The Donna Reed Show
I don't know about you, but I find this video almost hypnotic. It demonstrates how descent with modification--evolution, in other words--is present not only in biological lifeforms, but in all things.
For those who have yet to watch the video, it is simply a montage of all of the opening sequences from the run of this classic TV show. The changes to the sequence from year to year tend to be mild, yet there is no denying the ultimate transformation from the demure 1950s culture of Season One, where Mom stays at home, to the much more dynamic mid-60s world of Season Eight, where Mom is dressed for success and headed out the door right behind Dad.
For someone of my generation (I was born 21 years after the show premiered), it is kind of remarkable to sit back and think about the changes that took place in the world while this show was on: the blossoming of television, the civil rights movement, women's lib, the Cuban missle crisis, the Kennedy assassination, and on and on. Donna's fictional family was subject to these forces along with everyone else, and we can get a sense of that through the changes in styles and the family's daily routine. Their world starts out rather quiet and simple, orderly, but it becomes increasingly brassy and complex with the years. Sure, part of this was due to no more than the basic tropes inherent to sitcoms, such as the constant need to inject fresh dynamics to keep the viewers' interest. Yet, even those tropes were shaped by the events of the age. You really can't separate out the parts.
A lot more than Donna's hair changed in those years, and we'd do well to remember that. The world moved on, and even the blissful denizens of TV Land could not escape the inevitable. Donna's hair was just the signpost marking the time.