There’s been a lot of talk about fake news running rampant online, but now there’s data to back up the discussion.

An analysis of more than 4.5 million tweets and retweets posted from 2006 to 2017 indicates that inaccurate news stories spread faster and further on the social media platform than true stories. The research also suggests that people play a bigger role in sharing falsehoods than bots.

These findings, reported in the March 9 Science, could guide strategies for curbing misinformation on social media. Until now, most investigations into the spread of fake news have been anecdotal, says Filippo Menczer, an informatics and computer scientist at Indiana University Bloomington not involved in the work. “We didn’t have a really large-scale, systematic study evaluating the spread of misinformation,” he says.
To study rumormongering trends on Twitter, researchers examined about 126,000 tweet cascades — families of tweets composed of one original tweet and all the retweets born of that original post. All of those cascades centered on one of about 2,400 news stories that had been verified or debunked by at least one fact-checking organization.
Deb Roy, a media scientist at MIT, and colleagues investigated how far and fast each cascade spread. Discussions of false stories tended to start from fewer original tweets, but some of those retweet chains then reached tens of thousands of users, while true news stories never spread to more than about 1,600 people. True news stories also took about six times as long as false ones to reach 1,500 people. Overall, fake news was about 70 percent more likely to be retweeted than real news.
Roy and colleagues initially removed the activity of automated Twitter accounts called bots from the analysis. But when bot traffic was added back into the mix, the researchers found that these computer programs spread false and true news about equally. This finding indicates that humans, rather than bots, are primarily to blame for spreading fake news on the platform.

People may be more inclined to spread tall tales because these stories are perceived to be more novel, says study coauthor Soroush Vosoughi, a data scientist at MIT. Compared to the topics of true news stories, fake news topics tended to deviate more from the tweet themes users were exposed to in the two months before a user retweeted a news story. Tweet replies to false news stories also contained more words indicating surprise.

It’s not entirely clear what kinds of conversations these stories sparked among users, as the researchers didn’t inspect the full content of all the posts in the dataset. Some people who retweeted fake news posts may have added comments to debunk those stories. But Menczer says the analysis still provides a “very good first step” in understanding what kinds of posts grab the most attention.

The study could help guide strategies for fighting the spread of fake news, says Paul Resnick, a computational social scientist at the University of Michigan in Ann Arbor who was not involved in the work. For instance, the finding that humans are more liable to retweet falsehoods than bots may mean that social media platforms should focus on discouraging humans from spreading rumors, rather than simply booting off misbehaved bots.

To help users identify true stories online, social media sites could label news pieces or media outlets with veracity scores — similar to how grocery stores and food producers offer nutrition facts, says study coauthor Sinan Aral, an expert on information diffusion in social networks at MIT. Platforms also could restrict accounts reputed to spread lies. It’s still unclear how successful such interventions might be, Aral says. “We’re barely starting to scratch the surface on the scientific evidence about false news, its consequences and its potential solutions.”

Adult mice and other rodents sprout new nerve cells in memory-related parts of their brains. People, not so much. That’s the surprising conclusion of a series of experiments on human brains of various ages first described at a meeting in November (SN: 12/9/17, p. 10). A more complete description of the finding, published online March 7 in Nature, gives heft to the controversial result, as well as ammo to researchers looking for reasons to be skeptical of the findings.

In contrast to earlier prominent studies, Shawn Sorrells of the University of California, San Francisco and his colleagues failed to find newborn nerve cells in the memory-related hippocampi of adult brains. The team looked for these cells in nonliving brain samples in two ways: molecular markers that tag dividing cells and young nerve cells, and telltale shapes of newborn cells. Using these metrics, the researchers saw signs of newborn nerve cells in fetal brains and brains from the first year of life, but they became rarer in older children. And the brains of adults had none.

There is no surefire way to spot new nerve cells, particularly in live brains; each way comes with caveats. “These findings are certain to stir up controversy,” neuroscientist Jason Snyder of the University of British Columbia writes in an accompanying commentary in the same issue of Nature.

“The strangest place in the whole universe might just be right here.” So says actor Will Smith, narrating the opening moments of a new documentary series about the wonderful unlikeliness of our own planet, Earth.

One Strange Rock, premiering March 26 on the National Geographic Channel, is itself a peculiar and unlikely creation. Executive produced by Academy Award–nominated Darren Aronofsky and by Jane Root of the production company Nutopia and narrated by Smith, the sprawling, ambitious 10-episode series is chock-full of stunningly beautiful images and CGI visuals of our dynamic planet. Each episode is united by a theme relating to Earth’s history, such as the genesis of life, the magnetic and atmospheric shields that protect the planet from solar radiation and the ways in which Earth’s denizens have shaped its surface.
The first episode, “Gasp,” ponders Earth’s atmosphere and where its oxygen comes from. In one memorable sequence, the episode takes viewers on a whirlwind journey from Ethiopia’s dusty deserts to the Amazon rainforest to phytoplankton blooms in the ocean. Dust storms from Ethiopia, Smith tells us, fertilize the rainforest. And that rainforest, in turn, feeds phytoplankton. A mighty atmospheric river, fueled by water vapor from the Amazon and heat from the sun, flows across South America until it reaches the Andes and condenses into rain. That rain erodes rock and washes nutrients into the ocean, feeding blooms of phytoplankton called diatoms. One out of every two breaths that we take comes from the photosynthesis of those diatoms, Smith adds.
As always, Smith is an appealing everyman. But the true stars of the series may be the eight astronauts, including Chris Hadfield and Nicole Stott, who appear throughout the series. In stark contrast to the colorful images of the planet, the astronauts are filmed alone, their faces half in shadow against a black background as they tell stories that loosely connect to the themes. The visual contrast emphasizes the astronauts’ roles as outsiders who have a rare perspective on the blue marble.
“Having flown in space, I feel this connection to the planet,” Stott told Science News . “I was reintroduced to the planet.” Hadfield had a similar sentiment: “It’s just one tiny place, but it’s the tiny place that is ours,” he added.
Each astronaut anchors a different episode. In “Gasp,” Hadfield describes a frightening moment during a spacewalk outside the International Space Station when his eyes watered. Without gravity, the water couldn’t form into teardrops, so it effectively blinded him. To remove the water, he was forced to allow some precious air to escape his suit. It’s a tense moment that underscores the pricelessness of the thin blue line, visible from space, that marks Earth’s atmosphere. “It contains everything that’s important to us,” Hadfield says in the episode. “It contains life.”

Stott, meanwhile, figures prominently in an episode called “Storm.” Instead of a weather system, the title refers to the rain of space debris that Earth has endured throughout much of its history — including the powerful collision that formed the moon (SN: 4/15/17, p. 18). Stott describes her own sense of wonder as a child, watching astronauts land on our closest neighbor — and how the travels of those astronauts and the rocks they brought back revealed that Earth and the moon probably originated from the same place.

It’s glimpses like these into the astronauts’ lives and personalities — scenes of Hadfield strumming “Space Oddity” on a guitar, for example, or Stott chatting with her son in the family kitchen — that make the episodes more than a series of beautiful and educational IMAX films. Having been away from the planet for a short time, the astronauts see Earth as precious, and they convey their affection for it well. Stott said she hopes that this will be the ultimate takeaway for viewers, for whom the series may serve as a reintroduction to the planet they thought they knew so well. “I hope that people will … appreciate and acknowledge the significance of [this reintroduction],” she said, “that it will result in an awareness and obligation to take care of each other.”
Editor’s note: This story was updated on March 19, 2018, to add a mention of a second executive producer.