Originally posted by Data
Nah we'll find new tribes. People from Earth will still care about where on Earth they are from. Off planet people will form identities around planets, colonies, and space stations. Dialects and cultures will form in great isolation and shit will get weird. We may not form tribes based on race so much but we will find other ways to discriminate.
You are forgetting two key things:
First, the cosmopolitan cultural influence that are consequent to increasingly globalized and interconnected markets, that's not going to reduce as time goes on or stop with the earth itself, it's only going to increase. Someone born on Phobos will know their world as one of many worlds and will probably view it as less special than a singular Earth that has been the center of the development of every organism we have ever known as well as every cultural convention we have ever constructed. Look how fervently some clung on to geocentrism as a matter of not just fact but of faith, because it preserved our position in the universe as special, central and unique.
This sense of exceptionalism also pervades much of nationalism throughout history, nations believing they are special either because they are the first set of colonies to free themselves and establish a federal republic, or some historical set of unique identity.
Perhaps the first offworld colony might feel special for the same reasons, the first to do something or the other. But the cumulative weight of history from such events will progressively iron out the tribalism as it already has, not increase it. That would be counter to all historical trends.
Certainly subcultures will exist and that's not a bad thing. But what these divisions mean will stop being sourced from ill-recorded historical disputes and prescientific superstitions.
Additionally these colonies will select for people of higher education and technical skill first, and will require extensive connectivity with Earth (and then other colonies) to get established and become economically viable in the first place, and will be hostile to isolationism. We will grow as one civilisation.
That brings me to the second point that you forgot, which is that economic activity will be centered around the Earth for the foreseeable future due to sheer differences in growth statistics. Colonies will pose harsh living conditions and won't be as conducive to population or economic growth as Earth, as Earth already has the overwhelming bulk of the population i.e. market. Until more people are leaving earth than staying, it will continue to be the economic center of our civilisation. For example resource extraction will only be valued based on either how much Earth centered industries will pay for them or what other parts of your colony's industries are worth to Earth centered industries. Even now most people are transitioning into a global marketplace either directly or indirectly, and it will only become more and more direct as time goes by. People from all colonies will fly all over the place for professional reasons or trade or academic purposes. They will communicate, share information and technology and benefit from the growth of the entire human civilisation's continued, ever more connected development.
Of course in the long term, as the progress of history branches off and grows further from Earth, eventually they will indeed lose any sense of belonging to the Earth itself and perhaps turn back towards their colonies as the epicenter of their lives, yet still they will remain economically connected to the rest of human civilisation more than not, purely by proportion of economic influence of the entirety of humanity vs their one planet. This phenomenon is already presently observable amongst nations here on Earth.
The key asymmetry between the examples of history and our outlook of the future is communication and information. And as we spread out through the solar system and across the stars, our civilisational structure will gain more redundancies and become essentially impossible to collapse with any one particular catastrophic event.
Hot war will also become increasingly unpopular as a course of action because offence will naturally outpace defence: stationary colonies and barely mobile space stations will be easy targets, whereas creating a big explosive and strapping a strong thruster to it will be incredibly easy (ships will likely be using nuclear propulsion so there won't be as much of a restriction to accessing nuclear materials as there is now). 2nd strike measures will also be almost impossible to find and eliminate, as now they could be positioned anywhere in space, it will be like finding a needle in a haystack. So Mutually Assured Destruction will be in play all the time.
