My favorite example of unnoticed cultural change: In 1978 or so, when I was in high school, I found it strange that when a man and a woman were in a car the man would insist on driving, even if it were her car. I took numbers—I carried a sheet and when I saw a car with two people, a man and a woman, I made a tick. I don’t have the numbers any more, but I remember that the bias was big. A few years later when I was back on break from college it seemed different so I took new numbers, and they came out nearly even. In only a few years, in one place, an ancient practice had gone from unmissable to undetectable, and almost nobody noticed. Maybe I only realized myself because I had been away.
originally written April 2012, updated and added here May 2016