So social constructs don't prevent us evolving? I'm confused now.
False dichotomy. The same factors that contribute to selection bias (and thus evolution) contribute to stalling evolution where there ceases to be a significant advantage for one trait over another. Put another way, changing social conditions can remove evolutionary advantages where they used to exist.
I don't think it's entirely realistic that we can treat every new sickness as it arises. We're still having trouble understanding some of the bigger names out there.
My argument doesn't rest on us being able to treat every sickness; only those created by our new environment. That is, sicknesses that put some at a disadvantage compared to others, such as weakened bone structure from prolonged low-gravity exposure (assuming we don't have artificial gravity by then).
No, but we've come pretty far in just under 4 billion years. All it took was some simple organic molecules and enough time.
It took a lot more than that. Evolution hasn't been a linear progression; notably, nothing much happened for the first 2 billion years because the blue-green algae were still busy sorting out the lack of oxygen. Generally, significant evolutionary change happens in bursts after a significant change in environment, followed by millions of years of relative stagnation.
If we put everyone on a spaceship with a regulated climate, we're going to see far fewer sudden changes in environment than on a natural planet. When we can change the environment to accommodate us, there is no longer a need to change to accommodate the environment.
There's bound to be some influences at play, especially in an environment as inhospitable as space.
Name one.
While you're right about the small time period, we are still evolving as the processes that drive evolution cannot be stopped by modern society. Taken from a pop-sci article:
There are a lot of other ways that evolutionary change will march on, no matter what. Those that survive may have a higher tolerance for drinking milk. Babies in industrialized societies have access to milk like no one before us. Maybe a genetic tolerance for milk will slowly help more of those babies survive until they have kids of their own. There is evidence that people with both especially high and especially low blood sugar levels have fewer offspring. So subtle changes at least will make their way into the human population’s gene pool. It’s going on right now.
I agree that it's probable that we are still evolving; I just don't see any direct evidence to substantiate that.
That's small speculation, sure, but what do you think will happen as we spend thousands of years in space?
Perhaps the same thing that has
happened to sharks in the past 100 million years; absolutely nothing.