Unanswered by science
Laughter, like crying, may have developed as a social tool, according to Mental Floss. "Laughter doesn't appear to be a uniquely human behaviour, and it may not even be limited to primates. Rats produce laughter when tickled and many other social animals, such as dolphins, make specific sounds associated with play-fighting that have been likened to laughter. A leading hypothesis for why we laugh is that laughter promotes pro-social behaviour by letting playmates know that the fighting is just a game. But even if our interpretations of these behaviours are correct, it's possible that humans evolved different uses for laughter after our evolutionary splits with other animal species, making the reason for human laughter another open question."
Laundry anachronism
A reader writes: "Found in back of laundry cupboard at Far North family bach with no washing machine. Been in the family since 1974. Is it a Northland thing, a bach thing, or do people not wash their clothes when on holiday?
