History and Societal Homogeneity

I'm guessing the election is at the top of everyone's mind today, but I'm afraid I couldn't come up with a topic that was election-related yet not political. So I'm going in another direction...

I'm thinking about the history of worlds. The reason it's valuable to consider a world's history is essentially that it's impossible to create a world without history. Every artifact or object you place in the world is a product of and a clue to its history. Every bit of architecture or infrastructure. It's there, begging to be considered and deepened.

I think as a basic example about the architecture I've seen in California versus Boston, or in the US versus in Europe. The longer the people have been in the area, the more you'll find remnants of the past, buildings that were put up and never taken down. Monuments and ruins don't appear out of thin air. Look at Greece or the Middle East, where cities have been built, rebuilt, rebuilt again layer upon layer over thousands of years. If your world has a long history, that will show in its present.

If the past doesn't show in the present, that is, if the society is extremely homogeneous, then that's usually a different kind of clue as to its history. Look at the city of Tokyo, which was essentially completely destroyed by the Kanto Earthquake, and then by the firebombings of World War II. A lack of visible history will point to great destruction such as this, or it will point to a vigorous standard of reform and modernism - possibly something born of a culture where renewal is highly valued, or where a past history is being suppressed. It can also result from new arrival, i.e. the fact that people haven't been on a planet very long. One example of this would be Wave Without a Shore by C.J. Cherryh.

However, even when the past doesn't show in obvious ways, it can still show. A new colony on a planet will have artifacts from its arrival that suggest the deeper history of the colonizers. Peripheral cultural groups, or oppressed ones, or geographically isolated groups, can preserve elements of a history that are lost to the population at large. I think here of Ursula LeGuin's The Telling, in which the human Sutty goes about discovering a suppressed and overwritten culture.

There's something of a trope in SF/F about the old nursery rhyme, or the long-lost book of science or prophecy, that has greater meaning than anyone suspects. While I'm not suggesting that every world has to have something like this, that goes from seeming unimportance to deciding the fate of the world, it's still good to consider how the past of a society is carried forward in its details, both physical and cultural.