Humans cannot have experimental evidence about anything that exceeds or precedes our spatiotemporal environment. The only thing that can be known about that is what any previous Intelligence reveal about the whole process and so on.
For example: we could never know what exists outside of
what came into existence from the BigBang onwards. We cannot know who caused it, where the energy that caused the explosion came from, what kind of infinitesimally small particle exploded, who was manipulating the process to obtain the precise results that emerged later, how many
intelligences existed at that moment, what relationship these intelligences may have with what emerged later, how life as we know it in our planet came to be, etc.
The results of the process are evident samples of design, although many cannot distinguish that. Those who do not admit design say that
human intelligence (which is sometimes indistinguishable from what the concept of
science defines) arose from an unguided, chaotic process, which eventually led to this magnificent result that is the rational thought supported on the modern human's brain.
In this context I repeat the initial question:
if they say that human consciousness eventually appear in an autonomous process without designer ... and considering
TIME like
the number line, with a past infinity and a posterior infinity with 0 in the middle, as we mentally conceive it:
What blocks the minds of some and makes it seem impossible
to them that in
THE INFINITE pre-bigbang (whatever it may have been),
predecessors intelligences already existed?
PS: I read few interesting answers... most of these known guys I talk about are just spoilling the thread though... normal in them