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FORTUNE.COM // SEPTEMBER 2019
IN HIS 41 YEARS ON EARTH SO FAR, Luis von Ahn has changed the world
three times. People still blame him for the first.
That invention, which had its public debut on Yahoo in 2000, had
a mouthful of a name; the Guatemalan-born computer scientist called
it a “completely automated public Turing test to tell computers and
humans apart,” or “Captcha” for short. Captchas, you’ll recall, are those
often- agonizing boxes of stretched and twisted letters that mortals must
correctly identify and retype to gain access to certain websites. That
invention, says von Ahn, has on multiple occasions provoked strangers to
tell him, “Oh, my God, I hate you.”
For all the fleeting angst they may have caused, though, Captchas have
long been effective in preventing antisocial types from using computers—
whose optical readers, until recently, had trouble reading such misshapen
type—to rapidly buy up tickets on Ticketmaster, sign up for millions of
email accounts, and do a host of other spammy and scammy things.
Captchas also unfortunately have consumed countless hours of exertion
(albeit in 10-second intervals) as users strain to decipher the characters.
So von Ahn, now a consulting professor at Carnegie Mellon and winner of
a MacArthur “genius” grant, wondered, What better thing could people do
with that same 10 seconds of effort? The answer was ReCaptcha—which
ingeniously tweaked the Captcha test so that web surfers actually deci-
phered the hard-to-read text of ancient manuscripts as they proved they
weren’t bots. With ReCaptcha, which Google bought in 2009, von Ahn
crowdsourced the decoding of lost literature—by 35 million words a day.
Which brings us to invention No. 3. In 2011, von Ahn and one of his
former graduate students at Carnegie Mellon, Severin Hacker, cre-
ated Duolingo, No. 36 on Fortune’s 2019 Change the World list (please
see page 70). Their language-learning app, whose free, ad-supported
programs (and a paid option) are actively used by 28 million people, has
once again mastered the art of converting human downtime into some-
thing valuable: the ability to speak a foreign tongue. In the process, they
are helping save a few from extinction too. Among the 36 languages that
Duolingo teaches, three—Hawaiian, Navajo, and Irish—were once in
danger of fading into history. In Ireland, for instance, fewer than 75,
people speak Irish, or Gaeilge, daily; today, 4.4 million budding linguists
are learning to labhair on Duolingo. When new acquaintances learn that
von Ahn built it, they tell him, “Oh, my God, I love you.”
Happily, von Ahn and his team can afford to keep being loved: Duo-
lingo’s projected revenues for this year are $86 million—more than
double 2018’s take of $36 mil-
lion—and he expects sales to
roughly double again next year.
The growth, in turn, has allowed
the serial inventor to invest in
finding even better ways to help
people learn languages—and to
fund his next project: teaching
people how to read.
Our fifth annual Change the
World package—my favorite
of Fortune’s many benchmark
lists—offers a rich supply of
companies that are finding
sustainable (and often profit-
able) ways to address societal
challenges. As always, we’re
not weighing companies on a
scale of “good” or “bad”—we
couldn’t if we tried. Nor are
we suggesting that the proj-
ects we’re highlighting absolve
companies of things they may be
doing that aren’t beneficial for
society. (Read Adam Lashinsky’s
probing interview with Anand
Giridharadas, on page 98, for a
more skeptical view.)
But we think doing well by do-
ing good is a smart way to change
the world. Let us know what you
think, at [email protected].
CLIFTON LEAF
Editor-in-Chief, Fortune
@CliftonLeaf
TR ANSL AT ING
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