"A social experiment like never before," host Jeff Probst declared. Three weeks after unveiling a new "Survivor" gimmick — its rival tribes would be split along racial lines — the CBS adventure-game show returned Thursday to let viewers see if this was a crass ploy for ratings or a welcome new twist after a dozen previous editions.

The upshot after the first hour: too soon to tell.

Marooned on the Cook Islands in the South Pacific, the 20 castaways were assigned to live on four different islands according to their ethnic background — black, Hispanic, Asian-American and white. Much of the season premiere was given over to watching them get settled, and hearing them reflect on the challenges ahead.

"Oh, God, this is gonna be hard," said Ozzy, a waiter from the Aitu (Hispanic) tribe. "I feel like the people who have the same ethnicity maybe are gonna clash on things."

"I could care less about divisions by ethnicity," said Sundra, an actress from the Hiki (black) tribe. "When it comes to surviving, it's a human effort."

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As for dividing up by ethnic groups — "I mean, is that kosher?" laughed Parvati, a boxer from the Raro (white) tribe.

One member of the Puka (Asian-American) tribe wasted no time winning favor from a fellow teammate. Cao Boi, a nail salon manager with a mystical touch, massaged a migraine headache out of fashion director Brad.

"What I'm gonna do is pull this `bad wind' out of you," Cao Boi said, as he plucked at Brad's face.

"I had a headache and he got rid of it," said Brad a few moments later.

Thus did Cao Boi emerge early on as a character to watch.

The season's first challenge: a complex multistage race whose rewards for the first three tribes to finish were fire (in the form of a kindling kit) and immunity.

The loser: Hiki. But it came with one consolation: These tribemates could choose one member from any other tribe for two nights' banishment to so-called Exile Island. Hiki chose Jonathan of the Raro tribe.

Then came the tribal council, when Hiki had to decide who from its ranks would be the first castaway voted off the show after just three days' exploits. Jazz musician Sekou was elected the weakest link. It was time for him to go.

From the announcement of the show's new concept last month, reaction was heated from some quarters.

A Wall Street Journal editorial accused "Survivor" of "playing up identity-politics in a crude and potentially rancorous way," while the Hollywood Reporter blasted the series' creator, Mark Burnett, for "tapping a raw segregationist nerve and exploiting America's obsession with race for personal gain."

Members of the New York City Council denounced the show for promoting divisiveness. "How could anybody be so desperate for ratings?" posed one councilman, an Asian-American.

But in a teleconference with reporters last week, Probst argued that the new season features "the most ethnic-diverse cast in the history of TV, as far as I know."

The organizing principal, Probst said, was conceived "in terms of ethnic pride, not discrimination."