Humor, like beauty, doesn’t always last. Chevy Chase and Eddie Murphy proved that.

And even the most secure institutions aren’t impregnable, as Jerry Seinfeld’s joke about the disgraced NBC News anchor Brian Williams suggested. But Sunday night’s three-and-a-half-hour special honoring the 40th anniversary of “Saturday Night Live” worked and was well deserved. The NBC show, which in 1975 seemed likely not to live out its decade, turns out to have great bones and enduring blood lines.

The event had as many stars in the audience as onstage, and it also had many of the strengths and failings of “S.N.L.,” which has been on television longer than any other sketch comedy or variety show. It remains a standard-bearer, even for people who never watch it.