The technology that enabled us to reach LEO also enabled incredibly destrictive wars including a near-apocalypse in the Cuban Missile Crisis. It also required resource use in such a way to sigificantly alter the natural environment and, in some scenarios, significantly threaten our survivability.
I've no idea if there's other worlds out there capable of supporting advanced multicellular life (though it seems far from impossible). I've no idea if any of them are presently inhabited with such life. Based on the timings alone though, it seems far from impossible that the level of advanced civilisation to enable interstellar communication is sufficiently short-lived and accident-prone as to entirely preclude it from happening.
Or - we might as well just enjoy working out how to chat with Dolphins.
Also, slightly contradictarily, natural selection/evolution don't provide much pressure for a species to change after it's gotten wildly successful. Have we had any physiological brain changes since agriculture? Not really. And now that medicine is becoming so effective, natural selection doesn't really work on the fitness of people, just their ability to have more children.
So, I don't think ET will be vastly more intelligent than us without having to resort to redesigning itself.
I'm not so sure. In that scenario, there's something that we're communicating with, right? Given humanity's limited capacity in that regard, the mere fact that we've found something that can reciprocate would, to me, indicate that it's likely to be a little further along than we are.
It's really a matter of who goes to whom. If we meet aliens on our turf, well, they had to get here somehow. And since we can't really get there too easily, they must be a bit better off.
We can't say that X achievement in distance shows intelligence higher than ours just because we haven't matched it yet.
Also, re: "ability to have more children"--that is exactly what the evolutionary definition of fitness is. Your concept of fitness as an animal that's strong and smart and whatever else is purely a byproduct of that definition.
It provides pressure for the species to change to adapt to its wild success (e.g. to become "fat and lazy"). That development of the wild success may also lead to significantly changed conditions (e.g. global warming as a result of the wild success of homo sapiens)
>Have we had any physiological brain changes since agriculture?
it is only 10000 years, and yes, we had. The physiological changes are observable even for the last 100 years.
>And now that medicine is becoming so effective, natural selection doesn't really work on the fitness of people, just their ability to have more children.
that phrase sounds like oxymoron.
Anyway, natural selection is like Newton's laws - it can't be turned off. It works non-stop. It ensures fitness to whatever current conditions are. In particular, right now, it ensures fitness of human species to the condition of "medicine is becoming so effective".
Now natural selection is still occurring, but it may be leading to specization rather than intra-species evolution.
That just even more shifts the weight of human species selection machinery from r-selection (muliple, and thus more diverse, offsprinfgs, i.e. selection mainly by the best static fit) to K-selection - selection mainly by the best ability for behavioral adaptation. Ie. the natural selection, in the classical sense, is still there. It is the most important traits for defining best fit that are changing.
Define "wildly successful". Humans have clearly changed overtime. Look at the color of skin relative to geography. The closer to the equator you get the darker people get. That's natural selection. Another example is sickle cell and malaria. Natural selection in action!
Look at modern domesticated dogs. They've all evolved from wolves in a fairly short time frame.
Instant communication is a nice luxury, but it's by no means essential.