In 1976, Francis Crick arrived at the Salk Institute in La Jolla, California, overlooking a Pacific Shangri-La with cotton candy skies and a beaming, blue-green sea. He had already won the Nobel Prize for co-discovering the double-helix structure of DNA, revealing the basis of life to be a purely physical, not a mystical, process. He hoped to do the same thing for consciousness. If matter was strange enough to explain a creature's life code, he thought, maybe it's strange enough to explain a creature's mind, too. For something that everybody walks around with everyday, consciousness wouldn't seem to be as immense a puzzle as the origin of the universe.

In mammals this incorporates the cortex, the hippocampus, the claustrum, the amygdala, the basal ganglia, and the olfactory bulb. Convergent evolution results in analogous characters with similar appearances or functions, although these were not present in the last common ancestor of the two lineages. Most species are characterized by a high brain-to-body mass ratio, ecological flexibility, and a complex social life, featuring long-term partnerships and dynamic groups structured by social relationships. The term derives from the Greek word hodos which means'road'. Each layer is constituted by distinctive cell populations with unique connectivity patterns. At first glance, neocortical lamination looks uniform (and is therefore sometimes called'isocortical').

If consciousness is not algorithmic, then how is it created? Obviously we do not know. Scientists who are interested in subjective awareness study the objective facts of neurology and behaviour and have shed new light on how our nervous system processes and discriminates among stimuli. But although such sensory mechanisms are necessary for consciousness, it does not help to unlock the secrets of the cognitive mind as we can perceive things and respond to them without being aware of them. A prime example of this is sleepwalking.