(This isn't a rant or anything that aims to vent out some frustration; it's more of a confusing question and an attempt to self-analyze the topic.)

I do wonder why people proclaim that their characters are "mature" by saying they're "over 18 years old". While this may be true for human characters and characters that act like humans (you know who they are), I don't understand why the same numerical value of maturity also applies to other types of characters. I mean, we see dogs and cats and other animals (and dare I say it: "other sentient beings, fictional and otherwise") become mature and we certainly do not say they're around 18 years of age, right?

All these circle around the thought of "why people brand their characters as over the human age limit to prove they are mature", and while this isn't something that needs a very strict pattern of remedies and fixations, it is something that one might not help but think of its logical reasons. Personally, I see it as a way for them to point something out without having to explain much about it. It's something that people almost immediately recognize.

Just don't be surprised if an eighteen-year-old dragon isn't really mature yet. Or that actual dogs mature in a year or so.