Our Galaxy

[altezon]

That would be very unlikely, no matter what the scifi shows would have you believe

Aside from being carbon-based organisms, there were probably billions upon billions of little coincidences that led us to evolve exactly as we did, and so successfully. It's really amazing to think.

I think it's unlikely that the likelihood can be estimated.

Panspermia is an interesting concept. We already know that some primitive invertebrates can survive the cold and vacuum of space and the heat of reentry to the atmosphere. Comets originating outside our solar system are thought to have brought our oceans, to some extent. And meteorites have been found on earth that are thought to have originated as Martian crustal rocks displaced by cosmic collisions. So it seems plausible that natural processes cause astronomical objects in general to exchange material, some of which may either be living or have a significant effect on the later development of life.

Organic materials such as amino acids form spontaneously in interstellar gas and dust.

And recent developments in DNA technology suggest that the ultimate form of creatures depends more on the demands made by their ecological niche than previously assumed. So the human form could be a universal response to the demands made on us by our planet (this is a familiar science fiction theme BTW ).