I observe that the children of people that I know, if judged entirely on photography, would appear to be all stunningly attractive. Photographs that I own of people that I know from their own teen and childhood years, and photos of members of my own family suggest that by comparison, humanity up to about 20 years ago was largely composed of odd-looking, grumpy-faced or mad-looking and somewhat furtive trolls.
Either some sort of alien intervention has taken place unnoticed, or nowadays, people get photographed so often, and get to see the results so instantly, they have on the whole, got a lot better at being in photographs.
I expect Future Historians to come up with a complicated theory about nutrition and dentistry. Or to go with the alien intervention thing.