This a speculative idea that came to my mind recently.
I'm not really trying to defend it as a theory,
instead I was wondering if there is any evidence supporting or refuting this idea
(if this is inadequate for this section, don't hesitate to move it elsewhere)
Ok, here's where it came to my mind:
On another thread somebody argued that the potential for intelligence among our ancestors in the primate order
would have been obvious for an ET observer already millions of years ago.
(I'm not so sure about that)
On the other hand, maybe the threshold to eventual intelligence was crossed way earlier,
for example when mammals started to dominate Earth.
Maybe eventual intelligence was just the logical conclusion of the current 'evolutionary stage'.
I think it's at least conceivable that many modern mammal orders (and maybe birds, too)
had the potential to eventually produce an intelligent species like homo sapiens.
Some species (like elephants, dolphins, parrots, etc) seem to be at least as intelligent as most primates.
So was an intelligent species eventually inevitable at this evolutionary stage?
(and was it just mere coincidence that the primates made it there first?)