Ever since Andrew Wiles solved Fermat's Last Theorem, the greatest intellectual puzzle facing humankind has been: How does The New York Times' "Most-emailed" list work? Science has finally given us the answer!

A team of sociologists at the University of Pennsylvania undertook an exhaustive study of the New York Times most-emailed list. They first assembled a data set based on the contents of the list over more than six months. Then they dug in to see why stories ended up there. Thus they unlocked the secret of journalism's holy grail—and perhaps even of virality itself.

Their findings, as reported by the Times' John Tierney, are a mix of the totally obvious and the Slate-y counter-intuitive. The obvious: A prominently-featured article is more likely to make the list, as is one written by a famous person. Slightly more surprising is the fact that longer articles were more e-mail-worthy.

But the most fascinating findings are also the most useful for anyone hoping to make it on the only list that matters, journalism-wise. (Apparently, it is not as easy as compiling a list of the top-ten things your babies play with that have lead in them.) Using complicated math, researchers identified four qualities of an article which resonate with the 'email-this' part of readers' brains. Most-emailed articles are:

  • Awe-inspiring: Being 'awe-inspiring' was the quality which most improved an item's odds of making the list. These articles blow readers' minds by dealing with something physically or intellectually enormous—a natural wonder, a work of art, a big idea, the indomitable human spirit, etc. People like to share awe-inspiring New York Times articles at lunch so they can forget their own puniness long enough to finish the workday. (Example articles: "Fury of Girl's Fists Lifts Up North Korean Refugee" and "The Promise and Power of RNA.")

  • Emotional: If you want to convince a reader to hit the 'email this article' button, try tugging on their heart-strings with a weepy tale of struggle or redemption. Soon, their offspring will be deleting yet another email from Mom with the subject "You HAVE to read this article. SO SAD!". (Example: "Redefining Depression as Mere Sadness.")

  • Positive:"If it bleeds it leads"—the old newspaperman's cliche—did not hold up under our researchers' critical gaze. People like to share happy things, apparently. (Example: "Wide-Eyed New Arrivals Falling in Love With the City")

  • Surprising: Unsurprisingly, people like to share articles that are surprising. Think, things that make you go "woah." (i.e. a story about chickens in Harlem, or a marathon-running restaurateur.)

  • Using these four variables, we have visually dissected the top five most e-mailed Times articles as of 11pm, Feb. 9th, 2010. Study them, for they hold the secret to Internet immortality:

1. America is not Yet Lost
2. Sinatra Song Often Strikes Deadly Chord
2. The New Math on Campus
4. Have Faith in Love
5. For Students at Risk, Early College Proves a Draw