Origin of consciousness: the missing principles.
The genius of Darwin lay in the fact that he tried to bring together the miscellaneous facts known at that time about living forms on the earth, and made an amalgam of them to come to a plausible story behind speciation based on the key concepts of random mutation and natural selection.
Since then, it took some time for the theoretical and empirical basis of evolution to be solidified and detailed. It was not until 1900 that the works of Gregor Mendel were rediscovered. The classical genetics of Dorosphila melanogaster by Thomas Hunt Morgan was developed, followed by the genetical theory of natural selection by Ronald Aymer Fisher. Even at the time of the modern evolutionary synthesis ("neo-Darwinism") in the 1930s and 1940s, the physical foundations of evolution were not known. The discovery of the double helical structure of DNA by James Watson and Francis Crick in 1953 led to the final and definitive verification of the principles laid by Darwin almost 100 years before.
As to the origin of consciousness, we may be in a similar state of affairs as that which faced Charles Darwin at the time of the conception of the ideas described in the Origin of Species. It is not necessary or possible, at this stage, to work out all the details how and why consciousness arises from the activities of billions of neurons in the brain.
Some possible theories clearly need some time for maturation. For example, many people suspect that quantum mechanical effects (understood in the most general and possibly an extended sense) have something to do with the non-locality apparent in conscious experience. However, as it stands, it is extremely difficult to coin any sensible theory of quantum consciousness at this stage, linking the nanophenomena involving the biomolecuels with the macroscopic activities of neurons that are apparently responsible for producing the intriguing phenomenology we call consciousness (refer to the neuron doctrine in later entries).
In the face of the reality of the difficulties involved, the best we can do, at this stage, is probably something similar to what Charles Darwin did in 1859. We may hope to lay down some yet-to-be-discovered fundamental principles behind the origin of consciousness, which have enough explanatory power to tackle, for example, the zombie issue or the binding problem. The following consolidation and detailed theoretical development towards a final theory of the origin of consciousness might take another 100 years, just like it took almost 100 years for the theoretical possibility of genetic evolution to be materialized in the form of DNA.
The question, then, is this. Where can we find the fundamental principles behind the origin of consciousness, some key concepts that correspond to "random mutation" or "natural selection" that were so instrumental in the Darwinian theory of the origin of species?