So what exactly is in danger of “Extinction,” the play now on close-up view at the John Drew Theater? Is it the relationship of two young men entering their settling-down years? Or is it the human male gender that author Gabe McKinley is nominating for the endangered-species list?

In “Extinction,” friends 10 years removed from their college days of bacchanalia get together for a weekend reunion at Atlantic City’s Borgata Casino. One of them announces that he’s “moved on.” Finn is in graduate school studying to be an English professor. How tweedy. He bears other signs of maturity, which rowdy Max finds disgustingly conventional. Max makes enough dough in Pfizer pharmaceutical sales that he can spring for a swanky two-bedroom suite, score a wad of cocaine and still have enough to bankroll his buddy’s post-grad tuition. All he asks in return is for Finn to party with him like it’s only yesterday.

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Reluctantly, Finn agrees to meet Max halfway. Debauchery can go as far as booze, drugs and gambling. Dueling Mick Jagger imitations, too. But no girls. Please. Finn says he’s messed up every relationship he ever had with women and doesn’t want to blow the current one. But Max doesn’t count casino girls and prostitutes as relationship material. So imagine Finn’s surprise when one of them steps out of the bathroom wearing only a towel.

Sawyer Spielberg — yes, son of the Hollywood director — co-produces and convincingly co-stars in “Extinction” with Raye Levine, whose production contribution is on absorbing display all around the audience seated on stage like hotel-room voyeurs. Levine’s set, bathed in psychedelic lighting (Sebastian Paczynski) that suggests Dale Chihuly’s dreamscape glass-works accenting the real Borgata, offers both an almost-in-your-lap view and the removed distance of a second bedroom separated by see-through “walls.” The audience only occasionally feels as if we should look away to give the players some privacy. Such squirmy moments are provided as Max, portrayed with fierce, no-boundaries abandon by Eric Svendsen, stakes out Missy, played by Brynne Kraynak with the brave face of a been-around-the-boardwalk semi-pro. Spielberg as determined-to-be-good Finn and Levine as Victoria, tentative first-timer at this game, are heartbreakingly raw in their emotional defensiveness.

As directed by Josh Gladstone, “Extinction” is nasty but real. It’s just a matter of how much bad behavior you can tolerate.