The TIME 100

Paul Allen is the world's most obscure celebrity, its hippest geek, its most flamboyant introvert. He is also one of its most successful dropouts. The other is Bill Gates, Allen's Seattle high school chum, with whom he founded a company called Microsoft in 1975.

Having made his fortune as innovatively as he did, Allen has always been diligent about spending it just as imaginatively. He bought the Seattle Seahawks of the NFL and the Portland Trail Blazers of the NBA to keep them in his beloved Pacific Northwest, and he bankrolled SpaceShipOne, winner of the Ansari X Prize for the first private manned spaceflight.

Most promisingly, he established the Allen Institute for Brain Science, which has produced an atlas of gene activity in the mouse brain, mapping 20,000 genes so far. Nobody, arguably, needs to know that much about the brain of the mouse, but science always needs to know more about the human brain, and since the first often serves as such a fine template for the second, Allen's work can help advance the entire neuroscience field. Shy in personality but dashing in vision, Allen shows how a thoughtful billionaire can make the world not just a better place but also a far more interesting one.

Pinker is Harvard's Johnstone professor of psychology