journal's decision last year to publish a description of a newly discovered botulinum toxin while omitting key genetic details that researchers would normally disclose.

The unusual case highlights important unresolved issues in how to balance scientific openness with the worry that biological information could potentially be misused.

Scientists who have been hunting for another Earth beyond our solar system have come across a planet that's remarkably similar to our world.

It's almost the same size as Earth, and it orbits in its star's "Goldilocks zone" — where temperatures are not too hot, not too cold, and maybe just right for life.

But a lot about this planet is going to remain a mystery, because it's 500 light-years away.