Ever look at old photos around your house or in history books and wonder why people never seemed to smile?It's a little spooky, but there has to be a reason for it, right? A team of researchers led by PhD student Shiry Ginosar at UC Berkeley set out to study the "average" smile from high school yearbooks over the past 100 years.After the study, some experts have suggested their own theories on why people smile more or less over time. Think you might know why?Then read on to learn what makes us smile, and if we're better off looking happy or serious in pictures.
Source: Today/ Shiry Ginosar/ UC Berkeley
Start the slideshow below to see why people smile more or less in pictures, then SHARE the smiles with a friend!