This is my conceptual theory in the absence of a comprehensive material explanation:
How did the type of cognitive activity we have termed ‘conception’ (reasoning mind) emerge? Demystifying the processes of evolutionary development that gave rise to it is uncharted territory, but its apparent locus in modules of the brain clearly indicates that it must have appeared as a sequence of accretions allowing for greater degrees of specialized association-making as well as structures providing executive control in order to sync the disparate facets of these expanding minds. Some of this enhanced association-making is what we call ‘thought’, and the executive metaorganization of proliferating modularity in cognition is what we refer to as ‘self’.
The process of thinking seems firmly attached to the nervous system and principally brain matter. Cognitive configuring involved enhances the mind’s representation of environments, increasing the quantity and duration of phenomenal and physiological particulars that stimulus/response can confect and coordinate amongst at a given time, essentially diversifying and prolonging memory and its utilization in conjunction with less hardwired, more rewritable neuromaterial types of tissue.
The mind evolved a means for exerting control over which of its brain regions and nervous system components are active at a given time, what is approximately referred to as the ‘self’. This is the source of basic intentionality, found throughout the animal kingdom. While lacking command of most mental activities, such as vision, hearing, startling or noticing, which are all mostly unconscious, we can rapidly bring collections of these unconscious factors into synchronous alignments at will, a sort of mode-selection phenomenon generating overall dispositions via executive mechanism. These amalgamating states of intentionality are not freely chosen to the point of independence from context, for they get sculpted over time with conditioning as well as directed by instantaneous cues from both environments and the unconscious mind itself, but we can readily carry out feats such as waking ourselves up, suppressing affect in order to focus while we reason, purposely blocking out external stimuli, as well as adopting various social and communicative strategies. Introspective meditators can even learn to radically regulate their states of awareness with experience, which shows up on an EEG machine as crisp transitions between brain wave shapes.
Whether association-making thought or a mode-selecting self were the originating feature that initialized evolution of the conscious mind is a bit of a chicken and egg problem; which came first? It is not clear at this stage of science if the question can even be answered, but defining ‘self’ in terms of its anthromorphic form, as a phenomenon of introspective reflection, leads us to suspect that at least from this perspective, associational thinking was egg to the self’s chicken, an incredibly ancient type of cognitive modulization which preceded humanlike self-awareness and contributed to its construction. Regardless, it is clear that the interaction of thinking with self tended towards synergy in many lineages over vast spans of time, hundreds of millions of years, built up into more elaborate forms of pattern processing and intentionality.
The main mutative innovation in the realm of intention was an ability to concentrate, sustaining attentive states for longer timespans, allowing keener observation of both environments as well as the organism’s own phenomenal mind, a selection mechanism for associational thinking to become more astute. Thought simultaneously evolved towards greater apprehension of order amongst patterns until protological awareness had developed, an intuitive knack for grasping some prevalent kinds of cause and effect, fitting phenomenal interactivities into a kind of conceptualizing chassis of which the simplest qualities are those enumerated as basics of formal logic: negation (not p), conjunction (both p and q), disjunction (either p or q), conditional (if p then q), and similar notions. Association-making aptitude as logic’s precursor, together with better focus, capacitated problem-solving creativity that is a hallmark of species with the most elite technical thinking, a suite of traits we single out as elementary intelligence.
So the persistence of basic identity or "self" from moment to moment functions as a binding agent coordinating and directing the mind's modules. If you want any of the peripheral ideas, give my blog a look at
philosophyofhumanism.com . This quote is drawn from the post
Humanity and the Evolutionary Phenomenology of Preanthromorphic Cognition. A few additional posts, particularly those pertaining to perception and conception, explain further phenomena of consciousness.