People aren't getting dumber, despite what a prolific writer of fake news told The Washington Post last fall, but something funny is going on with American media. There's been an apparent surge in fabricated stories, while the president has accused the New York Times and other traditional journalism outlets of producing "fake news." With facts seemingly up for grabs, scientists are starting to see evidence that both ends of the political spectrum have splintered off into alternative realities.

But it's not just a matter of social media isolating conservatives and liberals in echo chambers. Instead, researchers who study how people share news via Facebook and Twitter say concerted efforts to misinform the public are becoming a threat. New forms of social media help deceivers reach a far larger audience than they could find using traditional outlets. So behavioral and computer scientists are searching for solutions.

Part of the problem dates back to our evolution as social animals, they say. "We have an innate tendency to copy popular behaviors," said Filippo Menczer, a professor at the Center for Complex Networks and Systems Research at Indiana University, and one of several speakers at a recent two-day seminar on combating fake news.