I recently saw this picture of the cast of Cheers from 1982, and was shocked at the age of some of the cast. John Ratzenberger, who plays Cliff, is only thirty-five; I would have easily put him at fifty, and even that guess is capped by my knowing he isn't currently in his nineties. And while the other young members of the cast aren't quite as far out of whack from my guesses, they still look much older than their age, to my eye. It reminded me of a line from Alan Bennett's Waiting for the Telegram:
"They look old in pictures compared with what they look now, but they weren't. They were lads, same as you."
I wonder to what extent this is fashion - whether hairstyles and clothing choices are what cause this effect. Or perhaps it's due to the lower standards for healthy lifestyles, greater wear-and-tear and the generally harsher environment of the past. Another pretty reasonable possibility in this case is, since these are actors cast to play specific parts, the producers of the show simply sought people who looked a certain age (in which case they did an excellent job). In reality it's probably a combination of all of these, but I bet in forty years' time people will be saying the same about today's thirty-five year olds.