There are various milestones in a person’s life: when you learn to ride a bicycle, get your driver’s license, graduate from high school or college — to name just a few examples.

Of course, those are things one looks forward to, but there is another, more-dubious line of demarcation people must cross if they are fortunate to hang around long enough, and that is when they become a so-called “senior citizen.”

But the question is, when does that actually occur and what is the criteria involved, other than the obvious factor of chronological age? (Which can be quite misleading.)

The impetus for my query was a situation this week involving a person I know who had what she considers a traumatic, life-altering experience: no, not a diagnosis of a serious illness or hearing a rumor that “Desperate Housewives” would be canceled.

What kicked her in the teeth was being charged a senior-citizen price for coffee at a local fast-food restaurant for the first time ever.

Any of us with even a smidgen of gray hair on our heads has been there. After first thinking that the person at the counter has grossly undercharged you, the grim realization then hits that the “senior-citizen” price has been charged for your order.

You are, at once, excited about paying less, but also insulted that someone is making such a value-judgment. I mean, let’s get real, those friendly folks who work at fast-food restaurants might be skilled in many things, but I don’t think they would qualify as expert witnesses in a court case to determine someone’s real age.

And what criteria do they use, anyhow? In the case of the lady involved in this week’s experience, she is in her early 50s, but looks much younger and is extremely athletic. In fact, she is employed in the physical fitness field and has been for many years. I’m sure she could run circles around any of those pimply faced punks at the fast-food places.

The only thing they must be going by is the possible presence of a stray wrinkle or gray hair when they look at a customer. Which is also misleading, since I’ve known hard-living 30-year-olds who appear to be 70 and 70-year-olds who look more like 30. Does the name Dick Clark ring a bell?

Signs are posted in some establishments selling alcoholic beverages which state that anyone who “appears” to be younger than 40 will be carded when making such a purchase. Again, how someone looks can be a grossly inaccurate measuring stick in pinpointing his or her actual time on Earth.

I’ve known individuals who looked old for their age who were able to buy beer at age 16 (without getting carded at all), and people in their 30s who looked 20 and couldn’t buy it because they neglected to bring their IDs with them. You see, it’s insulting for an adult to be treated like a child.

Naturally, those same folks feel good about themselves when they still get carded after turning 45, but are insulted all over again once they quit getting asked for their IDs altogether. Like being charged the senior price for coffee, this is an indicator that one has crossed the line, which, again, can be highly infuriating to us (I mean them!).

But this wicked cycle does not answer the core question of when someone officially becomes a senior citizen.

It seems to me that years ago, this term was applied to people in their 80s who appeared to fit a definable stereotype: folks who were elderly, but still active in many cases — enough so to represent a strong, visible presence in the community.

Then the magic number apparently dropped to 75 and later to 65, which makes some sense since 65 has been the traditional retirement age. But somehow, in the dark of the night while our backs were turned, the bar got moved down to 55 (the cutoff age for the Senior Olympics and other such things) and later to 50.

That wonderful group the AARP is mostly responsible for this ratcheting-down of the senior citizen index, being notorious for sending out its little membership cards as soon as people hit the half-century mark.

Yes, seeing that “thing” in your mailbox is another of those irritating milestones that makes one feel older, but not when you realize the true motive involved. Since AARP exists largely to sell insurance, it’s only logical that this organization wants to expand its potential customer base to as many folks as possible. If the AARP has its way, eventually people might be getting AARP cards on their 35th birthdays.

The same thing is true of those restaurants that sell “senior coffee,” which probably are just trying to seed the clouds for repeat business in as cheap a way as possible. You don’t see senior-citizen discounts on big-ticket items such as cars, do you?

I just think that at a time when Americans are more active and physically fit than ever before, everyone has to be careful about throwing around the term “senior citizen.” Especially since people are living longer and “older” residents are becoming more prevalent among the population as a whole. Sixty is the new 50, and 50 the new 40, or so I’ve heard.

And one recent statistic indicated that by 2050, the U.S. will have 1 million people who are at least 100 years old.

The most-appropriate way to view someone is not by looks or chronological age, but their lifestyles — and if anyone lacks knowledge of this, they shouldn’t be making judgments that are stupid as well as insulting. That person you see at the checkout counter might have just run a marathon, for all you know.

How about just selling coffee at the regular price, unless someone ASKS for the discount?

In closing, I’m reminded of the great Negro league pitcher Satchel Paige, who in the 1940s finally made it to Major League baseball when he was 42, and was still playing in his late 50s. When once asked what his age was, Paige responded, “How old would you be if you didn’t know how old you were?”

Tom Joyce is a staff reporter for The Mount Airy News. He can be reached at 719-1924 or tjoyce@heartlandpublications.com.