There have been few shows as underestimated by the theatre establishment as Rob Becker's Defending the Caveman, the one-person show about gender differences that now holds the record for the longest-running monodrama in Broadway history. It's now breaking box-office records on an extended national tour, which will be in Boston during October and in Buffalo, Philadelphia and Baltimore during November. Not bad for a show that New York critics dismissed and of which a leading producer once observed, "It'll never run."

Becker, the one-time West Coast stand-up comic and television performer, is, of course, having the last laugh on a number of counts. "You know, there are a lot of myths out there," he says, "and -- can I brag a bit? -- I think this show is putting a lot of them to rest." As examples, the comic cites one, that New York audiences are different from those in the rest of the country; two, that you need the approval of the critics in order to run; and three, that one-person shows can only succeed in small theatres.

"When we were coming into New York after being very successful in places like San Francisco, Dallas, Philadelphia, Chicago and D.C.," Becker recalled,, "we told some producers who were very skeptical that the show had largely succeeded by word-of-mouth. One very prominent producer actually said, 'Yeah, that might work on the road, but it won't work here. Word-of-mouth doesn't work in New York. People tell their friends, sure, but they don't listen. '"

Indeed, word-of-mouth largely sold Becker's show in New York as it is doing so on the road, although the subsequent media attention, which was grudging at first, has helped raise the profile on Caveman enormously, compared to the early days in 1991 when he began staging the show at a decrepit comedy club in San Francisco. While Becker says the show has been attacked by some of the leading critics as "un-politically correct," he maintains that the majority of reviewers have in fact looked favorably on his position that the best way for couples to get along is to suspend judgment and embrace personality differences rather than fight to change them."

At any rate, the disapproving critics have not been able to dampen the audience's enthusiasm for Becker's funny and recognizable scenarios of domestic unrest. On the road, he has been able to fill venues as large as 2,600 seats without, in his opinion, a noticeable difference in the quality or response. "If you bring the audience to you, a 2,500-seat space can feel very intimate," he says. "Sometimes it really depends on the configuration. If it's wrong, a 500-seat theatre can feel cold. But rather than the hall dictating how intimate the show is, I think the show should dictate the intimacy. If it's an intimate show, it'll be intimate for 2,600 people. I've been offered to play in Atlanta's Fox Theatre which has 4,400 seats, but I think that's too big."

Because of his enormous success, Becker is now considered something of an authority on family relationships, a reputation that he will exploit further, not only by touring through much of 1998, but also through the publication of a book and the development of a new show called Cave Dad about the perils and pitfalls of being a father. (He and his wife of ten years, Erin, have two sons). "Being a father is like being on parole," he explains,, although he adds that people should take his advice with a note of caution. "I want them to realize that they're getting it from a comedian," he says.

-- By Patrick Pacheco