A boss, in defining qualifications for some task: “As long as he can fog a mirror.”
What other ways to put the idea?
Body temperature above room temperature.
A warm body.
I don’t know about the “quaint” part, but among science geeks we use expressions on the order of “functioning metabolism”.
Can pass a Turing Test (which supposedly some software developers would fail).
Able to sit up and take nourishment.
We used to joke to get into a California Community College you have to be breathing and have a pulse. Should you fail either test, you would be hired on as staff (not as a teacher, as support or admin staff).
To be able to operate a revolving door.
having a strong back and a weak mind.