When Pilobolus last appeared at the Joyce Theater, five years ago, it was business as usual. This popular troupe of mime-acrobats named after a fungus used to sprout in Chelsea every summer with new and recent growths. Its return this week, was an opportunity for reintroduction. Only one work on the two programs is newish — “Branches,” a middling nature study created in 2017 — so the thrust turns out to be retrospective, a sampling of four decades of repertory. The question raised is what to make of a diminished thing.

These programs aren’t exactly a case of the older, the better. The earliest work, “Walklyndon,” from 1971 (the year that a group of Dartmouth College students formed Pilobolus), has decayed from deadpan to dead. People still laugh at its slapstick collisions and abusive gags, but the humor has gone stale.

The founding generation is no longer with the troupe, directed since 2016 by the dancers Renée Jaworski, who joined the company in 2000, and Matt Kent, who joined in 1996. The current members are excellent gymnasts but much less vivid theatrical personalities than the original oddballs. They are distanced from the Monty Python-era spirit of “Walklyndon,” as if dutifully telling jokes their father heard from his father.

Still, nothing created after 1975 comes close to matching Untitled,” made that year and opening Program B. It’s a work that seems to have invented a new kind of theater. What first appears to be a joke about Victorian female attire — two women in big-bustled dresses with too much fabric — soon becomes something stranger, a dream about female power.