[Balgair]

I don't know if that is true. I agree with you, but the obvious counterpoint is that a lioness has cubs and raises them to be apex predators just like herself, all without a language. You don't need a language to do things, there are many stories of people living just fine lives without language. To get to the stars, I'll bet on your hypothesis, but I think given enough time, some alien somewhere may have done the same without a thought in it's 'head' at all.

[duncan_bayne]

Larry Niven's "stage trees" - basically, naturally evolved rockets for seeds - spring to mind, where the space travel is an instinctive, unconscious behaviour.

But I'd bet on the OPs hypothesis as well. At a guess, most space travelling species will have had to climb a similar developmental curve to our own - including agriculture (or whatever passes for it in their biosphere, unless they photosynthesize themselves), tool making, metal smelting, nuclear power, etc. etc.