When I started teaching 'Creativity applied to Advertising', I got my hands into several historical reels donated by ad agencies. It didn't take too long to realize that the advertising history of a brand may say a lot about how the brand has changed its positioning, but it can also tell how much the world has changed.
I am not talking superficial changes --the ones that we all recognize, like hair styles, dressing styles or make up styles, or how our phones have changed and our way of using them. I am talking about values and perceptions.
Social changes can be studied by just seeing old ads, and you can find here two very good examples, that I believe speak by themselves.
2. And from Argentina, a Quilmes (beer) ad, in a hospital environment, with doctors and nurses drinking beer :
Both ads are from the early 60's and we know that none of this ideas could even be suggested today.
BTW, if you have other examples, please let me know!