Upworthy has run paid content, like a Microsoft-sponsored video of a Ugandan man talking to his family over Skype. But this is the first time that an organization like the Gates Foundation has paid to popularize a particular concept like global health and poverty. In a way, the partnership harkens back to Upworthy's founding idea to be a bullhorn for non-profits, amplifying their research and message, and then taking a cut. This pilot partnership will provide one full-time "curator" to trawl the Web for stories about toilets (Everyone Poops, But 2.6 Billion People Do It In A Really Crappy Way) and global disease (When Future Generations Look Back On Us, They'll Say We Had The Opportunity To End 3 Awful Epidemics).

"We've always wanted to draw attention to the most important issues," co-founder and CEO Eli Pariser told me. "The health and poverty of the lower third of the world's population is one of the least covered issues of our time. There are people who put incredible effort and creativity into making a YouTube video on malaria, and it just gets 5,000 views. We're hoping to go out and find those things and bring them to a much wider audience."

... And Made Me a Little Sick

Upworthy's vertiginous success isn't without criticism. The site's pleading, occasionally histrionic, gooeyness has inspired criticisms of so-called "glurge" and a popular parody account, @UpWorthIt. Here, for example, is a list of Upworthy's 11 greatest hits, whose pageviews are downright otherworldly.

There is an amygdala-tickling genius here, but also a kind of movie-trailer mawkishness. What's the "secret"? An entertaining slideshow of Upworthy's headline-writing strategies last year repeatedly references the "curiosity gap." The idea is both to share just enough that readers know what they're clicking and to withhold just enough to compel the click.

Upworthy rankles some journalists partly because, even as it innocently coos Web readers with tender headlines, the repetitiveness of its style suggests a rather cynical ploy to lasso cheap attention rather than fully engage an audience hunting anything more than a dopamine rush.

But Pariser has heard these critiques and has a ready rebuttal: What special virtue is there in letting great videos, articles, and images fall into the Internet's abyss simply because nobody thought of the right combination of words to unlock its audience? What's more, when readers find themselves hating a headline picked by a testing audience and shared by 10 million people, whose tastes are we really objecting to—Upworthy's or ours?

Pariser, who honed his data-driven chops at MoveOn.org, said the media's obsession with Upworthy headlines misses half the story. "Some of the stories about us have focused too much on the headlines, but to have content that's really shareable, it has to be something people actually want to share," he said. "We look at how much people click, but also how much people share [after they click]. The only way to get something that does really well is to deliver on the quality that you're promising in the headline."