Does this moustache make me look old?

College theatre has a unique challenge: how to cast a show with characters of varying ages with students within a four year age group?

One of the most common ways to combat this, at least for the men, was facial hair. In other words FACIAL HAIR = OLD & CLEAN SHAVEN = YOUTH. I knew plenty of guys who were mediocre actors who worked all the time in college in the older roles. Sadly some of these actors had a difficult time adjusting to working in the real world and being asked to play their age.

Another factor that influenced age was height. In college tall meant older than short. My big adjustment post college was seeing many of my super-tall friends plays characters their age.

What are other things that can represent age on stage? Hair color, obviously, jumps to mind. Physicality and vocal patterns can be assumed or put on. Ideology often too can help to age a character, but often this is being used as a plot device rather than a means to make a young actor look older.

What are other signifiers of age? How do these signifiers inform stereotypes? Why do these stereotypes exist? And are there age signifiers that exist in theatre that aren't actually present in the real world?