It may not be far off from the truth. It's been argued that, not that people smiled less overall back then, but that in earlier times, photograph etiquette was

It may not be far off from the truth. It's been argued that, not that people smiled less overall back then, but that in earlier times, photograph etiquette was in line with painting etiquette. You were expected to make a serious face preserved for posterity. It's only over time as photos become more spontaneous and ubiquitous that we have adopted the cultural vocabulary of smiling in response to having our picture taken, or so the argument goes. See here: https://time.com/4568032/smile-serious-old-photos/ https://time.com/4568032/smile-serious-old-photos/