I think 'speculate' is the wrong word. Questions arising from observations and ideas are constantly being raised, but unless tests can be devised to verify the guessed-at, possible answers, then you are back to your starting point of a guess.Quote
2. the evolution of complexity
3. our human species with consciousness
The fossil record can only point to what happened – we need to speculate on what might have been driving it.
And why do you say 'driving it'? Random mutations, natural selection, might - did- mean that species with lucky adaptations etc survived, those without did not. No species knew what the future would be nor could they plan for it.