For the third consecutive year, The Kennedy Center is going relatively young with its pick for the annual Mark Twain Prize for American Humor, selecting Ellen DeGeneres for the honor in 2012.

That’s no knock against DeGeneres. At 54, Ellen dances smoothly past all of her daytime talk-show competitors.

Her body of work — which began in the early 1980s with stand-up comedy in New Orleans, and saw her become the first female comedian summoned by Johnny Carson to the couch after her Tonight Show performance — has included 35 Daytime Emmy Awards, 12 People’s Choice Awards, three straight Teen Choice Awards for “Choice Comedian,” hosting duties at the Academy Awards, Emmy Awards and Grammy Awards, two HBO stand-up specials, best-selling books and a Grammy nomination. Oh, and she came out as a lesbian while starring in a prime-time ABC sitcom to 46 million viewers.

As the Kennedy Center Chairman, David M. Rubenstein, said in announcing the prize this week: “The Kennedy Center is happy to recognize Ellen DeGeneres’ unique contributions to the world of comedy. Through her television programs, stand-up appearances, movies, and even commercials, her special brand of humor has allowed us to find hilarity in the mundane and has kept us laughing for years.”

For her money quote, DeGeneres quipped: “It’s such an honor to receive the Mark Twain Prize. To get the same award that has been given to people like Bill Cosby, Tina Fey and Will Ferrell, it really makes me wonder… why didn’t I get this sooner?”

Sooner?!?

If anything, the perception for the first dozen years of the Mark Twain Prize had been that it was The Kennedy Center’s — and by extension, America’s — way of celebrating a lifetime of achievement by a legendary comedian. The first three winners: Richard Pryor (1998), Jonathan Winters (1999) and Carl Reiner (2000). Other past winners have included Bob Newhart, Lily Tomlin, Steve Martin, Neil Simon, Billy Crystal, George Carlin and Bill Cosby.

We’ve still got plenty of living legends of comedy yet to recognize in this way, too. Mel Brooks. Woody Allen. Joan Rivers. Just to name a few.

But in the past few years, The Kennedy Center has fast-forwarded past that generation of comedians to honor performers who are still in their prime form. Tina Fey in 2010 at the tender age of 40; Will Ferrell, 44, last year.

And now DeGeneres this coming fall, when she’ll be feted on Oct. 22, 2012 — taped for broadcast later on PBS.

All of the Mark Twain Prize winners certainly have earned their plaudits and kudos.

Could we receive a little more clarity from The Kennedy Center, though, about what we’re saying when we honor someone with the Mark Twain Prize? Because this recent trend suggests it’s not a lifetime achievement award (unlike the annual Kennedy Center Honors, which specifically cites a receipient’s “lifetime contributions to American culture”). And there’s no evidence that it’s a best or extraordinary comedic effort of the year award. So. What is the comedy prize meant to symbolize?