I suspect a large part of it is caused by facial expressions and how the people pose. Having your picture taken was very serious business, so no smiles were allowed. Show your most serious, regal pose.

If you look at the "Happiest man in China" photo, it doesn't look like an old photo - it looks like a modern photo of somebody dressed up in old time clothes. There is no hard evidence, but many people believe that the man just wasn't aware of how people were expected to pose for a picture.

http://www.todayifoundout.com/index.php/2017/09/story-behind...