As a primary task it should not be difficult to promote the thesis that understanding how and why consciousness emerged entails understanding the evolution of a hierarchy of systems-constructs. Why? If not irrefutable, it is at least commonly held and accepted that:
i) systems are self-organising and self-sustaining; ii) over the evolutionary history of the universe, systems-structures have increased in complexity and sophistication; and iii) while there has evolved physical complexities, so too has there evolved (on earth at least) increasingly sophisticated characteristics that we broadly associate with consciousness.
All things being equal, the three points above require us to Read on. . .