In the age of social media, we're living through a communications revolution. But this isn't the first one, nor is it the first time cats have been at the centre of social change.

It is a fundamental law of media history: as soon as a new communications technology emerges, people will use it to make pictures of cats. And those cat pictures show not only the special relationship between humans and their pets, but the changing ways that humans relate to one another.

Cat memes in their modern form date back to the 1990s, when email first allowed bored office workers and friends to message each other funny felines. The cats jumped from there to social media as the web developed, where viral videos like Keyboard Cat and memes such as Grumpy Cat bloomed across platforms. Demand for this content was so high that entire websites like ICanHasCheezburger sprung up to showcase the best e-cats, aggregating popular pet videos and cat memes.

But there was another trend long before any cat wanted to "has cheezburger", or any owner could even imagine taking a video of their pet with a handheld electronic rectangle: the Edwardian postcard. And, according to scholars of media history, understanding the cat postcards of the early 20th Century might help us to understand social media today.