Despite what many people think, we’ve been engaging in the same practises with the same amount of variety since people began.
Perhaps the idea of someone looking out at you from a picture taken hundreds of years ago is fascinating because it highlights the fact that humans never really change very much.
A good, genuinely informative series to watch would be Pornography: A Secret History of Civilisation, in which each episode outlines different eras with their new medium for pornography (ie. Georgian literature or Victorian photography) and the attitudes that surrounded it.
If you’re up to viewing risque pictures, this blog post by author Matthew Revert is very interesting.