The exposure times in old photos were simply too long for a person to maintain a smiling pose, according to a long-held belief. For example, one of the first photographs ever taken, of a busy street, by Louis Daguerre in 1838, probably took between 10 and 15 minutes of exposure time. Who were the people, horses, and carts lining the streets and sidewalks? They are completely invisible in the photograph, demonstrating what a blurry mess a photograph can be if there is movement.

However, advances in photography in the 1800s meant that exposure time was not the only reason people didn’t smile in photos, according to Voxfilmmaker Phil Edwards. We’re told that the Victorians were stern and taught not to smile, but that’s not entirely correct. In the video below, you’ll see another explanation for all the sad faces. Also, keep an eye out for some unsuspecting Victorians.