Another one I can think of is blushing ...
I mean, only humans blush. And even black people blush even if is not visible.
But music is still very interesting, the capacity of people to play music is also very interesting. How does it benefit your survival if you play music ? wouldn't it be more advantageous to hunt, etc. ?
I feel that these will reveal to be dumb questions, but I would still like to see the answer anyways