What about people of similar age, when you are unsure, meeting for social status?
If someone is doing the introduction, it would be easy. You can ask your friend/colleague if that person is senior or junior than you. Another clue is the person of a lower status will always be addressed first in an introduction. Thus, a junior employee will be introduced before her boss. It is unusual for someone to just walk right up and introduce himself or herself to a total stranger unless it takes place in a pub. But I can't help you with that. I have never been in that situation before.