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Ever come across a grainy black-and-white portrait dating back to your great grandmother's prime and asked yourself why they always looked so sullen, or sad, or just downright miserable? Turns out there's actually a perfectly reasonable explanation for all the straight faces in old photographs, and no, it wasn't because of The Great Depression or whatever economic catastrophe was adrift at that time.

Find out the real reason below. It's not as grim as you'd think!

This story originally appeared on Preview.ph.

* Minor edits have been made by the Femalenetwork.com editors.