1. If we're already going to do the journey to a far off planet, it'd be nice if we didn't have to have a huge amount of infrastructure to stay alive on the planet.
2. I feel like one of the ultimate goals of space travel is to find other life. The only life we know is on Earth. Earth-like planets are a good place to start.
I feel like one of the ultimate goals of space travel is to find other life.
Dangerous assumption. That's like saying the purpose of science is to unify nature. If nature isn't unified, the goal won't make it so.
The most likely outcome is probably that we will become our own aliens. Once we send out colony ships, those people will form their own branches of the evolutionary tree. Over millennia, that will equal aliens. It doesn't really matter that they're our ancestors when they end up looking, talking, and acting completely alien.
This seems far more likely than running across other life in the local group. We're forever imprisoned to our local group, which is something like 0.001% of the observable universe. And for all we know, the total universe could be infinite. This requires strange assumptions, like running into your own doppelgangers, and infinite energy. But we can't know it's not true. And in such a circumstance, we have to face the unsettling half-empty truth that we're simply alone.
We'd have to be totally separated from those colonies for an unthinkable amount of time for stuff like that to happen - I'd imagine we'd at least keep contact with our own colonies and the Native Americans were largely separated from Eurasia for thousands of years and crazy stuff didn't happen aside from a gap in immune system prep.
Not with the distances and times involved unless we develop FTL communication. At first we may not diverge biologically, but culturally, and that is quite enough to close most doors... after all how many Norwegians do you find that marry bushmen or aborigines and vice versa?
A lot of sci fi seems to somehow overlook our cultural/social baggage and yet those are precisely what are crippling us now, and likely to retard our progress in the future too, if not outright destroy us.
Earth would keep contact with colony A which would be slightly different. Colony A would keep contact with colony B which would be slightly more different. It would only take a few tens of hoops to get to something different enough that would classify as alien. At interstellar distances, this is a definite possibility. Isaac Asimov's empire, foundation and robot series have some fascinating (hypothetical) examples of this.
You don’t need evolution to make your aliens, cultural separation would immediately begin and do it for you.
To clarify, I believe that within a generation or two, people on another planet will hardly relate to their originating culture and will see it as an other. This change will at first be benign, merely based on differences of day-to-day life on a developing colony, but later, after initial material support largely dissipates, would see it as something to cast off or, should they not openly revolt or request a plebiscite, will treat it diplomatically as if it were another country, or as it is in this case, as literally another world.
Consider that when traveling between a host and colony settlement takes literal weeks, months, or years, sending information would likely also similarly be costly and would take prohibitively long times for many real time applications: latency up to several hours or days to arrive could be expected for even small downloads. This borderline resets communication the era of writing letters, if I may be a bit dramatic, because this absolutely neuters a huge amount of modern culture.
Cultural products made on earth would be costly and difficult to ship, so we’d find that earth films, games, internet, are mostly not going to bridge the gap. Even after infrastructure for communication improves, the latency problem of “space is big” isn’t going to go away. For example, would you read 15 HN pages if each page, no images, no modifications, took 15 minutes to load? I suspect not, and you’d fill that time with something else that an earthling software engineer might not.
It’s all elements of culture. The earth news cycle? Almost wholly irrelevant, besides economics and space-related news, which impacts what is sent and relations with home.
Celebrities? People will find it hard to care about celebrities who will never visit them, and who have works they’re not hearing until weeks, months, or years after they stopped being relevant on Earth.
To fill this gap, people on the colonies will be making their own, and however bad the gap is earth -> space culture wise, due to the difficulty that limited resources will impose, culture from space -> earth will likely be rather rare.
So, culture is going to start diverging, relatively hard and rapidly. Separated from leaders, most current cultural information, old national borders, credible risk of counterattack from earth for anything short of armed revolution (space war or military pacification against one’s own people would likely be an economic and political Vietnam, and you definitely can’t launch a surprise attack when people can see the weapons or troops launching), people will mostly stop giving a shit about their home world and will become naturalized on their new ones.
Two or three more generations like that and you’ll eventually be talking about people on Mars, for example, as if they were from Australia.
1. If we're already going to do the journey to a far off planet, it'd be nice if we didn't have to have a huge amount of infrastructure to stay alive on the planet.
2. I feel like one of the ultimate goals of space travel is to find other life. The only life we know is on Earth. Earth-like planets are a good place to start.