It’s like catching up with old friends. They’re a little heavier than when we last saw them and have a few more wrinkles, but they’re still very much who they always were.

We know that because, even as we’re looking at their 56-year old selves up on the screen, it is intercut with footage of them at 7, 14, 21, 28, 35, 42 or 49 years old, answering the same question or explaining how they were feeling then.

“56 UP” is the latest installment in director Michael Apted’s extraordinary documentary series that began in 1964 as “Seven UP,” a television documentary in Great Britain. That first film, on which a then young Apted (he’s now 71) served as a researcher, attempted to examine the British class system by profiling 14 kids, each one a 7-year old, who came from various strata in society.

The film, which opens Friday in New York and Jan. 18 in L.A., took as its inspiration the Jesuit maxim, “Give me the child until he is seven and I will give you the man.”

Every seven years since then, even as he became a major Hollywood director (“The World Is Not Enough”), Apted has served as director of the series. Backed by a camera crew, he visits individually with members of the original group of interviewees to see how their lives are turning out. 

In “56 UP,” 13 of the original 14 allowed Apted to interview and film them. (The only one missing is Charles Furneaux, one of three upper-class boys who sat together on a couch as 7 year olds and talked dismissively of “poor children.” He became a television documentarian himself -- he produced “Touching the Void” -- and has not participated since “21 UP.”)

The series would seem to indicate that England’s class system is still firmly in place. A few of subjects have moved up the social ladder; Sue Davis, a working class girl from London’s East End, has ended up a college administrator and Nick Hitchon, a Yorkshire farm lad, is now a university professor in the U.S.

One of the middle-class kids, Neil Hughes, who dreamed of being an astronaut at 7, had an apparent breakdown as young adult and has led a lonely and emotionally troubled life. He seems, though, at 56, to have found a small measure of contentment living in a small town, where he ekes out a minimal living as a local council representative.

In the “56 UP” installment, it’s clear that the recent worldwide recession and subsequent government austerity measures in the U.K. have affected several of the film’s subjects, costing them jobs, social benefits or putting a serious crimp in their retirement plans.

Many of the participants are now grandparents, some with a first spouse, some with a second. But Bruce Balden, a math teacher who didn’t wed until he was in his 40s, is at 56 the involved father to two young sons, who watch with amusement as their portly pop tries to erect a tent and play  cricket.

One has the usual quibbles with the “UP” series: only four of the original 14 subjects were girls, which means the film has been limited in its ability to portray the feminist revolution.  Only one participant, Symon Basterfield, was a person of color, which means the movie missed out on examining another major shift in the British population in the last half-century. And none of the kids turned out to be gay (or if they are, they’re not telling Apted), so that too is a missing element.

But overall, the “UP” series remains an amazing achievement. What’s most fascinating about the film is how everyone here, now well into middle age, is still completely engaged in life, is generally upbeat (despite some real struggles for several of them) and intends to carry on.

During the course of the film’s 144-minutes, as Apted skillfully cuts back and forth between his subjects now and then, it’s apparent that the more people change the more they stay the same. But, and this is where the series shines, it’s equally clear that people have an amazing capacity to change, grow and show enormous resilience when faced with daunting challenges.