The social rules for dating change from one generation to the next.
There was a time when a proper young man and woman could not speak to each other unless they had been formally introduced. On the other hand, I understand from my patients that it is considered bad manners now for young people to date someone who has previously dated one of their friends.
Index fossils are fossils that are known to only occur within a very specific age range.
It's sad that this generation's idea of dating has become so convoluted.
It has turned into bouncing from person to person and having random hookups, but not taking the time to get to know someone and fall in love.
Dating as an institution is a relatively recent phenomenon which has mainly emerged in the last few centuries.
From the standpoint of anthropology and sociology, dating is linked with other institutions such as marriage and the family which have also been changing rapidly and which have been subject to many forces, including advances in technology and medicine.