Social generations are cohorts of people born in the same date range and who share similar cultural experiences. The idea of a social generation has a long history and can be found in ancient literature, but did not gain currency in the sense that it is used today until the 19th century. Prior to that, the concept "generation" had generally referred to family relationships and not broader social groupings. In 1863, the French lexicographer Emile Littré had defined a generation as "all people coexisting in society at any give…